WorldWideScience

Sample records for composite amperometric sensors

  1. Polymer based amperometric hydrogen sensor

    International Nuclear Information System (INIS)

    Ramesh, C.; Periaswami, G.; Mathews, C.K.; Shankar, P.

    1993-01-01

    A polymer based amperometric hydrogen sensor has been developed for measuring hydrogen in argon. Polyvinyl alcohol-phosphoric acid serves as the solid electrolyte for proton conduction. The electrolyte is sandwiched between two palladium films. Short circuit current between the film at room temperature is measured and is found to be linearly dependant on hydrogen concentration in argon to which one side of the film is exposed. The other side is exposed to air. The response time of the sensor is found to be improved on application of a D.C. potential of 200 mV in series. The sensitivity of the sensor is in ppm range. This may be sufficient for monitoring cover gas hydrogen in FBTR. Work is underway to improve the long-term stability of the sensor. (author)

  2. Application of Ionic Liquids in Amperometric Gas Sensors.

    Science.gov (United States)

    Gębicki, Jacek; Kloskowski, Adam; Chrzanowski, Wojciech; Stepnowski, Piotr; Namiesnik, Jacek

    2016-01-01

    This article presents an analysis of available literature data on metrological parameters of the amperometric gas sensors containing ionic liquids as an electrolyte. Four mechanism types of signal generation in amperometric sensors with ionic liquid are described. Moreover, this article describes the influence of selected physico-chemical properties of the ionic liquids on the metrological parameters of these sensors. Some metrological parameters are also compared for amperometric sensors with GDE and SPE electrodes and with ionic liquids for selected analytes.

  3. Thick-film textile-based amperometric sensors and biosensors.

    Science.gov (United States)

    Yang, Yang-Li; Chuang, Min-Chieh; Lou, Shyh-Liang; Wang, Joseph

    2010-06-01

    The incorporation of amperometric sensors into clothing through direct screen-printing onto the textile substrate is described. Particular attention is given to electrochemical sensors printed directly on the elastic waist of underwear that offers tight direct contact with the skin. The textile-based printed carbon electrodes have a well-defined appearance with relatively smooth conductor edges and no apparent defects or cracks. Convenient voltammetric and chronoamperometric measurements of 0-3 mM ferrocyanide, 0-25 mM hydrogen peroxide, and 0-100 muM NADH have been documented. The favorable electrochemical behavior is maintained under folding or stretching stress, relevant to the deformation of clothing. The electrochemical performance and tolerance to mechanical stress are influenced by the physical characteristics of the textile substrate. The results indicate the potential of textile-based screen-printed amperometric sensors for future healthcare, sport or military applications. Such future applications would benefit from tailoring the ink composition and printing conditions to meet the specific requirements of the textile substrate.

  4. Amperometric sensor for carbon dioxide: design, characteristics, and perforance

    International Nuclear Information System (INIS)

    Evans, J.; Pletcher, D.; Warburton, P.R.G.; Gibbs, T.K.

    1989-01-01

    A new sensor for atmospheric carbon dioxide is described. It is an amperometric device based on a porous electrode in a three-electrode cell and the electrolyte is a copper diamine complex in aqueous potassium chloride. The platinum cathode, held at constant potential, is used to detect the formation of Cu 2+ following the change in the pH of the solution when the sensor is exposed to an atmosphere containing carbon dioxide. The sensor described is designed to monitor carbon dioxide concentrations in the range 0-5%, although with some modifications, other ranges would be possible. The response to a change in the carbon dioxide content of the atmosphere is rapid (about 10s) while the monitored current is strongly (but nonlinearly) dependent on carbon dioxide concentration. Unlike other amperometric devices for carbon dioxide, there is no interference from oxygen although other acid gases would lead to an interfering response

  5. Integration of amperometric sensors for microchip capillary electrophoresis application

    International Nuclear Information System (INIS)

    Dicorato, F; Moore, E; Glennon, J

    2011-01-01

    Capillary electrophoresis is a technique for the separation and analysis of chemical compounds. Techniques adopted from the microchip technology knowledge have led to recent developments of electrophoresis system with integration on microchip. Microchip Capillary Electrophoresis (μCE) systems offer a series of advantages as easy integration for Lab-on-a-chip applications, high performance, portability, speed, minimal solvent and sample requirements. A new technological challenge aims at the development of an economic modular microchip capillary electrophoresis systems using separable and independent units concerning the sensor. In this project we worked on the development of an interchangeable amperometric sensor in order to provide a solution to such electrode passivation and facilitating the use of tailored sensors for specific analyte detection besides. Fluidic chips have been machined from cyclic olefin polymer pallets (Zeonor) using a micro-injection molding machine.

  6. Integration of amperometric sensors for microchip capillary electrophoresis application

    Energy Technology Data Exchange (ETDEWEB)

    Dicorato, F; Moore, E [Life Sciences Interface Group, Tyndall National Institute, Lee Maltings, Dyke Parade, Cork (Ireland); Glennon, J, E-mail: eric.moore@tyndall.ie [Chemistry Department, University College Cork, College Road, Cork (Ireland)

    2011-08-17

    Capillary electrophoresis is a technique for the separation and analysis of chemical compounds. Techniques adopted from the microchip technology knowledge have led to recent developments of electrophoresis system with integration on microchip. Microchip Capillary Electrophoresis ({mu}CE) systems offer a series of advantages as easy integration for Lab-on-a-chip applications, high performance, portability, speed, minimal solvent and sample requirements. A new technological challenge aims at the development of an economic modular microchip capillary electrophoresis systems using separable and independent units concerning the sensor. In this project we worked on the development of an interchangeable amperometric sensor in order to provide a solution to such electrode passivation and facilitating the use of tailored sensors for specific analyte detection besides. Fluidic chips have been machined from cyclic olefin polymer pallets (Zeonor) using a micro-injection molding machine.

  7. A flow-type amperometric sensor in immunoenzyme analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ivnitskii, D.M.; Aronbaev, D.M.; Kashkin, A.P.; Meringova, L.F.; Yulaev, M.F.

    1986-06-01

    A portable flow-type amperometric sensor has been made for the immunoenzyme determination of L-asparaginase. The authors show it is possible to determine peroxidase (the marker enzyme) by this method over the concentration range 1.10/sup -11/-4.10/sup -10/ M. The limit of detection for L-asparaginase is 1.8.10/sup -10/ M, which corresponds to clinically significant enzyme concentrations. Various modifications of immunoenzyme analysis (IEA) are used in clinical and research laboratories, and have contributed to diagnosis as regards antigens and serum antibodies. The sensor used here uses the electrical reduction of the molecular ion at the surface of thr measurement electrode. The electrochemical reaction is preceded by a competing antigen-antibody reaction and by the peroxidase oxidation of the iodide in the depressions.

  8. A Printed Organic Circuit System for Wearable Amperometric Electrochemical Sensors.

    Science.gov (United States)

    Shiwaku, Rei; Matsui, Hiroyuki; Nagamine, Kuniaki; Uematsu, Mayu; Mano, Taisei; Maruyama, Yuki; Nomura, Ayako; Tsuchiya, Kazuhiko; Hayasaka, Kazuma; Takeda, Yasunori; Fukuda, Takashi; Kumaki, Daisuke; Tokito, Shizuo

    2018-04-23

    Wearable sensor device technologies, which enable continuous monitoring of biological information from the human body, are promising in the fields of sports, healthcare, and medical applications. Further thinness, light weight, flexibility and low-cost are significant requirements for making the devices attachable onto human tissues or clothes like a patch. Here we demonstrate a flexible and printed circuit system consisting of an enzyme-based amperometric sensor, feedback control and amplification circuits based on organic thin-film transistors. The feedback control and amplification circuits based on pseudo-CMOS inverters were successfuly integrated by printing methods on a plastic film. This simple system worked very well like a potentiostat for electrochemical measurements, and enabled the quantitative and real-time measurement of lactate concentration with high sensitivity of 1 V/mM and a short response time of a hundred seconds.

  9. Measurement system for nitrous oxide based on amperometric gas sensor

    Science.gov (United States)

    Siswoyo, S.; Persaud, K. C.; Phillips, V. R.; Sneath, R.

    2017-03-01

    It has been well known that nitrous oxide is an important greenhouse gas, so monitoring and control of its concentration and emission is very important. In this work a nitrous oxide measurement system has been developed consisting of an amperometric sensor and an appropriate lab-made potentiostat that capable measuring picoampere current ranges. The sensor was constructed using a gold microelectrode as working electrode surrounded by a silver wire as quasi reference electrode, with tetraethyl ammonium perchlorate and dimethylsulphoxide as supporting electrolyte and solvent respectively. The lab-made potentiostat was built incorporating a transimpedance amplifier capable of picoampere measurements. This also incorporated a microcontroller based data acquisition system, controlled by a host personal computer using a dedicated computer program. The system was capable of detecting N2O concentrations down to 0.07 % v/v.

  10. Pencil graphite leads as simple amperometric sensors for microchip electrophoresis.

    Science.gov (United States)

    Natiele Tiago da Silva, Eiva; Marques Petroni, Jacqueline; Gabriel Lucca, Bruno; Souza Ferreira, Valdir

    2017-11-01

    In this work we demonstrate, for the first time, the use of inexpensive commercial pencil graphite leads as simple amperometric sensors for microchip electrophoresis. A PDMS support containing one channel was fabricated through soft lithography and sanded pencil graphite leads were inserted into this channel to be used as working electrodes. The electrochemical and morphological characterization of the sensor was carried out. The graphite electrode was coupled to PDMS microchips in end-channel configuration and electrophoretic experiments were performed using nitrite and ascorbate as probe analytes. The analytes were successfully separated and detected in well-defined peaks with satisfactory resolution using the microfluidic platform proposed. The repeatability of the pencil graphite electrode was satisfactory (RSD values of 1.6% for nitrite and 12.3% for ascorbate, regarding the peak currents) and its lifetime was estimated to be ca. 700 electrophoretic runs over a cost of ca. $ 0.05 per electrode. The limits of detection achieved with this system were 2.8 μM for nitrite and 5.7 μM for ascorbate. For proof of principle, the pencil graphite electrode was employed for the real analysis of well water samples and nitrite was successfully quantified at levels below its maximum contaminant level established in Brazil and US. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. A flow-through amperometric sensor based on dialysis tubing and free enzyme reactors

    NARCIS (Netherlands)

    Bohm, S.; Pijanowska, D.G.; Pijanowska, D.; Olthuis, Wouter; Bergveld, Piet

    2001-01-01

    A generic flow-through amperometric microenzyme sensor is described, which is based on semi-permeable dialysis tubing carrying the sample to be analyzed. This tubing (300 μm OD) is led through a small cavity, containing the working and reference electrode. By filling this cavity with a few μl of an

  12. Amperometric Formaldehyde Sensor Based on a Pd Nanocrystal Modified C/Co2P Electrode

    Directory of Open Access Journals (Sweden)

    Huan Wang

    2017-01-01

    Full Text Available Ultrafine Pd nanocrystals were grown on the cobalt phosphide (Co2P decorated Vulcan XC-72 carbon (C/Co2P, which is realized by first implementing the corresponding metal precursor and then the further chemical reduction process. The as-synthesized C/Co2P/Pd composite was further constructed to form a gas permeable electrode. This electrode can be applied for formaldehyde (HCHO detection. The results demonstrate that the Co2P nanocrystal can significantly improve the sensing performance of the C/Co2P/Pd electrode for catalytic oxidation of HCHO, which is considered to be attributed to the effective electron transfer from Co2P to Pd in the C/Co2P/Pd composites. Furthermore, the assembled C/Co2P/Pd sensor exhibits high sensitivity of 617 nA/ppm and good selectivity toward various interfering gases such as NO2, NO, SO2, CO2, and CO. It also shows the excellent linear response that the correlation coefficient is 0.994 in the concentration range of 1–10 ppm. Therefore, the proposed cost-effective C/Co2P/Pd nanocomposite, which owns advantages such as high activity and good stability, has the potential to be applied as an effective electrocatalyst for amperometric HCHO detection.

  13. Amperometric Acetylcholinesterase Biosensor Based on Multilayer Multiwall Carbon Nanotubes-chitosan Composite

    Directory of Open Access Journals (Sweden)

    Xia SUN

    2011-11-01

    Full Text Available A simple method for immobilization of acetylcholinesterase (AChE onto the glassy carbon electrode (GCE modified with five layers of multiwall carbon nanotubes (MWNTs-chitosan (CHIT composite was proposed, and thus a fast, sensitive and stable amperometric sensor for quantitative determination of pesticides was developed. Five layers of MWNTs-CHIT promoted electron transfer reactions at a lower potential and catalyzed the electro-oxidation of thiocholine, thus, it improved the detection sensitivity of biosensor. Based on the inhibition of pesticides to the enzymatic activity of AChE, using carbofuran as a model compound, under optimal conditions, the inhibition of carbofuran was proportional to its concentration in two ranges, from 5×10-4 to 7.5 μg/mL and 7.5 to 20 μg/mL with a detection limit of 1×10-4 μg/mL. The constructed biosensor showed prominent characteristics and performances such as good precision, acceptable stability, fast response and low detection limit, which provided a new promising tool for pesticide analysis.

  14. Electrochemical formation of InP porous nanostructures and its application to amperometric chemical sensors

    International Nuclear Information System (INIS)

    Sato, Taketomo; Mizohata, Akinori; Fujino, Toshiyuki; Hashizume, Tamotsu

    2008-01-01

    In this paper, we report the electrochemical formation of the InP porous nanostructures and their feasibility for the application to the amperometric chemical sensors. Our two step electrochemical process consists of the pore formation on a (001) n-type InP substrate and the subsequent etching of pore walls caused by changing the polarity of the InP electrode in a HCl-based electrolyte. By applying the anodic bias to the InP electrode, the high-density array of uniform nanopores was formed on the surface. Next, the cathodic bias was applied to the porous sample to reduce the wall thickness by cathodic decomposition of InP, where the thickness of InP nanowall decreased uniformly along the entire depth of the porous layer. From the amperometric measurements of the porous electrode, it was found that the electrocatalytic activity was much higher than that of the planar electrode. Furthermore, the current sensitivity for the H 2 O 2 detection was much enhanced after the cathodic decomposition process. The InP porous nanostructure formed by the present process is one of the promising structures for the application to the semiconductor-based bio/chemical sensors. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Development of amperometric L-tyrosine sensor based on Fe-doped hydroxyapatite nanoparticles

    International Nuclear Information System (INIS)

    Kanchana, P.; Lavanya, N.; Sekar, C.

    2014-01-01

    A novel biosensor based on Fe-doped hydroxyapatite (Fe-HA) nanoparticles and tyrosinase has been developed for the detection of L-tyrosine. Nanostructured Fe-HA was synthesized by a simple microwave irradiation method, and its phase formation, morphology and magnetic property were examined by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). Electrochemical performance of the nano Fe-HA/tyrosinase modified glassy carbon electrode (GCE) for detection of L-tyrosine was investigated by cyclic voltammetry (CV) and amperometric methods. The fabricated biosensor exhibited a linear response to L-tyrosine over a wide concentration range of 1.0 × 10 −7 to 1.0 × 10 −5 M with a detection limit of 245 nM at pH 7.0. In addition, the fabricated sensor showed an excellent selectivity, good reproducibility, long-term stability and anti-interference towards the determination of L-tyrosine. - Highlights: • A novel amperometric L-tyrosine biosensor has been fabricated using nanostructured Fe-HA. • The fabricated sensor exhibits a wide linear range, good stability and high reproducibility. • Fe-HA assists microenvironment and direct electron transfer between enzyme and electrode surface. • The nano Fe-HA and electrode fabrication procedure are simple and less expensive

  16. Real-Time Telemetry System for Amperometric and Potentiometric Electrochemical Sensors

    Directory of Open Access Journals (Sweden)

    Ching-Hsing Luo

    2011-09-01

    Full Text Available A real-time telemetry system, which consists of readout circuits, an analog-to-digital converter (ADC, a microcontroller unit (MCU, a graphical user interface (GUI, and a radio frequency (RF transceiver, is proposed for amperometric and potentiometric electrochemical sensors. By integrating the proposed system with the electrochemical sensors, analyte detection can be conveniently performed. The data is displayed in real-time on a GUI and optionally uploaded to a database via the Internet, allowing it to be accessed remotely. An MCU was implemented using a field programmable gate array (FPGA to filter noise, transmit data, and provide control over peripheral devices to reduce power consumption, which in sleep mode is 70 mW lower than in operating mode. The readout circuits, which were implemented in the TSMC 0.18-μm CMOS process, include a potentiostat and an instrumentation amplifier (IA. The measurement results show that the proposed potentiostat has a detectable current range of 1 nA to 100 μA, and linearity with an R2 value of 0.99998 in each measured current range. The proposed IA has a common-mode rejection ratio (CMRR greater than 90 dB. The proposed system was integrated with a potentiometric pH sensor and an amperometric nitrite sensor for in vitro experiments. The proposed system has high linearity (an R2 value greater than 0.99 was obtained in each experiment, a small size of 5.6 cm × 8.7 cm, high portability, and high integration.

  17. A Differential Electrochemical Readout ASIC With Heterogeneous Integration of Bio-Nano Sensors for Amperometric Sensing.

    Science.gov (United States)

    Ghoreishizadeh, Sara S; Taurino, Irene; De Micheli, Giovanni; Carrara, Sandro; Georgiou, Pantelis

    2017-10-01

    A monolithic biosensing platform is presented for miniaturized amperometric electrochemical sensing in CMOS. The system consists of a fully integrated current readout circuit for differential current measurement as well as on-die sensors developed by growing platinum nanostructures (Pt-nanoS) on top of electrodes implemented with the top metal layer. The circuit is based on the switch-capacitor technique and includes pseudodifferential integrators for concurrent sampling of the differential sensor currents. The circuit further includes a differential to single converter and a programmable gain amplifier prior to an ADC. The system is fabricated in [Formula: see text] technology and measures current within [Formula: see text] with minimum input-referred noise of [Formula: see text] and consumes [Formula: see text] from a [Formula: see text] supply. Differential sensing for nanostructured sensors is proposed to build highly sensitive and offset-free sensors for metabolite detection. This is successfully tested for bio-nano-sensors for the measurement of glucose in submilli molar concentrations with the proposed readout IC. The on-die electrodes are nanostructured and cyclic voltammetry run successfully through the readout IC to demonstrate detection of [Formula: see text].

  18. Amperometric Enzyme-based Gas Sensor for Formaldehyde: Impact of Possible Interferences

    Directory of Open Access Journals (Sweden)

    Ralf Moos

    2007-02-01

    Full Text Available In this work, cross-sensitivities and environmental influences on the sensitivityand the functionality of an enzyme-based amperometric sensor system for the directdetection of formaldehyde from the gas phase are studied. The sensor shows a linearresponse curve for formaldehyde in the tested range (0 - 15 vppm with a sensitivity of1.9 μA/ppm and a detection limit of about 130 ppb. Cross-sensitivities by environmentalgases like CO2, CO, NO, H2, and vapors of organic solvents like methanol and ethanol areevaluated as well as temperature and humidity influences on the sensor system. The sensorshowed neither significant signal to CO, H2, methanol or ethanol nor to variations in thehumidity of the test gas. As expected, temperature variations had the biggest influence onthe sensor sensitivity with variations in the sensor signal of up to 10 % of the signal for 5vppm CH2O in the range of 25 - 30 °C.

  19. A CMOS analog front-end chip for amperometric electrochemical sensors

    International Nuclear Information System (INIS)

    Li Zhichao; Chen Min; Xiao Jingbo; Chen Jie; Liu Yuntao

    2015-01-01

    This paper reports a complimentary metal–oxide–semiconductor (CMOS) analog front-end chip for amperometric electrochemical sensors. The chip includes a digital configuration circuit, which can communicate with an external microcontroller by employing an I 2 C interface bus, and thus is highly programmable. Digital correlative double samples technique and an incremental sigma–delta analog to digital converter (Σ–Δ ADC) are employed to achieve a new proposed system architecture with double samples. The chip has been fabricated in a standard 0.18-μm CMOS process with high-precision and high-linearity performance occupying an area of 1.3 × 1.9 mm 2 . Sample solutions with various phosphate concentrations have been detected with a step concentration of 0.01 mg/L. (paper)

  20. Amperometric Metronidazole Sensor Based on the Supermolecular Recognition by Metalloporphyrin Incorporated In Carbon Paste Electrode

    Directory of Open Access Journals (Sweden)

    Ru-Qin Yu

    2003-03-01

    Full Text Available An amperometric metronidazole (MTZ sensor using a glycosylated metalloporphyrin as a recognition element, which was incorporated in a carbon paste electrode, is reported. For the preparation of a MTZ-sensitive active material, 5, 10, 15, 20-tetrakis [2-(2, 3, 4, 6-tetraacetyl-β-D-glucopyranosyl-1-O-phenyl]porphyrin (T(oglu PPH2 and its Mn(III complex MnT(o-gluPPCl were synthesized from the reaction of pyrrole with ortho-acetylglycosylated benzaldehyde by Lindsay’s method. The MnT(oglu PPCl-modified electrode showed excellent selectivity toward MTZ with respect to a number of interferents and exhibited stable response. The calibration graph obtained with the proposed sensor was linear over the range of 2.9×10-3-5.8×10-8 M/L, with a detection limit of 5.8×10-8 M/L for MTZ. Cyclic voltammetric measurements indicated that MnT(oglu PPCl included in graphite-epoxy resin matrices could efficiently mediate electron transfer from the base electrode to MTZ causing a decrease of reduction potential for MTZ detection. The sensor could be regenerated by simply polishing with an alumina paper, with an excellent reproducibility (RSD=1.6%. The experimental conditions such as pH and applied working potential were optimized. The prepared sensor is applied for the determination of MTZ in pharmaceutical preparations and the results agreed with the values obtained by the pharmacopoeia method.

  1. Amperometric nitrite sensor based on a glassy carbon electrode modified with multi-walled carbon nanotubes and poly(toluidine blue)

    International Nuclear Information System (INIS)

    Dai, Juan; Deng, Fei; He, Shuang; Deng, Dongli; Yuan, Yali; Zhang, Jinzhong

    2016-01-01

    An amperometric nitrite sensor modified with multi-walled carbon nanotubes (MWCNTs) and poly(toluidine blue) (PTB) on glassy carbon electrode was constructed. The surface morphology of the composite- modified electrode was characterized by scanning electron microscopy, and the electrochemical response behavior and electrocatalytic oxidation mechanism of nitrite were investigated by cyclic voltammetry. The high surface-to-volume ratio of MWCNTs and PTB brings the electrochemical sensing unit and nitrite in full contact. This renders the electrochemical response extremely sensitive to nitrite. Under the optimal measurement conditions and a working voltage of 0.73 V (vs. SCE), a linear relationship is obtained between the oxidation peak current and nitrite concentration in the range of 39 nM–1.1 mM, and the limit of detection is lowered to 19 nM (at an S/N ratio of 3). The sensor was successfully applied to the determination of nitrite in greenhouse soils. (author)

  2. Amperometric Gas Sensors as a Low Cost Emerging Technology Platform for Air Quality Monitoring Applications: A Review.

    Science.gov (United States)

    Baron, Ronan; Saffell, John

    2017-11-22

    This review examines the use of amperometric electrochemical gas sensors for monitoring inorganic gases that affect urban air quality. First, we consider amperometric gas sensor technology including its development toward specifically designed air quality sensors. We then review recent academic and research organizations' studies where this technology has been trialed for air quality monitoring applications: early studies showed the potential of electrochemical gas sensors when colocated with reference Air Quality Monitoring (AQM) stations. Spatially dense networks with fast temporal resolution provide information not available from sparse AQMs with longer recording intervals. We review how this technology is being offered as commercial urban air quality networks and consider the remaining challenges. Sensors must be sensitive, selective, and stable; air quality monitors/nodes must be electronically and mechanically well designed. Data correction is required and models with differing levels of sophistication are being designed. Data analysis and validation is possibly the biggest remaining hurdle needed to deliver reliable concentration readings. Finally, this review also considers the roles of companies, urban infrastructure requirements, and public research in the development of this technology.

  3. Nafion/lead nitroprusside nanoparticles modified carbon ceramic electrode as a novel amperometric sensor for L-cysteine.

    Science.gov (United States)

    Razmi, H; Heidari, H

    2009-05-01

    This work describes the electrochemical and electrocatalytic properties of carbon ceramic electrode (CCE) modified with lead nitroprusside (PbNP) nanoparticles as a new electrocatalyst material. The structure of deposited film on the CCE was characterized by energy dispersive X-ray (EDX), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM). The cyclic voltammogram (CV) of the PbNP modified CCE showed two well-defined redox couples due to [Fe(CN)5NO](3-)/[Fe(CN)5NO](2-) and Pb(IV)/Pb(II) redox reactions. The modified electrode showed electrocatalytic activity toward the oxidation of L-cysteine and was used as an amperometric sensor. Also, to reduce the fouling effect of L-cysteine and its oxidation products on the modified electrode, a thin film of Nafion was coated on the electrode surface. The sensor response was linearly changed with L-cysteine concentration in the range of 1 x 10(-6) to 6.72 x 10(-5)mol L(-1) with a detection limit (signal/noise ratio [S/N]=3) of 0.46 microM. The sensor sensitivity was 0.17 microA (microM)(-1), and some important advantages such as simple preparation, fast response, good stability, interference-free signals, antifouling properties, and reproducibility of the sensor for amperometric determination of L-cysteine were achieved.

  4. Covalent modification of multiwalled carbon nanotubes with neutral red for the fabrication of an amperometric hydrogen peroxide sensor

    International Nuclear Information System (INIS)

    Jeykumari, D R Shobha; Narayanan, S Sriman

    2007-01-01

    The nanoscale dimensions, graphitic surface chemistry and electronic properties of multiwalled carbon nanotubes (MWNTs) make them an ideal candidate for chemical and biochemical sensing. In this paper we explore a covalent chemical strategy for functionalization of MWNTs with neutral red through carbodiimide coupling between the primary amine of neutral red and carboxyl groups of the carbon nanotubes. The construction of an amperometric sensor was achieved by abrasive immobilization of the functionalized MWNTs on a paraffin impregnated graphite electrode followed by a coating of a thin film of nafion. The neutral red functionalized MWNTs were characterized by spectroscopic and electroanalytical methods. From the voltammetric studies, MWNTs were found to exhibit a higher accessible surface area in electrochemical reactions. The modified electrode exhibited stable electrocatalytic activity toward hydrogen peroxide reduction in a wide potential range. A significant decrease in overvoltage for the reduction of hydrogen peroxide, as well as a dramatic increase in the peak currents in comparison with a bare graphite electrode were observed. Such an ability of neutral red functionalized carbon nanotubes to promote the hydrogen peroxide electron transfer reaction with a short response time (<4 s) and long-term stability, a low detection limit, an extended linear concentration range and a high sensitivity suggest great promise for dehydrogenase and oxidase based amperometric biosensors

  5. Covalent modification of multiwalled carbon nanotubes with neutral red for the fabrication of an amperometric hydrogen peroxide sensor

    Energy Technology Data Exchange (ETDEWEB)

    Jeykumari, D R Shobha; Narayanan, S Sriman [Department of Analytical Chemistry, School of Chemical Sciences, University of Madras, Guindy Campus, Chennai-600 025 (India)

    2007-03-28

    The nanoscale dimensions, graphitic surface chemistry and electronic properties of multiwalled carbon nanotubes (MWNTs) make them an ideal candidate for chemical and biochemical sensing. In this paper we explore a covalent chemical strategy for functionalization of MWNTs with neutral red through carbodiimide coupling between the primary amine of neutral red and carboxyl groups of the carbon nanotubes. The construction of an amperometric sensor was achieved by abrasive immobilization of the functionalized MWNTs on a paraffin impregnated graphite electrode followed by a coating of a thin film of nafion. The neutral red functionalized MWNTs were characterized by spectroscopic and electroanalytical methods. From the voltammetric studies, MWNTs were found to exhibit a higher accessible surface area in electrochemical reactions. The modified electrode exhibited stable electrocatalytic activity toward hydrogen peroxide reduction in a wide potential range. A significant decrease in overvoltage for the reduction of hydrogen peroxide, as well as a dramatic increase in the peak currents in comparison with a bare graphite electrode were observed. Such an ability of neutral red functionalized carbon nanotubes to promote the hydrogen peroxide electron transfer reaction with a short response time (<4 s) and long-term stability, a low detection limit, an extended linear concentration range and a high sensitivity suggest great promise for dehydrogenase and oxidase based amperometric biosensors.

  6. Amperometric sensor for detection of bisphenol A using a pencil graphite electrode modified with polyaniline nanorods and multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    Poorahong, S.; Thammakhet, C.; Numnuam, A.; Kanatharana, P.; Thavarungkul, P.; Limbut, W.

    2012-01-01

    We report on a simple and highly sensitive amperometric method for the determination of bisphenol A (BPA) using pencil graphite electrodes modified with polyaniline nanorods and multiwalled carbon nanotubes. The modified electrodes display enhanced electroactivity for the oxidation of BPA compared to the unmodified pencil graphite electrode. Under optimized conditions, the sensor has a linear response to BPA in the 1. 0 and 400 μM concentration range, with a limit of detection of 10 nM (at S/N = 3). The modified electrode also has a remarkably stable response, and up to 95 injections are possible with a relative standard deviation of 4. 2% at 100 μM of BPA. Recoveries range from 86 to 102% for boiling water spiked with BPA from four brands of baby bottles. (author)

  7. Surface modification of amine-functionalised graphite for preparation of cobalt hexacyanoferrate (CoHCF)-modified electrode: an amperometric sensor for determination of butylated hydroxyanisole (BHA).

    Science.gov (United States)

    Prabakar, S J Richard; Narayanan, S Sriman

    2006-12-01

    A cobalt hexacyanoferrate (CoHCF)-modified graphite paraffin wax composite electrode was prepared by a new approach. An amine-functionalised graphite powder was used for the fabrication of the electrode. A functionalised graphite paraffin wax composite electrode was prepared and the surface of the electrode was modified with a thin film of CoHCF. Various parameters that influence the electrochemical behaviour of the modified electrode were studied by varying the background electrolytes, scan rates and pH. The modified electrode showed good electrocatalytic activity towards the oxidation of butylated hydroxyanisole (BHA) under optimal conditions and showed a linear response over the range from 7.9 x 10(-7) to 1.9 x 10(-4) M of BHA with a correlation coefficient of 0.9988. The limit of detection was 1.9 x 10(-7) M. Electrocatalytic oxidation of BHA was effective at the modified electrode at a significantly reduced potential and at a broader pH range. The utility of the modified electrode as an amperometric sensor for the determination of BHA in flow systems was evaluated by carrying out hydrodynamic and chronoamperometric experiments. The modified electrode showed very good stability and a longer shelf life. The modified electrode was applied for the determination of BHA in spiked samples of chewing gum and edible sunflower oil. The advantage of this method is the ease of electrode fabrication, good stability, longer shelf life, low cost and its diverse application for BHA determination.

  8. Synthesis of novel amperometric urea-sensor using hybrid synthesized NiO-NPs/GO modified GCE in aqueous solution of cetrimonium bromide.

    Science.gov (United States)

    Parsaee, Zohreh

    2018-06-01

    In this study NiO nanostructures were synthesized via combinational synthetic method (ultrasound-assisted biosynthesis) and immobilized on the glassy carbon electrode (GCE) as a highly sensitive and selective enzyme-less sensor for urea detection. NiO-NPs were fully characterized using SEM, EDX, XRD, BET, TGA, FT-IR, UV-vis and Raman methods which revealed the formation of NiO nanostructures in the form of cotton like porous material and crystalline in nature with the average size of 3.8 nm. GCE was modified with NiO-NPs in aqueous solution of cetrimonium bromide(CTAB). Highly adhesive NiO/CTAB/GO nanocomposite membrane has been formed on GCE by immersing NiO/CTAB modified GCE in GO suspension. CTAB has a major role in the production and immobilization of the nanocomposites on the GCE surface and the binding NiO nanoparticles on GO plates. In addition, CTAB/GO composition made a highly adhesive surface on the GCE. The resulting NiO/CTAB/GO/GCE contains potently sensitive to urea in aqueous environments. The response of as developed amperometric sensor was linear in the range of 100-1200 µM urea with R 2 value of 0.991 and limit of detection (LOD), 8 µM. The sensor responded negligibly to various interfering species like glucose, uric acid and ascorbic acid. This sensor was applied successfully for determining urea in real water samples such as mineral water, tap water and river water with acceptable recovery. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Development of sensitive amperometric hydrogen peroxide sensor using a CuNPs/MB/MWCNT-C_6_0-Cs-IL nanocomposite modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Roushani, Mahmoud; Bakyas, Kobra; Zare Dizajdizi, Behruz

    2016-01-01

    A sensitive hydrogen peroxide (H_2O_2) sensor was constructed based on copper nanoparticles/methylene blue/multiwall carbon nanotubes–fullerene–chitosan–ionic liquid (CuNPs/MB/MWCNTs–C_6_0–Cs–IL) nanocomposites. The MB/MWCNTs–C_6_0–Cs–IL and CuNPs were modified glassy carbon electrode (GCE) by the physical adsorption and electrodeposition of copper nitrate solution, respectively. The physical morphology and chemical composition of the surface of modified electrode was investigated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. The electrochemical properties of CuNPs/MB/MWCNTs–C_6_0–Cs–IL/GCE were investigated by cyclic voltammetry (CV) and amperometry techniques and the sensor exhibited remarkably strong electrocatalytic activities toward the reduction of hydrogen peroxide. The peak currents possess a linear relationship with the concentration of H_2O_2 in the range of 0.2 μM to 2.0 mM, and the detection limit is 55.0 nM (S/N = 3). In addition, the modified electrode was used to determine H_2O_2 concentration in human blood serum sample with satisfactory results. - Highlights: • CuNPs/MB/MWCNT-C_6_0-Cs-IL/GC electrode was constructed by layer-by-layer method. • The catalytic performance of the sensor was studied with the use of amperometric technique. • The constructed sensor showed enhanced electrocatalytic activity toward the reduction of H_2O_2. • The CuNPs/MB/MWCNT-C_6_0-Cs-IL/GC electrode demonstrated high stability for the detection of H_2O_2.

  10. Development of sensitive amperometric hydrogen peroxide sensor using a CuNPs/MB/MWCNT-C{sub 60}-Cs-IL nanocomposite modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Roushani, Mahmoud, E-mail: mahmoudroushani@yahoo.com; Bakyas, Kobra; Zare Dizajdizi, Behruz

    2016-07-01

    A sensitive hydrogen peroxide (H{sub 2}O{sub 2}) sensor was constructed based on copper nanoparticles/methylene blue/multiwall carbon nanotubes–fullerene–chitosan–ionic liquid (CuNPs/MB/MWCNTs–C{sub 60}–Cs–IL) nanocomposites. The MB/MWCNTs–C{sub 60}–Cs–IL and CuNPs were modified glassy carbon electrode (GCE) by the physical adsorption and electrodeposition of copper nitrate solution, respectively. The physical morphology and chemical composition of the surface of modified electrode was investigated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. The electrochemical properties of CuNPs/MB/MWCNTs–C{sub 60}–Cs–IL/GCE were investigated by cyclic voltammetry (CV) and amperometry techniques and the sensor exhibited remarkably strong electrocatalytic activities toward the reduction of hydrogen peroxide. The peak currents possess a linear relationship with the concentration of H{sub 2}O{sub 2} in the range of 0.2 μM to 2.0 mM, and the detection limit is 55.0 nM (S/N = 3). In addition, the modified electrode was used to determine H{sub 2}O{sub 2} concentration in human blood serum sample with satisfactory results. - Highlights: • CuNPs/MB/MWCNT-C{sub 60}-Cs-IL/GC electrode was constructed by layer-by-layer method. • The catalytic performance of the sensor was studied with the use of amperometric technique. • The constructed sensor showed enhanced electrocatalytic activity toward the reduction of H{sub 2}O{sub 2}. • The CuNPs/MB/MWCNT-C{sub 60}-Cs-IL/GC electrode demonstrated high stability for the detection of H{sub 2}O{sub 2}.

  11. Non-enzymatic amperometric sensor for hydrogen peroxide based on a biocomposite made from chitosan, hemoglobin, and silver nanoparticles

    International Nuclear Information System (INIS)

    Tian, L.; Feng, Y.; Qi, Y.; Wang, B.; Chen, Y.; Fu, X.

    2012-01-01

    We report on a novel non-enzymatic sensor for hydrogen peroxide (HP) that is based on a biocomposite made up from chitosan (CS), hemoglobin (Hb), and silver nanoparticles (AgNPs). The AgNPs were prepared in the presence of CS and glucose in an ultrasonic bath, and CS is found to act as a stabilizing agent. They were then combined with Hb and CS to construct a carbon paste biosensor. The resulting electrode gave a well-defined redox couple for Hb, with a formal potential of about -0.17 V (vs. SCE) at pH 6. 86 and exhibited a remarkable electrocatalytic activity for the reduction of HP. The sensor was used to detect HP by flow injection analysis, and a linear response is obtained in the 0. 08 to 250 μM concentration range. The detection limit is 0.05 μM (at S/N = 3). These characteristics, along with its long-term stability make the sensor highly promising for the amperometric determination of HP. (author)

  12. Amperometric NOx-sensor for Combustion Exhaust Gas Control. Studies on transport properties and catalytic activity of oxygen permeable ceramic membranes

    International Nuclear Information System (INIS)

    Romer, E.W.J.

    2001-01-01

    The aim of the research described in this thesis is the development of a mixed conducting oxide layer, which can be used as an oxygen permselective membrane in an amperometric NOx sensor. The sensor will be used in exhaust gas systems. The exhaust gas-producing engine will run in the lean mix mode. The preparation of this sensor is carried out using screen-printing technology, in which the different layers of the sensor are applied successively. Hereafter, a co-firing step is applied in which all layers are sintered together. This co-firing step imposes several demands on the selection of materials. The design specifications of the sensor further include requirements concerning the operating temperature, measurement range and overall stability. The operating temperature of the sensor varies between 700 and 850C, enabling measurement of NOx concentrations between 50 and 1200 ppm with a measurement accuracy of 10 ppm. Concerning the stability of the sensor, it must withstand the exhaust gas atmosphere containing, amongst others, smoke, acids, abrasive particles and sulphur. Because of the chosen lean-mix engine concept, in which the fuel/air mixture switches continuously between lean (excess oxygen) and fat (excess fuel) mixtures, the sensor must withstand alternately oxidising and reducing atmospheres. Besides, it should be resistant to thermal shock and show no cross-sensitivity of NOx with other exhaust gas constituents like oxygen and hydrocarbons. The response time should be short, typically less than 500 ms. Because of the application in combustion engines of cars, the operational lifetime should be longer than 10 years. Demands on the mixed conducting oxide layer include the following ones. The layer should show minimal catalytic activity towards NOx-reduction. The oxygen permeability must be larger than 6.22 10 -8 mol/cm 2 s at a layer thickness between 3-50 μm. Since the mixed conducting oxide layer is coated on the YSZ electrolyte embodiment, the two

  13. Novel amperometric sensor using metolcarb-imprinted film as the recognition element on a gold electrode and its application

    International Nuclear Information System (INIS)

    Pan Mingfei; Fang Guozhen; Liu Bing; Qian Kun; Wang Shuo

    2011-01-01

    A molecularly imprinted film is electrochemically synthesized on a gold electrode using cyclic voltammetry to electropolymerize o-aminothiophenol in the presence of metolcarb (MTMC). The mechanism of the imprinting process and a number of factors affecting the activity of the imprinted film are discussed and optimized. Scanning electron microscope observations and binding measurements have proved that an MTMC-imprinted film (with a thickness of nearly 100 nm) was formed on the surface of the gold electrode. The film exhibited high binding affinity and selectivity towards the template MTMC, as well as good penetrability, reproducibility and stability. A novel amperometry sensor using the imprinted film as recognition element was developed for MTMC determination in food samples. Under the experimental conditions, the MTMC standard is linear within the concentration range studied (r 2 = 0.9906). The limit of detection (S/N = 3) of the modified electrode was achieved to 1.34 x 10 -8 mol L -1 . Recoveries of MTMC from spiked apple juice, cabbage and cucumber samples for the developed electrochemical assay ranged from 94.80% to 102.43%, which was with great correlation coefficient (0.9929) with results from high-performance liquid chromatography. In practical application, the prepared amperometric sensor also showed good reproducibility and long lifetime for storage. The research in this study has offered a rapid, accurate and sensitive electrochemical method for quantitative determination of MTMC in food products.

  14. Novel amperometric sensor using metolcarb-imprinted film as the recognition element on a gold electrode and its application

    Energy Technology Data Exchange (ETDEWEB)

    Pan Mingfei; Fang Guozhen; Liu Bing; Qian Kun [Key Laboratory of Food Nutrition and Safety, Ministry of Education of China, Tianjin University of Science and Technology, Tianjin 300457 (China); Wang Shuo, E-mail: pmf2006@126.com [Key Laboratory of Food Nutrition and Safety, Ministry of Education of China, Tianjin University of Science and Technology, Tianjin 300457 (China)

    2011-04-01

    A molecularly imprinted film is electrochemically synthesized on a gold electrode using cyclic voltammetry to electropolymerize o-aminothiophenol in the presence of metolcarb (MTMC). The mechanism of the imprinting process and a number of factors affecting the activity of the imprinted film are discussed and optimized. Scanning electron microscope observations and binding measurements have proved that an MTMC-imprinted film (with a thickness of nearly 100 nm) was formed on the surface of the gold electrode. The film exhibited high binding affinity and selectivity towards the template MTMC, as well as good penetrability, reproducibility and stability. A novel amperometry sensor using the imprinted film as recognition element was developed for MTMC determination in food samples. Under the experimental conditions, the MTMC standard is linear within the concentration range studied (r{sup 2} = 0.9906). The limit of detection (S/N = 3) of the modified electrode was achieved to 1.34 x 10{sup -8} mol L{sup -1}. Recoveries of MTMC from spiked apple juice, cabbage and cucumber samples for the developed electrochemical assay ranged from 94.80% to 102.43%, which was with great correlation coefficient (0.9929) with results from high-performance liquid chromatography. In practical application, the prepared amperometric sensor also showed good reproducibility and long lifetime for storage. The research in this study has offered a rapid, accurate and sensitive electrochemical method for quantitative determination of MTMC in food products.

  15. Improvement of Amperometric Sensor Used for Determination of Nitrate with Polypyrrole Nanowires Modified Electrode

    Directory of Open Access Journals (Sweden)

    Shi-chang Wang

    2005-12-01

    Full Text Available Polypyrrole(PPy nanowire modified electrodes were developed by template-freeelectrochemical method based on graphite electrode. The modified electrode wascharacterized by their amperometric response towards nitrate ions. Before reduction ofnitrate ions, electrochemical solid-phase extraction (EC-SPE of nitrate in/on modifiedelectrodes was conducted. It is found that the unusual nanowired structure of polypyrrolelayer (instead of well known cauliflower structure allows us to increase the effectivesurface area of the electrode and subsequently the sensitivity. And the effects ofelectrochemical preparation parameters of PPy nanowire modified electrodes on theircorresponding characters were evaluated. The experimental results show that theelectrochemical preparation parameters of the modified electrodes such as scan rate,polymerization potential, temperature of polymerization solution and polymerization timehave significantly effects on the morphology of PPy nanowires and subsequently effectivesurface area of the electrode and electroreduction current density of nitrate. Thedetermination sensitivity may be varied according to the modification parameters. Under acertain polymerization conditions, the corresponding sensitivity reaches 336.28 mA/M cm2 and the detection limit is 1.52×10-6 M. The proposed method was successfully applied in thedetection of nitrate in the real samples.

  16. Light-addressable amperometric electrodes for enzyme sensors based on direct quantum dot-electrode contacts

    Science.gov (United States)

    Riedel, M.; Göbel, G.; Parak, W. J.; Lisdat, F.

    2014-03-01

    Quantum dots allow the generation of charge carriers upon illumination. When these particles are attached to an electrode a photocurrent can be generated. This allows their use as a light-switchable layer on the surface. The QDs can not only exchange electronics with the electrode, but can also interact with donor or acceptor compounds in solution providing access to the construction of signal chains starting from an analytic molecule. The magnitude and the direction of the photocurrent depend on several factors such as electrode polarization, solution pH and composition. These defined dependencies have been evaluated with respect to the combination of QD-electrodes with enzyme reactions for sensorial purpose. CdSe/ZnS-QD-modified electrodes can be used to follow enzymatic reactions in solution based on the oxygen sensitivity. In order to develop a photoelectrochemical biosensor, e.g. glucose oxidase is immobilized on the CdSe/ZnS-electrode. One immobilization strategy applies the layer-by-layer-technique of GOD and a polyelectrolyte. Photocurrent measurements of such a sensor show a clear concentration dependent behavior. The principle of combing QD oxidase. The sensitivity of quantum dot electrodes can be influenced by additional nanoparticles, but also by multiple layers of the QDs. In another direction of research it can be influenced by additional nanoparticles, but also by multiple layers of the QDs. In another direction of research it can be demonstrated that direct electron transfer from excited quantum dots can be achieved with the redox protein cytochrome c. This allows the detection of the protein, but also interaction partners such as a enzymes or superoxide.

  17. Nonenzymatic amperometric sensor for ascorbic acid based on hollow gold/ruthenium nanoshells

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Ara; Kang, Minkyung; Cha, Areum; Jang, Hye Su [Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Shim, Jun Ho [Department of Chemistry, Daegu University, Gyeongsan 712-714 (Korea, Republic of); Lee, Nam-Suk [National Center for Nanomaterials Technology (NCNT), Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Kim, Myung Hwa [Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Lee, Youngmi, E-mail: youngmilee@ewha.ac.kr [Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Lee, Chongmok, E-mail: cmlee@ewha.ac.kr [Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea, Republic of)

    2014-03-01

    Highlights: • We synthesized hollow gold/ruthenium (hAu–Ru) nanoshells for ascorbic acid sensing. • The hAu–Ru nanoshells showed sensitivity of 426 μA mM⁻¹ cm⁻² for ascorbic acid. • Good selectivity against glucose, uric acid, dopamine, 4-acetamidophenol, and NADH. • The linear dynamic range appeared from zero to 2.0 mM (R = 0.9995). • Response time (1.6 s) and low detection limit (2.2 μM) were obtained at pH 7.40. Abstract: We report a new nonenzymatic amperometric detection of ascorbic acid (AA) using a glassy carbon (GC) disk electrode modified with hollow gold/ruthenium (hAu–Ru) nanoshells, which exhibited decent sensing characteristics. The hAu–Ru nanoshells were prepared by the incorporation of Ru on hollow gold (hAu) nanoshells from Co nanoparticle templates, which enabled AA selectivity against glucose without aid of enzyme or membrane. The structure and electrocatalytic activities of the hAu–Ru catalysts were characterized by spectroscopic and electrochemical techniques. The hAu–Ru loaded on GC electrode (hAu–Ru/GC) showed sensitivity of 426 μA mM⁻¹ cm⁻² (normalized to the GC disk area) for the linear dynamic range of <5 μM to 2 mM AA at physiological pH. The response time and detection limit were 1.6 s and 2.2 μM, respectively. Furthermore, the hAu–Ru/GC electrode displayed remarkable selectivity for ascorbic acid over all potential biological interferents, including glucose, uric acid (UA), dopamine (DA), 4-acetamidophenol (AP), and nicotinamide adenine dinucleotide (NADH), which could be especially good for biological sensing.

  18. Nonenzymatic amperometric sensor for ascorbic acid based on hollow gold/ruthenium nanoshells

    International Nuclear Information System (INIS)

    Jo, Ara; Kang, Minkyung; Cha, Areum; Jang, Hye Su; Shim, Jun Ho; Lee, Nam-Suk; Kim, Myung Hwa; Lee, Youngmi; Lee, Chongmok

    2014-01-01

    Highlights: • We synthesized hollow gold/ruthenium (hAu–Ru) nanoshells for ascorbic acid sensing. • The hAu–Ru nanoshells showed sensitivity of 426 μA mM −1 cm −2 for ascorbic acid. • Good selectivity against glucose, uric acid, dopamine, 4-acetamidophenol, and NADH. • The linear dynamic range appeared from zero to 2.0 mM (R = 0.9995). • Response time (1.6 s) and low detection limit (2.2 μM) were obtained at pH 7.40. - Abstract: We report a new nonenzymatic amperometric detection of ascorbic acid (AA) using a glassy carbon (GC) disk electrode modified with hollow gold/ruthenium (hAu–Ru) nanoshells, which exhibited decent sensing characteristics. The hAu–Ru nanoshells were prepared by the incorporation of Ru on hollow gold (hAu) nanoshells from Co nanoparticle templates, which enabled AA selectivity against glucose without aid of enzyme or membrane. The structure and electrocatalytic activities of the hAu–Ru catalysts were characterized by spectroscopic and electrochemical techniques. The hAu–Ru loaded on GC electrode (hAu–Ru/GC) showed sensitivity of 426 μA mM −1 cm −2 (normalized to the GC disk area) for the linear dynamic range of <5 μM to 2 mM AA at physiological pH. The response time and detection limit were 1.6 s and 2.2 μM, respectively. Furthermore, the hAu–Ru/GC electrode displayed remarkable selectivity for ascorbic acid over all potential biological interferents, including glucose, uric acid (UA), dopamine (DA), 4-acetamidophenol (AP), and nicotinamide adenine dinucleotide (NADH), which could be especially good for biological sensing

  19. Computer-assisted electrochemical fabrication of a highly selective and sensitive amperometric nitrite sensor based on surface decoration of electrochemically reduced graphene oxide nanosheets with CoNi bimetallic alloy nanoparticles.

    Science.gov (United States)

    Gholivand, Mohammad-Bagher; Jalalvand, Ali R; Goicoechea, Hector C

    2014-07-01

    For the first time, a novel, robust and very attractive statistical experimental design (ED) using minimum-run equireplicated resolution IV factorial design (Min-Run Res IV FD) coupled with face centered central composite design (FCCCD) and Derringer's desirability function (DF) was developed to fabricate a highly selective and sensitive amperometric nitrite sensor based on electrodeposition of CoNi bimetallic alloy nanoparticles (NPs) on electrochemically reduced graphene oxide (ERGO) nanosheets. The modifications were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), energy dispersive X-ray spectroscopic (EDS), scanning electron microscopy (SEM) techniques. The CoNi bimetallic alloy NPs were characterized using digital image processing (DIP) for particle counting (density estimation) and average diameter measurement. Under the identified optimal conditions, the novel sensor detects nitrite in concentration ranges of 0.1-30.0 μM and 30.0-330.0 μM with a limit of detection (LOD) of 0.05 μM. This sensor selectively detects nitrite even in the presence of high concentration of common ions and biological interferents therefore, we found that the sensor is highly selective. The sensor also demonstrated an excellent operational stability and good antifouling properties. The proposed sensor was used to the determination of nitrite in several foodstuff and water samples. Copyright © 2014. Published by Elsevier B.V.

  20. A highly sensitive hydrogen peroxide amperometric sensor based on MnO2-modified vertically aligned multiwalled carbon nanotubes.

    Science.gov (United States)

    Xu, Bin; Ye, Min-Ling; Yu, Yu-Xiang; Zhang, Wei-De

    2010-07-26

    In this report, a highly sensitive amperometric sensor based on MnO(2)-modified vertically aligned multiwalled carbon nanotubes (MnO(2)/VACNTs) for determination of hydrogen peroxide (H(2)O(2)) was fabricated by electrodeposition. The morphology of the nanocomposite was characterized by scanning electron microscopy, energy-dispersive X-ray spectrometer and X-ray diffraction. Cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy were applied to investigate the electrochemical properties of the MnO(2)/VACNTs nanocomposite electrode. The mechanism for the electrochemical reaction of H(2)O(2) at the MnO(2)/VACNTs nanocomposite electrode was also discussed. In borate buffer (pH 7.8, 0.20 M), the MnO(2)/VACNTs nanocomposite electrode exhibits a linear dependence (R=0.998) on the concentration of H(2)O(2) from 1.2 x 10(-6)M to 1.8 x 10(-3)M, a high sensitivity of 1.08 x 10(6) microA M(-1) cm(-2) and a detection limit of 8.0 x 10(-7) M (signal/noise=3). Meanwhile, the MnO(2)/VACNTs nanocomposite electrode is also highly resistant towards typical inorganic salts and some biomolecules such as acetic acid, citric acid, uric acid and D-(+)-glucose, etc. In addition, the sensor based on the MnO(2)/VACNTs nanocomposite electrode was applied for the determination of trace of H(2)O(2) in milk with high accuracy, demonstrating its potential for practical application. Copyright 2010 Elsevier B.V. All rights reserved.

  1. A novel amperometric sensor for peracetic acid based on a polybenzimidazole-modified gold electrode

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Mu-Yi, E-mail: huamy@mail.cgu.edu.t [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Chen, Hsiao-Chien [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Tsai, Rung-Ywan [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, 195, Sec. 4, Chung Hsing Rd., Hsinchu 31040, Taiwan (China); Lin, Yu-Chen [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China)

    2011-04-30

    We have developed a peracetic acid (PAA) sensor based on a polybenzimidazole-modified gold (PBI/Au) electrode. Fourier transform infrared and X-ray photoelectron spectroscopy indicated that PAA oxidized 69.4% of the imine in PBI to form PBI N-oxide, increasing the electrochemical reduction current during cyclic voltammetry. The chemical oxidation of the PBI/Au electrode by PAA, followed by its electrochemical reduction, allowed PAA to be detected directly and consecutively by assessing its reduction current. The PAA sensor had a broad linear detection range (3.1 {mu}M-1.5 mM) and a rapid response time (3.9 s) at an applied potential of -0.3 V. Potentially interfering substances, such as hydrogen peroxide, acetic acid, and oxygen, had no effect on the ability of the probe to detect PAA, indicating high selectivity of the probe. Furthermore, the detection range, response time, and sensitivity of the sensor could all be improved by modification of the smooth planar electrode surface to a porous three-dimensional configuration. When compared to the analytical characteristics of other PAA sensors operating under optimal conditions, the three-dimensional PBI/Au electrode offers a rapid detection time, a usable linear range, and a relatively low detection limit.

  2. A novel amperometric sensor for peracetic acid based on a polybenzimidazole-modified gold electrode

    International Nuclear Information System (INIS)

    Hua, Mu-Yi; Chen, Hsiao-Chien; Tsai, Rung-Ywan; Lin, Yu-Chen

    2011-01-01

    We have developed a peracetic acid (PAA) sensor based on a polybenzimidazole-modified gold (PBI/Au) electrode. Fourier transform infrared and X-ray photoelectron spectroscopy indicated that PAA oxidized 69.4% of the imine in PBI to form PBI N-oxide, increasing the electrochemical reduction current during cyclic voltammetry. The chemical oxidation of the PBI/Au electrode by PAA, followed by its electrochemical reduction, allowed PAA to be detected directly and consecutively by assessing its reduction current. The PAA sensor had a broad linear detection range (3.1 μM-1.5 mM) and a rapid response time (3.9 s) at an applied potential of -0.3 V. Potentially interfering substances, such as hydrogen peroxide, acetic acid, and oxygen, had no effect on the ability of the probe to detect PAA, indicating high selectivity of the probe. Furthermore, the detection range, response time, and sensitivity of the sensor could all be improved by modification of the smooth planar electrode surface to a porous three-dimensional configuration. When compared to the analytical characteristics of other PAA sensors operating under optimal conditions, the three-dimensional PBI/Au electrode offers a rapid detection time, a usable linear range, and a relatively low detection limit.

  3. Characterization of the Ionic Liquid/Electrode Interfacial Relaxation Processes Under Potential Polarization for Ionic Liquid Amperometric Gas Sensor Method Development.

    Science.gov (United States)

    Lin, Lu; Zhao, Peng; Mason, Andrew J; Zeng, Xiangqun

    2018-06-04

    Electrochemical amperometric sensors require a constant or varying potential at the working electrode that drives redox reactions of the analyte for detection. The interfacial redox reaction(s) can result in the formation of new chemical products that could change the initial condition of the electrode/electrolyte interface. If the products are not inert and/or cannot be removed from the system such that the initial condition of the electrode/electrolyte interface cannot be restored, the sensor signal baseline would consequently drift, which is problematic for the continuous and real-time sensors. By setting the electrode potential with the periodical ON-OFF mode, electrolysis can be forestalled during the off mode which can minimize the sensor signal baseline drift and reduce the power consumption of the sensor. However, it is known that the relaxation of the structure in the electrical double layer at the ionic liquid/electrode interface to the steps of the electrode potential is slow. This work characterized the electrode/electrolyte interfacial relaxation process of an ionic liquid based electrochemical gas (IL-EG) sensor by performing multiple potential step experiments in which the potential is stepped from an open circuit potential (OCP) to the amperometric sensing potential at various frequencies with different time periods. Our results showed that by shortening the sensing period as well as extending the idle period (i.e., enlarge the ratio of idle period versus sensing period) of the potential step experiments, the electrode/electrolyte interface is prone to relax to its original state, and thus reduces the baseline drift. Additionally, the high viscosity of the ionic liquids is beneficial for electrochemical regeneration via the implementation of a conditioning step at zero volts at the electrode/electrolyte. By setting the working electrode at zero volts instead of OCP, our results showed that it could further minimize the baseline drift, enhance the

  4. Fabrication of Amperometric Glucose Sensor Using Glucose Oxidase-Cellulose Nanofiber Aqueous Solution.

    Science.gov (United States)

    Yasuzawa, Mikito; Omura, Yuya; Hiura, Kentaro; Li, Jiang; Fuchiwaki, Yusuke; Tanaka, Masato

    2015-01-01

    Cellulose nanofiber aqueous solution, which remained virtually transparent for more than one week, was prepared by using the clear upper layer of diluted cellulose nanofiber solution produced by wet jet milling. Glucose oxidase (GOx) was easily dissolved in this solution and GOx-immobilized electrode was easily fabricated by simple repetitious drops of GOx-cellulose solution on the surface of a platinum-iridium electrode. Glucose sensor properties of the obtained electrodes were examined in phosphate buffer solution of pH 7.4 at 40°C. The obtained electrode provided a glucose sensor response with significantly high response speed and good linear relationship between glucose concentration and response current. After an initial decrease of response sensitivity for a few days, relatively constant sensitivity was obtained for about 20 days. Nevertheless, the influence of electroactive compounds such as ascorbic acid, uric acid and acetoaminophen were not negletable.

  5. Amperometric sensor for ascorbic acid based on a glassy carbon electrode modified with gold-silver bimetallic nanotubes in a chitosan matrix

    International Nuclear Information System (INIS)

    Yang, Penghao; Gao, Xia; Wang, Lisha; Wu, Qi; Chen, Zhichun; Lin, Xianfu

    2014-01-01

    We report on an amperometric sensor for ascorbic acid (AA) that is based on highly dense gold-silver nanotubes in a chitosan film on a glassy carbon electrode. The nanotubes were synthesized by a poly(vinyl pyrrolidone)-mediated polyol method employing a replacement reaction with silver nanowires as templates, and were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Under the optimal conditions, the sensor exhibits good electrocatalytic activity towards the oxidation of AA, and this enables the determination of AA in the 5 μM to 2 mM concentration range, with a detection limit at 2 μM (at an S/N of 3). The response time is 2 s. The sensor displays good reproducibility, selectivity, sensitivity, and long-term stability. (author)

  6. Water-dispersible triethylenetetramine-functionalized graphene: Preparation, characterization and application as an amperometric glucose sensor

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Qunxiang; Feng, Li; Fan, Ronghua; Ge, Xin; Sun, Yingying, E-mail: syyxiluda@hotmail.com

    2016-11-01

    The triethylenetetramine-functionalized graphene (TFGn) was prepared using graphene oxide (GO) and triethylenetetramine as raw materials through a one-step reaction under alkaline condition. The triethylenetetramine not only acted as cross-linker to combine GO, but also as reductant of GO. The TFGn was characterized by its ultraviolet spectrum (UV), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopy (SEM). The results showed that triethylenetetramine was successfully grafted onto the surface of the GO through covalent bonding between amine and epoxy groups. The resultant TFGn was uniformly dispersed in water over several weeks, suggesting that the introduction of amino groups greatly increased the hydrophilicity of TFGn. The triethylenetetramine-functionalized graphene was then applied to fabricate glucose biosensors with IO{sub 4}{sup −} oxidized glucose oxidase (GOx) through layer-by-layer (LBL) self-assembly by the covalent bonding between the aldehyde groups of GOx and amino groups of TFGn. The gold electrodes modified with the (GOx/TFGn){sub n} multilayer films were studied by cyclic voltammetry (CV) and showed outstanding electrocatalytical response to the oxidation of glucose when ferrocenemethanol was used as an artificial redox mediator. The response increased with an increasing number of GOx/TFGn bilayers, indicating that the analytical performance, such as the sensitivity of the glucose biosensor, could be adjusted by tuning the number of deposited GOx/TFGn bilayers. The linear response range of the biosensor constructed with six bilayers of GOx/TFGn to the concentration of glucose can extend to at least 8 mM with a sensitivity of 19.9 μA mM{sup −1} cm{sup −2}. In addition, the sensor exhibited good stability due to the covalent interactions between the GOx and TFGn. - Highlights: • Water-dispersible triethylenetetramine

  7. Computer-assisted electrochemical fabrication of a highly selective and sensitive amperometric nitrite sensor based on surface decoration of electrochemically reduced graphene oxide nanosheets with CoNi bimetallic alloy nanoparticles

    International Nuclear Information System (INIS)

    Gholivand, Mohammad-Bagher; Jalalvand, Ali R.; Goicoechea, Hector C.

    2014-01-01

    For the first time, a novel, robust and very attractive statistical experimental design (ED) using minimum-run equireplicated resolution IV factorial design (Min-Run Res IV FD) coupled with face centered central composite design (FCCCD) and Derringer's desirability function (DF) was developed to fabricate a highly selective and sensitive amperometric nitrite sensor based on electrodeposition of CoNi bimetallic alloy nanoparticles (NPs) on electrochemically reduced graphene oxide (ERGO) nanosheets. The modifications were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), energy dispersive X-ray spectroscopic (EDS), scanning electron microscopy (SEM) techniques. The CoNi bimetallic alloy NPs were characterized using digital image processing (DIP) for particle counting (density estimation) and average diameter measurement. Under the identified optimal conditions, the novel sensor detects nitrite in concentration ranges of 0.1–30.0 μM and 30.0–330.0 μM with a limit of detection (LOD) of 0.05 μM. This sensor selectively detects nitrite even in the presence of high concentration of common ions and biological interferents therefore, we found that the sensor is highly selective. The sensor also demonstrated an excellent operational stability and good antifouling properties. The proposed sensor was used to the determination of nitrite in several foodstuff and water samples. - Highlights: • Eight variables were screened by Min Run Res IV FD to identify the key variables. • Mathematical models for the two studied responses were developed by FCCCD. • By using DF the responses were optimized simultaneously. • The SEM image of the modified electrode was processed by digital image processing. • The sensor was successfully applied to determination of nitrite in real samples

  8. Computer-assisted electrochemical fabrication of a highly selective and sensitive amperometric nitrite sensor based on surface decoration of electrochemically reduced graphene oxide nanosheets with CoNi bimetallic alloy nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gholivand, Mohammad-Bagher, E-mail: mbgholivand2013@gmail.com [Faculty of Chemistry, Razi University, Kermanshah 671496734 (Iran, Islamic Republic of); Jalalvand, Ali R. [Faculty of Chemistry, Razi University, Kermanshah 671496734 (Iran, Islamic Republic of); Laboratorio de Desarrollo Analítico y Quimiometría (LADAQ), Cátedra de Química Analítica I, Universidad Nacional del Litoral, Ciudad Universitaria, CC 242 (S3000ZAA), Santa Fe (Argentina); Goicoechea, Hector C. [Laboratorio de Desarrollo Analítico y Quimiometría (LADAQ), Cátedra de Química Analítica I, Universidad Nacional del Litoral, Ciudad Universitaria, CC 242 (S3000ZAA), Santa Fe (Argentina)

    2014-07-01

    For the first time, a novel, robust and very attractive statistical experimental design (ED) using minimum-run equireplicated resolution IV factorial design (Min-Run Res IV FD) coupled with face centered central composite design (FCCCD) and Derringer's desirability function (DF) was developed to fabricate a highly selective and sensitive amperometric nitrite sensor based on electrodeposition of CoNi bimetallic alloy nanoparticles (NPs) on electrochemically reduced graphene oxide (ERGO) nanosheets. The modifications were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), energy dispersive X-ray spectroscopic (EDS), scanning electron microscopy (SEM) techniques. The CoNi bimetallic alloy NPs were characterized using digital image processing (DIP) for particle counting (density estimation) and average diameter measurement. Under the identified optimal conditions, the novel sensor detects nitrite in concentration ranges of 0.1–30.0 μM and 30.0–330.0 μM with a limit of detection (LOD) of 0.05 μM. This sensor selectively detects nitrite even in the presence of high concentration of common ions and biological interferents therefore, we found that the sensor is highly selective. The sensor also demonstrated an excellent operational stability and good antifouling properties. The proposed sensor was used to the determination of nitrite in several foodstuff and water samples. - Highlights: • Eight variables were screened by Min Run Res IV FD to identify the key variables. • Mathematical models for the two studied responses were developed by FCCCD. • By using DF the responses were optimized simultaneously. • The SEM image of the modified electrode was processed by digital image processing. • The sensor was successfully applied to determination of nitrite in real samples.

  9. Portable Amperometric Perchlorate Selective Sensors with Microhole Array-water/organic Gel Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Hyuk; Girault, Hubert H.; Lee, Hye Jin [Kyungpook National Univ., Daegu (Korea, Republic of); Kim, Hyungi [Gyeongbuk Technopark, Gyeongsan (Korea, Republic of); Girault, Hubert H. [Ecole Polytechnique Federale de Lausanne, Lausanne (Switzerland)

    2013-09-15

    A novel stick-shaped portable sensing device featuring a microhole array interface between the polyvinylchloride-2-nitrophenyloctylether (PVC-NPOE) gel and water phase was developed for in-situ sensing of perchlorate ions in real water samples. Perchlorate sensitive sensing responses were obtained based on measuring the current changes with respect to the assisted transfer reaction of perchlorate ions by a perchlorate selective ligand namely, bis(dibenzoylmethanato)Ni(II) (Ni(DBM){sub 2}) across the polarized microhole array interface. Cyclic voltammetry was used to characterize the assisted transfer reaction of perchlorate ions by the Ni(DBM){sub 2} ligand when using the portable sensing device. The current response for the transfer of perchlorate anions by Ni(DBM){sub 2} across the micro-water/gel interface linearly increased as a function of the perchlorate ion concentration. The technique of differential pulse stripping voltammetry was also utilized to improve the sensitivity of the perchlorate anion detection down to 10 ppb. This was acquired by preconcentrating perchlorate anions in the gel layer by means of holding the ion transfer potential at 0 mV (vs. Ag/AgCl) for 30 s followed by stripping the complexed perchlorate ion with the ligand. The effect of various potential interfering anions on the perchlorate sensor was also investigated and showed an excellent selectivity over Br{sup -}, NO{sub 2}{sup -}, NO{sub 3}{sup -}, CO{sub 3}{sup 2-}, CH{sub 3}COO{sup -} and SO{sub 4}{sup 2-} ions. As a final demonstration, some regional water samples from the Sincheon river in Daegu city were analyzed and the data was verified with that of ion chromatography (IC) analysis from one of the Korean-certified water quality evaluation centers.

  10. Flow injection determination of choline in milk hydrolysates by an immobilized enzyme reactor coupled to a selective hydrogen peroxide amperometric sensor

    Energy Technology Data Exchange (ETDEWEB)

    Pati, Sandra [Dipartimento di Chimica, Universita degli Studi di Bari, Via Orabona 4, 70126 Bari (Italy); Quinto, Maurizio [Dipartimento di Scienze Agroambientali, Chimica e Difesa Vegetale, Universita degli Studi di Foggia, Via Napoli 25, 71100 Foggia (Italy); Palmisano, Francesco [Dipartimento di Chimica, Universita degli Studi di Bari, Via Orabona 4, 70126 Bari (Italy)]. E-mail: palmisano@chimica.uniba.it

    2007-07-02

    A choline oxidase (ChO) immobilized enzyme reactor (IMER) prepared by glutaraldehyde coupling of the enzyme on aminopropyl modified controlled pore glass beads is described. The ChO-IMER was coupled, in a flow injection configuration system, to an interference free hydrogen peroxide amperometric sensor based on a Pt surface modified by an overoxidized polypyrrole film. The resulting analytical device responds selectively to choline and displays a sensitivity of 46.9 {+-} 0.2 {mu}C mM{sup -1} and a limit of detection, calculated at a signal-to-noise ratio equal to 3, of 7 {mu}M. Sensitivity remains constant for about 20 days and then starts to slowly deteriorate and after 2 months a 70% of the initial sensitivity was still retained. The application to choline determination in milk hydrolysates is demonstrated. Short- and long-term drift observed in the analytical response can be corrected by a bracketing technique.

  11. Towards the conception of an amperometric sensor of L-tyrosine based on Hemin/PAMAM/MWCNT modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Ma Qiang; Ai Shiyun; Yin Huanshun; Chen Quanpeng; Tang Tiantian

    2010-01-01

    A novel amperometric sensor was fabricated based on the immobilization of hemin onto the poly (amidoamine)/multi-walled carbon nanotube (PAMAM/MWCNT) nanocomposite film modified glassy carbon electrode (GCE). Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and ultraviolet visible (UV-vis) adsorption spectroscopy were used to investigate the possible state and electrochemical activity of the immobilized hemin. In the Hemin/PAMAM/MWCNT nanocomposite film, MWCNT layer possessed excellent inherent conductivity to enhance the electron transfer rate, while the layer of PAMAM greatly enlarged the surface average concentration of hemin (Γ) on the modified electrode. Therefore, the nanocomposite film showed enhanced electrocatalytical activity towards the oxidation of L-tyrosine. The kinetic parameters of the modified electrode were investigated. In pH 7.0 phosphate buffer solution (PBS), the sensor exhibits a wide linear range from 0.1 μM to 28.8 μM L-tyrosine with a detection limit of 0.01 μM and a high sensitivity of 0.31 μA μM -1 cm -2 . In addition, the response time of the L-tyrosine sensor is less than 5 s. The excellent performance of the sensor is largely attributed to the electro-generated high reactive oxoiron (IV) porphyrin (O = Fe IV -P) which effectively catalyzed the oxidation of L-tyrosine. A mechanism was herein proposed for the catalytic oxidation of L-tyrosine by oxoiron (IV) porphyrin complexes.

  12. Influence of zirconium doping in ceria lattice as an active electrode in amperometric electrochemical ammonia gas sensor using oxygen pumping current

    International Nuclear Information System (INIS)

    Sharan, R.; Dutta, Atanu; Roy, Mainak

    2016-01-01

    An amperometric electrochemical sensor using Ce-Zr system as ammonia gas detecting electrode is reported. Using lanthanum gallate based electrolyte La_0_._8Sr_0_._2Ga_0_._8Mg_0_._1Ni_0_._1O_3 (LSGMN) and lanthanum strontium cobaltite La_0_._5Sr_0_._5CoO_3 (LSC) as oxygen reduction electrode, the sensor was found to be highly sensitive to NH_3 gas down to few ppm level, when operated in the temperature range 300-450°C. Keeping LSC electrodecomposition same, when sensing properties were studied with the variation of Zr concentration in ceria for active electrode, sensor with 30 mol % Zr doped ceria showed highest sensitivity of 28μA/ decade at 400°C. For all active electrodecompositions Ce_1_-_xZr_xO_2 (x = 0 to 0.7) highest sensitivity was observed at 400°C. All the sensors performed reproducibly with time response and recovery time 40 and 120 seconds respectively. (author)

  13. Amperometric glucose sensor based on enhanced catalytic reduction of oxygen using glucose oxidase adsorbed onto core-shell Fe3O4-silica-Au magnetic nanoparticles

    International Nuclear Information System (INIS)

    Wang Aijun; Li Yongfang; Li Zhonghua; Feng Jiuju; Sun Yanli; Chen Jianrong

    2012-01-01

    Monodisperse Fe 3 O 4 magnetic nanoparticles (NPs) were prepared under facile solvothermal conditions and successively functionalized with silica and Au to form core/shell Fe 3 O 4 -silica-Au NPs. Furthermore, the samples were used as matrix to construct a glucose sensor based on glucose oxidase (GOD). The immobilized GOD retained its bioactivity with high protein load of 3.92 × 10 −9 mol·cm −2 , and exhibited a surface-controlled quasi-reversible redox reaction, with a fast heterogeneous electron transfer rate of 7.98 ± 0.6 s −1 . The glucose biosensor showed a broad linear range up to 3.97 mM with high sensitivity of 62.45 μA·mM −1 cm −2 and fast response (less than 5 s). - Graphical abstract: Core-shell structured Fe 3 O 4 -silica-Au nanoparticles were prepared and used as matrix to construct an amperometric glucose sensor based on glucose oxidase, which showed broad linear range, high sensitivity, and fast response. Highlights: ► Synthesis of monodispersed Fe 3 O 4 nanoparticles. ► Fabrication of core/shell Fe 3 O 4 -silica-Au nanoparticles. ► Construction of a novel glucose sensor with wide linear range, high sensitivity and fast response.

  14. Magnetic Beads-Based Sensor with Tailored Sensitivity for Rapid and Single-Step Amperometric Determination of miRNAs

    Directory of Open Access Journals (Sweden)

    Eva Vargas

    2017-11-01

    Full Text Available This work describes a sensitive amperometric magneto-biosensor for single-step and rapid determination of microRNAs (miRNAs. The developed strategy involves the use of direct hybridization of the target miRNA (miRNA-21 with a specific biotinylated DNA probe immobilized on streptavidin-modified magnetic beads (MBs, and labeling of the resulting heteroduplexes with a specific DNA–RNA antibody and the bacterial protein A (ProtA conjugated with an horseradish peroxidase (HRP homopolymer (Poly-HRP40 as an enzymatic label for signal amplification. Amperometric detection is performed upon magnetic capture of the modified MBs onto the working electrode surface of disposable screen-printed carbon electrodes (SPCEs using the H2O2/hydroquinone (HQ system. The magnitude of the cathodic signal obtained at −0.20 V (vs. the Ag pseudo-reference electrode demonstrated linear dependence with the concentration of the synthetic target miRNA over the 1.0 to 100 pM range. The method provided a detection limit (LOD of 10 attomoles (in a 25 μL sample without any target miRNA amplification in just 30 min (once the DNA capture probe-MBs were prepared. This approach shows improved sensitivity compared with that of biosensors constructed with the same anti-DNA–RNA Ab as capture instead of a detector antibody and further labeling with a Strep-HRP conjugate instead of the Poly-HRP40 homopolymer. The developed strategy involves a single step working protocol, as well as the possibility to tailor the sensitivity by enlarging the length of the DNA/miRNA heteroduplexes using additional probes and/or performing the labelling with ProtA conjugated with homopolymers prepared with different numbers of HRP molecules. The practical usefulness was demonstrated by determination of the endogenous levels of the mature target miRNA in 250 ng raw total RNA (RNAt extracted from human mammary epithelial normal (MCF-10A and cancer (MCF-7 cells and tumor tissues.

  15. Sensor platform for gas composition measurement

    NARCIS (Netherlands)

    De Graaf, G.; Bakker, F.; Wolffenbuttel, R.F.

    2011-01-01

    The gas sensor research presented here has a focus on the measurement of the composition of natural gas and gases from sustainable resources, such as biogas. For efficient and safe combustion, new sensor systems need to be developed to measure the composition of these new gases. In general about 6

  16. Carbon nanotubes and graphene modified screen-printed carbon electrodes as sensitive sensors for the determination of phytochelatins in plants using liquid chromatography with amperometric detection.

    Science.gov (United States)

    Dago, Àngela; Navarro, Javier; Ariño, Cristina; Díaz-Cruz, José Manuel; Esteban, Miquel

    2015-08-28

    Nanomaterials are of great interest for the development of electrochemical sensors. Multi-walled carbon nanotubes and graphene were used to modify the working electrode surface of different screen-printed carbon electrodes (SPCE) with the aim of improving the sensitivity of the SPCE and comparing it with the conventional glassy carbon electrode. To assay the usability of these sensors, a HPLC methodology with amperometric detection was developed to analyze several phytochelatins in plants of Hordeum vulgare and Glycine max treated with Hg(II) or Cd(II) giving detection limits in the low μmolL(-1) range. Phytochelatins are low molecular weight peptides with the general structure γ-(Glu-Cys)n-Gly (n=2-5) which are synthesized in plants in the presence of heavy metal ions. These compounds can chelate heavy metal ions by the formation of complexes which, are transported to the vacuoles, where the toxicity is not threatening. For this reason phytochelatins are essential in the detoxification of heavy metal ions in plants. The developed HPLC method uses a mobile phase of 1% of formic acid in water with KNO3 or NaCl (pH=2.00) and 1% of formic acid in acetonitrile. Electrochemical detection at different carbon-based electrodes was used. Among the sensors tested, the conventional glassy carbon electrode offers the best sensitivity although modification improves the sensitivity of the SPCE. Glutathione and several isoforms of phytochelatin two were found in plant extracts of both studied species. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. A novel nonenzymatic amperometric hydrogen peroxide sensor based on CuO@Cu2O nanowires embedded into poly(vinyl alcohol).

    Science.gov (United States)

    Chirizzi, Daniela; Guascito, Maria Rachele; Filippo, Emanuela; Tepore, Antonio

    2016-01-15

    A new, very simple, rapid and inexpensive nonenzymatic amperometric sensor for hydrogen peroxide (H2O2) detection is proposed. It is based on the immobilization of cupric/cuprous oxide core shell nanowires (CuO@Cu2O-NWs) in a poly(vinyl alcohol) (PVA) matrix directly drop casted on a glassy carbon electrode surface to make a CuO@Cu2O core shell like NWs PVA embedded (CuO@Cu2O-NWs/PVA) sensor. CuO nanowires with mean diameters of 120-170nm and length in the range 2-5μm were grown by a simple catalyst-free thermal oxidation process based on resistive heating of pure copper wires at ambient conditions. The oxidation process of the copper wire surface led to the formation of a three layered structure: a thick Cu2O bottom layer, a CuO thin intermediate layer and CuO nanowires. CuO nanowires were carefully scratched from Cu2O layer with a sharp knife, dispersed into ethanol and sonicated. Then, the NWs were embedded in PVA matrix. The morphological and spectroscopic characterization of synthesized CuO-NWs and CuO@Cu2O-NWs/PVA were performed by transmission electron microscopy (TEM), selected area diffraction pattern (SAD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. Moreover a complete electrochemical characterization of these new CuO@Cu2O-NWs/PVA modified glassy carbon electrodes was performed by Cyclic Voltammetry (CV) and Cronoamperometry (CA) in phosphate buffer (pH=7; I=0.2) to investigate the sensing properties of this material against H2O2. The electrochemical performances of proposed sensors as high sensitivity, fast response, reproducibility and selectivity make them suitable for the quantitative determination of hydrogen peroxide substrate in batch analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. A planar, solid-state amperometric sensor for nitrogen dioxide, employing an ionic liquid electrolyte contained in a polymeric matrix

    Czech Academy of Sciences Publication Activity Database

    Nádherná, M.; Opekar, F.; Reiter, Jakub; Stulík, K.

    2012-01-01

    Roč. 161, č. 1 (2012), s. 811-817 ISSN 0925-4005 R&D Projects: GA MŠk LC523; GA AV ČR KJB200320901 Institutional research plan: CEZ:AV0Z40320502 Keywords : Amperometry * Gas sensor * Solid-state sensor * Planar sensor * Ionic liquid * Solid polymer electrolyte * Gold minigrid electrode * Nitrogen dioxide Subject RIV: CG - Electrochemistry Impact factor: 3.535, year: 2012

  19. Detection of Ca2+-induced acetylcholine released from leukemic T-cells using an amperometric microfluidic sensor.

    Science.gov (United States)

    Akhtar, Mahmood H; Hussain, Khalil K; Gurudatt, N G; Shim, Yoon-Bo

    2017-12-15

    A microfluidic structured-dual electrodes sensor comprising of a pair of screen printed carbon electrodes was fabricated to detect acetylcholine, where one of them was used for an enzyme reaction and another for a detection electrode. The former was coated with gold nanoparticles and the latter with a porous gold layer, followed by electropolymerization of 2, 2:5,2-terthiophene-3-(p-benzoic acid) (pTTBA) on both the electrodes. Then, acetylcholinesterase was covalently attached onto the reaction electrode, and hydrazine and choline oxidase were co-immobilized on the detection electrode. The layers of both modified electrodes were characterized employing voltammetry, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and quartz crystal microscopy. After the modifications of both electrode surfaces, they were precisely faced each other to form a microfluidic channel structure, where H 2 O 2 produced from the sequential enzymatic reactions was reduced by hydrazine to obtain the analytical signal which was analyzed by the detection electrode. The microfluidic sensor at the optimized experimental conditions exhibited a wide dynamic range from 0.7nM to 1500μM with the detection limit of 0.6 ± 0.1nM based on 3s (S/N = 3). The biomedical application of the proposed sensor was evaluated by detecting acetylcholine in human plasma samples. Moreover, the Ca 2+ -induced acetylcholine released in leukemic T-cells was also investigated to show the in vitro detection ability of the designed microfluidic sensor. Interference due to the real component matrix were also studied and long term stability of the designed sensor was evaluated. The analytical performance of the designed sensor was also compared with commercially available ACh detection kit. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Amperometric hydrogen peroxide biosensor based on the immobilization of horseradish peroxidase on core-shell organosilica-chitosan nanospheres and multiwall carbon nanotubes composite

    International Nuclear Information System (INIS)

    Chen Shihong; Yuan Ruo; Chai Yaqin; Yin Bin; Li Wenjun; Min Ligen

    2009-01-01

    The application of the composites of multiwall carbon nanotubes (MWNTs) and core-shell organosilica-chitosan crosslinked nanospheres as an immobilization matrix for the construction of an amperometric hydrogen peroxide (H 2 O 2 ) biosensor was described. MWNTs and positively charged organosilica-chitosan nanospheres were dispersed in acetic acid solution (0.6 wt%) to achieve organosilica-chitosan/MWNTs composites, which were cast onto a glass carbon electrode (GCE) surface directly. And then, horseradish peroxidase (HRP), as a model enzyme, was immobilized onto it through electrostatic interaction between oppositely charged organosilica-chitosan nanospheres and HRP. The direct electron transfer of HRP was achieved at HRP/organosilica-chitosan/MWNTs/GCE, which exhibited excellent electrocatalytic activity for the reduction of H 2 O 2 . The catalysis currents increased linearly to H 2 O 2 concentration in a wide range of 7.0 x 10 -7 to 2.8 x 10 -3 M, with a sensitivity of 49.8 μA mM -1 cm -2 and with a detection limit of 2.5 x 10 -7 M at 3σ. A Michaelies-Menten constant K M app value was estimated to be 0.32 mM, indicating a high-catalytic activity of HRP. Moreover, the proposed biosensor displayed a rapid response to H 2 O 2 and possessed good stability and reproducibility. When used to detect H 2 O 2 concentration in disinfector samples and sterilized milks, respectively, it showed satisfactory results

  1. Amperometric pyruvate sensor based on a pyruvate dehydrogenase-immobilized carbon paste electrode containing vitamin K3 as a mediator

    Energy Technology Data Exchange (ETDEWEB)

    Miki, K. [Nara National College of Technology, Nara (Japan); Kinoshita, H. [Kawassui Women`s College, Nagasaki (Japan); Yamamoto, Y. [Kyoto Municipal Junior College of Nursing, Kyoto (Japan); Taniguchi, N. [Kyoto Research Center for Hygiene, Kyoto (Japan); Ikeda, T. [Kyoto University, Kyoto (Japan). Faculty of Agriculture

    1995-12-05

    Pyruvate dehydrogenase (PDH) was immobilized on the surface of a carbon paste electrode containing vitamin K3 (2-Methyl-1,4-naphthoquinone, VK), and the electrode surface was covered with a dialysis membrane. The enzyme electrode produced an anodic current starting from -0.2 V to reach a limiting current at +0.1 V vs. Ag/AgCl due to the enzyme-catalyzed oxidation of pyruvate in a phosphate buffer solution of pH 7.0. The current response to pyruvate depended on the amounts of both the immobilized-PDH and VK mixed in the carbon paste electrode at low amount of the enzyme and VK, and became independent at above 0.15 mg PDH and 0.65% (w/w) VK. The electrode with 0.15mg PDH and 0.65% (w/w) VK could be used as a pyruvate sensor to measure in the range of 2 ,{mu}M to 3mM. The response time was about 60 sec, and the current was independent of pH in the range of 5.7 - 7.2. The presence of L-ascorbic acid didn`t interfere with this measurement. Phosphate ion could also be determined with this electrode in a citrate buffer solution. 14 refs., 6 figs., 1 tab.

  2. Implantable enzyme amperometric biosensors.

    Science.gov (United States)

    Kotanen, Christian N; Moussy, Francis Gabriel; Carrara, Sandro; Guiseppi-Elie, Anthony

    2012-05-15

    The implantable enzyme amperometric biosensor continues as the dominant in vivo format for the detection, monitoring and reporting of biochemical analytes related to a wide range of pathologies. Widely used in animal studies, there is increasing emphasis on their use in diabetes care and management, the management of trauma-associated hemorrhage and in critical care monitoring by intensivists in the ICU. These frontier opportunities demand continuous indwelling performance for up to several years, well in excess of the currently approved seven days. This review outlines the many challenges to successful deployment of chronically implantable amperometric enzyme biosensors and emphasizes the emerging technological approaches in their continued development. The foreign body response plays a prominent role in implantable biotransducer failure. Topics considering the approaches to mitigate the inflammatory response, use of biomimetic chemistries, nanostructured topographies, drug eluting constructs, and tissue-to-device interface modulus matching are reviewed. Similarly, factors that influence biotransducer performance such as enzyme stability, substrate interference, mediator selection and calibration are reviewed. For the biosensor system, the opportunities and challenges of integration, guided by footprint requirements, the limitations of mixed signal electronics, and power requirements, has produced three systems approaches. The potential is great. However, integration along the multiple length scales needed to address fundamental issues and integration across the diverse disciplines needed to achieve success of these highly integrated systems, continues to be a challenge in the development and deployment of implantable amperometric enzyme biosensor systems. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Amperometric Biosensor Based on Zirconium Oxide/Polyethylene Glycol/Tyrosinase Composite Film for the Detection of Phenolic Compounds.

    Science.gov (United States)

    Ahmad, Nor Monica; Abdullah, Jaafar; Yusof, Nor Azah; Ab Rashid, Ahmad Hazri; Abd Rahman, Samsulida; Hasan, Md Rakibul

    2016-06-29

    A phenolic biosensor based on a zirconium oxide/polyethylene glycol/tyrosinase composite film for the detection of phenolic compounds has been explored. The formation of the composite film was expected via electrostatic interaction between hexacetyltrimethylammonium bromide (CTAB), polyethylene glycol (PEG), and zirconium oxide nanoparticles casted on screen printed carbon electrode (SPCE). Herein, the electrode was treated by casting hexacetyltrimethylammonium bromide on SPCE to promote a positively charged surface. Later, zirconium oxide was mixed with polyethylene glycol and the mixture was dropped cast onto the positively charged SPCE/CTAB. Tyrosinase was further immobilized onto the modified SPCE. Characterization of the prepared nanocomposite film and the modified SPCE surface was investigated by scanning electron microscopy (SEM), Electrochemical Impedance Spectroscopy (EIS), and Cyclic voltamogram (CV). The developed biosensor exhibits rapid response for less than 10 s. Two linear calibration curves towards phenol in the concentrations ranges of 0.075-10 µM and 10-55 µM with the detection limit of 0.034 µM were obtained. The biosensor shows high sensitivity and good storage stability for at least 30 days.

  4. Amperometric Biosensor Based on Zirconium Oxide/Polyethylene Glycol/Tyrosinase Composite Film for the Detection of Phenolic Compounds

    Directory of Open Access Journals (Sweden)

    Nor Monica Ahmad

    2016-06-01

    Full Text Available A phenolic biosensor based on a zirconium oxide/polyethylene glycol/tyrosinase composite film for the detection of phenolic compounds has been explored. The formation of the composite film was expected via electrostatic interaction between hexacetyltrimethylammonium bromide (CTAB, polyethylene glycol (PEG, and zirconium oxide nanoparticles casted on screen printed carbon electrode (SPCE. Herein, the electrode was treated by casting hexacetyltrimethylammonium bromide on SPCE to promote a positively charged surface. Later, zirconium oxide was mixed with polyethylene glycol and the mixture was dropped cast onto the positively charged SPCE/CTAB. Tyrosinase was further immobilized onto the modified SPCE. Characterization of the prepared nanocomposite film and the modified SPCE surface was investigated by scanning electron microscopy (SEM, Electrochemical Impedance Spectroscopy (EIS, and Cyclic voltamogram (CV. The developed biosensor exhibits rapid response for less than 10 s. Two linear calibration curves towards phenol in the concentrations ranges of 0.075–10 µM and 10–55 µM with the detection limit of 0.034 µM were obtained. The biosensor shows high sensitivity and good storage stability for at least 30 days.

  5. Composite Structure Monitoring using Direct Write Sensors, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This NASA SBIR Phase II project seeks to develop and demonstrate a suite of sensor products to monitor the health of composite structures. Sensors will be made using...

  6. Amperometric glucose sensor based on enhanced catalytic reduction of oxygen using glucose oxidase adsorbed onto core-shell Fe{sub 3}O{sub 4}-silica-Au magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wang Aijun [College of Geography and Environmental Science, College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004 (China); Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Environmental Science, Henan Normal University, Xinxiang 453007 (China); Li Yongfang [College of Chemistry and Chemical Engineering, Henan Institute of Science and Technology, Xinxiang 453003 (China); Li Zhonghua [Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Environmental Science, Henan Normal University, Xinxiang 453007 (China); Feng Jiuju, E-mail: jjfengnju@gmail.com [College of Geography and Environmental Science, College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004 (China); Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Environmental Science, Henan Normal University, Xinxiang 453007 (China); Sun Yanli [Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Environmental Science, Henan Normal University, Xinxiang 453007 (China); Chen Jianrong [College of Geography and Environmental Science, College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004 (China)

    2012-08-01

    Monodisperse Fe{sub 3}O{sub 4} magnetic nanoparticles (NPs) were prepared under facile solvothermal conditions and successively functionalized with silica and Au to form core/shell Fe{sub 3}O{sub 4}-silica-Au NPs. Furthermore, the samples were used as matrix to construct a glucose sensor based on glucose oxidase (GOD). The immobilized GOD retained its bioactivity with high protein load of 3.92 Multiplication-Sign 10{sup -9} mol{center_dot}cm{sup -2}, and exhibited a surface-controlled quasi-reversible redox reaction, with a fast heterogeneous electron transfer rate of 7.98 {+-} 0.6 s{sup -1}. The glucose biosensor showed a broad linear range up to 3.97 mM with high sensitivity of 62.45 {mu}A{center_dot}mM{sup -1} cm{sup -2} and fast response (less than 5 s). - Graphical abstract: Core-shell structured Fe{sub 3}O{sub 4}-silica-Au nanoparticles were prepared and used as matrix to construct an amperometric glucose sensor based on glucose oxidase, which showed broad linear range, high sensitivity, and fast response. Highlights: Black-Right-Pointing-Pointer Synthesis of monodispersed Fe{sub 3}O{sub 4} nanoparticles. Black-Right-Pointing-Pointer Fabrication of core/shell Fe{sub 3}O{sub 4}-silica-Au nanoparticles. Black-Right-Pointing-Pointer Construction of a novel glucose sensor with wide linear range, high sensitivity and fast response.

  7. Optimization of sensor introduction into laminated composite materials

    Science.gov (United States)

    Schaaf, Kristin; Nemat-Nasser, Sia

    2008-03-01

    This work seeks to extend the functionality of the composite material beyond that of simply load-bearing and to enable in situ sensing, without compromising the structural integrity of the host composite material. Essential to the application of smart composites is the issue of the mechanical coupling of the sensor to the host material. Here we present various methods of embedding sensors within the host composite material. In this study, quasi-static three-point bending (short beam) and fatigue three-point bending (short beam) tests are conducted in order to characterize the effects of introducing the sensors into the host composite material. The sensors that are examined include three types of polyvinylidene fluoride (PVDF) thin film sensors: silver ink with a protective coating of urethane, silver ink without a protective coating, and nickel-copper alloy without a protective coating. The methods of sensor integration include placement at the midplane between the layers of prepreg material as well as a sandwich configuration in which a PVDF thin film sensor is placed between the first and second and nineteenth and twentieth layers of prepreg. Each PVDF sensor is continuous and occupies the entire layer, lying in the plane normal to the thickness direction in laminated composites. The work described here is part of an ongoing effort to understand the structural effects of integrating microsensor networks into a host composite material.

  8. Melt quenched vanadium oxide embedded in graphene oxide sheets as composite electrodes for amperometric dopamine sensing and lithium ion battery applications

    Science.gov (United States)

    Sreejesh, M.; Shenoy, Sulakshana; Sridharan, Kishore; Kufian, D.; Arof, A. K.; Nagaraja, H. S.

    2017-07-01

    Electrochemical sensors and lithium-ion batteries are two important topics in electrochemistry that have attracted much attention owing to their extensive applications in enzyme-free biosensors and portable electronic devices. Herein, we report a simple hydrothermal approach for synthesizing composites of melt quenched vanadium oxide embedded on graphene oxide of equal proportion (MVGO50) for the fabrication of electrodes for nonenzymatic amperometic dopamine sensor and lithium-ion battery applications. The sensing performance of MVGO50 electrodes through chronoamperometry studies in 0.1 M PBS solution (at pH 7) over a wide range of dopamine concentration exhibited a highest sensitivity of 25.02 μA mM-1 cm-2 with the lowest detection limit of 0.07 μM. In addition, the selective sensing capability of MVGO50 was also tested through chronoamperometry studies by the addition of a very small concentration of dopamine (10 μM) in the presence of a fairly higher concentration of uric acid (10 mM) as the interfering species. Furthermore, the reversible lithium cycling properties of MVGO50 are evaluated by galvanostatic charge-discharge cycling studies. MVGO50 electrodes exhibited enhanced rate capacity of up to 200 mAhg-1 at a current of 0.1C rate and remained stable during cycling. These results indicate that MVGO composites are potential candidates for electrochemical device applications.

  9. Embedded Bragg grating fiber optic sensor for composite flexbeams

    Science.gov (United States)

    Bullock, Daniel; Dunphy, James; Hufstetler, Gerard

    1993-03-01

    An embedded fiber-optic (F-O) sensor has been developed for translaminar monitoring of the structural integrity of composites, with a view to application in composite helicopter flexbeams for bearingless main rotor hubs. This through-thickness strain sensor is much more sensitive than conventional in-plane embedded F-O sensors to ply delamination, on the basis of a novel insertion technique and innovative Bragg grating sensor. Experimental trials have demonstrated the detection by this means of potential failures in advance of the edge-delamination or crack-propagation effect.

  10. Melt quenched vanadium oxide embedded in graphene oxide sheets as composite electrodes for amperometric dopamine sensing and lithium ion battery applications

    Energy Technology Data Exchange (ETDEWEB)

    Sreejesh, M. [Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India); Shenoy, Sulakshana [Functional Nanostructured Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India); Sridharan, Kishore, E-mail: kishore@nitk.edu.in [Functional Nanostructured Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India); Kufian, D.; Arof, A.K. [Centre for Ionics, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Nagaraja, H.S., E-mail: nagaraja@nitk.edu.in [Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India)

    2017-07-15

    Highlights: • Layered vanadium oxides (MVO) are prepared through melt quenching process. • MVO is hydrothermally treated with graphene oxide to form MVGO composites. • Dopamine detection capacity using MVGO is 0.07 μM with good selectivity. • Sensitivity of dopamine detection is 25.02 μA mM{sup −1} cm{sup −2}. • Discharge capacity of MVGO electrode is 200 mAhg{sup −1} after 10 cycles. - Abstract: Electrochemical sensors and lithium-ion batteries are two important topics in electrochemistry that have attracted much attention owing to their extensive applications in enzyme-free biosensors and portable electronic devices. Herein, we report a simple hydrothermal approach for synthesizing composites of melt quenched vanadium oxide embedded on graphene oxide of equal proportion (MVGO50) for the fabrication of electrodes for nonenzymatic amperometic dopamine sensor and lithium-ion battery applications. The sensing performance of MVGO50 electrodes through chronoamperometry studies in 0.1 M PBS solution (at pH 7) over a wide range of dopamine concentration exhibited a highest sensitivity of 25.02 μA mM{sup −1} cm{sup −2} with the lowest detection limit of 0.07 μM. In addition, the selective sensing capability of MVGO50 was also tested through chronoamperometry studies by the addition of a very small concentration of dopamine (10 μM) in the presence of a fairly higher concentration of uric acid (10 mM) as the interfering species. Furthermore, the reversible lithium cycling properties of MVGO50 are evaluated by galvanostatic charge-discharge cycling studies. MVGO50 electrodes exhibited enhanced rate capacity of up to 200 mAhg{sup −1} at a current of 0.1C rate and remained stable during cycling. These results indicate that MVGO composites are potential candidates for electrochemical device applications.

  11. Ethylene vinylacetate copolymer and nanographite composite as chemical vapour sensor

    International Nuclear Information System (INIS)

    Stepina, Santa; Sakale, Gita; Knite, Maris

    2013-01-01

    Polymer-nanostructured carbon composite as chemical vapour sensor is described, made by the dissolution method of a non-conductive polymer, ethylene vinylacetate copolymer, mixed with conductive nanographite particles (carbon black). Sensor exhibits relative electrical resistance change in chemical vapours, like ethanol and toluene. Since the sensor is relatively cheap, easy to fabricate, it can be used in air quality monitoring and at industries to control hazardous substance concentration in the air, for example, to protect workers from exposure to chemical spills

  12. A model for ionic polymer metal composites as sensors

    Science.gov (United States)

    Bonomo, C.; Fortuna, L.; Giannone, P.; Graziani, S.; Strazzeri, S.

    2006-06-01

    This paper introduces a comprehensive model of sensors based on ionic polymer metal composites (IPMCs) working in air. Significant quantities ruling the sensing properties of IPMC-based sensors are taken into account and the dynamics of the sensors are modelled. A large amount of experimental evidence is given for the excellent agreement between estimations obtained using the proposed model and the observed signals. Furthermore, the effect of sensor scaling is investigated, giving interesting support to the activities involved in the design of sensing devices based on these novel materials. We observed that the need for a wet environment is not a key issue for IPMC-based sensors to work well. This fact allows us to put IPMC-based sensors in a totally different light to the corresponding actuators, showing that sensors do not suffer from the same drawbacks.

  13. Cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode as electrochemical sensor on microfluidic chip

    International Nuclear Information System (INIS)

    Li Xinchun; Chen Zuanguang; Zhong Yuwen; Yang Fan; Pan Jianbin; Liang Yajing

    2012-01-01

    Highlights: ► CoHCF nanoparticles modified MWCNTs/graphite electrode use for electrochemistry on electrophoresis microchip for the first time. ► Simultaneous, rapid, and sensitive electrochemical detection of hydrazine and isoniazid in real samples. ► An exemplary work of CME sensor assembly onto microchip for determination of analytes with environmental significance. ► Manifestation of the applicability and flexibility of CME sensor for electroanalysis on microfluidic chip. - Abstract: Nanomaterial-based electrochemical sensor has received significant interest. In this work, cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode was electrochemically prepared and exploited as an amperometric detector for microchip electrophoresis. The prepared sensor displayed rapid and sensitive response towards hydrazine and isoniazid oxidation, which was attributed to synergetic electrocatalytic effect of cobalt hexacyanoferrate and multi-walled carbon nanotubes. The sensitivity enhancement with nearly two orders of magnitude was gained, compared with the bare carbon paste electrode, with the detection limit of 0.91 μM (S/N = 3) for hydrazine. Acceptable repeatability of the microanalysis system was verified by consecutive eleven injections of hydrazine without chip and electrode treatments, the RSDs for peak current and migration time were 3.4% and 2.1%, respectively. Meanwhile, well-shaped electrophoretic peaks were observed, mainly due to fast electron transfer of electroactive species on the modified electrode. The developed microchip-electrochemistry setup was successfully applied to the determination of hydrazine and isoniazid in river water and pharmaceutical preparation, respectively. Several merits of the novel electrochemical sensor coupled with microfluidic platform, such as comparative stability, easy fabrication and high sensitivity, hold great potential for hydrazine compounds assay in the lab-on-a-chip system.

  14. Cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode as electrochemical sensor on microfluidic chip

    Energy Technology Data Exchange (ETDEWEB)

    Li Xinchun [School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road of Higher Education Mega Centre, Guangzhou 510006 (China); Chen Zuanguang, E-mail: chenzg@mail.sysu.edu.cn [School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road of Higher Education Mega Centre, Guangzhou 510006 (China); Zhong Yuwen, E-mail: yu0106@163.com [Center for Disease Control and Prevention of Guangdong Province, 176 Xingangxi, Guangzhou 510300 (China); Yang Fan; Pan Jianbin; Liang Yajing [School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road of Higher Education Mega Centre, Guangzhou 510006 (China)

    2012-01-13

    Highlights: Black-Right-Pointing-Pointer CoHCF nanoparticles modified MWCNTs/graphite electrode use for electrochemistry on electrophoresis microchip for the first time. Black-Right-Pointing-Pointer Simultaneous, rapid, and sensitive electrochemical detection of hydrazine and isoniazid in real samples. Black-Right-Pointing-Pointer An exemplary work of CME sensor assembly onto microchip for determination of analytes with environmental significance. Black-Right-Pointing-Pointer Manifestation of the applicability and flexibility of CME sensor for electroanalysis on microfluidic chip. - Abstract: Nanomaterial-based electrochemical sensor has received significant interest. In this work, cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode was electrochemically prepared and exploited as an amperometric detector for microchip electrophoresis. The prepared sensor displayed rapid and sensitive response towards hydrazine and isoniazid oxidation, which was attributed to synergetic electrocatalytic effect of cobalt hexacyanoferrate and multi-walled carbon nanotubes. The sensitivity enhancement with nearly two orders of magnitude was gained, compared with the bare carbon paste electrode, with the detection limit of 0.91 {mu}M (S/N = 3) for hydrazine. Acceptable repeatability of the microanalysis system was verified by consecutive eleven injections of hydrazine without chip and electrode treatments, the RSDs for peak current and migration time were 3.4% and 2.1%, respectively. Meanwhile, well-shaped electrophoretic peaks were observed, mainly due to fast electron transfer of electroactive species on the modified electrode. The developed microchip-electrochemistry setup was successfully applied to the determination of hydrazine and isoniazid in river water and pharmaceutical preparation, respectively. Several merits of the novel electrochemical sensor coupled with microfluidic platform, such as comparative stability, easy fabrication and

  15. A novel way for detection of antiparkinsonism drug entacapone via electrodeposition of silver nanoparticles/functionalized multi-walled carbon nanotubes as an amperometric sensor

    Energy Technology Data Exchange (ETDEWEB)

    Baghayeri, Mehdi, E-mail: m.baghayeri@hsu.ac.ir [Department of Chemistry, Faculty of Science, Hakim Sabzevari University, P.O. Box 397, Sabzevar (Iran, Islamic Republic of); Tehrani, Maliheh Barazandeh [Department of Medicinal Chemistry, Faculty of Pharmacy, Pharmaceutical Research Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Amiri, Amirhassan; Maleki, Behrooz; Farhadi, Samaneh [Department of Chemistry, Faculty of Science, Hakim Sabzevari University, P.O. Box 397, Sabzevar (Iran, Islamic Republic of)

    2016-09-01

    Silver (Ag) nanoparticles were electrochemically deposited on the film of a metformin functionalized multi-walled carbon nanotube modified glassy carbon electrode (Met-MWCNT/GCE), which fabricated an Ag@Met-MWCNT nanocomposite sensor (Ag@Met-MWCNT/GCE) to detect entacapone (ENT). The Ag@Met-MWCNT nanocomposite was characterized by field emission scanning electrochemical microscopy (FESEM), X-ray diffraction (XRD) analysis, FT-IR and electrochemical tests. The modified electrode showed a large electrocatalytic activity for reduction of ENT. This improved activity indicates that Met@MWCNT plays a crucial role in the dispersion and stabilization of Ag nanoparticles on GCE. Under the optimized conditions the linear range for the detection of the ENT was obtained to be 0.05 to 70.0 μM with a low detection limit of 15.3 nM. The proposed sensor can effectively analyse ENT concentration in pharmaceutical formulations and human urine samples, avoiding interference, and is a promising ENT sensor due to good sensitivity, stability and low cost. - Graphical abstract: Schematic graph for fabrication and application of sensor. Display Omitted - Highlights: • Silver nanoparticles were electrochemically deposited on the modified glassy carbon electrode. • The modified electrode showed a large electrocatalytic activity for reduction of entacapone. • The proposed sensor can effectively analyse entacapone concentration in pharmaceutical formulations and human urine samples.

  16. Amperometric glucose sensor based on the Ni(OH){sub 2}/Al(OH){sub 4}{sup −} electrode obtained from a thin Ni{sub 3}Al foil

    Energy Technology Data Exchange (ETDEWEB)

    Jarosz, Magdalena, E-mail: jarosz@chemia.uj.edu.pl [Department of Physical Chemistry and Electrochemistry, Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30060 Krakow (Poland); Socha, Robert P. [Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, Niezapominajek 8, 30239 Krakow (Poland); Jóźwik, Paweł [Faculty of Advanced Technology and Chemistry, Military University of Technology, Kaliskiego 2, 00908 Warsaw (Poland); Sulka, Grzegorz D. [Department of Physical Chemistry and Electrochemistry, Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30060 Krakow (Poland)

    2017-06-30

    Highlights: • Chemical etching of Ni{sub 3}Al alloy in an acidic mixture was performed. • Electrochemical activity of samples was achieved by their oxidation in NaOH. • Ni(OH){sub 2}/Al(OH){sub 4}{sup −} electrode showed electrochemical activity towards glucose. • Synthesized material is characterized by high sensitivity and short response time. - Abstract: In this report, we present a facile and relatively fast method to roughen the surface of Ni{sub 3}Al–based intermetallic foil, and test it as an amperometric non-enzymatic glucose sensor. The alloy samples underwent chemical etching in a H{sub 3}PO{sub 4}:CH{sub 3}COOH (HAc):HNO{sub 3}:H{sub 2}O (24:1:1:7 in volume) solution in order to achieve a high surface area with more electroactive sites. The Ni(OH){sub 2}/Al(OH){sub 4}{sup −} electrode was fabricated using potential cycling technique in a highly concentrated alkaline solution. The electrodes were tested electrochemically for oxidation of glucose. We have demonstrated that Ni(OH){sub 2}/Al(OH){sub 4}{sup −} electrodes exhibit high sensitivity towards glucose detection (796 μAmM{sup -1}cm{sup -2}) and short response time (3 s) upon successive addition of glucose. Moreover, as for a non-nanometric material, prepared electrodes show a relatively good linear correlation between current density and glucose concentration (0.025–0.45 mM) and limit of detection (47.6 μM). For more in-depth characterization of presented material, electrodes were examined using scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).

  17. A highly sensitive amperometric sensor for oxygen based on iron(II) tetrasulfonated phthalocyanine and iron(III) tetra-(N-methyl-pyridyl)-porphyrin multilayers

    International Nuclear Information System (INIS)

    Duarte, Juliana C.; Luz, Rita C.S.; Damos, Flavio S.; Tanaka, Auro A.; Kubota, Lauro T.

    2008-01-01

    The development of a highly sensitive sensor for oxygen is proposed using a glassy carbon (GC) electrode modified with alternated layers of iron(II) tetrasulfonated phthalocyanine (FeTsPc) and iron(III) tetra-(N-methyl-pyridyl)-porphyrin (FeT4MPyP). The modified electrode showed excellent catalytic activity for the oxygen reduction. The reduction potential of the oxygen was shifted about 330 mV toward less negative values with this modified electrode, presenting a peak current much higher than those observed on a bare GC electrode. Cyclic voltammetry and rotating disk electrode (RDE) experiments indicated that the oxygen reduction reaction involves 4 electrons with a heterogenous rate constant (k obs ) of 3 x 10 5 mol -1 L s -1 . A linear response range from 0.2 up to 6.4 mg L -1 , with a sensitivity of 4.12 μA L mg -1 (or 20.65 μA cm -2 L mg -1 ) and a detection limit of 0.06 mg L -1 were obtained with this sensor. The repeatability of the proposed sensor, evaluated in terms of relative standard deviation (R.S.D.) was 2.0% for 10 measurements of a solution of 6.4 mg L -1 oxygen. The sensor was applied to determine oxygen in pond and tap water samples showing to be a promising tool for this purpose

  18. A novel nonenzymatic hydrogen peroxide amperometric sensor based on Pd@CeO2-NH2 nanocomposites modified glassy carbon electrode.

    Science.gov (United States)

    Guler, Muhammet; Turkoglu, Vedat; Kivrak, Arif; Karahan, Fatih

    2018-09-01

    Herein, (3-aminopropyl)triethoxysilane functionalized cerium (IV) oxide (CeO 2 -NH 2 ) supported Pd nanoparticles were synthesized. The nanocomposites were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and High-resolution transmission electron microscopy (HRTEM). The Pd@CeO 2 -NH 2 showed better electrocatalytic response to the reduction of H 2 O 2 than CeO 2 -NH 2 . The fabricated sensor exhibited two linear responses to the reduction of H 2 O 2 . The first one was from 0.001 to 3.276 mM with 0.47 μM of a limit of detection (LOD) (S/N = 3) and excellent sensitivity of 440.72 μA mM -1  cm -2 and the second one was from 3.276 to 17.500 mM with the sensitivity of 852.65 μA mM -1  cm -2 in the optimum conductions. Also, the sensor exhibited 91% of electrocatalytic activity toward H 2 O 2 after having been used for 30 days and the reproducibility was also satisfactory. The sensor response to H 2 O 2 was not affected by ascorbic acid, fructose, glycine, dopamine, arginine, mannose, glucose, uric acid, Mg +2 , Ca +2 , and phenylalanine at the studied potential. Also, the fabricated sensor was used to determine H 2 O 2 in milk samples. The results show that the constructed sensor can be a promising devise for the determination of H 2 O 2 in real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Amperometric L-cysteine sensor based on a carbon paste electrode modified with Y_2O_3 nanoparticles supported on nitrogen-doped reduced graphene oxide

    International Nuclear Information System (INIS)

    Yang, Suling; Li, Gang; Wang, Yuanyuan; Wang, Guifang; Qu, Lingbo

    2016-01-01

    We describe an electrochemical sensor for L-cysteine that is based on the use of Y_2O_3 nanoparticles (Y_2O_3-NPs) supported on nitrogen-doped reduced graphene oxide (N-rGO). The material was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and electrochemical methods. Deposited on a carbon paste electrode, the material displays a strongly oxidation peak for L-cysteine at pH 7.0 (compared to an unmodified electrode). The current, measured at a potential 0.7 V (vs. Ag/AgCl), increases linearly in the 1.3 to 720 μM L-cysteine concentration range, and the detection limit is 0.8 μM. The sensor was successfully applied to the determination L-cysteine in spiked syrup. (author)

  20. Electrodeposition of gold-platinum alloy nanoparticles on ionic liquid-chitosan composite film and its application in fabricating an amperometric cholesterol biosensor.

    Science.gov (United States)

    Safavi, Afsaneh; Farjami, Fatemeh

    2011-01-15

    An electrodeposition method was applied to form gold-platinum (AuPt) alloy nanoparticles on the glassy carbon electrode (GCE) modified with a mixture of an ionic liquid (IL) and chitosan (Ch) (AuPt-Ch-IL/GCE). AuPt nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical methods. AuPt-Ch-IL/GCE electrocatalyzed the reduction of H(2)O(2) and thus was suitable for the preparation of biosensors. Cholesterol oxidase (ChOx) was then, immobilized on the surface of the electrode by cross-linking ChOx and chitosan through addition of glutaraldehyde (ChOx/AuPt-Ch-IL/GCE). The fabricated biosensor exhibited two wide linear ranges of responses to cholesterol in the concentration ranges of 0.05-6.2 mM and 6.2-11.2 mM. The sensitivity of the biosensor was 90.7 μA mM(-1) cm(-2) and the limit of detection was 10 μM of cholesterol. The response time was less than 7 s. The Michaelis-Menten constant (K(m)) was found as 0.24 mM. The effect of the addition of 1 mM ascorbic acid and glucose was tested on the amperometric response of 0.5 mM cholesterol and no change in response current of cholesterol was observed. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. Coplanar capacitance sensors for detecting water intrusion in composite structures

    International Nuclear Information System (INIS)

    Nassr, Amr A; El-Dakhakhni, Wael W; Ahmed, Wael H

    2008-01-01

    Composite materials are becoming more affordable and widely used for retrofitting, rehabilitating and repairing reinforced concrete structures designed and constructed under older specifications. However, the mechanical properties and long-term durability of composite materials may degrade severely in the presence of water intrusion. This study presents a new non-destructive evaluation (NDE) technique for detecting the water intrusion in composite structures by evaluating the dielectric properties of different composite system constituent materials. The variation in the dielectric signatures was employed to design a coplanar capacitance sensor with high sensitivity to detect such defects. An analytical model was used to study the effect of the sensor geometry on the output signal and to optimize sensor design. A finite element model was developed to validate analytical results and to evaluate other sensor design-related parameters. Experimental testing of a concrete specimen wrapped with composite laminate and containing a series of pre-induced water intrusion defects was conducted in order to validate the concept of the new technique. Experimental data showed excellent agreement with the finite element model predictions and confirmed sensor performance

  2. EXPERIMENTAL SENSOR OF THE BENZOETHANOL COMPOSITION FOR ENGINE FUEL SYSTEM

    Directory of Open Access Journals (Sweden)

    V. Bgantsev

    2017-12-01

    Full Text Available An important aspect of the economy of internal combustion engine on benzoethanol is the accuracy of regulation of the fuel-air mixture composition. This task is complicated by fluctuations in the composition of benzoethanol, depending on the refueling of the vehicle at various filling stations. In this connection, there is a need to control the composition of benzoethanol in the fuel system of the engine and adjust the fuel supply system. With this purpose, fuel systems are equipped with special sensors that generate a signal, depending on the alcohol content of the mixed fuel. In the article one of the design solutions of the experimental sensor of the benzoethanol composition and the results of its testing with fuels of various composition are given.

  3. Highly sensitive amperometric sensor for micromolar detection of trichloroacetic acid based on multiwalled carbon nanotubes and Fe(II)–phtalocyanine modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Kurd, Masoumeh; Salimi, Abdollah; Hallaj, Rahman

    2013-01-01

    A highly sensitive electrochemical sensor for the detection of trichloroacetic acid (TCA) is developed by subsequent immobilization of phthalocyanine (Pc) and Fe(II) onto multiwalled carbon nanotubes (MWCNTs) modified glassy carbon (GC) electrode. The GC/MWCNTs/Pc/Fe(II) electrode showed a pair of well-defined and nearly reversible redox couple correspondent to (Fe(III)Pc/Fe(II)Pc) with surface-confined characteristics. The surface coverage (Γ) and heterogeneous electron transfer rate constant (k s ) of immobilized Fe(II)–Pc were calculated as 1.26 × 10 −10 mol cm −2 and 28.13 s −1 , respectively. Excellent electrocatalytic activity of the proposed GC/MWCNTs/Pc/Fe(II) system toward TCA reduction has been indicated and the three consequent irreversible peaks for electroreduction of CCl 3 COOH to CH 3 COOH have been clearly seen. The observed chronoamperometric currents are linearly increased with the concentration of TCA at concentration range up to 20 mM. Detection limit and sensitivity of the modified electrode were 2.0 μM and 0.10 μA μM −1 cm −2 , respectively. The applicability of the sensor for TCA detection in real samples was tested. The obtained results suggest that the proposed system can serve as a promising electrochemical platform for TCA detection. Highlights: ► Phthalocyanine (PC) and Fe(II) immobilized onto MWCNTs modified GC electrode. ► A pair of well-defined redox couple correspondent to (Fe(III)Pc/Fe(II)Pc) observed. ► Modified electrode shows excellent catalytic activity to electroreduction of CCl 3 COOH. ► Amperometry and cyclic voltammetry techniques were used for detection of CCl 3 COOH. ► Detection limit and sensitivity were 2.0 μM and 0.10 μA μM −1 cm −2 , respectively

  4. Process monitoring of fibre reinforced composites using optical fibre sensors

    Energy Technology Data Exchange (ETDEWEB)

    Fernando, G.F.; Degamber, B.

    2006-04-15

    The deployment of optical fibre based sensor systems for process monitoring of advanced fibre reinforced organic matrix composites is reviewed. The focus is on thermosetting resins and the various optical and spectroscopy-based techniques that can be used to monitor the processing of these materials. Following brief consideration of the manufacturing methods commonly used in the production of thermoset based composites, a discussion is presented on sensor systems that can be used to facilitate real-time chemical process monitoring. Although the focus is on thermosets, the techniques described can be adapted for chemical monitoring of organic species in general. (author)

  5. Highly sensitive amperometric sensor for micromolar detection of trichloroacetic acid based on multiwalled carbon nanotubes and Fe(II)–phtalocyanine modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Kurd, Masoumeh [Department of Chemistry, University of Kurdistan, P. O. Box 416, Sanandaj (Iran, Islamic Republic of); Salimi, Abdollah, E-mail: absalimi@uok.ac.ir [Department of Chemistry, University of Kurdistan, P. O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P. O. Box 416, Sanandaj (Iran, Islamic Republic of); Hallaj, Rahman [Department of Chemistry, University of Kurdistan, P. O. Box 416, Sanandaj (Iran, Islamic Republic of)

    2013-04-01

    A highly sensitive electrochemical sensor for the detection of trichloroacetic acid (TCA) is developed by subsequent immobilization of phthalocyanine (Pc) and Fe(II) onto multiwalled carbon nanotubes (MWCNTs) modified glassy carbon (GC) electrode. The GC/MWCNTs/Pc/Fe(II) electrode showed a pair of well-defined and nearly reversible redox couple correspondent to (Fe(III)Pc/Fe(II)Pc) with surface-confined characteristics. The surface coverage (Γ) and heterogeneous electron transfer rate constant (k{sub s}) of immobilized Fe(II)–Pc were calculated as 1.26 × 10{sup −10} mol cm{sup −2} and 28.13 s{sup −1}, respectively. Excellent electrocatalytic activity of the proposed GC/MWCNTs/Pc/Fe(II) system toward TCA reduction has been indicated and the three consequent irreversible peaks for electroreduction of CCl{sub 3}COOH to CH{sub 3}COOH have been clearly seen. The observed chronoamperometric currents are linearly increased with the concentration of TCA at concentration range up to 20 mM. Detection limit and sensitivity of the modified electrode were 2.0 μM and 0.10 μA μM{sup −1} cm{sup −2}, respectively. The applicability of the sensor for TCA detection in real samples was tested. The obtained results suggest that the proposed system can serve as a promising electrochemical platform for TCA detection. Highlights: ► Phthalocyanine (PC) and Fe(II) immobilized onto MWCNTs modified GC electrode. ► A pair of well-defined redox couple correspondent to (Fe(III)Pc/Fe(II)Pc) observed. ► Modified electrode shows excellent catalytic activity to electroreduction of CCl{sub 3}COOH. ► Amperometry and cyclic voltammetry techniques were used for detection of CCl{sub 3}COOH. ► Detection limit and sensitivity were 2.0 μM and 0.10 μA μM{sup −1} cm{sup −2}, respectively.

  6. Improved Internal Reference Oxygen Sensors with Composite Ceramic Electrodes

    DEFF Research Database (Denmark)

    Hu, Qiang; Jacobsen, Torben; Hansen, Karin Vels

    2012-01-01

    Potentiometric oxygen sensors with an internal reference electrode, which uses the equilibrium pO2 of the binary mixture of Ni/NiO as the reference, are demonstrated. The cells employ Pt or composite ceramics as the sensing electrode. The cells are fabricated by a flexible and potentially low cost...... and performance are highly reproducible. The composite ceramics, based on strontium doped manganite and yttria doped zirconia, are proven superior over Pt to serve as the electrode material....

  7. A magnetostrictive composite-fiber Bragg Grating sensor.

    Science.gov (United States)

    Quintero, Sully M M; Braga, Arthur M B; Weber, Hans I; Bruno, Antonio C; Araújo, Jefferson F D F

    2010-01-01

    This paper presents a light and compact optical fiber Bragg Grating sensor for DC and AC magnetic field measurements. The fiber is coated by a thick layer of a magnetostrictive composite consisting of particles of Terfenol-D dispersed in a polymeric matrix. Among the different compositions for the coating that were tested, the best magnetostrictive response was obtained using an epoxy resin as binder and a 30% volume fraction of Terfenol-D particles with sizes ranging from 212 to 300 μm. The effect of a compressive preload in the sensor was also investigated. The achieved resolution was 0.4 mT without a preload or 0.3 mT with a compressive pre-stress of 8.6 MPa. The sensor was tested at magnetic fields of up to 750 mT under static conditions. Dynamic measurements were conducted with a magnetic unbalanced four-pole rotor.

  8. A Magnetostrictive Composite-Fiber Bragg Grating Sensor

    Directory of Open Access Journals (Sweden)

    Jefferson F. D. F. Araújo

    2010-08-01

    Full Text Available This paper presents a light and compact optical fiber Bragg Grating sensor for DC and AC magnetic field measurements. The fiber is coated by a thick layer of a magnetostrictive composite consisting of particles of Terfenol-D dispersed in a polymeric matrix. Among the different compositions for the coating that were tested, the best magnetostrictive response was obtained using an epoxy resin as binder and a 30% volume fraction of Terfenol-D particles with sizes ranging from 212 to 300 µm. The effect of a compressive preload in the sensor was also investigated. The achieved resolution was 0.4 mT without a preload or 0.3 mT with a compressive pre-stress of 8.6 MPa. The sensor was tested at magnetic fields of up to 750 mT under static conditions. Dynamic measurements were conducted with a magnetic unbalanced four-pole rotor

  9. Gas Composition Sensor for Natural Gas and Biogas

    NARCIS (Netherlands)

    Boersma, A.; Sweelsen, J.; Blokland, H.

    2016-01-01

    The calorific value of energetic gasses is an important parameter in the quality assessment of gas steams, and can be calculated from the chemical composition of the gas. An array of capacitive sensor electrodes was developed, each functionalized with a gas responsive coating to measure the

  10. A resonant force sensor based on ionic polymer metal composites

    International Nuclear Information System (INIS)

    Bonomo, Claudia; Fortuna, Luigi; Giannone, Pietro; Graziani, Salvatore; Strazzeri, Salvatore

    2008-01-01

    In this paper a novel force sensor, based on ionic polymer metal composites (IPMCs), is presented. The system has DC sensing capabilities and is able to work in the range of a few millinewtons. IPMCs are emerging materials used to realize motion actuators and sensors. An IPMC strip is activated in a beam fixed/simply-supported configuration. The beam is tightened at the simply-supported end by a force. This influences the natural resonant frequency of the beam; the value of the resonant frequency is used in the proposed system to estimate the force applied in the axial direction. The performance of the system based on the IPMC material has proved to be comparable with that of sensors based on other sensing mechanisms. This suggests the possibility of using this class of polymeric devices to realize PMEMS (plastic micro electrical mechanical systems) sensors

  11. A resonant force sensor based on ionic polymer metal composites

    Science.gov (United States)

    Bonomo, Claudia; Fortuna, Luigi; Giannone, Pietro; Graziani, Salvatore; Strazzeri, Salvatore

    2008-02-01

    In this paper a novel force sensor, based on ionic polymer metal composites (IPMCs), is presented. The system has DC sensing capabilities and is able to work in the range of a few millinewtons. IPMCs are emerging materials used to realize motion actuators and sensors. An IPMC strip is activated in a beam fixed/simply-supported configuration. The beam is tightened at the simply-supported end by a force. This influences the natural resonant frequency of the beam; the value of the resonant frequency is used in the proposed system to estimate the force applied in the axial direction. The performance of the system based on the IPMC material has proved to be comparable with that of sensors based on other sensing mechanisms. This suggests the possibility of using this class of polymeric devices to realize PMEMS (plastic micro electrical mechanical systems) sensors.

  12. Dynamic curvature sensing employing ionic-polymer–metal composite sensors

    International Nuclear Information System (INIS)

    Bahramzadeh, Yousef; Shahinpoor, Mohsen

    2011-01-01

    A dynamic curvature sensor is presented based on ionic-polymer–metal composite (IPMC) for curvature monitoring of deployable/inflatable dynamic space structures. Monitoring the curvature variation is of high importance in various engineering structures including shape monitoring of deployable/inflatable space structures in which the structural boundaries undergo a dynamic deployment process. The high sensitivity of IPMCs to the applied deformations as well as its flexibility make IPMCs a promising candidate for sensing of dynamic curvature changes. Herein, we explore the dynamic response of an IPMC sensor strip with respect to controlled curvature deformations subjected to different forms of input functions. Using a specially designed experimental setup, the voltage recovery effect, phase delay, and rate dependency of the output voltage signal of an IPMC curvature sensor are analyzed. Experimental results show that the IPMC sensor maintains the linearity, sensitivity, and repeatability required for curvature sensing. Besides, in order to describe the dynamic phenomena such as the rate dependency of the IPMC sensor, a chemo-electro-mechanical model based on the Poisson–Nernst–Planck (PNP) equation for the kinetics of ion diffusion is presented. By solving the governing partial differential equations the frequency response of the IPMC sensor is derived. The physical model is able to describe the dynamic properties of the IPMC sensor and the dependency of the signal on rate of excitations

  13. Amperometric Bioelectronic Tongue for glucose determination

    Directory of Open Access Journals (Sweden)

    Yazan Al-Issa

    2015-03-01

    Full Text Available An amperometric Bioelectronic Tongue is reported for glucose determination that contains eight sensor electrodes constructed using different metal electrodes (Pt, Au, oxidoreductase enzymes (glucose oxidase, ascorbate oxidase, uricase, and membrane coatings (Nafion, chitosan. The response to varying concentrations of glucose, ascorbic acid, uric acid, and acetaminophen was tested for two models, concentration determination by current density measurements at individual electrodes and concentration determination by a linear regression model for the entire electrode array. The reduced chi-squared for the full array model was found to be about one order of magnitude lower than that for the individual-electrode model. Discrimination of glucose from chemical interference by the other three species is accomplished through a combination of enzyme catalysis, metal electrocatalysis, and membrane surface charge. The benefit of incorporating enzyme electrodes into the sensor array is illustrated by the lower correlation coefficients between different enzyme electrodes relative to non-enzyme coated electrodes. This approach can be more generally applied to detection of other substrates of oxidoreductase enzymes.

  14. Bi-enzyme L-arginine-selective amperometric biosensor based on ammonium-sensing polyaniline-modified electrode.

    Science.gov (United States)

    Stasyuk, Nataliya; Smutok, Oleh; Gayda, Galina; Vus, Bohdan; Koval'chuk, Yevgen; Gonchar, Mykhailo

    2012-01-01

    A novel L-arginine-selective amperometric bi-enzyme biosensor based on recombinant human arginase I isolated from the gene-engineered strain of methylotrophic yeast Hansenula polymorpha and commercial urease is described. The biosensing layer was placed onto a polyaniline-Nafion composite platinum electrode and covered with a calcium alginate gel. The developed sensor revealed a good selectivity to L-arginine. The sensitivity of the biosensor was 110 ± 1.3 nA/(mM mm(2)) with the apparent Michaelis-Menten constant (K(M)(app)) derived from an L-arginine (L-Arg) calibration curve of 1.27 ± 0.29 mM. A linear concentration range was observed from 0.07 to 0.6mM, a limit of detection being 0.038 mM and a response time - 10s. The developed biosensor demonstrated good storage stability. A laboratory prototype of the proposed amperometric biosensor was applied to the samples of three commercial pharmaceuticals ("Tivortin", "Cytrarginine", "Aminoplazmal 10% E") for L-Arg testing. The obtained L-Arg-content values correlated well with those declared by producers. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. The effects of embedded piezoelectric fiber composite sensors on the structural integrity of glass-fiber–epoxy composite laminate

    International Nuclear Information System (INIS)

    Konka, Hari P; Wahab, M A; Lian, K

    2012-01-01

    Piezoelectric fiber composite sensors (PFCSs) made from micro-sized lead zirconate titanate (PZT) fibers have many advantages over the traditional bulk PZT sensors for embedded sensor applications. PFCSs as embedded sensors will be an ideal choice to continuously monitor the stress/strain levels and health conditions of composite structures. PFCSs are highly flexible, easily embeddable, have high compatibility with composite structures, and also provides manufacturing flexibility. This research is focused on examining the effects of embedding PFCS sensors (macro-fiber composite (MFC) and piezoelectric fiber composite (PFC)) on the structural integrity of glass-fiber–epoxy composite laminates. The strengths of composite materials with embedded PFCSs and conventional PZT sensors were compared, and the advantages of PFCS sensors over PZTs were demonstrated. Initially a numerical simulation study is performed to understand the local stress/strain field near the embedded sensor region inside a composite specimen. High stress concentration regions were observed near the embedded sensor corner edge. Using PFCS leads to a reduction of 56% in longitudinal stress concentration and 38% in transverse stress concentration, when compared to using the conventional PZTs as embedded sensors. In-plane tensile, in-plane tension–tension fatigue, and short beam strength tests are performed to evaluate the strengths/behavior of the composite specimens containing embedded PFCS. From the tensile test it is observed that embedding PFCS and PZT sensors in the composite structures leads to a reduction in ultimate strength by 3 and 6% respectively. From the fatigue test results it is concluded that both embedded PFCS and PZT sensors do not have a significant effect on the fatigue behavior of the composite specimens. From the short beam strength test it is found that embedding PFCS and PZT sensors leads to a reduction in shear strength by 7 and 15% respectively. Overall the pure PZT

  16. The effects of embedded piezoelectric fiber composite sensors on the structural integrity of glass-fiber-epoxy composite laminate

    Science.gov (United States)

    Konka, Hari P.; Wahab, M. A.; Lian, K.

    2012-01-01

    Piezoelectric fiber composite sensors (PFCSs) made from micro-sized lead zirconate titanate (PZT) fibers have many advantages over the traditional bulk PZT sensors for embedded sensor applications. PFCSs as embedded sensors will be an ideal choice to continuously monitor the stress/strain levels and health conditions of composite structures. PFCSs are highly flexible, easily embeddable, have high compatibility with composite structures, and also provides manufacturing flexibility. This research is focused on examining the effects of embedding PFCS sensors (macro-fiber composite (MFC) and piezoelectric fiber composite (PFC)) on the structural integrity of glass-fiber-epoxy composite laminates. The strengths of composite materials with embedded PFCSs and conventional PZT sensors were compared, and the advantages of PFCS sensors over PZTs were demonstrated. Initially a numerical simulation study is performed to understand the local stress/strain field near the embedded sensor region inside a composite specimen. High stress concentration regions were observed near the embedded sensor corner edge. Using PFCS leads to a reduction of 56% in longitudinal stress concentration and 38% in transverse stress concentration, when compared to using the conventional PZTs as embedded sensors. In-plane tensile, in-plane tension-tension fatigue, and short beam strength tests are performed to evaluate the strengths/behavior of the composite specimens containing embedded PFCS. From the tensile test it is observed that embedding PFCS and PZT sensors in the composite structures leads to a reduction in ultimate strength by 3 and 6% respectively. From the fatigue test results it is concluded that both embedded PFCS and PZT sensors do not have a significant effect on the fatigue behavior of the composite specimens. From the short beam strength test it is found that embedding PFCS and PZT sensors leads to a reduction in shear strength by 7 and 15% respectively. Overall the pure PZT sensors

  17. Amperometric Sensor for Detection of Chloride Ions

    Directory of Open Access Journals (Sweden)

    Rene Kizek

    2008-09-01

    Full Text Available Chloride ion sensing is important in many fields such as clinical diagnosis, environmental monitoring and industrial applications. We have measured chloride ions at a carbon paste electrode (CPE and at a CPE modified with solid AgNO3, a solution of AgNO3 and/or solid silver particles. Detection limits (3 S/N for chloride ions were 100 μM, 100 μM and 10 μM for solid AgNO3, solution of AgNO3 and/or solid silver particles, respectively. The CPE modified with silver particles is the most sensitive to the presence chloride ions. After that we approached to the miniaturization of the whole electrochemical instrument. Measurements were carried out on miniaturized instrument consisting of a potentiostat with dimensions 35 × 166 × 125 mm, screen printed electrodes, a peristaltic pump and a PC with control software. Under the most suitable experimental conditions (Britton-Robinson buffer, pH 1.8 and working electrode potential 550 mV we estimated the limit of detection (3 S/N as 500 nM.

  18. Amperometric Sensor for Detection of Chloride Ions†

    Science.gov (United States)

    Trnkova, Libuse; Adam, Vojtech; Hubalek, Jaromir; Babula, Petr; Kizek, Rene

    2008-01-01

    Chloride ion sensing is important in many fields such as clinical diagnosis, environmental monitoring and industrial applications. We have measured chloride ions at a carbon paste electrode (CPE) and at a CPE modified with solid AgNO3, a solution of AgNO3 and/or solid silver particles. Detection limits (3 S/N) for chloride ions were 100 μM, 100 μM and 10 μM for solid AgNO3, solution of AgNO3 and/or solid silver particles, respectively. The CPE modified with silver particles is the most sensitive to the presence chloride ions. After that we approached to the miniaturization of the whole electrochemical instrument. Measurements were carried out on miniaturized instrument consisting of a potentiostat with dimensions 35 × 166 × 125 mm, screen printed electrodes, a peristaltic pump and a PC with control software. Under the most suitable experimental conditions (Britton-Robinson buffer, pH 1.8 and working electrode potential 550 mV) we estimated the limit of detection (3 S/N) as 500 nM. PMID:27873832

  19. Amperometric Sensor for Detection of Chloride Ions.

    Science.gov (United States)

    Trnkova, Libuse; Adam, Vojtech; Hubalek, Jaromir; Babula, Petr; Kizek, Rene

    2008-09-15

    Chloride ion sensing is important in many fields such as clinical diagnosis, environmental monitoring and industrial applications. We have measured chloride ions at a carbon paste electrode (CPE) and at a CPE modified with solid AgNO₃, a solution of AgNO₃ and/or solid silver particles. Detection limits (3 S/N) for chloride ions were 100 μM, 100 μM and 10 μM for solid AgNO₃, solution of AgNO₃ and/or solid silver particles, respectively. The CPE modified with silver particles is the most sensitive to the presence chloride ions. After that we approached to the miniaturization of the whole electrochemical instrument. Measurements were carried out on miniaturized instrument consisting of a potentiostat with dimensions 35 × 166 × 125 mm, screen printed electrodes, a peristaltic pump and a PC with control software. Under the most suitable experimental conditions (Britton-Robinson buffer, pH 1.8 and working electrode potential 550 mV) we estimated the limit of detection (3 S/N) as 500 nM.

  20. Fuzzy Fiber Sensors for Structural Composite Health Monitoring (Preprint)

    Science.gov (United States)

    2011-12-01

    fuzzy fibers to applied strain was measured in the following configurations: individual fiber, fiber tow, tow in matrix, and tow in laminated composite...panels, 12″ × 12″, were fabricated with IM7/977-2 prepreg unidirectional carbon fiber tape. Three panels each were prepared with unidirectional [0]8 or...were fabricated with 6″-long fuzzy fiber strain sensors embedded at the midpoint of the laminate plies. Eight straight-sided specimens (as shown in

  1. Packaging of active fiber composites for improved sensor performance

    International Nuclear Information System (INIS)

    Melnykowycz, M; Barbezat, M; Koller, R; Brunner, A J

    2010-01-01

    Active fiber composites (AFC) composed of lead zirconate titanate (PZT) fibers embedded in an epoxy matrix and sandwiched between two interdigitated electrodes provide a thin and flexible smart material device which can act as a sensor or actuator. The thin profiles of AFC make them ideal for integration in glass or carbon fiber composite laminates. However, due to the low tensile limit of the PZT fibers, AFC can fail at strains below the tensile limit of many composites. This makes their use as a component in an active laminate design somewhat undesirable. In the current work, tensile testing of smart laminates composed of AFC integrated in glass fiber laminates was conducted to assess the effectiveness of different packaging strategies for improving AFC sensor performance at high strains relative to the tensile limit of the AFC. AFC were encased in carbon fiber, silicon, and pre-stressed carbon fiber to improve the tensile limit of the AFC when integrated in glass fiber laminates. By laminating AFC with pre-stressed carbon fiber, the tensile limit and strain sensor ability of the AFC were significantly improved. Acoustic emission monitoring was used and the results show that PZT fiber breakage was reduced due to the pre-stressed packaging process

  2. Amperometric biosensor for lactate analysis in wine and must during fermentation

    OpenAIRE

    Shkotova , L.V.; Goriushkina , T.B.; Tran-Minh , Canh; Chovelon , Jean-Marc; Soldatkin , A.P.; Dzyadevych , S.V.

    2008-01-01

    MADICA 2006 Conference, Fifth Maghreb-Europe Meeting on Materials and their Applicatons for Devices and Physical, Chemical and Biological Sensors, MADICA 2006 Conference, Fifth Maghreb-Europe Meeting on Materials and their Applicatons for Devices and Physical, Chemical and Biological Sensors; International audience; A lactate oxidase-based amperometric biosensor is designed for lactate determination. Two methods of lactate oxidase immobilization on the surface of commercial SensLab platinum p...

  3. Robust high temperature composite and CO sensor made from such composite

    Science.gov (United States)

    Dutta, Prabir K.; Ramasamy, Ramamoorthy; Li, Xiaogan; Akbar, Sheikh A.

    2010-04-13

    Described herein is a composite exhibiting a change in electrical resistance proportional to the concentration of a reducing gas present in a gas mixture, detector and sensor devices comprising the composite, a method for making the composite and for making devices comprising the composite, and a process for detecting and measuring a reducing gas in an atmosphere. In particular, the reducing gas may be carbon monoxide and the composite may comprise rutile-phase TiO2 particles and platinum nanoclusters. The composite, upon exposure to a gas mixture containing CO in concentrations of up to 10,000 ppm, exhibits an electrical resistance proportional to the concentration of the CO present. The composite is useful for making sensitive, low drift, fast recovering detectors and sensors, and for measuring CO concentrations in a gas mixture present at levels from sub-ppm up to 10,000 ppm. The composites, and devices made from the composites, are stable and operable in a temperature range of from about 450.degree. C. to about 700.degree. C., such as may be found in a combustion chamber.

  4. Surfactant Sensors in Biotechnology; Part 1 – Electrochemical Sensors

    Directory of Open Access Journals (Sweden)

    Milan Sak-Bosnar

    2004-01-01

    Full Text Available An overview on electrochemical surfactant sensors is given with special attention to papers published since 1993. The importance of surfactants in modern biotechnology is stressed out. Electrochemical sensors are usually divided according to the measured physical quantity to potentiometric, amperometric, conductometric and impedimetric surfactant sensors. The last ones are very few. Potentiometric surfactant sensors are the most numerous due to their simplicity and versatility. They can be used either as end-point titration sensors or as direct EMF measurement sensors, in batch or flow-through mode. Some amperometric surfactant sensors are true biosensors that use microorganisms or living cells.

  5. Highly sensitive strain sensors based on fragmentized carbon nanotube/polydimethylsiloxane composites.

    Science.gov (United States)

    Gao, Yang; Fang, Xiaoliang; Tan, Jianping; Lu, Ting; Pan, Likun; Xuan, Fuzhen

    2018-06-08

    Wearable strain sensors based on nanomaterial/elastomer composites have potential applications in flexible electronic skin, human motion detection, human-machine interfaces, etc. In this research, a type of high performance strain sensors has been developed using fragmentized carbon nanotube/polydimethylsiloxane (CNT/PDMS) composites. The CNT/PDMS composites were ground into fragments, and a liquid-induced densification method was used to fabricate the strain sensors. The strain sensors showed high sensitivity with gauge factors (GFs) larger than 200 and a broad strain detection range up to 80%, much higher than those strain sensors based on unfragmentized CNT/PDMS composites (GF sensors is ascribed to the sliding of individual fragmentized-CNT/PDMS-composite particles during mechanical deformation, which causes significant resistance change in the strain sensors. The strain sensors can differentiate mechanical stimuli and monitor various human body motions, such as bending of the fingers, human breathing, and blood pulsing.

  6. Monitoring Pre-Stressed Composites Using Optical Fibre Sensors.

    Science.gov (United States)

    Krishnamurthy, Sriram; Badcock, Rodney A; Machavaram, Venkata R; Fernando, Gerard F

    2016-05-28

    Residual stresses in fibre reinforced composites can give rise to a number of undesired effects such as loss of dimensional stability and premature fracture. Hence, there is significant merit in developing processing techniques to mitigate the development of residual stresses. However, tracking and quantifying the development of these fabrication-induced stresses in real-time using conventional non-destructive techniques is not straightforward. This article reports on the design and evaluation of a technique for manufacturing pre-stressed composite panels from unidirectional E-glass/epoxy prepregs. Here, the magnitude of the applied pre-stress was monitored using an integrated load-cell. The pre-stressing rig was based on a flat-bed design which enabled autoclave-based processing. A method was developed to end-tab the laminated prepregs prior to pre-stressing. The development of process-induced residual strain was monitored in-situ using embedded optical fibre sensors. Surface-mounted electrical resistance strain gauges were used to measure the strain when the composite was unloaded from the pre-stressing rig at room temperature. Four pre-stress levels were applied prior to processing the laminated preforms in an autoclave. The results showed that the application of a pre-stress of 108 MPa to a unidirectional [0]16 E-glass/913 epoxy preform, reduced the residual strain in the composite from -600 µε (conventional processing without pre-stress) to approximately zero. A good correlation was observed between the data obtained from the surface-mounted electrical resistance strain gauge and the embedded optical fibre sensors. In addition to "neutralising" the residual stresses, superior axial orientation of the reinforcement can be obtained from pre-stressed composites. A subsequent publication will highlight the consequences of pres-stressing on fibre alignment, the tensile, flexural, compressive and fatigue performance of unidirectional E-glass composites.

  7. Monitoring Pre-Stressed Composites Using Optical Fibre Sensors

    Directory of Open Access Journals (Sweden)

    Sriram Krishnamurthy

    2016-05-01

    Full Text Available Residual stresses in fibre reinforced composites can give rise to a number of undesired effects such as loss of dimensional stability and premature fracture. Hence, there is significant merit in developing processing techniques to mitigate the development of residual stresses. However, tracking and quantifying the development of these fabrication-induced stresses in real-time using conventional non-destructive techniques is not straightforward. This article reports on the design and evaluation of a technique for manufacturing pre-stressed composite panels from unidirectional E-glass/epoxy prepregs. Here, the magnitude of the applied pre-stress was monitored using an integrated load-cell. The pre-stressing rig was based on a flat-bed design which enabled autoclave-based processing. A method was developed to end-tab the laminated prepregs prior to pre-stressing. The development of process-induced residual strain was monitored in-situ using embedded optical fibre sensors. Surface-mounted electrical resistance strain gauges were used to measure the strain when the composite was unloaded from the pre-stressing rig at room temperature. Four pre-stress levels were applied prior to processing the laminated preforms in an autoclave. The results showed that the application of a pre-stress of 108 MPa to a unidirectional [0]16 E-glass/913 epoxy preform, reduced the residual strain in the composite from −600 µε (conventional processing without pre-stress to approximately zero. A good correlation was observed between the data obtained from the surface-mounted electrical resistance strain gauge and the embedded optical fibre sensors. In addition to “neutralising” the residual stresses, superior axial orientation of the reinforcement can be obtained from pre-stressed composites. A subsequent publication will highlight the consequences of pres-stressing on fibre alignment, the tensile, flexural, compressive and fatigue performance of unidirectional E

  8. Monitoring Pre-Stressed Composites Using Optical Fibre Sensors

    Science.gov (United States)

    Krishnamurthy, Sriram; Badcock, Rodney A.; Machavaram, Venkata R.; Fernando, Gerard F.

    2016-01-01

    Residual stresses in fibre reinforced composites can give rise to a number of undesired effects such as loss of dimensional stability and premature fracture. Hence, there is significant merit in developing processing techniques to mitigate the development of residual stresses. However, tracking and quantifying the development of these fabrication-induced stresses in real-time using conventional non-destructive techniques is not straightforward. This article reports on the design and evaluation of a technique for manufacturing pre-stressed composite panels from unidirectional E-glass/epoxy prepregs. Here, the magnitude of the applied pre-stress was monitored using an integrated load-cell. The pre-stressing rig was based on a flat-bed design which enabled autoclave-based processing. A method was developed to end-tab the laminated prepregs prior to pre-stressing. The development of process-induced residual strain was monitored in-situ using embedded optical fibre sensors. Surface-mounted electrical resistance strain gauges were used to measure the strain when the composite was unloaded from the pre-stressing rig at room temperature. Four pre-stress levels were applied prior to processing the laminated preforms in an autoclave. The results showed that the application of a pre-stress of 108 MPa to a unidirectional [0]16 E-glass/913 epoxy preform, reduced the residual strain in the composite from −600 µε (conventional processing without pre-stress) to approximately zero. A good correlation was observed between the data obtained from the surface-mounted electrical resistance strain gauge and the embedded optical fibre sensors. In addition to “neutralising” the residual stresses, superior axial orientation of the reinforcement can be obtained from pre-stressed composites. A subsequent publication will highlight the consequences of pres-stressing on fibre alignment, the tensile, flexural, compressive and fatigue performance of unidirectional E-glass composites. PMID

  9. Improved Internal Reference Oxygen Sensors Using Composite Oxides as Electrodes

    DEFF Research Database (Denmark)

    Hu, Qiang

    The thesis describes the research on and development of an internal reference oxygen sensor (IROS). The IROS is potentiometric and uses the equilibrium pO2of the binary mixture of Ni/NiO as the reference pO2. The sensing electrode of the IROS are made from metallic Pt or the composite of (La0.75S...... the application of IROSes are provided. Based on the concepts and fundamentals of the IROS, internal reference sensors that detect other gas species such as hydrogen, chlorine and bromine may be developed.......The thesis describes the research on and development of an internal reference oxygen sensor (IROS). The IROS is potentiometric and uses the equilibrium pO2of the binary mixture of Ni/NiO as the reference pO2. The sensing electrode of the IROS are made from metallic Pt or the composite of (La0.75Sr0...... from 8YSZ is evaluated quantitatively and figures that may be used to design the depletion period of an IROS due to the electronic leak of 8YSZ are provided. One dimensional numerical simulations are performed to study the variation in cell voltage during the process of gas mixing, and the asymmetric...

  10. Simple flow injection for determination of sulfite by amperometric detection using glassy carbon electrode modified with carbon nanotubes-PDDA-gold nanoparticles.

    Science.gov (United States)

    Amatatongchai, Maliwan; Sroysee, Wongduan; Chairam, Sanoe; Nacapricha, Duangjai

    2015-02-01

    A new approach is presented for sensitive and selective measurement of sulfite (SO3(2-)) in beverages based on a simple flow injection system with amperometric detection. In this work, the sulfite sensor was a glassy carbon electrode modified with multiwall carbon nanotubes-poly(diallyldimethylammonium chloride)-gold nanoparticles composites (CNTs-PDDA-AuNPs/GC). Electrochemical oxidation of sulfite with this electrode was first studied in 0.1M phosphate buffer (pH 7.0) using cyclic voltammetry. The results indicated that the CNTs-PDDA-AuNPs/GC electrode possesses electrocatalytic activity for the oxidation of sulfite with high sensitivity and selectivity. Sulfite was quantified using amperometric measurement with the new sensor at +0.4V vs Ag/AgCl in conjunction with flow injection. The linear working range for the quantitation of sulfite was 2-200 mg L(-1) (r(2)=0.998) with a detection limit of 0.03 mg L(-1) (3σ of blank) and an estimated precision of 1.5%.The proposed method was successfully applied to the determination of sulfite in fruit juices and wines with a sample throughput of 23 samples per hour. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. A composite hydrogels-based photonic crystal multi-sensor

    International Nuclear Information System (INIS)

    Chen, Cheng; Zhu, Zhigang; Zhu, Xiangrong; Yu, Wei; Liu, Mingju; Ge, Qiaoqiao; Shih, Wei-Heng

    2015-01-01

    A facile route to prepare stimuli-sensitive poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) gelated crystalline colloidal array photonic crystal material was developed. PVA was physically gelated by utilizing an ethanol-assisted method, the resulting hydrogel/crystal composite film was then functionalized with PAA to form an interpenetrating hydrogel film. This sensor film is able to efficiently diffract the visible light and rapidly respond to various environmental stimuli such as solvent, pH and strain, and the accompanying structural color shift can be repeatedly changed and easily distinguished by naked eye. (paper)

  12. Development of an Amperometric Glucose Biosensor Based on the Immobilization of Glucose Oxidase on the Se-MCM-41 Mesoporous Composite

    Directory of Open Access Journals (Sweden)

    Sabriye Yusan

    2018-01-01

    Full Text Available A new bioenzymatic glucose biosensor for selective and sensitive detection of glucose was developed by the immobilization of glucose oxidase (GOD onto selenium nanoparticle-mesoporous silica composite (MCM-41 matrix and then prepared as a carbon paste electrode (CPE. Cyclic voltammetry was employed to probe the catalytic behavior of the biosensor. A linear calibration plot is obtained over a wide concentration range of glucose from 1 × 10−5 to 2 × 10−3 M. Under optimal conditions, the biosensor exhibits high sensitivity (0.34 µA·mM−1, low detection limit (1 × 10−4 M, high affinity to glucose (Km = 0.02 mM, and also good reproducibility (R.S.D. 2.8%, n=10 and a stability of about ten days when stored dry at +4°C. Besides, the effects of pH value, scan rate, mediator effects on the glucose current, and electroactive interference of the biosensor were also discussed. As a result, the biosensor exhibited an excellent electrocatalytic response to glucose as well as unique stability and reproducibility.

  13. Highly sensitive strain sensors based on fragmentized carbon nanotube/polydimethylsiloxane composites

    Science.gov (United States)

    Gao, Yang; Fang, Xiaoliang; Tan, Jianping; Lu, Ting; Pan, Likun; Xuan, Fuzhen

    2018-06-01

    Wearable strain sensors based on nanomaterial/elastomer composites have potential applications in flexible electronic skin, human motion detection, human–machine interfaces, etc. In this research, a type of high performance strain sensors has been developed using fragmentized carbon nanotube/polydimethylsiloxane (CNT/PDMS) composites. The CNT/PDMS composites were ground into fragments, and a liquid-induced densification method was used to fabricate the strain sensors. The strain sensors showed high sensitivity with gauge factors (GFs) larger than 200 and a broad strain detection range up to 80%, much higher than those strain sensors based on unfragmentized CNT/PDMS composites (GF composite particles during mechanical deformation, which causes significant resistance change in the strain sensors. The strain sensors can differentiate mechanical stimuli and monitor various human body motions, such as bending of the fingers, human breathing, and blood pulsing.

  14. Amperometric sensing of anti-HIV drug zidovudine on Ag nanofilm-multiwalled carbon nanotubes modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Rafati, Amir Abbas, E-mail: aa_rafati@basu.ac.ir; Afraz, Ahmadreza

    2014-06-01

    The zidovudine (ZDV) is the first drug approved for the treatment of HIV virus infection. The detection and determination of this drug are very importance in human serum because of its undesirable effects. A new ZDV sensor was fabricated on the basis of nanocomposite of silver nanofilm (Ag-NF) and multiwalled carbon nanotubes (MWCNTs) immobilized on glassy carbon electrode (GCE). The modified electrodes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), cyclic voltammetry (CV), and linear sweep voltammetry (LSV) techniques. Results showed that the electrodeposited silver has a nanofilm structure and further electrochemical studies showed that the prepared nanocomposite has high electrocatalytic activity and is appropriate for using in sensors. The amperometric technique under optimal conditions is used for the determination of ZDV ranging from 0.1 to 400 ppm (0.37 μM–1.5 mM) with a low detection limit of 0.04 ppm (0.15 μM) (S/N = 3) and good sensitivity. The prepared sensor possessed accurate and rapid response to ZDV and shows an average recovery of 98.6% in real samples. - Highlights: • New anti-HIV drug sensor was fabricated on the basis of nanomaterials composite. • The GCE modified by prepared hydrophilic MWCNT silver nanoparticles. • Silver nanofilm electrodeposited on MWCNT/GCE and characterized by SEM, EDX, CV and LSV • Response of electrode to ZDV was thoroughly investigated by electrochemical techniques.

  15. Fabrication and characterization of magnetic composite membrane pressure sensor

    KAUST Repository

    Khan, Mohammed Asadullah

    2016-04-20

    This paper describes a magnetic field powered pressure sensor, which comprises a coil array and a magnetic composite membrane. The composite membrane is made by embedding a ribbon of the amorphous soft magnetic alloy Vitrovac®, in a 17 mm x 25 mm x 1.5 mm Polydimethylsiloxane (PDMS) layer. PDMS is chosen for its low Young\\'s modulus and the amorphous alloy for its high permeability. The membrane is suspended 1.5 mm above a 17x19 array of microfabricated planar coils. The coils are fabricated by patterning a 620 nm thick gold layer. Each coil occupies an area of 36000 μm2 and consists of 14 turns. The sensor is tested by subjecting it to pressure and simultaneously exciting it by a 24 A/m, 100 kHz magnetic field. A pressure change from 0 kPa to 5.1 kPa, results in a 5400 ppm change in the voltage output.

  16. Carbon nanotube—cuprous oxide composite based pressure sensors

    International Nuclear Information System (INIS)

    Karimov, Kh. S.; Chani, Muhammad Tariq Saeed; Khalid, Fazal Ahmad; Khan, Adam; Khan, Rahim

    2012-01-01

    In this paper, we present the design, the fabrication, and the experimental results of carbon nanotube (CNT) and Cu 2 O composite based pressure sensors. The pressed tablets of the CNT—Cu 2 O composite are fabricated at a pressure of 353 MPa. The diameters of the multiwalled nanotubes (MWNTs) are between 10 nm and 30 nm. The sizes of the Cu 2 O micro particles are in the range of 3–4 μm. The average diameter and the average thickness of the pressed tablets are 10 mm and 4.0 mm, respectively. In order to make low resistance electric contacts, the two sides of the pressed tablet are covered by silver pastes. The direct current resistance of the pressure sensor decreases by 3.3 times as the pressure increases up to 37 kN/m 2 . The simulation result of the resistance—pressure relationship is in good agreement with the experimental result within a variation of ±2%. (condensed matter: structural, mechanical, and thermal properties)

  17. Fabrication and characterization of magnetic composite membrane pressure sensor

    KAUST Repository

    Khan, Mohammed Asadullah; Alfadhel, Ahmed; Kosel, Jü rgen; Bakolka, M.

    2016-01-01

    This paper describes a magnetic field powered pressure sensor, which comprises a coil array and a magnetic composite membrane. The composite membrane is made by embedding a ribbon of the amorphous soft magnetic alloy Vitrovac®, in a 17 mm x 25 mm x 1.5 mm Polydimethylsiloxane (PDMS) layer. PDMS is chosen for its low Young's modulus and the amorphous alloy for its high permeability. The membrane is suspended 1.5 mm above a 17x19 array of microfabricated planar coils. The coils are fabricated by patterning a 620 nm thick gold layer. Each coil occupies an area of 36000 μm2 and consists of 14 turns. The sensor is tested by subjecting it to pressure and simultaneously exciting it by a 24 A/m, 100 kHz magnetic field. A pressure change from 0 kPa to 5.1 kPa, results in a 5400 ppm change in the voltage output.

  18. Nano-Composite Foam Sensor System in Football Helmets.

    Science.gov (United States)

    Merrell, A Jake; Christensen, William F; Seeley, Matthew K; Bowden, Anton E; Fullwood, David T

    2017-12-01

    American football has both the highest rate of concussion incidences as well as the highest number of concussions of all contact sports due to both the number of athletes and nature of the sport. Recent research has linked concussions with long term health complications such as chronic traumatic encephalopathy and early onset Alzheimer's. Understanding the mechanical characteristics of concussive impacts is critical to help protect athletes from these debilitating diseases and is now possible using helmet-based sensor systems. To date, real time on-field measurement of head impacts has been almost exclusively measured by devices that rely on accelerometers or gyroscopes attached to the player's helmet, or embedded in a mouth guard. These systems monitor motion of the head or helmet, but do not directly measure impact energy. This paper evaluates the accuracy of a novel, multifunctional foam-based sensor that replaces a portion of the helmet foam to measure impact. All modified helmets were tested using a National Operating Committee Standards for Athletic Equipment-style drop tower with a total of 24 drop tests (4 locations with 6 impact energies). The impacts were evaluated using a headform, instrumented with a tri-axial accelerometer, mounted to a Hybrid III neck assembly. The resultant accelerations were evaluated for both the peak acceleration and the severity indices. These data were then compared to the voltage response from multiple Nano Composite Foam sensors located throughout the helmet. The foam sensor system proved to be accurate in measuring both the HIC and Gadd severity index, as well as peak acceleration while also providing additional details that were previously difficult to obtain, such as impact energy.

  19. Implantable bladder volume sensor based on resistor ladder network composed of conductive hydrogel composite.

    Science.gov (United States)

    Mi Kyung Kim; Hyojung Kim; Jung, Yeon Su; Adem, Kenana M A; Bawazir, Sarah S; Stefanini, Cesare; Lee, Hyunjoo J

    2017-07-01

    An accurate bladder volume monitoring system is a critical component in diagnosis and treatment of urological disorders. Here, we report an implantable bladder volume sensor with a multi-level resistor ladder which estimates the bladder volume through discrete resistance values. Discretization allows the sensor output to be resilient to the long-term drift, hysteresis, and degradation of the sensor materials. Our sensor is composed of biocompatible polypyrrole/agarose hydrogel composite. Because Young's modulus of this composite is comparable to that of the bladder wall, the effect of mechanical loading of the sensor on the bladder movement is minimized which allows more accurate volume monitoring. We also demonstrate the patterning and molding capability of this material by fabrication various structures. Lastly, we successfully demonstrate the functionality of the multi-level resistor ladder sensor as a bladder volume sensor by attaching the sensor on the pig's bladder and observing the impedance change of the sensor.

  20. Automated amperometric plutonium assay system

    International Nuclear Information System (INIS)

    Burt, M.C.

    1985-01-01

    The amperometric titration for plutonium assay has been used in the nuclear industry for over twenty years and has been in routine use at the Hanford Engineering Development Laboratory since 1976 for the analysis of plutonium oxide and mixed oxide fuel material for the Fast Flux Test Facility. It has proven itself to be an accurate and reliable method. The method may be used as a direct end point titration or an excess of titrant may be added and a back titration performed to aid in determination of the end point. Due to the slowness of the PuVI-FeII reaction it is difficult to recognize when the end point is being approached and is very time consuming if the current is allowed to decay to the residual value after each titrant addition. For this reason the back titration in which the rapid FeII-CrVI reaction occurs is used by most laboratories. The back titration is performed by the addition of excess ferrous solution followed by two measured aliquots of standard dichromate with measurement of cell current after each addition

  1. AMPEROMETRIC THICK-FILM STRIP ELECTRODES FOR MONITORING ORGANOPHOSPHATE NERVE AGENTS BASED ON IMMOBILIZED ORGANOPHOSPHORUS HYDROLASE. (R823663)

    Science.gov (United States)

    An amperometric biosensor based on the immobilization of organophosphorus hydrolase(OPH) onto screen-printed carbon electrodes is shown useful for the rapid, sensitive, and low-costdetection of organophosphate (OP) nerve agents. The sensor relies upon the sensitive and ra...

  2. Ultra-high sensitive hydrazine chemical sensor based on low-temperature grown ZnO nanoparticles

    International Nuclear Information System (INIS)

    Mehta, S.K.; Singh, Kulvinder; Umar, Ahmad; Chaudhary, G.R.; Singh, Sukhjinder

    2012-01-01

    Graphical abstract: Systematic representation of the fabricated amperometric hydrazine chemical sensor based on ZnO NPs/Au modified electrode. Highlights: ► Synthesis of well-crystalline ZnO NPs has been achieved in aqueous solution. ► ZnO NPs act as efficient electron mediators for hydrazine sensor. ► Extremely high sensitivity and low-detection limit have been obtained. - Abstract: Using well-crystalline ZnO nanoparticles (NPs), an ultra high sensitive hydrazine amperometric sensor has been fabricated and reported in this paper. The ZnO NPs have been synthesized by very simple aqueous solution process at 90 °C and characterized in detail in terms of their morphological, compositional, structural and optical properties. The detailed investigations reveal that the synthesized products are well-crystalline NPs, possessing wurtzite hexagonal phase and exhibit good optical properties. The fabricated amperometric hydrazine sensor exhibits ultra-high sensitivity of ∼97.133 μA cm −2 μM −1 and very low-detection limit of 147.54 nM. To the best of our knowledge, this is the first report in which an ultra-high sensitivity and low-detection limit have been obtained for the hydrazine chemical sensor based on ZnO nanostructures.

  3. Functional materials in amperometric sensing polymeric, inorganic, and nanocomposite materials for modified electrodes

    CERN Document Server

    Seeber, Renato; Zanardi, Chiara

    2014-01-01

    Amperometric sensors, biosensors included, particularly rely on suitable electrode materials. Progress in material science has led to a wide variety of options that are available today. For the first time, these novel functional electrode coating materials are reviewed in this monograph, written by and for electroanalytical chemists. This includes intrinsically conducting, redox and ion-exchange polymers, metal and carbon nanostructures, silica based materials. Monolayers and relatively thick films are considered. The authors critically discuss preparation methods, in addition to chemical and

  4. Embedding of MEMS pressure and temperature sensors in carbon fiber composites: a manufacturing approach

    Science.gov (United States)

    Javidinejad, Amir; Joshi, Shiv P.

    2000-06-01

    In this paper embedding of surface mount pressure and temperature sensors in the Carbon fiber composites are described. A commercially available surface mount pressure and temperature sensor are used for embedding in a composite lay- up of IM6/HST-7, IM6/3501 and AS4/E7T1-2 prepregs. The fabrication techniques developed here are the focus of this paper and provide for a successful embedding procedure of pressure sensors in fibrous composites. The techniques for positioning and insulating, the sensor and the lead wires, from the conductive carbon prepregs are described and illustrated. Procedural techniques are developed and discussed for isolating the sensor's flow-opening, from the exposure to the prepreg epoxy flow and exposure to the fibrous particles, during the autoclave curing of the composite laminate. The effects of the autoclave cycle (if any) on the operation of the embedded pressure sensor are discussed.

  5. Development of temperature stable charge based piezoelectric composite quasi-static pressure sensors

    NARCIS (Netherlands)

    Ende, D.A. van den; Groen, W.A.; Zwaag, S. van der

    2010-01-01

    In this work piezoelectric composite charge based sensors are developed, aimed at quasi-static pressure sensor or switch type applications. The use of piezoelectric composite materials allows for manufacturing robust devices which can easily be integrated with conventional polymer processing.

  6. Amperometric micro pH measurements in oxygenated saliva.

    Science.gov (United States)

    Chaisiwamongkhol, Korbua; Batchelor-McAuley, Christopher; Compton, Richard G

    2017-07-24

    An amperometric micro pH sensor has been developed based on the chemical oxidation of carbon fibre surfaces (diameter of 9 μm and length of ca. 1 mm) to enhance the population of surface quinone groups for the measurement of salivary pH. The pH analysis utilises the electrochemically reversible two-electron, two-proton behaviour of surface quinone groups on the micro-wire electrodes. A Nernstian response is observed across the pH range 2-8 which is the pH range of many biological fluids. We highlight the measurement of pH in small volumes of biological fluids without the need for oxygen removal and specifically the micro pH electrode is examined by measuring the pH of commercial synthetic saliva and authentic human saliva samples. The results correspond well with those obtained by using commercial glass pH electrodes on large volume samples.

  7. Amperometric Noise at Thin Film Band Electrodes

    DEFF Research Database (Denmark)

    Larsen, Simon T.; Heien, Michael L.; Taboryski, Rafael

    2012-01-01

    Background current noise is often a significant limitation when using constant-potential amperometry for biosensor application such as amperometric recordings of transmitter release from single cells through exocytosis. In this paper, we fabricated thin-film electrodes of gold and conductive...

  8. The Effects of Changing Membrane Compositions and Internal Electrolytes on the Respon of Potassium Ion Sensor

    OpenAIRE

    Ulianas, Alizar; Heng, Lee Yook

    2015-01-01

    A study on the changing of membrane compositions and internal solution towards the response potassium ion sensor was carried out. Potassium ion sensor based on photocured cross linking poly(n-butyl acrylate) membranes with varying composition of valinomycin (val), sodium tetrakis [3.5-bis(trifluoro-methyl) phenyl] borat (NaTFPB), types ion of internal solution were investigated. Effects of varying composition of val, NaTFPB, types and concentration of internal solution were observed on potass...

  9. Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors

    OpenAIRE

    R. Brian Jenkins; Peter Joyce; Deborah Mechtel

    2017-01-01

    Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initia...

  10. Facile Fabrication of Multi-hierarchical Porous Polyaniline Composite as Pressure Sensor and Gas Sensor with Adjustable Sensitivity

    Science.gov (United States)

    He, Xiao-Xiao; Li, Jin-Tao; Jia, Xian-Sheng; Tong, Lu; Wang, Xiao-Xiong; Zhang, Jun; Zheng, Jie; Ning, Xin; Long, Yun-Ze

    2017-08-01

    A multi-hierarchical porous polyaniline (PANI) composite which could be used in good performance pressure sensor and adjustable sensitivity gas sensor has been fabricated by a facile in situ polymerization. Commercial grade sponge was utilized as a template scaffold to deposit PANI via in situ polymerization. With abundant interconnected pores throughout the whole structure, the sponge provided sufficient surface for the growth of PANI nanobranches. The flexible porous structure helped the composite to show high performance in pressure detection with fast response and favorable recoverability and gas detection with adjustable sensitivity. The sensing mechanism of the PANI/sponge-based flexible sensor has also been discussed. The results indicate that this work provides a feasible approach to fabricate efficient sensors with advantages of low cost, facile preparation, and easy signal collection.

  11. Carbon Nanotube Composite SHM Sensor using Additive Manufacturing

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a piezoelectric sensors made of carbon nanotube and lead zirconium titanate (PZT) nanopower dispersed in a polymer matrix. These sensors will...

  12. Facile Fabrication of Multi-hierarchical Porous Polyaniline Composite as Pressure Sensor and Gas Sensor with Adjustable Sensitivity

    OpenAIRE

    He, Xiao-Xiao; Li, Jin-Tao; Jia, Xian-Sheng; Tong, Lu; Wang, Xiao-Xiong; Zhang, Jun; Zheng, Jie; Ning, Xin; Long, Yun-Ze

    2017-01-01

    A multi-hierarchical porous polyaniline (PANI) composite which could be used in good performance pressure sensor and adjustable sensitivity gas sensor has been fabricated by a facile in situ polymerization. Commercial grade sponge was utilized as a template scaffold to deposit PANI via in situ polymerization. With abundant interconnected pores throughout the whole structure, the sponge provided sufficient surface for the growth of PANI nanobranches. The flexible porous structure helped the co...

  13. Strength and fatigue life evaluation of composite laminate with embedded sensors

    Science.gov (United States)

    Rathod, Vivek T.; Hiremath, S. R.; Roy Mahapatra, D.

    2014-04-01

    Prognosis regarding durability of composite structures using various Structural Health Monitoring (SHM) techniques is an important and challenging topic of research. Ultrasonic SHM systems with embedded transducers have potential application here due to their instant monitoring capability, compact packaging potential toward unobtrusiveness and noninvasiveness as compared to non-contact ultrasonic and eddy current techniques which require disassembly of the structure. However, embedded sensors pose a risk to the structure by acting as a flaw thereby reducing life. The present paper focuses on the determination of strength and fatigue life of the composite laminate with embedded film sensors like CNT nanocomposite, PVDF thin films and piezoceramic films. First, the techniques of embedding these sensors in composite laminates is described followed by the determination of static strength and fatigue life at coupon level testing in Universal Testing Machine (UTM). Failure mechanisms of the composite laminate with embedded sensors are studied for static and dynamic loading cases. The coupons are monitored for loading and failure using the embedded sensors. A comparison of the performance of these three types of embedded sensors is made to study their suitability in various applications. These three types of embedded sensors cover a wide variety of applications, and prove to be viable in embedded sensor based SHM of composite structures.

  14. Fabrication and characterization of aerosol-jet printed strain sensors for multifunctional composite structures

    Science.gov (United States)

    Zhao, Da; Liu, Tao; Zhang, Mei; Liang, Richard; Wang, Ben

    2012-11-01

    Traditional multifunctional composite structures are produced by embedding parasitic parts, such as foil sensors, optical fibers and bulky connectors. As a result, the mechanical properties of the composites, especially the interlaminar shear strength (ILSS), could be largely undermined. In the present study, we demonstrated an innovative aerosol-jet printing technology for printing electronics inside composite structures without degrading the mechanical properties. Using the maskless fine feature deposition (below 10 μm) characteristics of this printing technology and a pre-cure protocol, strain sensors were successfully printed onto carbon fiber prepregs to enable fabricating composites with intrinsic sensing capabilities. The degree of pre-cure of the carbon fiber prepreg on which strain sensors were printed was demonstrated to be critical. Without pre-curing, the printed strain sensors were unable to remain intact due to the resin flow during curing. The resin flow-induced sensor deformation can be overcome by introducing 10% degree of cure of the prepreg. In this condition, the fabricated composites with printed strain sensors showed almost no mechanical degradation (short beam shearing ILSS) as compared to the control samples. Also, the failure modes examined by optical microscopy showed no difference. The resistance change of the printed strain sensors in the composite structures were measured under a cyclic loading and proved to be a reliable mean strain gauge factor of 2.2 ± 0.06, which is comparable to commercial foil metal strain gauge.

  15. Damage and failure detection of composites using optical fiber vibration sensor

    International Nuclear Information System (INIS)

    Yang, Y. C.; Han, K. S.

    2001-01-01

    An intensity-based optical fiber vibration sensor is applied to detect and evaluate damages and fiber failure of composites. The optical fiber vibration sensor is constructed by placing two cleaved fiber end, one of which is cantilevered in a hollow glass tube. The movement of the cantilevered section lags behind the rest of the sensor in response to an applied vibration and the amount of light coupled between the two fibers is thereby modulated. Vibration characteristics of the optical fiber vibration sensor are investigated. Surface mounted optical fiber vibration sensor is used in tensile and indentation test. Experimental results show that the optical fiber sensor can detect damages and fiber failure of composites correctly

  16. Improvement of amperometric transducer selectivity using nanosized phenylenediamine films

    Science.gov (United States)

    Soldatkina, O. V.; Kucherenko, I. S.; Pyeshkova, V. M.; Alekseev, S. A.; Soldatkin, O. O.; Dzyadevych, S. V.

    2017-11-01

    In this work, we studied the conditions of deposition of a semipermeable polyphenylenediamine (PPD)-based membrane on amperometric disk platinum electrodes. Restricting an access of interfering substances to the electrode surface, the membrane prevents their impact on the sensor operation. Two methods of membrane deposition by electropolymerization were compared—at varying potential (cyclic voltammetry) and at constant potential. The cyclic voltammetry was shown to be easier in performing and providing better properties of the membrane. The dependence of PPD membrane effectiveness on the number of cyclic voltammograms and phenylenediamine concentration was analyzed. It was shown that the impact of interfering substances (ascorbic acid, dopamine, cysteine, uric acid) on sensor operation could be completely avoided using three cyclic voltammograms in 30 mM phenylenediamine. On the other hand, when working with diluted samples, i.e., at lower concentrations of electroactive substances, it is reasonable to decrease the phenylenediamine concentration to 5 mM, which would result in a higher sensitivity of transducers to hydrogen peroxide due to a thinner PPD layer. The PPD membrane was tested during continuous operation and at 8-day storage and turned out to be efficient in sensor and biosensors.

  17. Potentiometric and amperometric titration of ferrocene by cerium(4)

    International Nuclear Information System (INIS)

    Solomatin, V.T.

    1985-01-01

    Redox-potentials (E) of ferrocene (ferricenium-cation), Ce(4)/Ce(3) pairs are investigated and a possibility of regulating E value of these systems depending on the composition of water-organic media is shown. E value of Ce(4)/Ce(3) system decreases as increasing H 2 SO 4 concentration and CH 3 COOH mol share in the water-organic phase. Kinetic investigations of Ce(4)-ferrocene reactions shown that E constant value is achieved in 12-16 s depending on donor-acceptor properties of the solvent. Optimum conditions are chosen for potentiometric and amperometric titration of ferrocene by ceruium (4) in technological products. The method is versatile and permits to determine from tenths to dozens per cent of ferrocene

  18. Polymer−metal organic framework composite films as affinity layer for capacitive sensor devices

    NARCIS (Netherlands)

    Sachdeva, S.; Gravesteijn, Dirk J; Soccol, D.; Kapteijn, F.; Sudhölter, E.J.R.; Gascon, J.; Smet, de L.C.P.M.

    2016-01-01

    We report a simple method for sensor development using polymer-MOF composite films. Nanoparticles of NH2-MIL-53(Al) dispersed in a Matrimid polyimide were applied as a thin film on top of capacitive sensor devices with planar electrodes. These drop-cast films act as an affinity layer. Sensing

  19. Polymer-metal organic framework composite films as affinity layer for capacitive sensor devices

    NARCIS (Netherlands)

    Sachdeva, Sumit; Soccol, Dimitri; Gravesteijn, Dirk J.; Kapteijn, Freek; Sudhölter, E.J.R.; Gascon, Jorge; Smet, de L.C.P.M.

    2016-01-01

    We report a simple method for sensor development using polymer-
    MOF composite films. Nanoparticles of NH2-MIL-53(Al) dispersed in a Matrimid
    polyimide were applied as a thin film on top of capacitive sensor devices with planar electrodes. These drop-cast films act as an affinity layer.

  20. Piezoelectric Lead Zirconium Titanate Composite Touch Sensors for Integration with Flexible OLED Technology

    NARCIS (Netherlands)

    Deutz, D.B.; Tempelman, E.; Zwaag, S. van der; Groen, W.A.

    2015-01-01

    To enable the design of more intuitive product user interfaces, the prospects of matching piezoelectric touch sensors with flexible organic light emitting diode (OLED) technology are investigated. Low stiffness piezoelectric composite sensors, combining piezoelectric Pb(Zr,Ti)O3 powder with a

  1. Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    R. Brian Jenkins

    2017-01-01

    Full Text Available Fiber Bragg grating (FBG temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay.

  2. Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors.

    Science.gov (United States)

    Jenkins, R Brian; Joyce, Peter; Mechtel, Deborah

    2017-01-27

    Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay.

  3. The Packaging Technology Study on Smart Composite Structure Based on The Embedded FBG Sensor

    Science.gov (United States)

    Zhang, Youhong; Chang, Xinlong; Zhang, Xiaojun; He, Xiangyong

    2018-03-01

    It is convenient to carry out the health monitoring of the solid rocket engine composite shell based on the embedded FBG sensor. In this paper, the packaging technology using one-way fiber layer of prepreg fiberglass/epoxy resin was proposed. The proposed packaging process is simple, and the packaged sensor structure size is flexible and convenient to use, at the mean time, the packaged structure has little effect on the pristine composite material structure.

  4. Determination of uranium by an amperometric method

    International Nuclear Information System (INIS)

    John, Mary; Venkataramana, P.; Vaidyanathan, S.; Natarajan, P.R.

    1981-01-01

    An amperometric method has been standardised for the determination of uranium. Uranium is reduced to its quadrivalent state in concentrated phosphoric acid medium with ferrous iron. The excess iron is destroyed with nitric acid in presence of Mo(VI). The medium is diluted and U(IV) is titrated with standard potassium dichromate to an amperometric end point using a pair of identical plantinum wires as electrodes. The reagent volumes and uranium quantities have been scaled down to 30 ml. and 2-5 mg of uranium in the present work with a view to minimising the problems associated with recovery of plutonium. The results are quantitative with an R.S.D. of 0.2% in the present version of weight based titrations. (author)

  5. Guided wave and damage detection in composite laminates using different fiber optic sensors.

    Science.gov (United States)

    Li, Fucai; Murayama, Hideaki; Kageyama, Kazuro; Shirai, Takehiro

    2009-01-01

    Guided wave detection using different fiber optic sensors and their applications in damage detection for composite laminates were systematically investigated and compared in this paper. Two types of fiber optic sensors, namely fiber Bragg gratings (FBG) and Doppler effect-based fiber optic (FOD) sensors, were addressed and guided wave detection systems were constructed for both types. Guided waves generated by a piezoelectric transducer were propagated through a quasi-isotropic carbon fiber reinforced plastic (CFRP) laminate and acquired by these fiber optic sensors. Characteristics of these fiber optic sensors in ultrasonic guided wave detection were systematically compared. Results demonstrated that both the FBG and FOD sensors can be applied in guided wave and damage detection for the CFRP laminates. The signal-to-noise ratio (SNR) of guided wave signal captured by an FOD sensor is relatively high in comparison with that of the FBG sensor because of their different physical principles in ultrasonic detection. Further, the FOD sensor is sensitive to the damage-induced fundamental shear horizontal (SH(0)) guided wave that, however, cannot be detected by using the FBG sensor, because the FOD sensor is omnidirectional in ultrasound detection and, in contrast, the FBG sensor is severely direction dependent.

  6. Highly selective room temperature NO2 gas sensor based on rGO-ZnO composite

    Science.gov (United States)

    Jyoti, Kanaujiya, Neha; Varma, G. D.

    2018-05-01

    Blending metal oxide nanoparticles with graphene or its derivatives can greatly enhance gas sensing characteristics. In the present work, ZnO nanoparticles have been synthesized via reflux method. Thin films of reduced graphene oxide (rGO) and composite of rGO-ZnO have been fabricated by drop casting method for gas sensing application. The samples have been characterized by X-ray diffraction (XRD) and Field-emission scanning electron microscope (FESEM) for the structural and morphological studies respectively. Sensing measurements have been carried out for the composite film of rGO-ZnO for different concentrations of NO2 ranging from 4 to 100 ppm. Effect of increasing temperature on the sensing performance has also been studied and the rGO-ZnO composite sensor shows maximum percentage response at room temperature. The limit of detection (LOD) for rGO-ZnO composite sensor is 4ppm and it exhibits a high response of 48.4% for 40 ppm NO2 at room temperature. To check the selectivity of the composite sensor, sensor film has been exposed to 40 ppm different gases like CO, NH3, H2S and Cl2 at room temperature and the sensor respond negligibly to these gases. The present work suggests that rGO-ZnO composite material can be a better candidate for fabrication of highly selective room temperature NO2 gas sensor.

  7. Polymer-carbon black composite sensors in an electronic nose for air-quality monitoring

    Science.gov (United States)

    Ryan, M. A.; Shevade, A. V.; Zhou, H.; Homer, M. L.

    2004-01-01

    An electronic nose that uses an array of 32 polymer-carbon black composite sensors has been developed, trained, and tested. By selecting a variety of chemical functionalities in the polymers used to make sensors, it is possible to construct an array capable of identifying and quantifying a broad range of target compounds, such as alcohols and aromatics, and distinguishing isomers and enantiomers (mirror-image isomers). A model of the interaction between target molecules and the polymer-carbon black composite sensors is under development to aid in selecting the array members and to enable identification of compounds with responses not stored in the analysis library.

  8. Prediction of Composite Pressure Vessel Failure Location using Fiber Bragg Grating Sensors

    Science.gov (United States)

    Kreger, Steven T.; Taylor, F. Tad; Ortyl, Nicholas E.; Grant, Joseph

    2006-01-01

    Ten composite pressure vessels were instrumented with fiber Bragg grating sensors in order to assess the strain levels of the vessel under various loading conditions. This paper and presentation will discuss the testing methodology, the test results, compare the testing results to the analytical model, and present a possible methodology for predicting the failure location and strain level of composite pressure vessels.

  9. A Compact Ionic Polymer Metal Composite (IPMC System with Inductive Sensor for Closed Loop Feedback

    Directory of Open Access Journals (Sweden)

    Jiaqi Wang

    2015-05-01

    Full Text Available Ionic polymer metal composite (IPMC, of which a low actuating voltage (<5 V, high power efficiency and biocompatibility makes it a proven candidate for low power devices. However, due to its inherent nonlinear behaviour and time-variance, feedback control, as well as reliable sensing means, are required for accurate operations. This paper presents an IPMC actuator implemented with an inductive sensor to enhance the reliability and compactness of the overall device. A practical, low cost and importantly, compact inductive sensor fabricated on a printed circuit board (PCB is proposed here. Target material selections and coil design considerations are discussed. It is experimentally determined that the inductive sensor has comparable performance to a laser sensor. Based on a proportional-integral-derivative (PID control results the inductive sensor has demonstrated to be an alternative to a laser sensor allowing devices using IPMC actuators to be compact.

  10. Nonenzymatic amperometric determination of glucose by CuO nanocubes-graphene nanocomposite modified electrode.

    Science.gov (United States)

    Luo, Liqiang; Zhu, Limei; Wang, Zhenxin

    2012-12-01

    Here, we report a nonenzymatic amperometric glucose sensor based on copper oxide (CuO) nanocubes-graphene nanocomposite modified glassy carbon electrode (CuO-G-GCE). In this case, the graphene sheets were cast on the GCE directly. CuO nanocubes were obtained by oxidizing electrochemically deposited Cu on the graphene. The morphology of CuO-G nanocomposite was characterized by scanning electron microscopy. The CuO-G-GCE-based sensor exhibited excellent electrocatalytic activity and high stability for glucose oxidation. Under optimized conditions, the linearity between the current response and the glucose concentration was obtained in the range of 2μM to 4mM with a detection limit of 0.7μM (S/N=3), and a high sensitivity of 1360μAmM(-1)cm(-2). The proposed electrode showed a fast response time (less than 5s) and a good reproducibility. The as-made sensor was applied to determine the glucose levels in clinic human serum samples with satisfactory results. In addition, the effects of common interfering species, including ascorbic acid, uric acid, dopamine and other carbohydrates, on the amperometric response of the sensor were investigated and discussed in detail. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Fatigue Damage Monitoring of a Composite Step Lap Joint Using Distributed Optical Fibre Sensors

    Science.gov (United States)

    Wong, Leslie; Chowdhury, Nabil; Wang, John; Chiu, Wing Kong; Kodikara, Jayantha

    2016-01-01

    Over the past few decades, there has been a considerable interest in the use of distributed optical fibre sensors (DOFS) for structural health monitoring of composite structures. In aerospace-related work, health monitoring of the adhesive joints of composites has become more significant, as they can suffer from cracking and delamination, which can have a significant impact on the integrity of the joint. In this paper, a swept-wavelength interferometry (SWI) based DOFS technique is used to monitor the fatigue in a flush step lap joint composite structure. The presented results will show the potential application of distributed optical fibre sensor for damage detection, as well as monitoring the fatigue crack growth along the bondline of a step lap joint composite structure. The results confirmed that a distributed optical fibre sensor is able to enhance the detection of localised damage in a structure. PMID:28773496

  12. Parallel synthesis of libraries of anodic and cathodic functionalized electrodeposition paints as immobilization matrix for amperometric biosensors.

    Science.gov (United States)

    Ngounou, Bertrand; Aliyev, Elchin H; Guschin, Dmitrii A; Sultanov, Yusif M; Efendiev, Ayaz A; Schuhmann, Wolfgang

    2007-09-01

    The integration of flexible anchoring groups bearing imidazolyl or pyridyl substituents into the structure of electrodeposition paints (EDP) is the basis for the parallel synthesis of a library containing 107 members of different cathodic and anodic EDPs with a high variation in polymer properties. The obtained EDPs were used as immobilization matrix for biosensor fabrication using glucose oxidase as a model enzyme. Amperometric glucose sensors based on the different EDPs showed a wide variation in their sensor characteristics with respect to the apparent Michaelis-Menten constant (KM(app)) representing the linear measuring range and the maximum current (Imax(app)). Based on these results first assumptions concerning the impact of different side chains in the EDP on the expected biosensor properties could be obtained allowing for an improved rational optimization of EDPs used as immobilization matrix in amperometric biosensors.

  13. Feasibility study on measuring axial and transverse stress/strain components in composite materials using Bragg sensors

    Science.gov (United States)

    Luyckx, G.; Degrieck, J.; De Waele, W.; Van Paepegem, W.; Van Roosbroeck, J.; Chah, K.; Vlekken, J.; McKenzie, I.; Obst, A.

    2017-11-01

    A fibre optic sensor design is proposed for simultaneously measuring the 3D stress (or strain) components and temperature inside thermo hardened composite materials. The sensor is based on two fibre Bragg gratings written in polarisation maintaining fibre. Based on calculations of the condition number, it will be shown that reasonable accuracies are to be expected. First tests on the bare sensors and on the sensors embedded in composite material, which confirm the expected behaviour, will be presented.

  14. Embedding piezoresistive pressure sensors to obtain online pressure profiles inside fiber composite laminates.

    Science.gov (United States)

    Moghaddam, Maryam Kahali; Breede, Arne; Brauner, Christian; Lang, Walter

    2015-03-27

    The production of large and complex parts using fiber composite materials is costly due to the frequent formation of voids, porosity and waste products. By embedding different types of sensors and monitoring the process in real time, the amount of wastage can be significantly reduced. This work focuses on developing a knowledge-based method to improve and ensure complete impregnation of the fibers before initiation of the resin cure. Piezoresistive and capacitive pressure sensors were embedded in fiber composite laminates to measure the real-time the pressure values inside the laminate. A change of pressure indicates resin infusion. The sensors were placed in the laminate and the resin was infused by vacuum. The embedded piezoresistive pressure sensors were able to track the vacuum pressure in the fiber composite laminate setup, as well as the arrival of the resin at the sensor. The pressure increase due to closing the resin inlet was also measured. In contrast, the capacitive type of sensor was found to be inappropriate for measuring these quantities. The following study demonstrates real-time monitoring of pressure changes inside the fiber composite laminate, which validate the use of Darcy's law in porous media to control the resin flow during infusion.

  15. Monitoring cure properties of out-of-autoclave BMI composites using IFPI sensor

    Science.gov (United States)

    Kaur, Amardeep; Anandan, Sudharshan; Yuan, Lei; Watkins, Steve E.; Chandrashekhara, K.; Xiao, Hai; Phan, Nam

    2016-04-01

    A non-destructive technique for inspection of a Bismaleimide (BMI) composite is presented using an optical fiber sensor. High performance BMI composites are used for Aerospace application for their mechanical strength. They are also used as an alternative to toughened epoxy resins. A femtosecond-laser-inscribed Intrinsic Fabry-Perot Interferometer (IFPI) sensor is used to perform real time cure monitoring of a BMI composite. The composite is cured using the out-of-autoclave (OOA) process. The IFPI sensor was used for in-situ monitoring; different curing stages are analyzed throughout the curing process. Temperature-induced-strain was measured to analyze the cure properties. The IFPI structure comprises of two reflecting mirrors inscribed on the core of the fiber using a femtosecond-laser manufacturing process. The manufacturing process makes the sensor thermally stable and robust for embedded applications. The sensor can withstand very high temperatures of up to 850 °C. The temperature and strain sensitivities of embedded IFPI sensor were measured to be 1.4 pm/μepsilon and 0.6 pm/μepsilon respectively.

  16. Methods and Piezoelectric Imbedded Sensors for Damage Detection in Composite Plates Under Ambient and Cryogenic Conditions

    Science.gov (United States)

    Engberg, Robert; Ooi, Teng K.

    2004-01-01

    New methods for structural health monitoring are being assessed, especially in high-performance, extreme environment, safety-critical applications. One such application is for composite cryogenic fuel tanks. The work presented here attempts to characterize and investigate the feasibility of using imbedded piezoelectric sensors to detect cracks and delaminations under cryogenic and ambient conditions. A variety of damage detection methods and different Sensors are employed in the different composite plate samples to aid in determining an optimal algorithm, sensor placement strategy, and type of imbedded sensor to use. Variations of frequency, impedance measurements, and pulse echoing techniques of the sensors are employed and compared. Statistical and analytic techniques are then used to determine which method is most desirable for a specific type of damage. These results are furthermore compared with previous work using externally mounted sensors. Results and optimized methods from this work can then be incorporated into a larger composite structure to validate and assess its structural health. This could prove to be important in the development and qualification of any 2" generation reusable launch vehicle using composites as a structural element.

  17. Architecture of poly(o-phenylenediamine)–Ag nanoparticle composites for a hydrogen peroxide sensor

    International Nuclear Information System (INIS)

    Wang Li; Zhu Haozhi; Song Yonghai; Liu Li; He Zhifang; Wan Lingli; Chen Shouhui; Xiang Ying; Chen Shusheng; Chen Jie

    2012-01-01

    Graphical abstract: Schematic representation of the formation process of AgNPs/PoPD/GCE via a two-step procedure consisting of electropolymerization of o-PD and electrodeposition of AgNPs and their application in H 2 O 2 detection. Highlights: ► o-Phenylenediamine (o-PD) was electropolymerized on a glassy carbon electrode (GCE). ► The conductive PoPD film was three-dimensional (3D) porous structure. ► Ag NPs formed by electrodepositing and uniformly dispersed on the 3D PoPD film. ► AgNPs/PoPD/GCE displayed good electrocatalytic activity to the reduction of H 2 O 2 . - Abstract: A novel strategy to fabricate a hydrogen peroxide (H 2 O 2 ) sensor was developed by electrodepositing Ag nanoparticles (AgNPs) on a poly(o-phenylenediamine) (PoPD) film modified glassy carbon electrode (GCE). Firstly, the o-phenylenediamine was polymerized on a GCE by potential cycling to produce PoPD film. Then the AgNPs were electrodeposited on the PoPD film to form AgNPs/PoPD/GCE. The morphology of the electropolymerized PoPD film and the electrodeposited AgNPs were characterized by atomic force microscopy. The results showed the PoPD film was porous and the AgNPs dispersed uniformly on the PoPD film. Cylic voltammetry and amperometry were used to evaluate electrocatalytic properties of the AgNPs/PoPD/GCE. The electrode displayed good electrocatalytic activity in the reduction of H 2 O 2 and could be used as a sensor for H 2 O 2 detection. The sensor exhibited fast amperometric response to H 2 O 2 with high selectivity, good reproducibility and stability. The linear range was 6.0 μM to 67.3 mM with a detection limit of 1.5 μM. Thus, it is considered to be an ideal candidate for practical application.

  18. Modification of alumina matrices through chemical etching and electroless deposition of nano-Au array for amperometric sensing

    Directory of Open Access Journals (Sweden)

    Valinčius Gintaras

    2007-01-01

    Full Text Available AbstractSimple nanoporous alumina matrix modification procedure, in which the electrically highly insulating alumina barrier layer at the bottom of the pores is replaced with the conductive layer of the gold beds, was described. This modification makes possible the direct electron exchange between the underlying aluminum support and the redox species encapsulated in the alumina pores, thus, providing the generic platform for the nanoporous alumina sensors (biosensors with the direct amperometric signal readout fabrication.

  19. Colorimetric humidity sensor based on liquid composite materials for the monitoring of food and pharmaceuticals.

    Science.gov (United States)

    Bridgeman, Devon; Corral, Javier; Quach, Ashley; Xian, Xiaojun; Forzani, Erica

    2014-09-09

    Using supported ionic-liquid membrane (SILM)-inspired methodologies, we have synthesized, characterized, and developed a humidity sensor by coating a liquid composite material onto a hygroscopic, porous substrate. Similar to pH paper, the sensor responds to the environment's relative humidity and changes color accordingly. The humidity indicator is prepared by casting a few microliters of low-toxicity reagents on a nontoxic substrate. The sensing material is a newly synthesized liquid composite that comprises a hygroscopic medium for environmental humidity capture and a color indicator that translates the humidity level into a distinct color change. Sodium borohydride was used to form a liquid composite medium, and DenimBlu30 dye was used as a redox indicator. The liquid composite medium provides a hygroscopic response to the relative humidity, and DenimBlu30 translates the chemical changes into a visual change from yellow to blue. The borate-redox dye-based humidity sensor was prepared, and then Fourier transform infrared spectroscopy, differential scanning calorimetry, and image analysis methods were used to characterize the chemical composition, optimize synthesis, and gain insight into the sensor reactivity. Test results indicated that this new sensing material can detect relative humidity in the range of 5-100% in an irreversible manner with good reproducibility and high accuracy. The sensor is a low-cost, highly sensitive, easy-to-use humidity indicator. More importantly, it can be easily packaged with products to monitor humidity levels in pharmaceutical and food packaging.

  20. Embedding Piezoresistive Pressure Sensors to Obtain Online Pressure Profiles Inside Fiber Composite Laminates

    OpenAIRE

    Kahali Moghaddam, Maryam; Breede, Arne; Brauner, Christian; Lang, Walter

    2015-01-01

    The production of large and complex parts using fiber composite materials is costly due to the frequent formation of voids, porosity and waste products. By embedding different types of sensors and monitoring the process in real time, the amount of wastage can be significantly reduced. This work focuses on developing a knowledge-based method to improve and ensure complete impregnation of the fibers before initiation of the resin cure. Piezoresistive and capacitive pressure sensors were embedde...

  1. Amperometric Enzyme-Based Biosensors for Application in Food and Beverage Industry

    Science.gov (United States)

    Csöoregi, Elisabeth; Gáspñr, Szilveszter; Niculescu, Mihaela; Mattiasson, Bo; Schuhmann, Wolfgang

    Continuous, sensitive, selective, and reliable monitoring of a large variety of different compounds in various food and beverage samples is of increasing importance to assure a high-quality and tracing of any possible source of contamination of food and beverages. Most of the presently used classical analytical methods are often requiring expensive instrumentation, long analysis times and well-trained staff. Amperometric enzyme-based biosensors on the other hand have emerged in the last decade from basic science to useful tools with very promising application possibilities in food and beverage industry. Amperometric biosensors are in general highly selective, sensitive, relatively cheap, and easy to integrate into continuous analysis systems. A successful application of such sensors for industrial purposes, however, requires a sensor design, which satisfies the specific needs of monitoring the targeted analyte in the particular application, Since each individual application needs different operational conditions and sensor characteristics, it is obvious that biosensors have to be tailored for the particular case. The characteristics of the biosensors are depending on the used biorecognition element (enzyme), nature of signal transducer (electrode material) and the communication between these two elements (electron-transfer pathway).

  2. Bioinspired Flexible and Highly Responsive Dual-Mode Strain/Magnetism Composite Sensor.

    Science.gov (United States)

    Huang, Pei; Li, Yuan-Qing; Yu, Xiao-Guang; Zhu, Wei-Bin; Nie, Shu-Yan; Zhang, Hao; Liu, Jin-Rui; Hu, Ning; Fu, Shao-Yun

    2018-04-04

    The mimicry of human skin to detect both oncoming and physical-contacting object is of great importance in the fields of manufacturing, artificial robots and vehicles, etc. Herein, a novel bioinspired flexible and highly responsive dual-mode strain/magnetism composite sensor, which works via both contact and contactless modes, is first fabricated by incorporating Fe 3 O 4 /silicone system into a carbon fiber aerogel (CFA). The distance dependence of magnetic field endorses the CFA/Fe 3 O 4 /silicone composite possible for spatial sensing due to the introduction of Fe 3 O 4 magnetic nanoparticles. As a result, the as-prepared flexible sensor exhibits precise and real-time response not only to direct-contact compression as usual but also to contactless magnetic field in a wide frequency range from 0.1 to 10 Hz, achieving the maximum variance of 68% and 86% in relative electrical resistance, respectively. The contact and contactless sensing modes of the strain/magnetism sensor are clearly demonstrated by recording the speeds of bicycle riding and walking, respectively. Interestingly, this dual-mode composite sensor exhibits the capacity of identifying the contact and contactless state, which is the first report for flexible sensors. The current protocol is eco-friendly, facile, and thought-provoking for the fabrication of multifunctional sensors.

  3. Frequency Dependence of Electrical Parameters of an Organic-Inorganic Hybrid Composite Based Humidity Sensor

    Directory of Open Access Journals (Sweden)

    Rizwan Akram

    2016-05-01

    Full Text Available The present study highlights the interdependence of ambient humidity levels on the electrical parameters of organic-inorganic hybrid composite based humidity sensor at varied AC frequencies of input signal. Starting from the bottom, the layer stack of the fabricated humidity sensor was 200-nm silver (Ag thin film and 4 μm spun-coated PEPC+NiPC+Cu2O active layer. Silver thin films were deposited by thermal evaporator on well cleaned microscopic glass slides, which served as a substrate. Conventional optical lithography procedure was adapted to define pairs of silver-silver surface electrodes with two sorts of configurations, i.e., interdigitated and rectangular. Humidity-sensitive layers of organic-inorganic composite were then spun-cast upon the channel between the silver electrodes. The changes in relative humidity levels induced variation in capacitance and impedance of the sensors. These variations in electrical parameters of sensors were also found to be highly dependent upon frequency of input AC signal. Our findings reveal that the organic-inorganic composite shows higher humidity sensitivity at smaller orders of frequency. This finding is in accordance with the established fact that organic semiconductors-based devices are not applicable for high frequency applications due to their lower charge carrier mobility values. Two distinct geometries of semiconducting medium between the silver electrodes were investigated to optimize the sensing parameters of the humidity sensor. Furthermore, the effect of temperature change on the resistance of organic composite has also been studied.

  4. A Sensor Based on LiCl/NaA Zeolite Composites for Effective Humidity Sensing.

    Science.gov (United States)

    Zhang, Ying; Xiang, Hongyu; Sun, Liang; Xie, Qiuhong; Liu, Man; Chen, Yu; Ruan, Shengping

    2018-03-01

    LiCl/NaA zeolite composites were successfully prepared by doping 1 wt%, 2 wt%, 5 wt%, and 8 wt% of LiCl into NaA zeolite. The humidity sensing properties of LiCl/NaA composites were investigated among 11% 95% relative humidity (RH). The LiCl/NaA composites exhibited better humidity sensing properties than pure NaA zeolite. The sensor made by 2 wt% Li-doped NaA zeolite possesses the best linearly in the whole RH. These results demonstrate that the LiCl/NaA composites have the potential application in humidity sensing.

  5. Experimental and numerical studies on the sensitivity of carbon fibre/silicone rubber composite sensors

    International Nuclear Information System (INIS)

    Yang, Lili; Ge, Yong; Zhu, Qinghua; Zhang, Ce; Wang, Zongpeng; Liu, Penghuan

    2012-01-01

    Flexible conductive composite sensors are of great importance for applications in structural monitoring due to their low cost, high durability and excellent compatibility. In this work, carbon fibre/silicone rubber composites were prepared and their sensitivity near the percolation threshold was investigated experimentally and theoretically. Results show that carbon fibre/silicone rubber composites have great mechanical and sensitivity even under high strain conditions. Two models based on the tunnelling effect and general effective medium theory were found to understand the sensitivity of composites with lower and higher fractions of carbon fibre. Moreover, the reversibility of the sensing performance is improved with the increase of carbon fibre addition. (paper)

  6. Overview of Fiber Optic Sensor Technologies for Strain/Temperature Sensing Applications in Composite Materials

    Science.gov (United States)

    Ramakrishnan, Manjusha; Rajan, Ginu; Semenova, Yuliya; Farrell, Gerald

    2016-01-01

    This paper provides an overview of the different types of fiber optic sensors (FOS) that can be used with composite materials and also their compatibility with and suitability for embedding inside a composite material. An overview of the different types of FOS used for strain/temperature sensing in composite materials is presented. Recent trends, and future challenges for FOS technology for condition monitoring in smart composite materials are also discussed. This comprehensive review provides essential information for the smart materials industry in selecting of appropriate types of FOS in accordance with end-user requirements. PMID:26784192

  7. Sensitivity Enhancement in Magnetic Sensors Based on Ferroelectric-Bimorphs and Multiferroic Composites

    Directory of Open Access Journals (Sweden)

    Gollapudi Sreenivasulu

    2016-02-01

    Full Text Available Multiferroic composites with ferromagnetic and ferroelectric phases have been studied in recent years for use as sensors of AC and DC magnetic fields. Their operation is based on magneto-electric (ME coupling between the electric and magnetic subsystems and is mediated by mechanical strain. Such sensors for AC magnetic fields require a bias magnetic field to achieve pT-sensitivity. Novel magnetic sensors with a permanent magnet proof mass, either on a ferroelectric bimorph or a ferromagnetic-ferroelectric composite, are discussed. In both types, the interaction between the applied AC magnetic field and remnant magnetization of the magnet results in a mechanical strain and a voltage response in the ferroelectric. Our studies have been performed on sensors with a Nd-Fe-B permanent magnet proof mass on (i a bimorph of oppositely-poled lead zirconate titanate (PZT platelets and (ii a layered multiferroic composite of PZT-Metglas-Ni. The sensors have been characterized in terms of sensitivity and equivalent magnetic noise N. Noise N in both type of sensors is on the order of 200 pT/√Hz at 1 Hz, a factor of 10 improvement compared to multiferroic sensors without a proof mass. When the AC magnetic field is applied at the bending resonance for the bimorph, the measured N ≈ 700 pT/√Hz. We discuss models based on magneto-electro-mechanical coupling at low frequency and bending resonance in the sensors and theoretical estimates of ME voltage coefficients are in very good agreement with the data.

  8. Sensitivity Enhancement in Magnetic Sensors Based on Ferroelectric-Bimorphs and Multiferroic Composites.

    Science.gov (United States)

    Sreenivasulu, Gollapudi; Qu, Peng; Petrov, Vladimir; Qu, Hongwei; Srinivasan, Gopalan

    2016-02-20

    Multiferroic composites with ferromagnetic and ferroelectric phases have been studied in recent years for use as sensors of AC and DC magnetic fields. Their operation is based on magneto-electric (ME) coupling between the electric and magnetic subsystems and is mediated by mechanical strain. Such sensors for AC magnetic fields require a bias magnetic field to achieve pT-sensitivity. Novel magnetic sensors with a permanent magnet proof mass, either on a ferroelectric bimorph or a ferromagnetic-ferroelectric composite, are discussed. In both types, the interaction between the applied AC magnetic field and remnant magnetization of the magnet results in a mechanical strain and a voltage response in the ferroelectric. Our studies have been performed on sensors with a Nd-Fe-B permanent magnet proof mass on (i) a bimorph of oppositely-poled lead zirconate titanate (PZT) platelets and (ii) a layered multiferroic composite of PZT-Metglas-Ni. The sensors have been characterized in terms of sensitivity and equivalent magnetic noise N. Noise N in both type of sensors is on the order of 200 pT/√Hz at 1 Hz, a factor of 10 improvement compared to multiferroic sensors without a proof mass. When the AC magnetic field is applied at the bending resonance for the bimorph, the measured N ≈ 700 pT/√Hz. We discuss models based on magneto-electro-mechanical coupling at low frequency and bending resonance in the sensors and theoretical estimates of ME voltage coefficients are in very good agreement with the data.

  9. Van der Waals pressure sensors using reduced graphene oxide composites

    Science.gov (United States)

    Jung, Ju Ra; Ahn, Sung Il

    2018-04-01

    Reduced graphene oxide (RGO) films intercalated with various polymers were fabricated by reaction-based self-assembly, and their characteristics as vacuum pressure sensors based on van der Waals interactions were studied. At low temperature, the electrical resistances of the samples decrease linearly with increasing vacuum pressure, whereas at high temperature the variation of the electrical resistance shows secondary order curves. Among all samples, the poly vinyl alcohol intercalated RGO shows the highest sensitivity, being almost two times more sensitive than reference RGO. All samples show almost the same signal for repetitive sudden pressure changes, indicating reasonable reproducibility and durability.

  10. Structural Study of Reduced Graphene Oxide/ Polypyrrole Composite as Methanol Sensor in Direct Methanol Fuel Cell

    International Nuclear Information System (INIS)

    Mumtazah Atiqah Hassan; Siti Kartom Kamarudin; Siti Kartom Kamarudin

    2016-01-01

    Density functional theory (DFT) computations were performed on the optimized geometric and electronic properties of reduced graphene oxide/polypyrole (rGO/ PPy) composite in comparison with pure graphene and graphene oxide structures. Incorporation of both reduced GO (rGO) and PPy will form a good composite which have advantages from both materials such as good mechanical strength and excellent electrical conductivity. These composite would be very suitable in fabrication of methanol sensor in direct methanol fuel cell (DMFC). The HOMO-LUMO energy (eV) was also calculated. These computations provide a theoretical explanation for the good performance of rGO/ PPy composite as electrode materials in methanol sensor. (author)

  11. Low Working-Temperature Acetone Vapor Sensor Based on Zinc Nitride and Oxide Hybrid Composites.

    Science.gov (United States)

    Qu, Fengdong; Yuan, Yao; Guarecuco, Rohiverth; Yang, Minghui

    2016-06-01

    Transition-metal nitride and oxide composites are a significant class of emerging materials that have attracted great interest for their potential in combining the advantages of nitrides and oxides. Here, a novel class of gas sensing materials based on hybrid Zn3 N2 and ZnO composites is presented. The Zn3 N2 /ZnO (ZnNO) composites-based sensor exhibits selectivity and high sensitivity toward acetone vapor, and the sensitivity is dependent on the nitrogen content of the composites. The ZnNO-11.7 described herein possesses a low working temperature of 200 °C. The detection limit (0.07 ppm) is below the diabetes diagnosis threshold (1.8 ppm). In addition, the sensor shows high reproducibility and long-term stability. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Real time failure detection in unreinforced cementitious composites with triboluminescent sensor

    International Nuclear Information System (INIS)

    Olawale, David O.; Kliewer, Kaitlyn; Okoye, Annuli; Dickens, Tarik J.; Uddin, Mohammed J.; Okoli, Okenwa I.

    2014-01-01

    The in-situ triboluminescent optical fiber (ITOF) sensor has an integrated sensing and transmission component that converts the energy from damage events like impacts and crack propagation into optical signals that are indicative of the magnitude of damage in composite structures like concrete bridges. Utilizing the triboluminescence (TL) property of ZnS:Mn, the ITOF sensor has been successfully integrated into unreinforced cementitious composite beams to create multifunctional smart structures with in-situ failure detection capabilities. The fabricated beams were tested under flexural loading, and real time failure detection was made by monitoring the TL signals generated by the integrated ITOF sensor. Tested beam samples emitted distinctive TL signals at the instance of failure. In addition, we report herein a new and promising approach to damage characterization using TL emission profiles. Analysis of TL emission profiles indicates that the ITOF sensor responds to crack propagation through the beam even when not in contact with the crack. Scanning electron microscopy analysis indicated that fracto-triboluminescence was responsible for the TL signals observed at the instance of beam failure. -- Highlights: • Developed a new approach to triboluminescence (TL)-based sensing with ZnS:Mn. • Damage-induced excitation of ZnS:Mn enabled real time damage detection in composite. • Based on sensor position, correlation exists between TL signal and failure stress. • Introduced a new approach to damage characterization with TL profile analysis

  13. GaN nanostructures-poly(vinyl alcohol) composite based hydrostatic pressure sensor device

    CSIR Research Space (South Africa)

    Linganiso, EC

    2013-12-01

    Full Text Available pressure sensors were fabricated using a GaN/polyvinyl alcohol (PVA) composite film deposited onto an interdigitated electrode and studied by measuring the change in alternating current conductance of the devices at varied applied pressures. Three different...

  14. Improved in vivo performance of amperometric oxygen (PO2) sensing catheters via electrochemical nitric oxide generation/release.

    Science.gov (United States)

    Ren, Hang; Coughlin, Megan A; Major, Terry C; Aiello, Salvatore; Rojas Pena, Alvaro; Bartlett, Robert H; Meyerhoff, Mark E

    2015-08-18

    A novel electrochemically controlled release method for nitric oxide (NO) (based on electrochemical reduction of nitrite ions) is combined with an amperometric oxygen sensor within a dual lumen catheter configuration for the continuous in vivo sensing of the partial pressure of oxygen (PO2) in blood. The on-demand electrochemical NO generation/release method is shown to be fully compatible with amperometric PO2 sensing. The performance of the sensors is evaluated in rabbit veins and pig arteries for 7 and 21 h, respectively. Overall, the NO releasing sensors measure both venous and arterial PO2 values more accurately with an average deviation of -2 ± 11% and good correlation (R(2) = 0.97) with in vitro blood measurements, whereas the corresponding control sensors without NO release show an average deviation of -31 ± 28% and poor correlation (R(2) = 0.43) at time points >4 h after implantation in veins and >6 h in arteries. The NO releasing sensors induce less thrombus formation on the catheter surface in both veins and arteries (p < 0.05). This electrochemical NO generation/release method could offer a new and attractive means to improve the biocompatibility and performance of implantable chemical sensors.

  15. Fiber Bragg Grating Sensor System for Monitoring Smart Composite Aerospace Structures

    Science.gov (United States)

    Moslehi, Behzad; Black, Richard J.; Gowayed, Yasser

    2012-01-01

    Lightweight, electromagnetic interference (EMI) immune, fiber-optic, sensor- based structural health monitoring (SHM) will play an increasing role in aerospace structures ranging from aircraft wings to jet engine vanes. Fiber Bragg Grating (FBG) sensors for SHM include advanced signal processing, system and damage identification, and location and quantification algorithms. Potentially, the solution could be developed into an autonomous onboard system to inspect and perform non-destructive evaluation and SHM. A novel method has been developed to massively multiplex FBG sensors, supported by a parallel processing interrogator, which enables high sampling rates combined with highly distributed sensing (up to 96 sensors per system). The interrogation system comprises several subsystems. A broadband optical source subsystem (BOSS) and routing and interface module (RIM) send light from the interrogation system to a composite embedded FBG sensor matrix, which returns measurand-dependent wavelengths back to the interrogation system for measurement with subpicometer resolution. In particular, the returned wavelengths are channeled by the RIM to a photonic signal processing subsystem based on powerful optical chips, then passed through an optoelectronic interface to an analog post-detection electronics subsystem, digital post-detection electronics subsystem, and finally via a data interface to a computer. A range of composite structures has been fabricated with FBGs embedded. Stress tensile, bending, and dynamic strain tests were performed. The experimental work proved that the FBG sensors have a good level of accuracy in measuring the static response of the tested composite coupons (down to submicrostrain levels), the capability to detect and monitor dynamic loads, and the ability to detect defects in composites by a variety of methods including monitoring the decay time under different dynamic loading conditions. In addition to quasi-static and dynamic load monitoring, the

  16. Room temperature humidity sensor based on polyaniline-tungsten disulfide composite

    Science.gov (United States)

    Manjunatha, S.; Chethan, B.; Ravikiran, Y. T.; Machappa, T.

    2018-05-01

    Polyaniline-tungsten disulfide (PANI-WS2) composite was synthesized using in situ polymerization technique by adding finely grinded powder of WS2 during the polymerization of aniline. Field emission scanning electron microscopy (FESEM) images showed the granular morphology with porous nature. Energy dispersive X-ray spectroscopy (EDX) confirmed the presence of carbon, nitrogen, chlorine of PANI, tungsten and sulfur elements of WS2. Humidity sensing property of the composite was investigated by plotting change in its resistance with different relative humidity environments ranging from 10 to 97% RH. Decrease in resistance of the composite was observed with increase in relative humidity. Maximum sensing response of the composite was found to be 88.46%. Response and recovery times of the composite at 97%RH were fair enough to fabricate a sensor based on it. Stability of the composite with respect to the humidity sensing behavior was observed to be unchanged even after two months.

  17. Fabrication and characterization of artificial hair cell sensor based on MWCNT-PDMS composite

    Science.gov (United States)

    Kim, Chi Yeon; Lee, Hyun Sup; Cho, Yo Han; Joh, Cheeyoung; Choi, Pyung; Park, Seong Jin

    2011-06-01

    The aim of this work is to design and fabricate a flow sensor using an artificial hair cell (AHC) inspired by biological hair cells of fish. The sensor consists of a single cilium structure with high aspect ratio and a mechanoreceptor using force sensitive resistor (FSR). The cilium structure is designed for capturing a drag force with direction due to flow field around the sensor and the mechanoreceptor is designed for sensing the drag force with direction from the cilium structure and converting it into an electric signal. The mechanoreceptor has a symmetric four electrodes to sense the drag force and its direction. To fabricate the single cilium structure with high aspect ratio, we have proposed a new design concept using a separated micro mold system (SMS) fabricated by the LIGA process. For a successful replication of the cilium structure, we used the hot embossing process with the help of a double-sided mold system. We used a composite of multiwall carbon nanotube and polydimethylsiloxane (MWCNT-PDMS). The performance of the mechanoreceptors was measured by a computer-controlled nanoindenter. We carried out several experiments with the sensor in the different flow rate and direction using the experimental test apparatus. To calibrate the sensor and calculate the velocity with direction based the signal from the sensor, we analyzed the coupled phenomena between flow field and the cilium structure to calculate the deflection of the cilium structure and the drag force applying to the cilium structure due to the flow field around sensor.

  18. Band-type microelectrodes for amperometric immunoassays

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ga-Yeon; Chang, Young Wook; Ko, Hyuk [Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749 (Korea, Republic of); Kang, Min-Jung [Korea Institute of Science and Technology (KIST), Seoul (Korea, Republic of); Pyun, Jae-Chul, E-mail: jcpyun@yonsei.ac.kr [Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749 (Korea, Republic of)

    2016-07-20

    A band-type microelectrode was made using a parylene-N film as a passivation layer. A circular-type, mm-scale electrode with the same diameter as the band-type microelectrode was also made with an electrode area that was 5000 times larger than the band-type microelectrode. By comparing the amperometric signals of 3,5,3′,5′-tetramethylbenzidine (TMB) samples at different optical density (OD) values, the band-type microelectrode was determined to be 9 times more sensitive than the circular-type electrode. The properties of the circular-type and the band-type electrodes (e.g., the shape of their cyclic voltammograms, the type of diffusion layer used, and the diffusion layer thickness per unit electrode area) were characterized according to their electrode area using the COMSOL Multiphysics software. From these simulations, the band-type electrode was estimated to have the conventional microelectrode properties, even when the electrode area was 100 times larger than a conventional circular-type electrode. These results show that both the geometry and the area of an electrode can influence the properties of the electrode. Finally, amperometric analysis based on a band-type electrode was applied to commercial ELISA kits to analyze human hepatitis B surface antigen (hHBsAg) and human immunodeficiency virus (HIV) antibodies. - Highlights: • A band-type microelectrode was made using a parylene-N film as a passivation layer. • The band-type microelectrode was 14-times more sensitive than circular-type electrode. • The influence of geometry on microelectrode properties was simulated using COMSOL. • The band-type electrode was applied to ELISA kits for hHBsAg and hHIV-antibodies.

  19. Molecular modeling of polymer composite-analyte interactions in electronic nose sensors

    Science.gov (United States)

    Shevade, A. V.; Ryan, M. A.; Homer, M. L.; Manfreda, A. M.; Zhou, H.; Manatt, K. S.

    2003-01-01

    We report a molecular modeling study to investigate the polymer-carbon black (CB) composite-analyte interactions in resistive sensors. These sensors comprise the JPL electronic nose (ENose) sensing array developed for monitoring breathing air in human habitats. The polymer in the composite is modeled based on its stereoisomerism and sequence isomerism, while the CB is modeled as uncharged naphthalene rings with no hydrogens. The Dreiding 2.21 force field is used for the polymer, solvent molecules and graphite parameters are assigned to the carbon black atoms. A combination of molecular mechanics (MM) and molecular dynamics (NPT-MD and NVT-MD) techniques are used to obtain the equilibrium composite structure by inserting naphthalene rings in the polymer matrix. Polymers considered for this work include poly(4-vinylphenol), polyethylene oxide, and ethyl cellulose. Analytes studied are representative of both inorganic and organic compounds. The results are analyzed for the composite microstructure by calculating the radial distribution profiles as well as for the sensor response by predicting the interaction energies of the analytes with the composites. c2003 Elsevier Science B.V. All rights reserved.

  20. Experimental testing of a self-sensing FRP-concrete composite beam using FBG sensors

    Science.gov (United States)

    Wang, Yanlei; Hao, Qingduo; Ou, Jinping

    2009-03-01

    A new kind of self-sensing fiber reinforced polymer (FRP)-concrete composite beam, which consists of a FRP box beam combined with a thin layer of concrete in the compression zone, was developed by using two embedded FBG sensors in the top and bottom flanges of FRP box beam at mid-span section along longitudinal direction, respectively. The flexural behavior of the proposed self-sensing FRP-concrete composite beam was experimentally studied in four-point bending. The longitudinal strains of the composite beam were recorded using the embedded FBG sensors as well as the surfacebonded electric resistance strain gauges. Test results indicate that the FBG sensors can faithfully record the longitudinal strain of the composite beam in tension at bottom flange of the FRP box beam or in compression at top flange over the entire load range, as compared with the surface-bonded strain gauges. The proposed self-sensing FRP-concrete composite beam can monitor its longitudinal strains in serviceability limit state as well as in strength limit state, and will has wide applications for long-term monitoring in civil engineering.

  1. Electrically Conductive TPU Nanofibrous Composite with High Stretchability for Flexible Strain Sensor

    Science.gov (United States)

    Tong, Lu; Wang, Xiao-Xiong; He, Xiao-Xiao; Nie, Guang-Di; Zhang, Jun; Zhang, Bin; Guo, Wen-Zhe; Long, Yun-Ze

    2018-03-01

    Highly stretchable and electrically conductive thermoplastic polyurethane (TPU) nanofibrous composite based on electrospinning for flexible strain sensor and stretchable conductor has been fabricated via in situ polymerization of polyaniline (PANI) on TPU nanofibrous membrane. The PANI/TPU membrane-based sensor could detect a strain from 0 to 160% with fast response and excellent stability. Meanwhile, the TPU composite has good stability and durability. Besides, the composite could be adapted to various non-flat working environments and could maintain opportune conductivity at different operating temperatures. This work provides an easy operating and low-cost method to fabricate highly stretchable and electrically conductive nanofibrous membrane, which could be applied to detect quick and tiny human actions.

  2. Hysteresis Compensation of Piezoresistive Carbon Nanotube/Polydimethylsiloxane Composite-Based Force Sensors

    Directory of Open Access Journals (Sweden)

    Ji-Sik Kim

    2017-01-01

    Full Text Available This paper provides a preliminary study on the hysteresis compensation of a piezoresistive silicon-based polymer composite, poly(dimethylsiloxane dispersed with carbon nanotubes (CNTs, to demonstrate its feasibility as a conductive composite (i.e., a force-sensitive resistor for force sensors. In this study, the potential use of the nanotube/polydimethylsiloxane (CNT/PDMS as a force sensor is evaluated for the first time. The experimental results show that the electrical resistance of the CNT/PDMS composite changes in response to sinusoidal loading and static compressive load. The compensated output based on the Duhem hysteresis model shows a linear relationship. This simple hysteresis model can compensate for the nonlinear frequency-dependent hysteresis phenomenon when a dynamic sinusoidal force input is applied.

  3. A Spray-On Carbon Nanotube Artificial Neuron Strain Sensor for Composite Structural Health Monitoring

    Directory of Open Access Journals (Sweden)

    Gyeongrak Choi

    2016-07-01

    Full Text Available We present a nanocomposite strain sensor (NCSS to develop a novel structural health monitoring (SHM sensor that can be easily installed in a composite structure. An NCSS made of a multi-walled carbon nanotubes (MWCNT/epoxy composite was installed on a target structure with facile processing. We attempted to evaluate the NCSS sensing characteristics and benchmark compared to those of a conventional foil strain gauge. The response of the NCSS was fairly good and the result was nearly identical to the strain gauge. A neuron, which is a biomimetic long continuous NCSS, was also developed, and its vibration response was investigated for structural damage detection of a composite cantilever. The vibration response for damage detection was measured by tracking the first natural frequency, which demonstrated good result that matched the finite element (FE analysis.

  4. TiO2-TiO2 composite resistive humidity sensor: ethanol crosssensitivity

    International Nuclear Information System (INIS)

    Ghalamboran, Milad; Saedi, Yasin

    2016-01-01

    The fabrication method and characterization results of a TiO 2 -TiO 2 composite bead used for humidity sensing along with its negative cross-sensitivity to ethanol vapor are reported. The bead shaped resistive sample sensors are fabricated by the drop-casting of a TiO 2 slurry on two Pt wire segments. The dried bead is pre-fired at 750°C and subsequently impregnated with a Ti-based sol. The sample is ready for characterization after a thermal annealing at 600°C in air. Structurally, the bead is a composite of the micron-sized TiO 2 crystallites embedded in a matrix of nanometric TiO 2 particle aggregates. The performance of the beads as resistive humidity sensors is recorded at room temperature in standard humidity level chambers. Results evince the wide dynamic range of the sensors fabricated in the low relative humidity range. While the sensor conductance is not sensitive to ethanol vapor in dry air, in humid air, sensor's responses are negatively affected by the contaminant. (paper)

  5. Multi-axial strain transfer from laminated CFRP composites to embedded Bragg sensor: I. Parametric study

    International Nuclear Information System (INIS)

    Luyckx, G; Voet, E; De Waele, W; Degrieck, J

    2010-01-01

    Embedded optical fibre sensors are considered in numerous applications for structural health monitoring purposes. However, since the optical fibre and the host material in which it is embedded, will have different material properties, strain in both materials will not be equal when load is applied. Therefore, the multi-axial strain transfer from the host material to the embedded sensor (optical fibre) has to be considered in detail. In the first part of this paper the strain transfer will be determined using finite element modelling of a circular isotropic glass fibre embedded first in an isotropic host and second in an anisotropic composite material. The strain transfer or relation depends on the mechanical properties of the host material and the sensor (Young's modulus and Poisson's ratio), on the lay-up of the composite material (uni-directional lay-up/cross-ply lay-up) and the position of the sensor in a certain layer. In the second part of the paper the developed strain transfer model will be evaluated for one specific lay-up and sensor type

  6. Processing and Characterization of a Novel Distributed Strain Sensor Using Carbon Nanotube-Based Nonwoven Composites

    Directory of Open Access Journals (Sweden)

    Hongbo Dai

    2015-07-01

    Full Text Available This paper describes the development of an innovative carbon nanotube-based non-woven composite sensor that can be tailored for strain sensing properties and potentially offers a reliable and cost-effective sensing option for structural health monitoring (SHM. This novel strain sensor is fabricated using a readily scalable process of coating Carbon nanotubes (CNT onto a nonwoven carrier fabric to form an electrically-isotropic conductive network. Epoxy is then infused into the CNT-modified fabric to form a free-standing nanocomposite strain sensor. By measuring the changes in the electrical properties of the sensing composite the deformation can be measured in real-time. The sensors are repeatable and linear up to 0.4% strain. Highest elastic strain gage factors of 1.9 and 4.0 have been achieved in the longitudinal and transverse direction, respectively. Although the longitudinal gage factor of the newly formed nanocomposite sensor is close to some metallic foil strain gages, the proposed sensing methodology offers spatial coverage, manufacturing customizability, distributed sensing capability as well as transverse sensitivity.

  7. Vibration monitoring of carbon fiber composites by multiple fiber optic sensors

    Science.gov (United States)

    Olivero, Massimo; Perrone, Guido; Vallan, Alberto; Chen, Wei; Tosi, Daniele

    2014-05-01

    This work presents the comparison between the fiber Bragg grating technology and a vibration-measurement technique based on the detection of polarization rotation (polarimetric sensor) in a standard optical fiber, applied to the dynamic structural monitoring of carbon reinforced composites for the automotive industry. A carbon reinforced composite test plate in a 4-layer configuration was equipped with fiber Bragg gratings and polarimetric fiber sensors, then it was mechanically stressed by static and dynamic loads while monitoring the sensors response. The fiber Bragg grating setup exhibited 1.15+/-0.0016 pm/kg static load response and reproduced dynamic excitation with 0.1% frequency uncertainty, while the polarimetric sensing system exhibited a sensitivity of 1.74+/-0.001 mV/kg and reproduced the dynamic excitation with 0.5% frequency uncertainty. It is shown that the polarimetric sensor technology represents a cheap yet efficient alternative to the fiber Bragg grating sensors in the case of vibration-monitoring of small structures at high frequency.

  8. Stress-tuned conductor-polymer composite for use in sensors

    Science.gov (United States)

    Martin, James E; Read, Douglas H

    2013-10-22

    A method for making a composite polymeric material with electrical conductivity determined by stress-tuning of the conductor-polymer composite, and sensors made with the stress-tuned conductor-polymer composite made by this method. Stress tuning is achieved by mixing a miscible liquid into the polymer precursor solution or by absorbing into the precursor solution a soluble compound from vapor in contact with the polymer precursor solution. The conductor may or may not be ordered by application of a magnetic field. The composite is formed by polymerization with the stress-tuning agent in the polymer matrix. The stress-tuning agent is removed following polymerization to produce a conductor-polymer composite with a stress field that depends on the amount of stress-tuning agent employed.

  9. Sensor-Motor Maps for Describing Linear Reflex Composition in Hopping.

    Science.gov (United States)

    Schumacher, Christian; Seyfarth, André

    2017-01-01

    In human and animal motor control several sensory organs contribute to a network of sensory pathways modulating the motion depending on the task and the phase of execution to generate daily motor tasks such as locomotion. To better understand the individual and joint contribution of reflex pathways in locomotor tasks, we developed a neuromuscular model that describes hopping movements. In this model, we consider the influence of proprioceptive length (LFB), velocity (VFB) and force feedback (FFB) pathways of a leg extensor muscle on hopping stability, performance and efficiency (metabolic effort). Therefore, we explore the space describing the blending of the monosynaptic reflex pathway gains. We call this reflex parameter space a sensor-motor map . The sensor-motor maps are used to visualize the functional contribution of sensory pathways in multisensory integration. We further evaluate the robustness of these sensor-motor maps to changes in tendon elasticity, body mass, segment length and ground compliance. The model predicted that different reflex pathway compositions selectively optimize specific hopping characteristics (e.g., performance and efficiency). Both FFB and LFB were pathways that enable hopping. FFB resulted in the largest hopping heights, LFB enhanced hopping efficiency and VFB had the ability to disable hopping. For the tested case, the topology of the sensor-motor maps as well as the location of functionally optimal compositions were invariant to changes in system designs (tendon elasticity, body mass, segment length) or environmental parameters (ground compliance). Our results indicate that different feedback pathway compositions may serve different functional roles. The topology of the sensor-motor map was predicted to be robust against changes in the mechanical system design indicating that the reflex system can use different morphological designs, which does not apply for most robotic systems (for which the control often follows a specific

  10. Hazardous industrial gases identified using a novel polymer/MWNT composite resistance sensor array

    International Nuclear Information System (INIS)

    Yuana, C.L.; Chang, C.P.; Song, Y.

    2011-01-01

    Highlights: → In this work, a silicon wafer microelectrode substrate for a resistance sensor was fabricated using the semiconductor manufacturing process. → This work developed polymer-functionalized MWNT sensor plat forms for the detection of vapors from chemical agents at different temperatures. → Applied PCA to determine the performance of as-fabricated films for exposure to three chemical agents. - Abstract: Hazardous industrial chemical gases pose a significant threat to the environment and human life. Therefore, there is an urgent need to develop a reliable sensor for identifying these hazardous gases. In this work, a silicon wafer microelectrode substrate for a resistance sensor was fabricated using the semiconductor manufacturing process. Conductive carbon nanotubes were then mixed with six different polymers with different chemical adsorption properties to produce a composite thin film for the fabrication of a chemical sensor array. This array was then utilized to identify three hazardous gases at different temperatures. Experimental results for six polymers for chemical gases, such as tetrahydrofuran (THF), chloroform (CHCl 3 ) and methanol (MeOH) at different temperatures, indicate that the variation in sensitivity resistance increased when the sensing temperature increased. The poly(ethylene adipate)/MWNT sensing film had high sensitivity, excellent selectivity, and good reproducibility in detecting all chemical agent vapors. Additionally, this study utilized a bar chart and statistical methods in principal component analysis to identify gases with the polymer/MWNT sensor.

  11. Signal enhancement in amperometric peroxide detection by using graphene materials with low number of defects

    International Nuclear Information System (INIS)

    Zöpfl, Alexander; Matysik, Frank-Michael; Hirsch, Thomas; Sisakthi, Masoumeh; Eroms, Jonathan; Strunk, Christoph

    2016-01-01

    Two-dimensional carbon nanomaterials ranging from single-layer graphene to defective structures such as chemically reduced graphene oxide were studied with respect to their use in electrodes and sensors. Their electrochemical properties and utility in terms of fabrication of sensing devices are compared. Specifically, the electrodes have been applied to reductive amperometric determination of hydrogen peroxide. Low-defect graphene (SG) was obtained through mechanical exfoliation of natural graphite, while higher-defect graphenes were produced by chemical vapor deposition (CVDG) and by chemical oxidation of graphite and subsequent reduction (rGO). The carbonaceous materials were mainly characterized by Raman microscopy. They were applied as electrode material and the electrochemical behavior was investigated by chronocoulometry, cyclic voltammetry, electrochemical impedance spectroscopy and amperometry and compared to a carbon disc electrode. It is shown that the quality of the graphene has an enormous impact on the amperometric performance. The use of carbon materials with many defects (like rGO) does not result in a significant improvement in signal compared to a plain carbon disc electrode. The sensitivity is 173 mA · M −1  · cm −2 in case of using CVDG which is about 50 times better than that of a plain carbon disc electrode and about 7 times better than that of rGO. The limit of detection for hydrogen peroxide is 15.1 μM (at a working potential of −0.3 V vs SCE) for CVDG. It is concluded that the application of two-dimensional carbon nanomaterials offers large perspectives in amperometric detection systems due to electrocatalytic effects that result in highly sensitive detection. (author)

  12. Spirally Structured Conductive Composites for Highly Stretchable, Robust Conductors and Sensors.

    Science.gov (United States)

    Wu, Xiaodong; Han, Yangyang; Zhang, Xinxing; Lu, Canhui

    2017-07-12

    Flexible and stretchable electronics are highly desirable for next generation devices. However, stretchability and conductivity are fundamentally difficult to combine for conventional conductive composites, which restricts their widespread applications especially as stretchable electronics. Here, we innovatively develop a new class of highly stretchable and robust conductive composites via a simple and scalable structural approach. Briefly, carbon nanotubes are spray-coated onto a self-adhesive rubber film, followed by rolling up the film completely to create a spirally layered structure within the composites. This unique spirally layered structure breaks the typical trade-off between stretchability and conductivity of traditional conductive composites and, more importantly, restrains the generation and propagation of mechanical microcracks in the conductive layer under strain. Benefiting from such structure-induced advantages, the spirally layered composites exhibit high stretchability and flexibility, good conductive stability, and excellent robustness, enabling the composites to serve as highly stretchable conductors (up to 300% strain), versatile sensors for monitoring both subtle and large human activities, and functional threads for wearable electronics. This novel and efficient methodology provides a new design philosophy for manufacturing not only stretchable conductors and sensors but also other stretchable electronics, such as transistors, generators, artificial muscles, etc.

  13. Tapered Fiber Coated with Hydroxyethyl Cellulose/Polyvinylidene Fluoride Composite for Relative Humidity Sensor

    Directory of Open Access Journals (Sweden)

    M. Z. Muhammad

    2013-01-01

    Full Text Available A simple relative humidity (RH sensor is demonstrated using a tapered fiber coated with hydroxyethyl cellulose/polyvinylidene fluoride (HEC/PVDF composite as a probe. This coating acts as an inner cladding whose refractive index decreases with the rise in humidity and thus allows more light to be transmitted in humid state. A difference of up to 0.89 dB of the transmitted optical power is observed when RH changes from 50% to 80% in case of the silica fiber probe. The proposed sensor has a sensitivity of about 0.0228 dB/%RH with a slope linearity of more than 99.91%. In case of the plastic optical fiber (POF probe, the output voltage of the sensor increases linearly with a sensitivity of 0.0231 mV/%RH and a linearity of more than 99.65% as the relative humidity increases from 55% to 80%.

  14. Novel Mechano-Luminescent Sensors Based on Piezoelectric/Electroluminescent Composites

    Directory of Open Access Journals (Sweden)

    Yunzhang Fang

    2011-04-01

    Full Text Available A high-sensitivity mechano-luminescent sensor was fabricated on the basis of piezoelectric/electroluminescent composites. The working principle of this mechano-luminescent sensor was elucidated by analyzing the relationship between the piezoelectric-induced charges and the electroluminescent effects. When a stress is applied on the piezoelectric layer, electrical charges will be induced at both the top and bottom sides of the piezoelectric layer. The induced electrical charges will lead to a light output from the electroluminescent layer, thus producing a mechano-luminescence effect. By increasing the vibration strength or frequency applied, the mechano-luminescence output can be obviously enhanced. Mechano-luminescence sensors have potential in smart stress-to-light devices, such as foot-stress-distribution-diagnosis systems and dynamic-load-monitors for bridge hanging cables.

  15. Investigations of microelectronic humidity sensors made of composite oxides thin films

    International Nuclear Information System (INIS)

    Pogossyan, A.S.; Arutyunyan, V.M.

    1996-01-01

    Basic characteristics (the moisture sensitivity, lag, hysteresis and stability) of humidity sensors made of Fe 2 O 3 thin films with different K 2 content, as well as CaSiO 3 and NaBiTi 2 O 6 films,-new materials for the humidity sensors, are investigated. A composition Fe 2 O 3 (K) is found to be optimal with respect to high moisture sensitivity, speed of response, and a linearity in a wide range of the relative humidity. A mechanism of the moisture-sensitivity of films investigated is discussed. Criteria for the design parameters of the high-impedance humidity sensors are defined with the aim to broadening of the working range of the relative humidity in a side way of low values of the humidity.10 refs

  16. The role of film composition and nanostructuration on the polyphenol sensor performance

    Directory of Open Access Journals (Sweden)

    Cibely Silva Martin

    2016-12-01

    Full Text Available The recent advances in the supramolecular control in nanostructured films have improved the performance of organic-based devices. However, the effect of different supramolecular arrangement on the sensor or biosensor performance is poorly studied yet. In this paper, we show the role of the composition and nanostructuration of the films on the impedance and voltammetric-based sensor performance to catechol detection. The films here studied were composed by a perylene derivative (PTCD-NH2 and a metallic phthalocyanine (FePc, using Langmuir-Blodgett (LB and physical vapor deposition (PVD techniques. The deposition technique and intrinsic properties of compounds showed influence on electrical and electrocatalytic responses. The PVD PTCD-NH2 shows the best sensor performance to the detection of catechol. Quantification of catechol contents in mate tea samples was also evaluated, and the results showed good agreement compared with Folin-Ciocalteu standard method for polyphenol detection.

  17. Ionic polymer-metal composite torsional sensor: physics-based modeling and experimental validation

    Science.gov (United States)

    Aidi Sharif, Montassar; Lei, Hong; Khalid Al-Rubaiai, Mohammed; Tan, Xiaobo

    2018-07-01

    Ionic polymer-metal composites (IPMCs) have intrinsic sensing and actuation properties. Typical IPMC sensors are in the shape of beams and only respond to stimuli acting along beam-bending directions. Rod or tube-shaped IPMCs have been explored as omnidirectional bending actuators or sensors. In this paper, physics-based modeling is studied for a tubular IPMC sensor under pure torsional stimulus. The Poisson–Nernst–Planck model is used to describe the fundamental physics within the IPMC, where it is hypothesized that the anion concentration is coupled to the sum of shear strains induced by the torsional stimulus. Finite element simulation is conducted to solve for the torsional sensing response, where some of the key parameters are identified based on experimental measurements using an artificial neural network. Additional experimental results suggest that the proposed model is able to capture the torsional sensing dynamics for different amplitudes and rates of the torsional stimulus.

  18. Electrochemical sensors: a powerful tool in analytical chemistry

    Directory of Open Access Journals (Sweden)

    Stradiotto Nelson R.

    2003-01-01

    Full Text Available Potentiometric, amperometric and conductometric electrochemical sensors have found a number of interesting applications in the areas of environmental, industrial, and clinical analyses. This review presents a general overview of the three main types of electrochemical sensors, describing fundamental aspects, developments and their contribution to the area of analytical chemistry, relating relevant aspects of the development of electrochemical sensors in Brazil.

  19. Carbon coated magnesium oxide based amperometric glucose biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Silva, L.L.; Mello, J.M.M.; Fiori, M.A.; Duarte, G.W. [Universidade Comunitaria Regional de Chapeco (UNICHAPECO), SC (Brazil); Fernandes, S.C. [Instituto Federal Catarinense (IFC), Blumenau, SC (Brazil); Riella, H.G. [Centro Universitario Barriga Verde (UNIBAVE), Orleans, SC (Brazil); Anzolin, C.; Figueiro, A.; Grando, M.C. [Universidade Federal de Santa Catarina (UFSC), SC (Brazil)

    2016-07-01

    Full text: Diabetes is a serious disease that is harmful to human health since it is related to cardiovascular and stroke events. Since the first glucose oxidase (GOx) sensor, different approaches have been explored. Carbon was used to cover nano-magnesium oxide (MgO-C) forming a core-shell which was used to improve its biocompatibility and chemical stability for the preparation of GOx biosensor. MgO nanostructures have been prepared by calcination of the gel formed by the reaction of magnesium acetate tetrahydrate dissolved in cetyltrimethylammonium with the addition of tartaric acid solution. MgO-C nanostructures were obtained by heating MgO nanoparticles previously prepared together with glucose and PEG dissolved in an aqueous suspension. Reaction conditions such as concentration of magnesium precursor, temperature and aging time show important roles in the size, morphology and growth process of the final products. The core-shell structure was evidenced by SEM/FEG and XRD and showed that the product appeared to have morphological forms of nanowires. GOx was spread onto the surface of a modified carbon paste electrode (CPE) doped with MgO-C and the effect on the biosensing properties investigated by comparing the electrochemical properties of the proposed biosensor with bare and modified CPEs by cyclic voltammetry. The amount of modifier in CPE (5-75 weight% with respect to graphite) influences the peak current and the influence of different experimental parameters (enzyme percentage, pH solution and amperometric methods) was also investigated. The results demonstrate that the GOx retains its biocatalytic activity and that the bioelectrode modified can be a possible use for other nanotechnological purposes including biomedical ones. (author)

  20. Carbon coated magnesium oxide based amperometric glucose biosensor

    International Nuclear Information System (INIS)

    Silva, L.L.; Mello, J.M.M.; Fiori, M.A.; Duarte, G.W.; Fernandes, S.C.; Riella, H.G.; Anzolin, C.; Figueiro, A.; Grando, M.C.

    2016-01-01

    Full text: Diabetes is a serious disease that is harmful to human health since it is related to cardiovascular and stroke events. Since the first glucose oxidase (GOx) sensor, different approaches have been explored. Carbon was used to cover nano-magnesium oxide (MgO-C) forming a core-shell which was used to improve its biocompatibility and chemical stability for the preparation of GOx biosensor. MgO nanostructures have been prepared by calcination of the gel formed by the reaction of magnesium acetate tetrahydrate dissolved in cetyltrimethylammonium with the addition of tartaric acid solution. MgO-C nanostructures were obtained by heating MgO nanoparticles previously prepared together with glucose and PEG dissolved in an aqueous suspension. Reaction conditions such as concentration of magnesium precursor, temperature and aging time show important roles in the size, morphology and growth process of the final products. The core-shell structure was evidenced by SEM/FEG and XRD and showed that the product appeared to have morphological forms of nanowires. GOx was spread onto the surface of a modified carbon paste electrode (CPE) doped with MgO-C and the effect on the biosensing properties investigated by comparing the electrochemical properties of the proposed biosensor with bare and modified CPEs by cyclic voltammetry. The amount of modifier in CPE (5-75 weight% with respect to graphite) influences the peak current and the influence of different experimental parameters (enzyme percentage, pH solution and amperometric methods) was also investigated. The results demonstrate that the GOx retains its biocatalytic activity and that the bioelectrode modified can be a possible use for other nanotechnological purposes including biomedical ones. (author)

  1. Sensor-based vibration signal feature extraction using an improved composite dictionary matching pursuit algorithm.

    Science.gov (United States)

    Cui, Lingli; Wu, Na; Wang, Wenjing; Kang, Chenhui

    2014-09-09

    This paper presents a new method for a composite dictionary matching pursuit algorithm, which is applied to vibration sensor signal feature extraction and fault diagnosis of a gearbox. Three advantages are highlighted in the new method. First, the composite dictionary in the algorithm has been changed from multi-atom matching to single-atom matching. Compared to non-composite dictionary single-atom matching, the original composite dictionary multi-atom matching pursuit (CD-MaMP) algorithm can achieve noise reduction in the reconstruction stage, but it cannot dramatically reduce the computational cost and improve the efficiency in the decomposition stage. Therefore, the optimized composite dictionary single-atom matching algorithm (CD-SaMP) is proposed. Second, the termination condition of iteration based on the attenuation coefficient is put forward to improve the sparsity and efficiency of the algorithm, which adjusts the parameters of the termination condition constantly in the process of decomposition to avoid noise. Third, composite dictionaries are enriched with the modulation dictionary, which is one of the important structural characteristics of gear fault signals. Meanwhile, the termination condition of iteration settings, sub-feature dictionary selections and operation efficiency between CD-MaMP and CD-SaMP are discussed, aiming at gear simulation vibration signals with noise. The simulation sensor-based vibration signal results show that the termination condition of iteration based on the attenuation coefficient enhances decomposition sparsity greatly and achieves a good effect of noise reduction. Furthermore, the modulation dictionary achieves a better matching effect compared to the Fourier dictionary, and CD-SaMP has a great advantage of sparsity and efficiency compared with the CD-MaMP. The sensor-based vibration signals measured from practical engineering gearbox analyses have further shown that the CD-SaMP decomposition and reconstruction algorithm

  2. Sensor-Based Vibration Signal Feature Extraction Using an Improved Composite Dictionary Matching Pursuit Algorithm

    Directory of Open Access Journals (Sweden)

    Lingli Cui

    2014-09-01

    Full Text Available This paper presents a new method for a composite dictionary matching pursuit algorithm, which is applied to vibration sensor signal feature extraction and fault diagnosis of a gearbox. Three advantages are highlighted in the new method. First, the composite dictionary in the algorithm has been changed from multi-atom matching to single-atom matching. Compared to non-composite dictionary single-atom matching, the original composite dictionary multi-atom matching pursuit (CD-MaMP algorithm can achieve noise reduction in the reconstruction stage, but it cannot dramatically reduce the computational cost and improve the efficiency in the decomposition stage. Therefore, the optimized composite dictionary single-atom matching algorithm (CD-SaMP is proposed. Second, the termination condition of iteration based on the attenuation coefficient is put forward to improve the sparsity and efficiency of the algorithm, which adjusts the parameters of the termination condition constantly in the process of decomposition to avoid noise. Third, composite dictionaries are enriched with the modulation dictionary, which is one of the important structural characteristics of gear fault signals. Meanwhile, the termination condition of iteration settings, sub-feature dictionary selections and operation efficiency between CD-MaMP and CD-SaMP are discussed, aiming at gear simulation vibration signals with noise. The simulation sensor-based vibration signal results show that the termination condition of iteration based on the attenuation coefficient enhances decomposition sparsity greatly and achieves a good effect of noise reduction. Furthermore, the modulation dictionary achieves a better matching effect compared to the Fourier dictionary, and CD-SaMP has a great advantage of sparsity and efficiency compared with the CD-MaMP. The sensor-based vibration signals measured from practical engineering gearbox analyses have further shown that the CD-SaMP decomposition and

  3. Fibre Optic Sensors for Structural Health Monitoring of Aircraft Composite Structures: Recent Advances and Applications

    Science.gov (United States)

    Di Sante, Raffaella

    2015-01-01

    In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS) have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques. PMID:26263987

  4. Iron-Based Nanomaterials/Graphene Composites for Advanced Electrochemical Sensors

    Directory of Open Access Journals (Sweden)

    Kaveh Movlaee

    2017-11-01

    Full Text Available Iron oxide nanostructures (IONs in combination with graphene or its derivatives—e.g., graphene oxide and reduced graphene oxide—hold great promise toward engineering of efficient nanocomposites for enhancing the performance of advanced devices in many applicative fields. Due to the peculiar electrical and electrocatalytic properties displayed by composite structures in nanoscale dimensions, increasing efforts have been directed in recent years toward tailoring the properties of IONs-graphene based nanocomposites for developing more efficient electrochemical sensors. In the present feature paper, we first reviewed the various routes for synthesizing IONs-graphene nanostructures, highlighting advantages, disadvantages and the key synthesis parameters for each method. Then, a comprehensive discussion is presented in the case of application of IONs-graphene based composites in electrochemical sensors for the determination of various kinds of (biochemical substances.

  5. Iron-Based Nanomaterials/Graphene Composites for Advanced Electrochemical Sensors

    Science.gov (United States)

    Movlaee, Kaveh; Ganjali, Mohmmad Reza; Norouzi, Parviz

    2017-01-01

    Iron oxide nanostructures (IONs) in combination with graphene or its derivatives—e.g., graphene oxide and reduced graphene oxide—hold great promise toward engineering of efficient nanocomposites for enhancing the performance of advanced devices in many applicative fields. Due to the peculiar electrical and electrocatalytic properties displayed by composite structures in nanoscale dimensions, increasing efforts have been directed in recent years toward tailoring the properties of IONs-graphene based nanocomposites for developing more efficient electrochemical sensors. In the present feature paper, we first reviewed the various routes for synthesizing IONs-graphene nanostructures, highlighting advantages, disadvantages and the key synthesis parameters for each method. Then, a comprehensive discussion is presented in the case of application of IONs-graphene based composites in electrochemical sensors for the determination of various kinds of (bio)chemical substances. PMID:29168771

  6. Fibre Optic Sensors for Structural Health Monitoring of Aircraft Composite Structures: Recent Advances and Applications

    Directory of Open Access Journals (Sweden)

    Raffaella Di Sante

    2015-07-01

    Full Text Available In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques.

  7. A Study on AE Signal Analysis of Composite Materials Using Matrix Piezo Electric Sensor

    International Nuclear Information System (INIS)

    Yu, Yeun Ho; Choi, Jin Ho; Kweon, Jin Hwe

    2007-01-01

    As fiber reinforced composite materials are widely used in aircraft, space structures and robot arms, the study on non-destructive testing methods has become an important research area for improving their reliability and safety. AE (acoustic emission) can evaluate the defects by detecting the emitting strain energy when elastic waves are generated by the initiation and growth of crack, plastic deformation, fiber breakage, matrix cleavage, or delamination. In the paper, AE signals generated under uniaxial tension were measured and analyzed using the 8x8 matrix piezo electric sensor. The electronic circuit to control the transmitting distance of AE signals was designed and constructed. The optical data storage system was also designed to store the AE signal of 64 channels using LED (light emitting diode) elements. From the tests, it was shown that the source location and propagation path of AE signals in composite materials could be detected effectively by the 8x8 matrix piezo electric sensor

  8. Monitoring of fatigue damage in composite lap-joints using guided waves and FBG sensors

    Science.gov (United States)

    Karpenko, Oleksii; Khomenko, Anton; Koricho, Ermias; Haq, Mahmoodul; Udpa, Lalita

    2016-02-01

    Adhesive bonding is being increasingly employed in many applications as it offers possibility of light-weighting and efficient multi-material joining along with reduction in time and cost of manufacturing. However, failure initiation and progression in critical components like joints, specifically in fatigue loading is not well understood, which necessitates reliable NDE and SHM techniques to ensure structural integrity. In this work, concurrent guided wave (GW) and fiber Bragg grating (FBG) sensor measurements were used to monitor fatigue damage in adhesively bonded composite lap-joints. In the present set-up, one FBG sensor was strategically embedded in the adhesive bond-line of a lap-joint, while two other FBGs were bonded on the surface of the adherends. Full spectral responses of FBG sensors were collected and compared at specific intervals of fatigue loading. In parallel, guided waves were actuated and sensed using PZT wafers mounted on the composite adherends. Experimental results demonstrated that time-of-flight (ToF) of the fundamental modes transmitted through the bond-line and spectral response of FBG sensors were sensitive to fatigue loading and damage. Combination of guided wave and FBG measurements provided the desired redundancy and synergy in the data to evaluate the degradation in bond-line properties. Measurements taken in the presence of continuously applied load replicated the in-situ/service conditions. The approach shows promise in understanding the behavior of bonded joints subjected to complex loading.

  9. Highly stretchable resistive pressure sensors using a conductive elastomeric composite on a micropyramid array.

    Science.gov (United States)

    Choong, Chwee-Lin; Shim, Mun-Bo; Lee, Byoung-Sun; Jeon, Sanghun; Ko, Dong-Su; Kang, Tae-Hyung; Bae, Jihyun; Lee, Sung Hoon; Byun, Kyung-Eun; Im, Jungkyun; Jeong, Yong Jin; Park, Chan Eon; Park, Jong-Jin; Chung, U-In

    2014-06-04

    A stretchable resistive pressure sensor is achieved by coating a compressible substrate with a highly stretchable electrode. The substrate contains an array of microscale pyramidal features, and the electrode comprises a polymer composite. When the pressure-induced geometrical change experienced by the electrode is maximized at 40% elongation, a sensitivity of 10.3 kPa(-1) is achieved. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Monitoring Poisson's ratio degradation of FRP composites under fatigue loading using biaxially embedded FBG sensors

    OpenAIRE

    Akay, Erdem; Yılmaz, Çağatay; Yilmaz, Cagatay; Kocaman, Esat Selim; Türkmen, Halit S.; Turkmen, Halit S.; Yıldız, Mehmet; Yildiz, Mehmet

    2016-01-01

    The significance of strain measurement is obvious for the analysis of Fiber-Reinforced Polymer (FRP) composites. Conventional strain measurement methods are sufficient for static testing in general. Nevertheless, if the requirements exceed the capabilities of these conventional methods, more sophisticated techniques are necessary to obtain strain data. Fiber Bragg Grating (FBG) sensors have many advantages for strain measurement over conventional ones. Thus, the present paper suggests a novel...

  11. Piezoelectric Flexible LCP-PZT Composites for Sensor Applications at Elevated Temperatures

    Science.gov (United States)

    Tolvanen, Jarkko; Hannu, Jari; Juuti, Jari; Jantunen, Heli

    2018-03-01

    In this paper fabrication of piezoelectric ceramic-polymer composites is demonstrated via filament extrusion enabling cost-efficient large-scale production of highly bendable pressure sensors feasible for elevated temperatures. These composites are fabricated by utilizing environmentally resistant and stable liquid crystal polymer matrix with addition of lead zirconate titanate at loading levels of 30 vol%. These composites, of approximately 0.99 mm thick and length of > 50 cm, achieved excellent bendability with minimum bending radius of 6.6 cm. The maximum piezoelectric coefficients d33 and g33 of the composites were > 14 pC/N and > 108 mVm/N at pressure < 10 kPa. In all cases, the piezoelectric charge coefficient (d33) of the composites decreased as a function of pressure. Also, piezoelectric coefficient (d33) further decreased in the case of increased frequency press-release cycle sand pre-stress levels by approximately 37-50%. However, the obtained results provide tools for fabricating novel piezoelectric sensors in highly efficient way for environments with elevated temperatures.

  12. A Nafion -based co-planar electrode amperometric sensor for ...

    Indian Academy of Sciences (India)

    Administrator

    The methanol detector could be operated both in a nitrogen stream and (in what is essential for practical applications) in an air atmosphere too, with estimated detection limits of 1⋅2 and .... adsorption/desorption are not clear but this is a common finding of the enormous Pt/Nafion. ® litera- ture. For example, Mitsushima et al.

  13. Piezoresistive Composite Silicon Dioxide Nanocantilever Surface Stress Sensor: Design and Optimization.

    Science.gov (United States)

    Mathew, Ribu; Sankar, A Ravi

    2018-05-01

    In this paper, we present the design and optimization of a rectangular piezoresistive composite silicon dioxide nanocantilever sensor. Unlike the conventional design approach, we perform the sensor optimization by not only considering its electro-mechanical response but also incorporating the impact of self-heating induced thermal drift in its terminal characteristics. Through extensive simulations first we comprehend and quantify the inaccuracies due to self-heating effect induced by the geometrical and intrinsic parameters of the piezoresistor. Then, by optimizing the ratio of electrical sensitivity to thermal sensitivity defined as the sensitivity ratio (υ) we improve the sensor performance and measurement reliability. Results show that to ensure υ ≥ 1, shorter and wider piezoresistors are better. In addition, it is observed that unlike the general belief that high doping concentration of piezoresistor reduces thermal sensitivity in piezoresistive sensors, to ensure υ ≥ 1 doping concentration (p) should be in the range: 1E18 cm-3 ≤ p ≤ 1E19 cm-3. Finally, we provide a set of design guidelines that will help NEMS engineers to optimize the performance of such sensors for chemical and biological sensing applications.

  14. Novel ammonia sensor based on polyaniline/polylactic acid composite films

    International Nuclear Information System (INIS)

    Sotirov, S; Bodurov, I; Marudova, M

    2017-01-01

    We propose a new type of ammonia sensor based on composite film between polyaniline (emeraldine base) dissolved in dimethylformamide, and poly(DL-lactic) acid dissolved in chloroform. The two solutions were mixed in weight ratio of the components 1:1 and cast on Al 2 O 3 substrate, on which silver electrodes were deposited previously. The active layer structure and morphology were examined by atomic force microscopy. The sensor resistance at constant humidity and different ammonia concentrations was measured. It was found that an increase in the ammonia concentration leads to resistance increase. This result is explained in the terms of ionic interactions between the polyaniline and the ammonia, which change the permittivity of the sensor active media. A response between 2% and 590% was shown depending on the ammonia concentration. The sensor is reversible and possesses response time of typically 100 s. Based on the changes of the sensor resistance, ammonia concentration from 10 ppm to 1000 ppm could be detected. (paper)

  15. Novel ammonia sensor based on polyaniline/polylactic acid composite films

    Science.gov (United States)

    Sotirov, S.; Bodurov, I.; Marudova, M.

    2017-01-01

    We propose a new type of ammonia sensor based on composite film between polyaniline (emeraldine base) dissolved in dimethylformamide, and poly(DL-lactic) acid dissolved in chloroform. The two solutions were mixed in weight ratio of the components 1:1 and cast on Al2O3 substrate, on which silver electrodes were deposited previously. The active layer structure and morphology were examined by atomic force microscopy. The sensor resistance at constant humidity and different ammonia concentrations was measured. It was found that an increase in the ammonia concentration leads to resistance increase. This result is explained in the terms of ionic interactions between the polyaniline and the ammonia, which change the permittivity of the sensor active media. A response between 2% and 590% was shown depending on the ammonia concentration. The sensor is reversible and possesses response time of typically 100 s. Based on the changes of the sensor resistance, ammonia concentration from 10 ppm to 1000 ppm could be detected.

  16. Carbon nanotube/polymer composite electrodes for flexible, attachable electrochemical DNA sensors.

    Science.gov (United States)

    Li, Jianfeng; Lee, Eun-Cheol

    2015-09-15

    All-solution-processed, easily-made, flexible multi-walled carbon nanotube (MWCNT)/polydimethylsiloxane (PDMS)-based electrodes were fabricated and used for electrochemical DNA sensors. These electrodes could serve as a recognition layer for DNA, without any surface modification, through π-π interactions between the MWCNTs and DNA, greatly simplifying the fabrication process for DNA sensors. The electrodes were directly connected to an electrochemical analyzer in the differential pulse voltammetry (DPV) and cyclic voltammetry (CV) measurements, where methylene blue was used as a redox indicator. Since neither functional groups nor probe DNA were immobilized on the surfaces of the electrodes, the sensor can be easily regenerated by washing these electrodes with water. The limit of detection was found to be 1.3 × 10(2)pM (S/N=3), with good DNA sequence differentiation ability. Fast fabrication of a DNA sensor was also achieved by cutting and attaching the MWCNT-PDMS composite electrodes at an analyte solution-containable region. Our results pave the way for developing user-fabricated easily attached DNA sensors at low costs. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Analytical Parameters of an Amperometric Glucose Biosensor for Fast Analysis in Food Samples

    Directory of Open Access Journals (Sweden)

    Margalida Artigues

    2017-11-01

    Full Text Available Amperometric biosensors based on the use of glucose oxidase (GOx are able to combine the robustness of electrochemical techniques with the specificity of biological recognition processes. However, very little information can be found in literature about the fundamental analytical parameters of these sensors. In this work, the analytical behavior of an amperometric biosensor based on the immobilization of GOx using a hydrogel (Chitosan onto highly ordered titanium dioxide nanotube arrays (TiO2NTAs has been evaluated. The GOx–Chitosan/TiO2NTAs biosensor showed a sensitivity of 5.46 μA·mM−1 with a linear range from 0.3 to 1.5 mM; its fundamental analytical parameters were studied using a commercial soft drink. The obtained results proved sufficient repeatability (RSD = 1.9%, reproducibility (RSD = 2.5%, accuracy (95–105% recovery, and robustness (RSD = 3.3%. Furthermore, no significant interferences from fructose, ascorbic acid and citric acid were obtained. In addition, the storage stability was further examined, after 30 days, the GOx–Chitosan/TiO2NTAs biosensor retained 85% of its initial current response. Finally, the glucose content of different food samples was measured using the biosensor and compared with the respective HPLC value. In the worst scenario, a deviation smaller than 10% was obtained among the 20 samples evaluated.

  18. Analytical Parameters of an Amperometric Glucose Biosensor for Fast Analysis in Food Samples

    Science.gov (United States)

    2017-01-01

    Amperometric biosensors based on the use of glucose oxidase (GOx) are able to combine the robustness of electrochemical techniques with the specificity of biological recognition processes. However, very little information can be found in literature about the fundamental analytical parameters of these sensors. In this work, the analytical behavior of an amperometric biosensor based on the immobilization of GOx using a hydrogel (Chitosan) onto highly ordered titanium dioxide nanotube arrays (TiO2NTAs) has been evaluated. The GOx–Chitosan/TiO2NTAs biosensor showed a sensitivity of 5.46 μA·mM−1 with a linear range from 0.3 to 1.5 mM; its fundamental analytical parameters were studied using a commercial soft drink. The obtained results proved sufficient repeatability (RSD = 1.9%), reproducibility (RSD = 2.5%), accuracy (95–105% recovery), and robustness (RSD = 3.3%). Furthermore, no significant interferences from fructose, ascorbic acid and citric acid were obtained. In addition, the storage stability was further examined, after 30 days, the GOx–Chitosan/TiO2NTAs biosensor retained 85% of its initial current response. Finally, the glucose content of different food samples was measured using the biosensor and compared with the respective HPLC value. In the worst scenario, a deviation smaller than 10% was obtained among the 20 samples evaluated. PMID:29135931

  19. [Amperometric biosensor for lactate analysis in wines and grape must during fermentation].

    Science.gov (United States)

    Shkotova, L V; Horiushkina, T B; Slast'ia, E A; Soldatkin, O P; Tranh-Minh, S; Chovelon, J M; Dziadevych, S V

    2005-01-01

    The amperometric biosensor based on lactate oxidase for determination of lactate has been developed, and two methods of immobilization of lactate oxidase on the surface of industrial screen-printed platinum electrodes SensLab were compared. A sensor with immobilized in the Resydrol polymer lactate oxidase by the method of physical adsorption is characterized of narrow dynamic range and greater response value in comparison with a biosensor based on immobilised in poly(3,4-ethylenedioxythiophene) lactate oxidase by the method of electrochemical polymerization. Operational stability of the biosensor developed was studied and it was shown, that the immobilization method does not influence their stability. The analysis of the lactate in wine and during wine fermentation has been conducted. High correlation of the data obtained by means of amperometric lactate biosensor and a standard method of an ionic chromatography has been shown. The developed biosensor could be applied in the food industry for the control and optimization of the wine fermentation process, and quality control of wine.

  20. Carbon film resistor electrode for amperometric determination of acetaminophen in pharmaceutical formulations.

    Science.gov (United States)

    Felix, Fabiana S; Brett, Christopher M A; Angnes, Lúcio

    2007-04-11

    Flow injection analysis (FIA) with amperometric detection was employed for acetaminophen quantification in pharmaceutical formulations using a carbon film resistor electrode. This sensor exhibited sharp and reproducible current peaks for acetaminophen without chemical modification of its surface. A wide linear working range (8.0x10(-7) to 5.0x10(-4) mol L(-1)) in phosphate buffer solution as well as high sensitivity (0.143 A mol(-1) L cm(-2)) and low submicromolar detection limit (1.36x10(-7) mol L(-1)) were achieved. The repeatability (R.S.D. for 10 successive injections of 5.0x10(-6) and 5.0x10(-5) mol L(-1) acetaminophen solutions) was 3.1 and 1.3%, respectively, without any memory effect between injections. The new procedure was applied to the analyses of commercial pharmaceutical products and the results were in good agreement with those obtained utilizing a spectrophotometric method. Consequently, this amperometric method has been shown to be very suitable for quality control analyses and other applications with similar requirements.

  1. Amperometric morphine sensing using a molecularly imprinted polymer-modified electrode

    International Nuclear Information System (INIS)

    Yeh, W.-M.; Ho, K.-C.

    2005-01-01

    This study incorporates morphine into a molecularly imprinted polymer (MIP) for the amperometric detection of morphine. The polymer, poly(3,4-ethylenedioxythiophene), PEDOT, is an electroactive film that catalyzes morphine oxidation and lowers the oxidization potential on an indium tin oxide (ITO) electrode. The MIP-PEDOT modified electrode is prepared by electropolymerizing PEDOT onto an ITO electrode in a 0.1 M LiClO 4 solution with template addition (morphine). After template molecule extraction, the oxidizing current of the MIP-PEDOT modified electrode is measured in a 0.1 M KCl solution (pH = 5.3) at 0.75 V (versus Ag/AgCl/sat'd KCl) with the morphine concentration varying in the 0.1-5 mM range. A linear range, displaying the relationship between steady-state currents and morphine concentrations, from 0.1 to 1 mM, is obtained. The proposed amperometric sensor could be used for morphine detection with a sensitivity of 91.86 μA/cm 2 per mM. A detection limit of 0.2 mM at a signal-to-noise ratio of 3 is achieved. Moreover, the proposed method can discriminate between morphine and its analogs, such as codeine

  2. Analytical Parameters of an Amperometric Glucose Biosensor for Fast Analysis in Food Samples.

    Science.gov (United States)

    Artigues, Margalida; Abellà, Jordi; Colominas, Sergi

    2017-11-14

    Amperometric biosensors based on the use of glucose oxidase (GOx) are able to combine the robustness of electrochemical techniques with the specificity of biological recognition processes. However, very little information can be found in literature about the fundamental analytical parameters of these sensors. In this work, the analytical behavior of an amperometric biosensor based on the immobilization of GOx using a hydrogel (Chitosan) onto highly ordered titanium dioxide nanotube arrays (TiO₂NTAs) has been evaluated. The GOx-Chitosan/TiO₂NTAs biosensor showed a sensitivity of 5.46 μA·mM -1 with a linear range from 0.3 to 1.5 mM; its fundamental analytical parameters were studied using a commercial soft drink. The obtained results proved sufficient repeatability (RSD = 1.9%), reproducibility (RSD = 2.5%), accuracy (95-105% recovery), and robustness (RSD = 3.3%). Furthermore, no significant interferences from fructose, ascorbic acid and citric acid were obtained. In addition, the storage stability was further examined, after 30 days, the GOx-Chitosan/TiO₂NTAs biosensor retained 85% of its initial current response. Finally, the glucose content of different food samples was measured using the biosensor and compared with the respective HPLC value. In the worst scenario, a deviation smaller than 10% was obtained among the 20 samples evaluated.

  3. Monitoring Poisson's ratio of glass fiber reinforced composites as damage index using biaxial Fiber Bragg Grating sensors

    OpenAIRE

    Yılmaz, Çağatay; Yilmaz, Cagatay; Akalın, Çağdaş; Akalin, Cagdas; Kocaman, Esat Selim; Suleman, A.; Yıldız, Mehmet; Yildiz, Mehmet

    2016-01-01

    Damage accumulation in Glass Fiber Reinforced Polymer (GFRP) composites is monitored based on Poisson's ratio measurements for three different fiber stacking sequences subjected to both quasi-static and quasi-static cyclic tensile loadings. The sensor systems utilized include a dual-extensometer, a biaxial strain gage and a novel embedded-biaxial Fiber Bragg Grating (FBG) sensor. These sensors are used concurrently to measure biaxial strain whereby the evolution of Poisson's ratio as a functi...

  4. Sensors

    CERN Document Server

    Pigorsch, Enrico

    1997-01-01

    This is the 5th edition of the Metra Martech Directory "EUROPEAN CENTRES OF EXPERTISE - SENSORS." The entries represent a survey of European sensors development. The new edition contains 425 detailed profiles of companies and research institutions in 22 countries. This is reflected in the diversity of sensors development programmes described, from sensors for physical parameters to biosensors and intelligent sensor systems. We do not claim that all European organisations developing sensors are included, but this is a good cross section from an invited list of participants. If you see gaps or omissions, or would like your organisation to be included, please send details. The data base invites the formation of effective joint ventures by identifying and providing access to specific areas in which organisations offer collaboration. This issue is recognised to be of great importance and most entrants include details of collaboration offered and sought. We hope the directory on Sensors will help you to find the ri...

  5. Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, H. [PBI-Dansensor A/S (Denmark); Toft Soerensen, O. [Risoe National Lab., Materials Research Dept. (Denmark)

    1999-10-01

    A new type of ceramic oxygen sensors based on semiconducting oxides was developed in this project. The advantage of these sensors compared to standard ZrO{sub 2} sensors is that they do not require a reference gas and that they can be produced in small sizes. The sensor design and the techniques developed for production of these sensors are judged suitable by the participating industry for a niche production of a new generation of oxygen sensors. Materials research on new oxygen ion conducting conductors both for applications in oxygen sensors and in fuel was also performed in this project and finally a new process was developed for fabrication of ceramic tubes by dip-coating. (EHS)

  6. Amperometric and coulometric methods of platinum metal determination. (Review)

    International Nuclear Information System (INIS)

    Ezerskaya, N.A.

    1981-01-01

    Reviewed are works published in the period from 1957-1979, on amperometric and coulometric (potentiostatistic and amperostatistic variant) determination of platinum metals, Ru in particular. During amperometric titration of Ru the following titrantes are used: hydroquinone, thioxne thiourea, Na 2 S 2 O 3 . It is proposed to titrate Ru in the form of ruthenate-ion with hydrazine sulphate in alkal: medium according to the current of reagent oxidation. During coulometric determination of Ru the electrogenerating titrant TiCl 3 or Ti 2 (SO 4 ) 3 (for initial form of Ru [RuCl 6 ] 2- ) is used [ru

  7. Chemically designed Pt/PPy nano-composite for effective LPG gas sensor.

    Science.gov (United States)

    Gaikwad, Namrata; Bhanoth, Sreenu; More, Priyesh V; Jain, G H; Khanna, P K

    2014-03-07

    Simultaneous in situ reduction of hexachloroplatinic acid by the amine group in the pyrrole monomer and oxidation of pyrrole to form polypyrrole (PPy) was examined. The reactions were performed at various temperatures to understand the degree of reduction of platinum precursor as well as doping of polypyrrole with Pt(II) chloro-complex. Spectroscopic images revealed different morphologies for the Pt/PPy nano-composite prepared at various temperatures. The as-prepared Pt/PPy nano-composite samples were tested for their ability to sense liquefied petroleum gas (LPG) which resulted in excellent sensing at relatively low temperature. The porous nature and ohmic contact between the PPy and platinum nanoparticles makes the as-prepared Pt/PPy nano-composite highly useful for sensors as well as electronic applications.

  8. Highly sensitive amperometric sensing of nitrite utilizing bulk-modified MnO2 decorated Graphene oxide nanocomposite screen-printed electrodes

    International Nuclear Information System (INIS)

    Jaiswal, Nandita; Tiwari, Ida; Foster, Christopher W.; Banks, Craig E.

    2017-01-01

    A screen-printed amperometric sensor based on a carbon ink bulk-modified with MnO 2 decorated graphene oxide (MnO 2 /GO-SPE) nanocomposite was investigated for its ability to serve as a sensor towards nitrite. The composite was prepared by simple ultrasonication and reflux methodology and was characterized by FT-IR spectroscopy, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, atomic force microscopy and electrochemically using cyclic voltammetry, chronoamperometry and differential pulse voltammetry techniques. The MnO 2 /GO-SPE was found to exhibit an electro-catalytic activity for the electrochemical oxidation of nitrite in 0.1 M phosphate buffer solution (pH 7.4). The electrochemical oxidation of nitrite occurs at +0.55 V (Vs. Ag/AgCl) with a limit of detection (3σ) found to be 0.09 μM and with two linear ranges of 0.1 μM to 1 μM and 1 μM to 1000 μM with sensitivities of 1.25 μAμM −1 cm −2 and 0.005 μAμM −1 cm −2 respectively. Furthermore, the MnO 2 /GO-SPE showed an excellent anti-interference ability towards a range of commonly encountered electroactive species and metal ions. Additionally, the fabricated MnO 2 /GO-SPE nitrite sensor presented an excellent selectivity, reproducibility and stability. The presented study widens the scope of applications of graphene-based nanocomposite materials for on-site monitoring of nitrite.

  9. Ionic Polymer-Metal Composites (IPMCs) as Biomimetic Sensors, Actuators and Artificial Muscles: A Review

    Science.gov (United States)

    Shahinpoor, M.; Bar-Cohen, Y.; Simpson, J. O.; Smith, J.

    1998-01-01

    This paper presents an introduction to ionic polymer-metal composites and some mathematical modeling pertaining to them. It further discusses a number of recent findings in connection with ion-exchange polymer-metal composites (IPMCS) as biomimetic sensors and actuators. Strips of these composites can undergo large bending and flapping displacement if an electric field is imposed across their thickness. Thus, in this sense they are large motion actuators. Conversely by bending the composite strip, either quasi-statically or dynamically, a voltage is produced across the thickness of the strip. Thus, they are also large motion sensors. The output voltage can be calibrated for a standard size sensor and correlated to the applied loads or stresses. They can be manufactured and cut in any size and shape. In this paper first the sensing capability of these materials is reported. The preliminary results show the existence of a linear relationship between the output voltage and the imposed displacement for almost all cases. Furthermore, the ability of these IPMCs as large motion actuators and robotic manipulators is presented. Several muscle configurations are constructed to demonstrate the capabilities of these IPMC actuators. This paper further identifies key parameters involving the vibrational and resonance characteristics of sensors and actuators made with IPMCS. When the applied signal frequency varies, so does the displacement up to a critical frequency called the resonant frequency where maximum deformation is observed, beyond which the actuator response is diminished. A data acquisition system was used to measure the parameters involved and record the results in real time basis. Also the load characterizations of the IPMCs were measured and it was shown that these actuators exhibit good force to weight characteristics in the presence of low applied voltages. Finally reported are the cryogenic properties of these muscles for potential utilization in an outer space

  10. Sensor-Motor Maps for Describing Linear Reflex Composition in Hopping

    Directory of Open Access Journals (Sweden)

    Christian Schumacher

    2017-11-01

    Full Text Available In human and animal motor control several sensory organs contribute to a network of sensory pathways modulating the motion depending on the task and the phase of execution to generate daily motor tasks such as locomotion. To better understand the individual and joint contribution of reflex pathways in locomotor tasks, we developed a neuromuscular model that describes hopping movements. In this model, we consider the influence of proprioceptive length (LFB, velocity (VFB and force feedback (FFB pathways of a leg extensor muscle on hopping stability, performance and efficiency (metabolic effort. Therefore, we explore the space describing the blending of the monosynaptic reflex pathway gains. We call this reflex parameter space a sensor-motor map. The sensor-motor maps are used to visualize the functional contribution of sensory pathways in multisensory integration. We further evaluate the robustness of these sensor-motor maps to changes in tendon elasticity, body mass, segment length and ground compliance. The model predicted that different reflex pathway compositions selectively optimize specific hopping characteristics (e.g., performance and efficiency. Both FFB and LFB were pathways that enable hopping. FFB resulted in the largest hopping heights, LFB enhanced hopping efficiency and VFB had the ability to disable hopping. For the tested case, the topology of the sensor-motor maps as well as the location of functionally optimal compositions were invariant to changes in system designs (tendon elasticity, body mass, segment length or environmental parameters (ground compliance. Our results indicate that different feedback pathway compositions may serve different functional roles. The topology of the sensor-motor map was predicted to be robust against changes in the mechanical system design indicating that the reflex system can use different morphological designs, which does not apply for most robotic systems (for which the control often follows a

  11. An all-polymer airflow sensor using a piezoresistive composite elastomer

    International Nuclear Information System (INIS)

    Aiyar, Avishek R; Allen, Mark G; Song, Chao; Kim, Seong-Hyok

    2009-01-01

    This paper presents an all-polymer flexible micromachined flow sensor using a carbon-black based conductive composite elastomer as a piezoresistor. The device is composed of an out-of-plane curved flow sensing element formed using a polyimide film. The conductive composite elastomer combines a low Young's modulus (∼1.72 MPa) and a high piezoresistive gage factor (∼7.3), making it an ideal material for the sensing application. Moreover, the use of the polyimide film, which can be easily laser micromachined, as the material for device fabrication enables the use of planar micromachining techniques, which minimizes process complexities. The proposed fabrication sequence combines the benefits of the polymeric materials used, while simultaneously enabling a backside interconnect scheme for an array of devices, without additional processing steps. The backside interconnect scheme allows for flow field mapping with minimum interference due to the sensing circuitry. Individual sensors as small as 1.5 mm in length and 0.4 mm in width, with 70 µm wide and 20–50 µm thick piezoresistor lines, have been fabricated. Wind tunnel testing demonstrated sensitivities as high as 66Ω/(m s −1 ). The integration of polyimide films and conductive elastomers into a flow sensing device using the simple planar fabrication technologies discussed is suitable for reduced cost, large area sensor array development, and can also leverage traditional flexible circuit fabrication

  12. Tunable Diode Laser Sensors to Monitor Temperature and Gas Composition in High-Temperature Coal Gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, Ronald [Stanford Univ., CA (United States); Whitty, Kevin [Univ. of Utah, Salt Lake City, UT (United States)

    2014-12-01

    The integrated gasification combined cycle (IGCC) when combined with carbon capture and storage can be one of the cleanest methods of extracting energy from coal. Control of coal and biomass gasification processes to accommodate the changing character of input-fuel streams is required for practical implementation of integrated gasification combined-cycle (IGCC) technologies. Therefore a fast time-response sensor is needed for real-time monitoring of the composition and ideally the heating value of the synthesis gas (here called syngas) as it exits the gasifier. The goal of this project was the design, construction, and demonstration an in situ laserabsorption sensor to monitor multiple species in the syngas output from practical-scale coal gasifiers. This project investigated the hypothesis of using laser absorption sensing in particulateladen syngas. Absorption transitions were selected with design rules to optimize signal strength while minimizing interference from other species. Successful in situ measurements in the dusty, high-pressure syngas flow were enabled by Stanford’s normalized and scanned wavelength modulation strategy. A prototype sensor for CO, CH4, CO2, and H2O was refined with experiments conducted in the laboratory at Stanford University, a pilot-scale at the University of Utah, and an engineering-scale gasifier at DoE’s National Center for Carbon Capture with the demonstration of a prototype sensor with technical readiness level 6 in the 2014 measurement campaign.

  13. Printed hydrogen sulfide gas sensor on paper substrate based on polyaniline composite

    International Nuclear Information System (INIS)

    Sarfraz, J.; Ihalainen, P.; Määttänen, A.; Peltonen, J.; Lindén, M.

    2013-01-01

    The fabrication of a hydrogen sulfide (H 2 S) sensor based on polyaniline (PANI)-metal salt (CuCl 2 ) composite is demonstrated. The sensing film was produced by screen printing and spray coating of the sensing material on interdigitated silver electrodes inkjet-printed on a paper substrate. The H 2 S sensing functionality with respect to pH and metal salt concentration was optimized. In addition, the long term stability and humidity effects on the sensor performance were investigated. The printed chemiresistors showed more than five orders of magnitude change in resistance within 20 min of exposure of 15 ppm H 2 S at room temperature. The relatively fast kinetics and large response of the sensor can be explained by the formation of Cu 2 S and subsequent protonation of PANI. In addition, the relatively large roughness and porosity of the paper substrate offers an increased surface sensing area. - Highlights: • pH, salt concentration, film thickness, cross sensitivity • Printed sensor on paper substrate • Commercial polyaniline against special morphologies

  14. Structural Health Monitoring of a Composite Panel Based on PZT Sensors and a Transfer Impedance Framework.

    Science.gov (United States)

    Dziendzikowski, Michal; Niedbala, Patryk; Kurnyta, Artur; Kowalczyk, Kamil; Dragan, Krzysztof

    2018-05-11

    One of the ideas for development of Structural Health Monitoring (SHM) systems is based on excitation of elastic waves by a network of PZT piezoelectric transducers integrated with the structure. In the paper, a variant of the so-called Transfer Impedance (TI) approach to SHM is followed. Signal characteristics, called the Damage Indices (DIs), were proposed for data presentation and analysis. The idea underlying the definition of DIs was to maintain most of the information carried by the voltage induced on PZT sensors by elastic waves. In particular, the DIs proposed in the paper should be sensitive to all types of damage which can influence the amplitude or the phase of the voltage induced on the sensor. Properties of the proposed DIs were investigated experimentally using a GFRP composite panel equipped with PZT networks attached to its surface and embedded into its internal structure. Repeatability and stability of DI indications under controlled conditions were verified in tests. Also, some performance indicators for surface-attached and structure-embedded sensors were obtained. The DIs' behavior was dependent mostly on the presence of a simulated damage in the structure. Anisotropy of mechanical properties of the specimen, geometrical properties of PZT network as well as, to some extent, the technology of sensor integration with the structure were irrelevant for damage indication. This property enables the method to be used for damage detection and classification.

  15. A fiber optic Doppler sensor and its application in debonding detection for composite structures.

    Science.gov (United States)

    Li, Fucai; Murayama, Hideaki; Kageyama, Kazuro; Meng, Guang; Ohsawa, Isamu; Shirai, Takehiro

    2010-01-01

    Debonding is one of the most important damage forms in fiber-reinforced composite structures. This work was devoted to the debonding damage detection of lap splice joints in carbon fiber reinforced plastic (CFRP) structures, which is based on guided ultrasonic wave signals captured by using fiber optic Doppler (FOD) sensor with spiral shape. Interferometers based on two types of laser sources, namely the He-Ne laser and the infrared semiconductor laser, are proposed and compared in this study for the purpose of measuring Doppler frequency shift of the FOD sensor. Locations of the FOD sensors are optimized based on mechanical characteristics of lap splice joint. The FOD sensors are subsequently used to detect the guided ultrasonic waves propagating in the CFRP structures. By taking advantage of signal processing approaches, features of the guided wave signals can be revealed. The results demonstrate that debonding in the lap splice joint results in arrival time delay of the first package in the guided wave signals, which can be the characteristic for debonding damage inspection and damage extent estimation.

  16. Electrochemical evaluation of the a carbon-paste electrode modified with spinel manganese(IV) oxide under flow conditions for amperometric determination of lithium

    International Nuclear Information System (INIS)

    Raymundo-Pereira, Paulo A.; Martin, Cibely S.; Bergamini, Marcio F.; Bocchi, Nerilso; Teixeira, Marcos F.S.

    2011-01-01

    The participation of cations in redox reactions of manganese oxides provides an opportunity for development of chemical sensors for non-electroactive ions. This paper describes the amperometric determination of lithium ions using carbon-paste electrode modified with spinel manganese(IV) oxide under flow conditions. Systematic investigations were made to optimize the experimental parameters for lithium sensor by flow injection analysis. The detection was based on the measurement of anodic current generated by oxidation of Mn(III) to Mn(IV) at the surface of the electrode and consequently the lithium ions extraction into the spinel structure. An operating potential of 0.50 V (vs. Ag/AgCl/3 KCl mol/L) was exploited for amperometric monitoring. The amperometric signal was linearly dependent on the lithium ions concentration over the range 4.0 x 10 -5 to 1.0 x 10 -3 mol L -1 . The equilibrium constant of insertion/extraction of the lithium ion in the spinel structure, apparent Gibbs energy of insertion, and surface coverage of the electrode with manganese oxide, were calculated by peak charge (Q) in different concentration under flow conditions. Considering selectivity, the peak charge of the sensor was found to be linearly dependent on the ionic radius of the alkaline and earth-alkaline cations.

  17. Skin-Spar Failure Detection of a Composite Winglet Using FBG Sensors

    Directory of Open Access Journals (Sweden)

    Ciminello Monica

    2017-09-01

    Full Text Available Winglets are introduced into modern aircraft to reduce wing aerodynamic drag and to consequently optimize the fuel burn per mission. In order to be aerodynamically effective, these devices are installed at the wing tip section; this wing region is generally characterized by relevant oscillations induced by flights maneuvers and gust. The present work is focused on the validation of a continuous monitoring system based on fiber Bragg grating sensors and frequency domain analysis to detect physical condition of a skin-spar bonding failure in a composite winglet for in-service purposes. Optical fibers are used as deformation sensors. Short Time Fast Fourier Transform (STFT analysis is applied to analyze the occurrence of structural response deviations on the base of strain data. Obtained results showed high accuracy in estimating static and dynamic deformations and great potentials in detecting structural failure occurrences.

  18. Amperometric Morphine Detection Using Pt-Co Alloy Nanowire Array-modified Electrode

    International Nuclear Information System (INIS)

    Tao, Manlan; Xu, Feng; Li, Yueting; Xu, Quanqing; Chang, Yanbing; Yang, Yunhui; Wu, Zaisheng

    2010-01-01

    Pt-Co alloy nanowire array was directly synthesized by electrochemical deposition with polycarbonate template at -1.0V and subsequent chemical etching of the template. The use of Pt-Co alloy nanowire array-modified electrode (Pt- Co NAE) for the determination of morphine (MO) is described. The morphology of the Pt-Co alloy nanowire array has been investigated by scanning electron microscopy (SEM) and energy disperse X-ray spectroscopy (EDS) analysis), respectively. The resulting Pt-Co NAE offered a linear amperometric response for morphine ranging from 2.35 x 10 -5 to 2.39 x 10 -3 M with a detection limit of 7.83 x 10 -6 M at optimum conditions. This sensor displayed high sensitivity and long-term stability

  19. Temperature and strain registration by fibre-optic strain sensor in the polymer composite materials manufacturing

    Science.gov (United States)

    Matveenko; Kosheleva; Shardakov; Voronkov

    2018-04-01

    The presence of process-induced strains induced by various manufacturing and operational factors is one of the characteristics of polymer composite materials (PCM). Conventional methods of registration and evaluation of process-induced strains can be laborious, time-consuming and demanding in terms of technical applications. The employment of embedded fibre-optic strain sensors (FOSS) offers a real prospect of measuring residual strains. This paper demonstrates the potential for using embedded FOSS for recording technological strains in a PCM plate. The PCM plate is manufactured from prepreg, using the direct compression-moulding method. In this method, the prepared reinforcing package is placed inside a mould, heated, and then exposed to compaction pressure. The examined technology can be used for positioning FOSS between the layers of the composite material. Fibre-optic sensors, interacting with the material of the examined object, make it possible to register the evolution of the strain process during all stages of polymer-composite formation. FOSS data were recorded with interrogator ASTRO X 327. The obtained data were processed using specially developed algorithms.

  20. Graphene–Noble Metal Nano-Composites and Applications for Hydrogen Sensors

    Directory of Open Access Journals (Sweden)

    Sukumar Basu

    2017-10-01

    Full Text Available Graphene based nano-composites are relatively new materials with excellent mechanical, electrical, electronic and chemical properties for applications in the fields of electrical and electronic devices, mechanical appliances and chemical gadgets. For all these applications, the structural features associated with chemical bonding that involve other components at the interface need in-depth investigation. Metals, polymers, inorganic fibers and other components improve the properties of graphene when they form a kind of composite structure in the nano-dimensions. Intensive investigations have been carried out globally in this area of research and development. In this article, some salient features of graphene–noble metal interactions and composite formation which improve hydrogen gas sensing properties—like higher and fast response, quick recovery, cross sensitivity, repeatability and long term stability of the sensor devices—are presented. Mostly noble metals are effective for enhancing the sensing performance of the graphene–metal hybrid sensors, due to their superior catalytic activities. The experimental evidence for atomic bonding between metal nano-structures and graphene has been reported in the literature and it is theoretically verified by density functional theory (DFT. Multilayer graphene influences gas sensing performance via intercalation of metal and non-metal atoms through atomic bonding.

  1. N-m-nitrocinnamoylphenylhydroxyl-amine as reagent for amperometric determination of yttrium

    International Nuclear Information System (INIS)

    Oliferenko, G.L.; Gallaj, Z.A.; Sheina, N.M.; Shvedene, N.V.

    1983-01-01

    Possibility of using organic reagent of unsaturated N-arylsubstituted derivatives class of hydroxamic acids N-m-nitrocinnamoyl phenylhydroxylamire (NCPHA) for amperometric titration of yttrium using indication of e.t.p. by current of reagent oxidation on graphite electrode is investigated. Metal and the NCPHA form difficultly soluble complex with ratio of yttrium to the NCPHA, which is equal to 1:3. Buffer mixtures of 0.1MNH 3 +0.1MCH 3 COOH composis tion with pH 6.3-7.5 are optimal background solutions for amperometric titration of yttrium. The proposed method permits to determine 10-600 μkg of yttrium in the volume of 10 ml. Effect of the series of strange elements on titration of yttrium with NCPHA (Ca, Mg, Mn (2), Al, CU (2), Fe (3) REE and others) is studied. The developed method is used for yttrium determination in luminophores of Casub(n)-- Ysub(m)Fsub(z)xMn(2) (1-10%) composition

  2. A fine pointed glucose oxidase immobilized electrode for low-invasive amperometric glucose monitoring.

    Science.gov (United States)

    Li, Jiang; Koinkar, Pankaj; Fuchiwaki, Yusuke; Yasuzawa, Mikito

    2016-12-15

    A low invasive type glucose sensor, which has a sensing region at the tip of a fine pointed electrode, was developed for continuous glucose monitoring. Platinum-iridium alloy electrode with a surface area of 0.045mm(2) was settled at the middle of pointed PEEK (Polyetheretherketone) tubing and was employed as sensing electrode. Electrodeposition of glucose oxidase in the presence of surfactant, Triton X-100, was performed for high-density enzyme immobilization followed by the electropolymerization of o-phenylenediamine for the formation of functional entrapping and permselective polymer membrane. Ag/AgCl film was coated on the surface of PEEK tubing as reference electrode. Amperometric responses of the prepared sensors to glucose were measured at a potential of 0.60V (vs. Ag/AgCl). The prepared electrode showed the sensitivity of 2.55μA/cm(2) mM with high linearity of 0.9986, within the glucose concentration range up to 21mM. The detection limit (S/N=3) was determined to be 0.11mM. The glucose sensor properties were evaluated in phosphate buffer solution and in vivo monitoring by the implantation of the sensors in rabbit, while conventional needle type sensors as a reference were used. The results showed that change in output current of the proposed sensor fluctuated similar with one in output current of the conventional needle type sensors, which was also in similar accordance with actual blood sugar level measured by commercially glucose meter. One-point calibration method was used to calibrate the sensor output current. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Amperometric Carbon Fiber Nitrite Microsensor for In Situ Biofilm Monitoring

    Science.gov (United States)

    A highly selective needle type solid state amperometric nitrite microsensor based on direct nitrite oxidation on carbon fiber was developed using a simplified fabrication method. The microsensor’s tip diameter was approximately 7 µm, providing a high spatial resolution of at lea...

  4. Electrochemical sensor for dopamine based on a novel graphene-molecular imprinted polymers composite recognition element

    DEFF Research Database (Denmark)

    Mao, Yan; Bao, Yu; Gan, Shiyu

    2011-01-01

    A novel composite of graphene sheets/Congo red-molecular imprinted polymers (GSCR-MIPs) was synthesized through free radical polymerization (FRP) and applied as a molecular recognition element to construct dopamine (DA) electrochemical sensor. The template molecules (DA) were firstly absorbed...... at the GSCR surface due to their excellent affinity, and subsequently, selective copolymerization of methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) was further achieved at the GSCR surface. Potential scanning was presented to extract DA molecules from the imprinted polymers film...

  5. Pressure Sensitive Sensors Based on Carbon Nanotubes, Graphene, and Its Composites

    Directory of Open Access Journals (Sweden)

    Asar Ali

    2018-01-01

    Full Text Available Carbon nanotubes (CNTs and graphene have attracted a great deal of interest due to their outstanding mechanical, optical, electrical, and structural properties. Most of the scientists and researchers have investigated the optical and electrical properties of these materials. However, due to unique electromechanical properties of these materials, it is required to explore the piezoresistive properties of bulk nanostructured CNTs, graphene, and CNT-graphene composites. We investigated and compared the sensitivities and piezoresistive properties of sandwich-type pure CNT, pure graphene, and CNT-graphene composite pressure sensors. For all the samples, increase in pressure from 0 to 0.183 kNm−2 results in a decrease in the impedance and direct current (DC resistance. Sensitivity and percentage decrease in resistance and impedance of CNT-graphene composite were lower than pure CNT while being higher than pure graphene based sample. Moreover, under the same external applied pressure, the sensitivity and percentage decrease in impedance for pure CNT, pure graphene, and CNT-graphene composite were smaller than the corresponding sensitivity and percentage decrease in resistance. The achieved experimental results of the composite sample were compared with simulated results which exhibit reasonable agreement with each other. The deviations of simulated resistance-pressure and impedance-pressure curves from experimental graphs were 0.029% and 0.105%, respectively.

  6. Amperometric Detection of Sub-ppm Formaldehyde Using Single-Walled Carbon Nanotubes and Hydroxylamines: A Referenced Chemiresistive System.

    Science.gov (United States)

    Ishihara, Shinsuke; Labuta, Jan; Nakanishi, Takashi; Tanaka, Takeshi; Kataura, Hiromichi

    2017-10-27

    We report amperometric detection of formaldehyde (HCHO) using hydroxylamine hydrochloride and single-walled carbon nanotubes (SWCNTs). Hydroxylamine hydrochloride reacts with HCHO to emit HCl vapor, which injects a hole carrier into semiconducting SWCNTs. The increase of conductivity in SWCNTs is easily monitored using an ohmmeter. The debundling of SWCNTs with a metallo-supramolecular polymer (MSP) increased the active surface area in the SWCNTs network, leading to excellent sensitivity to HCHO with a limit of detection (LoD) of 0.016 ppm. The response of sensor is reversible, and the sensor is reusable. The selectivity to HCHO is 10 5 -10 6 times higher than interferences with other volatiles such as water, methanol, and toluene. Moreover, false-positive responses caused by a significant variation of humidity and/or temperature are successfully discriminated from true-positive responses by using two sensors, one with and the other without hydroxylamine hydrochloride, in a referenced system.

  7. Fuel cell-powered microfluidic platform for lab-on-a-chip applications: Integration into an autonomous amperometric sensing device.

    Science.gov (United States)

    Esquivel, J P; Colomer-Farrarons, J; Castellarnau, M; Salleras, M; del Campo, F J; Samitier, J; Miribel-Català, P; Sabaté, N

    2012-11-07

    The present paper reports for the first time the integration of a microfluidic system, electronics modules, amperometric sensor and display, all powered by a single micro direct methanol fuel cell. In addition to activating the electronic circuitry, the integrated power source also acts as a tuneable micropump. The electronics fulfil several functions. First, they regulate the micro fuel cell output power, which off-gas controls the flow rate of different solutions toward an electrochemical sensor through microfluidic channels. Secondly, as the fuel cell powers a three-electrode electrochemical cell, the electronics compare the working electrode output signal with a set reference value. Thirdly, if the concentration measured by the sensor exceeds this threshold value, the electronics switch on an integrated organic display. This integrated approach pushes forward the development of truly autonomous point-of-care devices relying on electrochemical detection.

  8. Simple approach for the fabrication of screen-printed carbon-based electrode for amperometric detection on microchip electrophoresis.

    Science.gov (United States)

    Petroni, Jacqueline Marques; Lucca, Bruno Gabriel; Ferreira, Valdir Souza

    2017-02-15

    This paper describes a simple method for the fabrication of screen-printed based electrodes for amperometric detection on microchip electrophoresis (ME) devices. The procedure developed is quite simple and does not require expensive instrumentation or sophisticated protocols commonly employed on the production of amperometric sensors, such as photolithography or sputtering steps. The electrodes were fabricated through manual deposition of home-made conductive carbon ink over patterned acrylic substrate. Morphological structure and electrochemical behavior of the carbon electrodes were investigated by scanning electron microscopy and cyclic voltammetry. The produced amperometric sensors were coupled to polydimethylsiloxane (PDMS) microchips at end-channel configuration in order to evaluate their analytical performance. For this purpose, electrophoretic experiments were carried out using nitrite and ascorbic acid as model analytes. Separation of these substances was successfully performed within 50s with good resolution (R = 1.2) and sensitivities (713.5 pA/μM for nitrite and 255.4 pA/μM for ascorbate). The reproducibility of the fabrication method was evaluated and revealed good values concerning the peak currents obtained (8.7% for nitrite and 9.3% for ascorbate). The electrodes obtained through this method exhibited satisfactory lifetime (ca. 400 runs) over low fabrication cost (less than $1 per piece). The feasibility of the proposed device for real analysis was demonstrated through the determination of nitrite concentration levels in drinking water samples. Based on the results achieved, the approach proposed here shows itself as an interesting alternative for simple fabrication of carbon-based electrodes. Furthermore, the devices indicate great promise for other kind of analytical applications involving ME devices. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Development of an Amperometric Biosensor Platform for the Combined Determination of L-Malic, Fumaric, and L-Aspartic Acid.

    Science.gov (United States)

    Röhlen, Désirée L; Pilas, Johanna; Schöning, Michael J; Selmer, Thorsten

    2017-10-01

    Three amperometric biosensors have been developed for the detection of L-malic acid, fumaric acid, and L -aspartic acid, all based on the combination of a malate-specific dehydrogenase (MDH, EC 1.1.1.37) and diaphorase (DIA, EC 1.8.1.4). The stepwise expansion of the malate platform with the enzymes fumarate hydratase (FH, EC 4.2.1.2) and aspartate ammonia-lyase (ASPA, EC 4.3.1.1) resulted in multi-enzyme reaction cascades and, thus, augmentation of the substrate spectrum of the sensors. Electrochemical measurements were carried out in presence of the cofactor β-nicotinamide adenine dinucleotide (NAD + ) and the redox mediator hexacyanoferrate (III) (HCFIII). The amperometric detection is mediated by oxidation of hexacyanoferrate (II) (HCFII) at an applied potential of + 0.3 V vs. Ag/AgCl. For each biosensor, optimum working conditions were defined by adjustment of cofactor concentrations, buffer pH, and immobilization procedure. Under these improved conditions, amperometric responses were linear up to 3.0 mM for L-malate and fumarate, respectively, with a corresponding sensitivity of 0.7 μA mM -1 (L-malate biosensor) and 0.4 μA mM -1 (fumarate biosensor). The L-aspartate detection system displayed a linear range of 1.0-10.0 mM with a sensitivity of 0.09 μA mM -1 . The sensor characteristics suggest that the developed platform provides a promising method for the detection and differentiation of the three substrates.

  10. Laser displacement sensor to monitor the layup process of composite laminate production

    Science.gov (United States)

    Miesen, Nick; Groves, Roger M.; Sinke, Jos; Benedictus, Rinze

    2013-04-01

    Several types of flaw can occur during the layup process of prepreg composite laminates. Quality control after the production process checks the end product by testing the specimens for flaws which are included during the layup process or curing process, however by then these flaws are already irreversibly embedded in the laminate. This paper demonstrates the use of a laser displacement sensor technique applied during the layup process of prepreg laminates for in-situ flaw detection, for typical flaws that can occur during the composite production process. An incorrect number of layers and fibre wrinkling are dominant flaws during the process of layup. These and other dominant flaws have been modeled to determine the requirements for an in-situ monitoring during the layup process of prepreg laminates.

  11. Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors

    Science.gov (United States)

    Dieu, Bjorn; Roeffaers, Maarten B.J.; Hofkens, Johan

    2016-01-01

    Small silver clusters confined inside zeolite matrices have recently emerged as a novel type of highly luminescent materials. Their emission has high external quantum efficiencies (EQE) and spans the whole visible spectrum. It has been recently reported that the UV excited luminescence of partially Li-exchanged sodium Linde type A zeolites [LTA(Na)] containing luminescent silver clusters can be controlled by adjusting the water content of the zeolite. These samples showed a dynamic change in their emission color from blue to green and yellow upon an increase of the hydration level of the zeolite, showing the great potential that these materials can have as luminescence-based humidity sensors at the macro and micro scale. Here, we describe the detailed procedure to fabricate a humidity sensor prototype using silver-exchanged zeolite composites. The sensor is produced by suspending the luminescent Ag-zeolites in an aqueous solution of polyethylenimine (PEI) to subsequently deposit a film of the material onto a quartz plate. The coated plate is subjected to several hydration/dehydration cycles to show the functionality of the sensing film. PMID:27911397

  12. Tin oxide quantum dots embedded iron oxide composite as efficient lead sensor

    Science.gov (United States)

    Dutta, Dipa; Bahadur, Dhirendra

    2018-04-01

    SnO2 quantum dots (QDs) embedded iron oxide (IO) nanocomposite is fabricated and explored as a capable sensor for lead detection. Square wave anodic stripping voltammetry (SWASV) and amperometry have been used to explore the proposed sensor's response towards lead detection. The modified electrode shows linear current response for concentration of lead ranging from 99 nM to 6.6 µM with limit of detection 0.42 µM (34 ppb). Amperometry shows a detection limit as low as 0.18 nM (0.015 ppb); which is far below the permissible limit of lead in drinking water by World Health Organization. This proposed sensor shows linear current response (R2 = 0.98) for the lead concentration ranging from 133 × 10-9 to 4.4 × 10-6M. It also exhibits rapid response time of 12 sec with an ultra high sensitivity of 5.5 µA/nM. These detection properties promise the use of SnO2 QDs -IO composite for detection of lead in environmental sample with great ease.

  13. A simple, low-cost conductive composite material for 3D printing of electronic sensors.

    Science.gov (United States)

    Leigh, Simon J; Bradley, Robert J; Purssell, Christopher P; Billson, Duncan R; Hutchins, David A

    2012-01-01

    3D printing technology can produce complex objects directly from computer aided digital designs. The technology has traditionally been used by large companies to produce fit and form concept prototypes ('rapid prototyping') before production. In recent years however there has been a move to adopt the technology as full-scale manufacturing solution. The advent of low-cost, desktop 3D printers such as the RepRap and Fab@Home has meant a wider user base are now able to have access to desktop manufacturing platforms enabling them to produce highly customised products for personal use and sale. This uptake in usage has been coupled with a demand for printing technology and materials able to print functional elements such as electronic sensors. Here we present formulation of a simple conductive thermoplastic composite we term 'carbomorph' and demonstrate how it can be used in an unmodified low-cost 3D printer to print electronic sensors able to sense mechanical flexing and capacitance changes. We show how this capability can be used to produce custom sensing devices and user interface devices along with printed objects with embedded sensing capability. This advance in low-cost 3D printing with offer a new paradigm in the 3D printing field with printed sensors and electronics embedded inside 3D printed objects in a single build process without requiring complex or expensive materials incorporating additives such as carbon nanotubes.

  14. A simple, low-cost conductive composite material for 3D printing of electronic sensors.

    Directory of Open Access Journals (Sweden)

    Simon J Leigh

    Full Text Available 3D printing technology can produce complex objects directly from computer aided digital designs. The technology has traditionally been used by large companies to produce fit and form concept prototypes ('rapid prototyping' before production. In recent years however there has been a move to adopt the technology as full-scale manufacturing solution. The advent of low-cost, desktop 3D printers such as the RepRap and Fab@Home has meant a wider user base are now able to have access to desktop manufacturing platforms enabling them to produce highly customised products for personal use and sale. This uptake in usage has been coupled with a demand for printing technology and materials able to print functional elements such as electronic sensors. Here we present formulation of a simple conductive thermoplastic composite we term 'carbomorph' and demonstrate how it can be used in an unmodified low-cost 3D printer to print electronic sensors able to sense mechanical flexing and capacitance changes. We show how this capability can be used to produce custom sensing devices and user interface devices along with printed objects with embedded sensing capability. This advance in low-cost 3D printing with offer a new paradigm in the 3D printing field with printed sensors and electronics embedded inside 3D printed objects in a single build process without requiring complex or expensive materials incorporating additives such as carbon nanotubes.

  15. Fiber optic sensor for continuous health monitoring in CFRP composite materials

    Science.gov (United States)

    Rippert, Laurent; Papy, Jean-Michel; Wevers, Martine; Van Huffel, Sabine

    2002-07-01

    An intensity modulated sensor, based on the microbending concept, has been incorporated in laminates produced from a C/epoxy prepreg. Pencil lead break tests (Hsu-Neilsen sources) and tensile tests have been performed on this material. In this research study, fibre optic sensors will be proven to offer an alternative for the robust piezoelectric transducers used for Acoustic Emission (AE) monitoring. The main emphasis has been put on the use of advanced signal processing techniques based on time-frequency analysis. The signal Short Time Fourier Transform (STFT) has been computed and several robust noise reduction algorithms, such as Wiener adaptive filtering, improved spectral subtraction filtering, and Singular Value Decomposition (SVD) -based filtering, have been applied. An energy and frequency -based detection criterion is put forward to detect transient signals that can be correlated with Modal Acoustic Emission (MAE) results and thus damage in the composite material. There is a strong indication that time-frequency analysis and the Hankel Total Least Squares (HTLS) method can also be used for damage characterization. This study shows that the signal from a quite simple microbend optical sensor contains information on the elastic energy released whenever damage is being introduced in the host material by mechanical loading. Robust algorithms can be used to retrieve and analyze this information.

  16. Impact Localization Method for Composite Plate Based on Low Sampling Rate Embedded Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Zhuo Pang

    2017-01-01

    Full Text Available Fiber Bragg Grating (FBG sensors have been increasingly used in the field of Structural Health Monitoring (SHM in recent years. In this paper, we proposed an impact localization algorithm based on the Empirical Mode Decomposition (EMD and Particle Swarm Optimization-Support Vector Machine (PSO-SVM to achieve better localization accuracy for the FBG-embedded plate. In our method, EMD is used to extract the features of FBG signals, and PSO-SVM is then applied to automatically train a classification model for the impact localization. Meanwhile, an impact monitoring system for the FBG-embedded composites has been established to actually validate our algorithm. Moreover, the relationship between the localization accuracy and the distance from impact to the nearest sensor has also been studied. Results suggest that the localization accuracy keeps increasing and is satisfactory, ranging from 93.89% to 97.14%, on our experimental conditions with the decrease of the distance. This article reports an effective and easy-implementing method for FBG signal processing on SHM systems of the composites.

  17. Fully integrated carbon nanotube composite thin film strain sensors on flexible substrates for structural health monitoring

    Science.gov (United States)

    Burton, A. R.; Lynch, J. P.; Kurata, M.; Law, K. H.

    2017-09-01

    Multifunctional thin film materials have opened many opportunities for novel sensing strategies for structural health monitoring. While past work has established methods of optimizing multifunctional materials to exhibit sensing properties, comparatively less work has focused on their integration into fully functional sensing systems capable of being deployed in the field. This study focuses on the advancement of a scalable fabrication process for the integration of multifunctional thin films into a fully integrated sensing system. This is achieved through the development of an optimized fabrication process that can create a broad range of sensing systems using multifunctional materials. A layer-by-layer deposited multifunctional composite consisting of single walled carbon nanotubes (SWNT) in a polyvinyl alcohol and polysodium-4-styrene sulfonate matrix are incorporated with a lithography process to produce a fully integrated sensing system deposited on a flexible substrate. To illustrate the process, a strain sensing platform consisting of a patterned SWNT-composite thin film as a strain-sensitive element within an amplified Wheatstone bridge sensing circuit is presented. Strain sensing is selected because it presents many of the design and processing challenges that are core to patterning multifunctional thin film materials into sensing systems. Strain sensors fabricated on a flexible polyimide substrate are experimentally tested under cyclic loading using standard four-point bending coupons and a partial-scale steel frame assembly under lateral loading. The study reveals the material process is highly repeatable to produce fully integrated strain sensors with linearity and sensitivity exceeding 0.99 and 5 {{V}}/{ε }, respectively. The thin film strain sensors are robust and are capable of high strain measurements beyond 3000 μ {ε }.

  18. A green synthetic strategy of nickel hexacyanoferrate nanoparticals supported on the graphene substrate and its non-enzymatic amperometric sensing application

    Science.gov (United States)

    xue, Zhonghua; He, Nan; Rao, Honghong; Hu, Chenxian; Wang, Xiaofen; Wang, Hui; Liu, Xiuhui; Lu, Xiaoquan

    2017-02-01

    Rapid glucose detection is a key requirement for both diagnosis and treatment of diabetes. A facile and green strategy to achieve spherical-shaped nickel hexacyanoferrate (NiHCF) nanoparticals supported on electrochemical reduction graphene oxide by using electrochemical cyclic voltammetry is explored. As a sensing substrate, electrochemical reduction graphene oxide deposited on a glassy carbon electrode surface exhibited obvious positive effect on the electrodeposition of NiHCF nanoparticals with spherical structure and thus effectively improved the electrical conductivity and electrochemical sensing of the proposed amperometric sensor. Proof-concept experiments demonstrated that the proposed nanocomposites modified electrode exhibited excellent sensitivity toward glucose oxidation as well as with a satisfying detection limit of 0.11 μM. More importantly, we also explore that as a simple, green and facile method, electrochemical technology can be employed and provide a new strategy for developing GO and metal hexacyanoferrate based amperometric sensing platform toward glucose and other biomolecules.

  19. Strain Measurement during Stress Rupture of Composite Over-Wrapped Pressure Vessel with Fiber Bragg Gratings Sensors

    Science.gov (United States)

    Banks, Curtis E.; Grant, Joseph; Russell, Sam; Arnett, Shawn

    2008-01-01

    Fiber optic Bragg gratings were used to measure strain fields during Stress Rupture (SSM) test of Kevlar Composite Over-Wrapped Pressure Vessels (COPV). The sensors were embedded under the over-wrapped attached to the liner released from the Kevlar and attached to the Kevlar released from the liner. Additional sensors (foil gages and fiber bragg gratings) were surface mounted on the COPY liner.

  20. Assessment of damage in composite laminates through dynamic, full-spectral interrogation of fiber Bragg grating sensors

    International Nuclear Information System (INIS)

    Propst, A; Peters, K; Zikry, M A; Schultz, S; Kunzler, W; Zhu, Z; Wirthlin, M; Selfridge, R

    2010-01-01

    In this study, we demonstrate the full-spectral interrogation of a fiber Bragg grating (FBG) sensor at 535 Hz. The sensor is embedded in a woven, graphite fiber–epoxy composite laminate subjected to multiple low-velocity impacts. The measurement of unique, time dependent spectral features from the FBG sensor permits classification of the laminate lifetime into five regimes. These damage regimes compare well with previous analysis of the same material system using combined global and local FBG sensor information. Observed transient spectral features include peak splitting, wide spectral broadening and a strong single peak at the end of the impact event. Such features could not be measured through peak wavelength interrogation of the FBG sensor. Cross-correlation of the measured spectra with the original embedded FBG spectrum permitted rapid visualization of average strains and the presence of transverse compressive strain on the optical fiber, but smeared out the details of the spectral profile

  1. Ultrasensitive molecularly imprinted electrochemical sensor based on magnetism graphene oxide/β-cyclodextrin/Au nanoparticles composites for chrysoidine analysis

    International Nuclear Information System (INIS)

    Wang, Xiaojiao; Li, Xiangjun; Luo, Chuannan; Sun, Min; Li, Leilei; Duan, Huimin

    2014-01-01

    Highlights: • Synthesis and application of MGO/β-CD@AuNPs as a sensor for chrysoidine analysis. • The synthesized polymer had a laminar structure with high surface. • The propose sensor showed high selectivity and good sensitivity. - Abstract: A imprinted electrochemical sensor based on glassy carbon electrode (GCE) for ultrasensitive detection of chrysoidine was fabricated. A GCE was modified by magnetic graphene oxide/β-cyclodextrin/gold nanoparticles composites (MGO/β-CD@AuNPs). The sensing surface area and electronic transmission rate were increased, which was benefited from the distribution property of MGO/β-CD@AuNPs. The MGO/β-CD@AuNPs composite improved electrochemical response and sensitivity of the sensor. The molecularly imprinted electrochemical sensor was prepared by electropolymerization on modified electrode. Chrysoidine and pyrrole were used as template molecule and functional monomer, respectively. Under the optimization experimental conditions, the electrochemical sensor exhibited excellent analytical performance: the detection of chrysoidine ranged from 5.0 × 10 −8 mol/L to 5.0 × 10 −6 mol/L with the detection limit of 1.7 × 10 −8 mol/L. The sensor was applied to determine chrysoidine in spiked water samples and showed high selectivity, good sensitivity and acceptable reproducibility. The proposed method provides a promising platform for trace amount detection of other food additives

  2. Simple approach for the fabrication of screen-printed carbon-based electrode for amperometric detection on microchip electrophoresis

    International Nuclear Information System (INIS)

    Petroni, Jacqueline Marques; Lucca, Bruno Gabriel; Ferreira, Valdir Souza

    2017-01-01

    This paper describes a simple method for the fabrication of screen-printed based electrodes for amperometric detection on microchip electrophoresis (ME) devices. The procedure developed is quite simple and does not require expensive instrumentation or sophisticated protocols commonly employed on the production of amperometric sensors, such as photolithography or sputtering steps. The electrodes were fabricated through manual deposition of home-made conductive carbon ink over patterned acrylic substrate. Morphological structure and electrochemical behavior of the carbon electrodes were investigated by scanning electron microscopy and cyclic voltammetry. The produced amperometric sensors were coupled to polydimethylsiloxane (PDMS) microchips at end-channel configuration in order to evaluate their analytical performance. For this purpose, electrophoretic experiments were carried out using nitrite and ascorbic acid as model analytes. Separation of these substances was successfully performed within 50s with good resolution (R = 1.2) and sensitivities (713.5 pA/μM for nitrite and 255.4 pA/μM for ascorbate). The reproducibility of the fabrication method was evaluated and revealed good values concerning the peak currents obtained (8.7% for nitrite and 9.3% for ascorbate). The electrodes obtained through this method exhibited satisfactory lifetime (ca. 400 runs) over low fabrication cost (less than $1 per piece). The feasibility of the proposed device for real analysis was demonstrated through the determination of nitrite concentration levels in drinking water samples. Based on the results achieved, the approach proposed here shows itself as an interesting alternative for simple fabrication of carbon-based electrodes. Furthermore, the devices indicate great promise for other kind of analytical applications involving ME devices. - Highlights: • A novel method to fabricate screen-printed electrodes for amperometric detection in ME is demonstrated. • No sophisticated

  3. Simple approach for the fabrication of screen-printed carbon-based electrode for amperometric detection on microchip electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Petroni, Jacqueline Marques [Instituto de Química, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, 79074-460 (Brazil); Lucca, Bruno Gabriel, E-mail: bruno.lucca@ufes.br [Departamento de Ciências Naturais, Universidade Federal do Espírito Santo, São Mateus, ES, 29932-540 (Brazil); Ferreira, Valdir Souza [Instituto de Química, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, 79074-460 (Brazil)

    2017-02-15

    This paper describes a simple method for the fabrication of screen-printed based electrodes for amperometric detection on microchip electrophoresis (ME) devices. The procedure developed is quite simple and does not require expensive instrumentation or sophisticated protocols commonly employed on the production of amperometric sensors, such as photolithography or sputtering steps. The electrodes were fabricated through manual deposition of home-made conductive carbon ink over patterned acrylic substrate. Morphological structure and electrochemical behavior of the carbon electrodes were investigated by scanning electron microscopy and cyclic voltammetry. The produced amperometric sensors were coupled to polydimethylsiloxane (PDMS) microchips at end-channel configuration in order to evaluate their analytical performance. For this purpose, electrophoretic experiments were carried out using nitrite and ascorbic acid as model analytes. Separation of these substances was successfully performed within 50s with good resolution (R = 1.2) and sensitivities (713.5 pA/μM for nitrite and 255.4 pA/μM for ascorbate). The reproducibility of the fabrication method was evaluated and revealed good values concerning the peak currents obtained (8.7% for nitrite and 9.3% for ascorbate). The electrodes obtained through this method exhibited satisfactory lifetime (ca. 400 runs) over low fabrication cost (less than $1 per piece). The feasibility of the proposed device for real analysis was demonstrated through the determination of nitrite concentration levels in drinking water samples. Based on the results achieved, the approach proposed here shows itself as an interesting alternative for simple fabrication of carbon-based electrodes. Furthermore, the devices indicate great promise for other kind of analytical applications involving ME devices. - Highlights: • A novel method to fabricate screen-printed electrodes for amperometric detection in ME is demonstrated. • No sophisticated

  4. Polyvinylpyrrolidone/ Poly aniline Composite Based 36 degree YX LiTaO3 Surface Acoustic Wave H2 Gas Sensor

    International Nuclear Information System (INIS)

    Amir Sidek; Rashidah Arsat; Xiuli, He; Kalantar-zadeh, K.; Wlodarski, W.

    2013-01-01

    Poly-vinyl-pyrrolidone (PVP)/ poly aniline based surface acoustic wave (SAW) sensors were fabricated and characterized and their performances towards hydrogen gas were investigated. The PVP/ poly aniline fibers composite were prepared by electro spinning of the composite aqueous solution deposited directly onto the active area of SAW transducers. Via scanning electron microscopy (SEM), the morphology of the deposited nano structure material was observed. From the dynamic response, frequency shifts of 6.243 kHz (1% H 2 ) and 8.051 kHz (1% H 2 ) were recorded for the sensors deposited with PVP/ ES and PVP/ EB, respectively. (author)

  5. Amperometric biosensors based on conducting nanotubes

    NARCIS (Netherlands)

    Kros, Alexander

    2000-01-01

    This thesis describes a multidisciplinary study towards the development of a glucose biosensor that in the future can be used for in vivo implantations. The research focuses on three major topics, viz. the construction of the glucose sensor, the development of a biocompatible coating and a study of

  6. An Amperometric Biosensor for Uric Acid Determination Prepared From Uricase Immobilized in Polyaniline-Polypyrrole Film

    Directory of Open Access Journals (Sweden)

    Fatma Arslan

    2008-09-01

    Full Text Available A new amperometric uric acid biosensor was developed by immobilizing uricase by a glutaraldehyde crosslinking procedure on polyaniline-polypyrrole (pani-ppy composite film on the surface of a platinum electrode. Determination of uric acid was performed by the oxidation of enzymatically generated H2O2 at 0.4 V vs. Ag/AgCl. The linear working range of the biosensor was 2.5×10-6 – 8.5×10-5 M and the response time was about 70 s. The effects of pH, temperature were investigated and optimum parameters were found to be 9.0, 55 oC, respectively. The stability and reproducibility of the enzyme electrode have been also studied.

  7. Resonance line shape, strain and electric potential distributions of composite magnetoelectric sensors

    Directory of Open Access Journals (Sweden)

    Martina Gerken

    2013-06-01

    Full Text Available Multiferroic composite magnetoelectric (ME sensors are based on the elastic coupling of a magnetostrictive phase and a piezoelectric phase. A deformation of the magnetostrictive phase causes strain in the piezoelectric phase and thus an induced voltage. Such sensors may be applied both for static as well as for dynamic magnetic field measurements. Particularly high sensitivities are achieved for operation at a mechanical resonance. Here, the resonance line shape of layered (2-2 composite cantilever ME sensors at the first bending-mode resonance is investigated theoretically. Finite element method (FEM simulations using a linear material model reveal an asymmetric resonance profile and a zero-response frequency for the ME coefficient. Frequency-dependent strain and electric potential distributions inside the magnetoelectric composite are studied for the case of a magnetostrictive-piezoelectric bilayer. It is demonstrated that a positive or a negative voltage may be induced across the piezoelectric layer depending on the position of the neutral plane. The frequency-dependent induced electric potential is investigated for structured cantilevers that exhibit magnetostriction only at specific positions. For static operation an induced voltage is obtained locally at positions with magnetostriction. In addition to this direct effect a resonance-assisted effect is observed for dynamic operation. Magnetostriction in a limited area of the cantilever causes a global vibration of the cantilever. Thus, deformation of the piezoelectric layer and an induced electric potential also occur in areas of the cantilever without magnetostriction. The direct and the resonance-assisted pathway may induce voltages of equal or of opposite sign. The net induced voltage results from the superposition of the two effects. As the resonance-assisted induced voltage changes sign upon passing the resonance frequency, while the direct component is constant, an asymmetric line

  8. Compositions of graphene materials with metal nanostructures and microstructures and methods of making and using including pressure sensors

    KAUST Repository

    Chen, Ye

    2017-01-26

    Composition comprising at least one graphene material and at least one metal. The metal can be in the form of nanoparticles as well as microflakes, including single crystal microflakes. The metal can be intercalated in the graphene sheets. The composition has high conductivity and flexibility. The composition can be made by a one-pot synthesis in which a graphene material precursor is converted to the graphene material, and the metal precursor is converted to the metal. A reducing solvent or dispersant such as NMP can be used. Devices made from the composition include a pressure sensor which has high sensitivity. Two two- dimension materials can be combined to form a hybrid material.

  9. Real-Time Impact Visualization Inspection of Aerospace Composite Structures with Distributed Sensors.

    Science.gov (United States)

    Si, Liang; Baier, Horst

    2015-07-08

    For the future design of smart aerospace structures, the development and application of a reliable, real-time and automatic monitoring and diagnostic technique is essential. Thus, with distributed sensor networks, a real-time automatic structural health monitoring (SHM) technique is designed and investigated to monitor and predict the locations and force magnitudes of unforeseen foreign impacts on composite structures and to estimate in real time mode the structural state when impacts occur. The proposed smart impact visualization inspection (IVI) technique mainly consists of five functional modules, which are the signal data preprocessing (SDP), the forward model generator (FMG), the impact positioning calculator (IPC), the inverse model operator (IMO) and structural state estimator (SSE). With regard to the verification of the practicality of the proposed IVI technique, various structure configurations are considered, which are a normal CFRP panel and another CFRP panel with "orange peel" surfaces and a cutout hole. Additionally, since robustness against several background disturbances is also an essential criterion for practical engineering demands, investigations and experimental tests are carried out under random vibration interfering noise (RVIN) conditions. The accuracy of the predictions for unknown impact events on composite structures using the IVI technique is validated under various structure configurations and under changing environmental conditions. The evaluated errors all fall well within a satisfactory limit range. Furthermore, it is concluded that the IVI technique is applicable for impact monitoring, diagnosis and assessment of aerospace composite structures in complex practical engineering environments.

  10. Study on the applicability of polytetrafluoroethylene–silver composite thin films as sensor material

    International Nuclear Information System (INIS)

    Smausz, Tomi; Kecskeméti, Gabriella; Csizmadia, Tamás; Benedek, Ferenc; Hopp, Béla

    2013-01-01

    A study on applicability of conductive high specific surface PTFE/Ag composite layers as active electrodes of a non-enzymatic cholesterol sensor is presented. The composite layers were prepared on one of the two neighboring electrode of a printed circuit board by pulsed laser deposition technique where targets composed of silver and PTFE were ablated by an ArF excimer laser. Cholesterol was dissolved in 0.1 M NaOH in different concentrations in 0–5 mM range. A drop of cholesterol covered the two electrodes and a constant current of 10 μA was forced through the sample while the voltage between the electrodes was measured by means of a high resolution A/D converter with 1 kHz sampling rate for 5 s periods. Instead of the time-averaged signal monitoring we applied the Fluctuation-Enhanced Sensing (FES) method which is based on the analysis of the stochastic component of the signal. The power spectral density of the fluctuation was found to be dependent on the cholesterol concentration of the samples. Principal Component Analysis method was used for quantifying the difference between the recorded spectra. A tendentious variation of the spectral properties as the function of the cholesterol concentration was observed. The results indicate that the FES technique combined with high specific surface composite electrodes may be a useful tool for cholesterol detection.

  11. Structural health monitoring of glass/epoxy composite plates with MEMS PMN-PT sensors

    Science.gov (United States)

    Simon, Brenton R.; Tang, Hong-Yue; Horsley, David A.; La Saponara, Valeria; Lestari, Wahyu

    2009-03-01

    Sensors constructed with single-crystal PMN-PT, i.e. Pb(Mg1/3Nb2/3)O3-PbTiO3 or PMN, are developed in this paper for structural health monitoring of composite plates. To determine the potential of PMN-PT for this application, glass/epoxy composite specimens were created containing an embedded delamination-starter. Two different piezoelectric materials were bonded to the surface of each specimen: PMN-PT, the test material, was placed on one side of the specimen, while a traditional material, PZT-4, was placed on the other. A comparison of the ability of both materials to transmit and receive an ultrasonic pulse was conducted, with the received signal detected by both a second surface-bonded transducer constructed of the same material, as well as a laser Doppler vibrometer (LDV) analyzing the same location. The optimal frequency range of both sets of transducers is discussed and a comparison is presented of the experimental results to theory. The specimens will be fatigued until failure with further data collected every 3,000 cycles to characterize the ability of each material to detect the growing delamination in the composite structure. This additional information will be made available during the conference.

  12. Demonstration and Methodology of Structural Monitoring of Stringer Runs out Composite Areas by Embedded Optical Fiber Sensors and Connectors Integrated during Production in a Composite Plant.

    Science.gov (United States)

    Miguel Giraldo, Carlos; Zúñiga Sagredo, Juan; Sánchez Gómez, José; Corredera, Pedro

    2017-07-21

    Embedding optical fibers sensors into composite structures for Structural Health Monitoring purposes is not just one of the most attractive solutions contributing to smart structures, but also the optimum integration approach that insures maximum protection and integrity of the fibers. Nevertheless this intended integration level still remains an industrial challenge since today there is no mature integration process in composite plants matching all necessary requirements. This article describes the process developed to integrate optical fiber sensors in the Production cycle of a test specimen. The sensors, Bragg gratings, were integrated into the laminate during automatic tape lay-up and also by a secondary bonding process, both in the Airbus Composite Plant. The test specimen, completely representative of the root joint of the lower wing cover of a real aircraft, is comprised of a structural skin panel with the associated stringer run out. The ingress-egress was achieved through the precise design and integration of miniaturized optical connectors compatible with the manufacturing conditions and operational test requirements. After production, the specimen was trimmed, assembled and bolted to metallic plates to represent the real triform and buttstrap, and eventually installed into the structural test rig. The interrogation of the sensors proves the effectiveness of the integration process; the analysis of the strain results demonstrate the good correlation between fiber sensors and electrical gauges in those locations where they are installed nearby, and the curvature and load transfer analysis in the bolted stringer run out area enable demonstration of the consistency of the fiber sensors measurements. In conclusion, this work presents strong evidence of the performance of embedded optical sensors for structural health monitoring purposes, where in addition and most importantly, the fibers were integrated in a real production environment and the ingress

  13. Amperometric titration of indium with edta solution in propanol

    International Nuclear Information System (INIS)

    Gevorgyan, A.M.; Talipov, Sh.T.; Khadeev, V.A.; Kostylev, V.S.; Khadeeva, L.A.

    1980-01-01

    Optimum conditions have been chosen for titration of indium with EDTA solution in anhydrous propanol and its mixtures with some aprotic solvents using amperometric and point detection. A procedure is suggested of determining indium microcontents in the presence of large amounts of other elements. The procedure is based on its extraction preseparation followed by direct titration in the extract with a standard EDTA solution [ru

  14. Development of a Telemetric, Miniaturized Electrochemical Amperometric Analyzer

    OpenAIRE

    Jaehyo Jung; Jihoon Lee; Siho Shin; Youn Tae Kim

    2017-01-01

    In this research, we developed a portable, three-electrode electrochemical amperometric analyzer that can transmit data to a PC or a tablet via Bluetooth communication. We performed experiments using an indium tin oxide (ITO) glass electrode to confirm the performance and reliability of the analyzer. The proposed analyzer uses a current-to-voltage (I/V) converter to convert the current generated by the reduction-oxidation (redox) reaction of the buffer solution to a voltage signal. This signa...

  15. An Electromagnetic Sensor with a Metamaterial Lens for Nondestructive Evaluation of Composite Materials

    Directory of Open Access Journals (Sweden)

    Adriana Savin

    2015-07-01

    Full Text Available This paper proposes the study and implementation of a sensor with a metamaterial (MM lens in electromagnetic nondestructive evaluation (eNDE. Thus, the use of a new type of MM, named Conical Swiss Rolls (CSR has been proposed. These structures can serve as electromagnetic flux concentrators in the radiofrequency range. As a direct application, plates of composite materials with carbon fibers woven as reinforcement and polyphenylene sulphide as matrix with delaminations due to low energy impacts were examined. The evaluation method is based on the appearance of evanescent modes in the space between carbon fibers when the sample is excited with a transversal magnetic along z axis (TMz polarized electromagnetic field. The MM lens allows the transmission and intensification of evanescent waves. The characteristics of carbon fibers woven structure became visible and delaminations are clearly emphasized. The flaws can be localized with spatial resolution better than λ/2000.

  16. An Electromagnetic Sensor with a Metamaterial Lens for Nondestructive Evaluation of Composite Materials.

    Science.gov (United States)

    Savin, Adriana; Steigmann, Rozina; Bruma, Alina; Šturm, Roman

    2015-07-03

    This paper proposes the study and implementation of a sensor with a metamaterial (MM) lens in electromagnetic nondestructive evaluation (eNDE). Thus, the use of a new type of MM, named Conical Swiss Rolls (CSR) has been proposed. These structures can serve as electromagnetic flux concentrators in the radiofrequency range. As a direct application, plates of composite materials with carbon fibers woven as reinforcement and polyphenylene sulphide as matrix with delaminations due to low energy impacts were examined. The evaluation method is based on the appearance of evanescent modes in the space between carbon fibers when the sample is excited with a transversal magnetic along z axis (TMz) polarized electromagnetic field. The MM lens allows the transmission and intensification of evanescent waves. The characteristics of carbon fibers woven structure became visible and delaminations are clearly emphasized. The flaws can be localized with spatial resolution better than λ/2000.

  17. Estimation of Curvature Changes for Steel-Concrete Composite Bridge Using Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Donghoon Kang

    2013-01-01

    Full Text Available This study is focused on the verification of the key idea of a newly developed steel-concrete composite bridge. The key idea of the proposed bridge is to reduce the design moment by applying vertical prestressing force to steel girders, so that a moment distribution of a continuous span bridge is formed in a simple span bridge. For the verification of the key technology, curvature changes of the bridge should be monitored sequentially at every construction stage. A pair of multiplexed FBG sensor arrays is proposed in order to measure curvature changes in this study. They are embedded in a full-scale test bridge and measured local strains, which are finally converted to curvatures. From the result of curvature changes, it is successfully ensured that the key idea of the proposed bridge, expected theoretically, is viable.

  18. MWCNT-ruthenium oxide composite paste electrode as non-enzymatic glucose sensor.

    Science.gov (United States)

    Tehrani, Ramin M A; Ab Ghani, Sulaiman

    2012-01-01

    A non-enzymatic glucose sensor of multi-walled carbon nanotube-ruthenium oxide/composite paste electrode (MWCNT-RuO(2)/CPE) was developed. The electrode was characterized by using XRD, SEM, TEM and EIS. Meanwhile, cyclic voltammetry and amperometry were used to check on the performances of the MWCNT-RuO(2)/CPE towards glucose. The proposed electrode has displayed a synergistic effect of RuO(2) and MWCNT on the electrocatalytic oxidation of glucose in 3M NaOH. This was possible via the formation of transitions of two redox pairs, viz. Ru(VI)/Ru(IV) and Ru(VII)/Ru(VI). A linear range of 0.5-50mM glucose and a limit of detection of 33 μM glucose (S/N=3) were observed. There was no significant interference observable from the traditional interferences, viz. ascorbic acid and uric acid. Indeed, results so obtained have indicated that the developed MWCNT-RuO(2)/CPE would pave the way for a better future to glucose sensor development as its fabrication was without the use of any enzyme. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Interaction of molybdenum (6) with potassium benzyldithiocarbaminate during amperometric titration

    International Nuclear Information System (INIS)

    Galushko, S.V.; Usatenko, Yu.I.

    1975-01-01

    The paper is an amperometric study of the mechanism of interaction between molybdenum (VI) and potassium benzyl dithiocarbamate [BDTC] which was based on the use of voltamperometry, electron paramagnetic resonance, infrared spectroscopy, potentiometry and elemental analysis. In amperometric titration Mo(VI) with BDTC (pH 4-2) forms a red compound of low solubility. In more acidic media the intensity of coloration is increased and a violet hue develops. On the basis of the data obtained it is concluded that in the amperometric titration of Mo(VI) with potassium BDTC there is first formation of a Mo(VI) compound, which subsequently acquires a red colour as a result of the reduction of Mo(VI) to Mo(V). It was also established that the degree of reduction is small where titration is carried out in the range pH 4.8-0.1. Quantitative determination of Mo is performed most effectively in slightly acidic media. Mo reacts with potassium BDTC in a ratio of 1:2. (E.P.)

  20. An Electrochemical pH Sensor Based on the Amino-Functionalized Graphene and Polyaniline Composite Film.

    Science.gov (United States)

    Su, W; Xu, J; Ding, Xianting

    2016-12-01

    Conventional glass-based pH sensors are usually fragile and space consuming. Herein, a miniature electrochemical pH sensor based on amino-functionalized graphene fragments and polyaniline (NH 2 -G/PANI) composite film is developed via simply one-pot electrochemical polymerization on the ITO-coated glass substrates. Cyclic Voltammetry (CV), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and Raman Spectra are involved to confirm the successful synthesis and to characterize the properties of the NH 2 -G/PANI composite film. The developed electrochemical pH sensor presents fast response, high sensitivity (51.1 mV/pH) and wide detection range when applied to PBS solutions of pH values from 1 to 11. The robust reproducibility and good stability of the developed pH sensors are investigated as well. Compared to the conventional glass-based pH meters, the NH 2 -G/PANI composite film-based pH sensor could be a promising contender for the flexible and miniaturized pH-sensing devices.

  1. Acoustic-wave sensor apparatus for analyzing a petroleum-based composition and sensing solidification of constituents therein

    Science.gov (United States)

    Spates, J.J.; Martin, S.J.; Mansure, A.J.

    1997-08-26

    An acoustic-wave sensor apparatus and method are disclosed. The apparatus for analyzing a normally liquid petroleum-based composition includes at least one acoustic-wave device in contact with the petroleum-based composition for sensing or detecting the presence of constituents (e.g. paraffins or petroleum waxes) therein which solidify upon cooling of the petroleum-based composition below a cloud-point temperature. The acoustic-wave device can be a thickness-shear-mode device (also termed a quartz crystal microbalance), a surface-acoustic-wave device, an acoustic-plate-mode device or a flexural plate-wave device. Embodiments of the present invention can be used for measuring a cloud point, a pour point and/or a freeze point of the petroleum-based composition, and for determining a temperature characteristic of each point. Furthermore, measurements with the acoustic-wave sensor apparatus can be made off-line by using a sample having a particular petroleum-based composition; or in-situ with the petroleum-based composition contained within a pipeline or storage tank. The acoustic-wave sensor apparatus has uses in many different petroleum technology areas, including the recovery, transport, storage, refining and use of petroleum and petroleum-based products. 7 figs.

  2. Effects of Operating Temperature on Droplet Casting of Flexible Polymer/Multi-Walled Carbon Nanotube Composite Gas Sensors

    Directory of Open Access Journals (Sweden)

    Jin-Chern Chiou

    2016-12-01

    Full Text Available This study examined the performance of a flexible polymer/multi-walled carbon nanotube (MWCNT composite sensor array as a function of operating temperature. The response magnitudes of a cost-effective flexible gas sensor array equipped with a heater were measured with respect to five different operating temperatures (room temperature, 40 °C, 50 °C, 60 °C, and 70 °C via impedance spectrum measurement and sensing response experiments. The selected polymers that were droplet cast to coat a MWCNT conductive layer to form two-layer polymer/MWCNT composite sensing films included ethyl cellulose (EC, polyethylene oxide (PEO, and polyvinylpyrrolidone (PVP. Electrical characterization of impedance, sensing response magnitude, and scanning electron microscope (SEM morphology of each type of polymer/MWCNT composite film was performed at different operating temperatures. With respect to ethanol, the response magnitude of the sensor decreased with increasing operating temperatures. The results indicated that the higher operating temperature could reduce the response and influence the sensitivity of the polymer/MWCNT gas sensor array. The morphology of polymer/MWCNT composite films revealed that there were changes in the porous film after volatile organic compound (VOC testing.

  3. Monitoring Poisson’s Ratio Degradation of FRP Composites under Fatigue Loading Using Biaxially Embedded FBG Sensors

    Science.gov (United States)

    Akay, Erdem; Yilmaz, Cagatay; Kocaman, Esat S.; Turkmen, Halit S.; Yildiz, Mehmet

    2016-01-01

    The significance of strain measurement is obvious for the analysis of Fiber-Reinforced Polymer (FRP) composites. Conventional strain measurement methods are sufficient for static testing in general. Nevertheless, if the requirements exceed the capabilities of these conventional methods, more sophisticated techniques are necessary to obtain strain data. Fiber Bragg Grating (FBG) sensors have many advantages for strain measurement over conventional ones. Thus, the present paper suggests a novel method for biaxial strain measurement using embedded FBG sensors during the fatigue testing of FRP composites. Poisson’s ratio and its reduction were monitored for each cyclic loading by using embedded FBG sensors for a given specimen and correlated with the fatigue stages determined based on the variations of the applied fatigue loading and temperature due to the autogenous heating to predict an oncoming failure of the continuous fiber-reinforced epoxy matrix composite specimens under fatigue loading. The results show that FBG sensor technology has a remarkable potential for monitoring the evolution of Poisson’s ratio on a cycle-by-cycle basis, which can reliably be used towards tracking the fatigue stages of composite for structural health monitoring purposes. PMID:28773901

  4. Evaluation of circuit models for an IPMC (ionic polymer-metal composite) sensor using a parameter estimate method

    International Nuclear Information System (INIS)

    Park, Kiwon; Lee, Hyungki

    2012-01-01

    The present study investigated a sensor system to effectively detect the bending angles applied on an ionic polymer metal composite sensor. Firstly, the amount of net charge produced by the motion of cations was correlated to the bending angle based on the geometric relationship between a flat and a bent IPMC, and the relationship was represented by linear and nonlinear polynomial equations. Secondly, several existing and modified R and C circuit models with a linear charge model were evaluated using the experimental data. Thirdly, the nonlinear charge model was applied to a selected circuit model, and the effectivenesses of the linear and the nonlinear charge models were compared. Finally, the sensor output signal was fed into the inverse model of the identified circuit model to reproduce the bending angles. This paper presents a simple data processing procedure using the inverse transfer function of a selected circuit model that successfully monitored various bending motions of an IPMC sensor.

  5. Sensor

    OpenAIRE

    Gleeson, Helen; Dierking, Ingo; Grieve, Bruce; Woodyatt, Christopher; Brimicombe, Paul

    2015-01-01

    An electrical temperature sensor (10) comprises a liquid crystalline material (12). First and second electrically conductive contacts (14), (16), having a spaced relationship there between, contact the liquid crystalline material (12). An electric property measuring device is electrically connected to the first and second contacts (14), (16) and is arranged to measure an electric property of the liquid crystalline material (12). The liquid crystalline material (12) has a transition temperatur...

  6. Analyzing Comprehensive QoS with Security Constraints for Services Composition Applications in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Naixue Xiong

    2014-12-01

    Full Text Available Services composition is fundamental to software development in multi-service wireless sensor networks (WSNs. The quality of service (QoS of services composition applications (SCAs are confronted with severe challenges due to the open, dynamic, and complex natures of WSNs. Most previous research separated various QoS indices into different fields and studied them individually due to the computational complexity. This approach ignores the mutual influence between these QoS indices, and leads to a non-comprehensive and inaccurate analysis result. The universal generating function (UGF shows the speediness and precision in QoS analysis. However, only one QoS index at a time can be analyzed by the classic UGF. In order to efficiently analyze the comprehensive QoS of SCAs, this paper proposes an improved UGF technique—vector universal generating function (VUGF—which considers the relationship between multiple QoS indices, including security, and can simultaneously analyze multiple QoS indices. The numerical examples demonstrate that it can be used for the evaluation of the comprehensive QoS of SCAs subjected to the security constraint in WSNs. Therefore, it can be effectively applied to the optimal design of multi-service WSNs.

  7. Analyzing comprehensive QoS with security constraints for services composition applications in wireless sensor networks.

    Science.gov (United States)

    Xiong, Naixue; Wu, Zhao; Huang, Yannong; Xu, Degang

    2014-12-01

    Services composition is fundamental to software development in multi-service wireless sensor networks (WSNs). The quality of service (QoS) of services composition applications (SCAs) are confronted with severe challenges due to the open, dynamic, and complex natures of WSNs. Most previous research separated various QoS indices into different fields and studied them individually due to the computational complexity. This approach ignores the mutual influence between these QoS indices, and leads to a non-comprehensive and inaccurate analysis result. The universal generating function (UGF) shows the speediness and precision in QoS analysis. However, only one QoS index at a time can be analyzed by the classic UGF. In order to efficiently analyze the comprehensive QoS of SCAs, this paper proposes an improved UGF technique-vector universal generating function (VUGF)-which considers the relationship between multiple QoS indices, including security, and can simultaneously analyze multiple QoS indices. The numerical examples demonstrate that it can be used for the evaluation of the comprehensive QoS of SCAs subjected to the security constraint in WSNs. Therefore, it can be effectively applied to the optimal design of multi-service WSNs.

  8. Amperometric detection of hydrazine utilizing synergistic action of prussian blue @ silver nanoparticles / graphite felt modified electrode

    International Nuclear Information System (INIS)

    Zhao, Jihua; Liu, Jianxin; Tricard, Simon; Wang, Lei; Liang, Yanling; Cao, Linghua; Fang, Jian; Shen, Weiguo

    2015-01-01

    Highlights: • Prussian Blue (PB) deposition on Ag/GF for electrochemical hydrazine sensing; • Lower detection limit of 4.9 × 10 −7 mol L −1 , stable over 24 days; • High sensitivity: 26.06 A mol −1 L. -- Abstract: In this study, a triple-component hydrazine sensor (PB@Ag/GF) was fabricated with freestanding graphite felt (GF), silver nanoparticles (Ag) and prussian blue (PB). The Ag nanoparticles were electrodeposited on GF ultrasonically (Ag/GF), and acted as a catalyst of the chemical deposition of PB. The electrode was characterized by scanning election microscopy (SEM), infrared spectroscopy (IR), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). The electrochemical behavior of PB@Ag/GF was measured by cyclic voltammetry and amperometric measurements. The sensor displayed a prominent electrocatalytic activity toward hydrazine oxidation, with a fast response time of 2 s, a low detection limit of 4.9 × 10 −7 mol L −1 and very high detection sensitivity of 26.06 A mol −1 L

  9. Design and Development of a Flexible Strain Sensor for Textile Structures Based on a Conductive Polymer Composite

    Directory of Open Access Journals (Sweden)

    Claude Dufour

    2007-04-01

    Full Text Available The aim of this work is to develop a smart flexible sensor adapted to textile structures, able to measure their strain deformations. The sensors are “smart” because of their capacity to adapt to the specific mechanical properties of textile structures that are lightweight, highly flexible, stretchable, elastic, etc. Because of these properties, textile structures are continuously in movement and easily deformed, even under very low stresses. It is therefore important that the integration of a sensor does not modify their general behavior. The material used for the sensor is based on a thermoplastic elastomer (Evoprene/carbon black nanoparticle composite, and presents general mechanical properties strongly compatible with the textile substrate. Two preparation techniques are investigated: the conventional melt-mixing process, and the solvent process which is found to be more adapted for this particular application. The preparation procedure is fully described, namely the optimization of the process in terms of filler concentration in which the percolation theory aspects have to be considered. The sensor is then integrated on a thin, lightweight Nylon fabric, and the electromechanical characterization is performed to demonstrate the adaptability and the correct functioning of the sensor as a strain gauge on the fabric. A normalized relative resistance is defined in order to characterize the electrical response of the sensor. Finally, the influence of environmental factors, such as temperature and atmospheric humidity, on the sensor performance is investigated. The results show that the sensor’s electrical resistance is particularly affected by humidity. This behavior is discussed in terms of the sensitivity of the carbon black filler particles to the presence of water.

  10. A Piezoelectroluminescent Fiber-Optical Sensor for Diagnostics of the 3D Stress State in Composite Structures

    Science.gov (United States)

    Pan'kov, A. A.

    2018-05-01

    The mathematical model of a piezoelectroluminescent fiber-optical sensor is developed for diagnostics of the 3D stress state of composite structures. The sensor model is a coaxial sector-compound layered cylinder consisting of a central optical fiber with electroluminescent and piezoelectric layers and an external uniform elastic buffer layer. The electroluminescent and piezoelectric layers are separated by radial-longitudinal boundaries, common for both layers, into geometrically equal six "measuring elements" — cylindrical two-layered sectors. The directions of 3D polarization of the piezoelectric phases and the frequencies of luminous efficacy of the electroluminescent phases are different in each sector. In the sensor, a thin translucent "internal" controlling electrode is located between the optical fiber and the electroluminescent layer, and the piezoelectric layer is coated by a thin "external" controlling electrode. The results of numerical modeling of the nonuniform coupled electroelastic fields of the piezoelectroluminescent fiber-optical sensor in the loaded "representative volume" of a composite, taking into account the action of the controlling voltage on the internal and external electrodes, of a numerical calculation of "informative and controlling coefficients" of the sensor, and of testing of an arbitrary 3D stress of state of a unidirectional glass-fiber plastic by the finite-element method are presented.

  11. The GOES-16 Energetic Heavy Ion Sensor (EHIS) Ion Composition and Flux Measurements

    Science.gov (United States)

    Connell, J. J.; Lopate, C.

    2017-12-01

    The Energetic Heavy Ion Sensor (EHIS) was built by the University of New Hampshire, subcontracted to Assurance Technology Corporation, as part of the Space Environmental In-Situ Suite (SEISS) on the new GOES-16 satellite (formerly GOES-R) in Geostationary orbit. EHIS measures energetic ions over the range 10-200 MeV for protons, and energy ranges for heavy ions corresponding to the same stopping range (e.g., 19-207 MeV/u for carbon and 38-488 MeV/u for iron). EHIS uses the Angle Detecting Inclined Sensors (ADIS) technique to provide single-element charge resolution. Though on an operational mission for Space Weather monitoring, EHIS can thus provide a new source of high quality Solar Particle Event (SPE) data for science studies. With a high rate of on-board processing ( 2000 events/s), EHIS will provide exceptional statistics for ion composition measurements in large SPEs. For the GOES Level 1-B and Level 2 data products, heavy ions are distinguished in EHIS using pulse-height analysis with on-board processing producing charge histograms for five energy bands. Fits to these data are normalized to priority rate data on the ground. The instrumental cadence for histograms is 1 minute and the primary Level 1-B heavy ion data products are 1-minute and 5-minute averages. We discuss the preliminary EHIS heavy ion data results which show elemental peaks from H to Fe, with peaks for the isotopes D and 3He. (GOES-16 was launched in 19 November, 2016 and data has, though July 2017, been dominated by Galactic Cosmic Rays.) The EHIS instrument development project was funded by NASA under contract NNG06HX01C.

  12. Development of a polydimethylsiloxane-thymol/nitroprusside composite based sensor involving thymol derivatization for ammonium monitoring in water samples.

    Science.gov (United States)

    Prieto-Blanco, M C; Jornet-Martínez, N; Moliner-Martínez, Y; Molins-Legua, C; Herráez-Hernández, R; Verdú Andrés, J; Campins-Falcó, P

    2015-01-15

    This report describes a polydimethylsiloxane (PDMS)-thymol/nitroprusside delivery composite sensor for direct monitoring of ammonium in environmental water samples. The sensor is based on a PDMS support that contains the Berthelot's reaction reagents. To prepare the PDMS-thymol/nitroprusside composite discs, thymol and nitroprusside have been encapsulated in the PDMS matrix, forming a reagent release support which significantly simplifies the analytical measurements, since it avoids the need to prepare derivatizing reagents and sample handling is reduced to the sampling step. When, the PDMS-thymol/nitroprusside composite was introduced in water samples spontaneous release of the chromophore and catalyst was produced, and the derivatization reaction took place to form the indothymol blue. Thus, qualitative analysis of NH4(+) could be carried out by visual inspection, but also, it can be quantified by measuring the absorbance at 690 nm. These portable devices provided good sensitivity (LODdetection of ammonium. The PDMS-NH4(+) sensor has been successfully applied to determine ammonium in water samples and in the aqueous extracts of particulate matter PM10 samples. Moreover, the reliability of the method for qualitative analysis has been demonstrated. Finally, the advantages of the PDMS-NH4(+) sensor have been examined by comparing some analytical and complementary characteristics with the properties of well-established ammonium determination methods. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Laser light-section sensor automating the production of textile-reinforced composites

    Science.gov (United States)

    Schmitt, R.; Niggemann, C.; Mersmann, C.

    2009-05-01

    Due to their advanced weight-specific mechanical properties, the application of fibre-reinforced plastics (FRP) has been established as a key technology in several engineering areas. Textile-based reinforcement structures (Preform) in particular achieve a high structural integrity due to the multi-dimensional build-up of dry-fibre layers combined with 3D-sewing and further textile processes. The final composite parts provide enhanced damage tolerances through excellent crash-energy absorbing characteristics. For these reasons, structural parts (e.g. frame) will be integrated in next generation airplanes. However, many manufacturing processes for FRP are still involving manual production steps without integrated quality control. The non-automated production implies considerable process dispersion and a high rework rate. Before the final inspection there is no reliable information about the production status. This work sets metrology as the key to automation and thus an economically feasible production, applying a laser light-section sensor system (LLSS) to measure process quality and feed back the results to close control loops of the production system. The developed method derives 3D-measurements from height profiles acquired by the LLSS. To assure the textile's quality a full surface scan is conducted, detecting defects or misalignment by comparing the measurement results with a CAD model of the lay-up. The method focuses on signal processing of the height profiles to ensure a sub-pixel accuracy using a novel algorithm based on a non-linear least-square fitting to a set of sigmoid functions. To compare the measured surface points to the CAD model, material characteristics are incorporated into the method. This ensures that only the fibre layer of the textile's surface is included and gaps between the fibres or overlaying seams are neglected. Finally, determining the uncertainty in measurement according to the GUM-standard proofed the sensor system's accuracy

  14. Manufacturing technology of integrated textile-based sensor networks for in situ monitoring applications of composite wind turbine blades

    Science.gov (United States)

    Haentzsche, Eric; Mueller, Ralf; Huebner, Matthias; Ruder, Tristan; Unger, Reimar; Nocke, Andreas; Cherif, Chokri

    2016-10-01

    Based on in situ strain sensors consisting of piezo-resistive carbon filament yarns (CFYs), which have been successfully integrated into textile reinforcement structures during their textile-technological manufacturing process, a continuous load of fibre-reinforced plastic (FRP) components has been realised. These sensors are also suitable for structural health monitoring (SHM) applications. The two-dimensional sensor layout is made feasible by the usage of a modular warp yarn path manipulation unit. Using a functional model of a small wind turbine blade in thermoset composite design, the sensor function for basic SHM applications (e.g. static load monitoring) are demonstrated. Any mechanical loads along the pressure or suction side of the wind turbine blade can be measured and calculated via a correlative change in resistance of the CFYs within the textile reinforcement plies. Performing quasi-static load tests on both tensile specimen and full-scale wind turbine blade, elementary results have been obtained concerning electro-mechanical behaviour and spatial resolution of global and even local static stresses according to the CFY sensor integration length. This paper demonstrates the great potential of textile-based and textile-technological integrated sensors in reinforcement structures for future SHM applications of FRPs.

  15. The quest for highly sensitive QCM humidity sensors: the coating of CNT/MOF composite sensing films as case study

    KAUST Repository

    Chappanda, Karumbaiah. N.

    2017-11-01

    The application of metal-organic frameworks (MOFs) as a sensing layer has been attracting great interest over the last decade, due to their uniform properties in terms of high porosity and tunability, which provides a large surface area and/or centers for trapping/binding a targeted analyte. Here we report the fabrication of a highly sensitive humidity sensor that is based on composite thin films of HKUST-1 MOF and carbon nanotubes (CNT). The composite sensing films were fabricated by spin coating technique on a quartz-crystal microbalance (QCM) and a comparison of their shift in resonance frequencies to adsorbed water vapor (5 to 75% relative humidity) is presented. Through optimization of the CNT and HKUST-1 composition, we could demonstrate a 230% increase in sensitivity compared to plain HKUST-1 film. The optimized CNT-HKUST-1 composite thin films are stable, reliable, and have an average sensitivity of about 2.5×10−5 (Δf/f) per percent of relative humidity, which is up to ten times better than previously reported QCM-based humidity sensors. The approach presented here is facile and paves a promising path towards enhancing the sensitivity of MOF-based sensors.

  16. Highly sensitive room temperature organic vapor sensor based on polybenzoxazine-derived carbon aerogel thin film composite

    Energy Technology Data Exchange (ETDEWEB)

    Thubsuang, Uthen [Materials Science and Engineering, School of Engineering and Resources, Walailak University, Nakhon Si Thammarat 80160 (Thailand); Sukanan, Darunee [The Petroleum and Petrochemical College and the Center of Excellence on Petrochemical and Materials Technology, Chulalongkorn University, Bangkok 10330 (Thailand); Sahasithiwat, Somboon [National Metal and Materials Technology Center, Thailand Science Park (TSP), Khlong Luang, Pathum Thani 12120 (Thailand); Wongkasemjit, Sujitra [The Petroleum and Petrochemical College and the Center of Excellence on Petrochemical and Materials Technology, Chulalongkorn University, Bangkok 10330 (Thailand); Chaisuwan, Thanyalak, E-mail: thanyalak.c@chula.ac.th [The Petroleum and Petrochemical College and the Center of Excellence on Petrochemical and Materials Technology, Chulalongkorn University, Bangkok 10330 (Thailand)

    2015-10-15

    Graphical abstract: - Highlights: • Activated carbon aerogel with high surface area can be prepared from polybenzoxazine. • Activated carbon aerogel enhances the adsorption capacity of gas sensor. • Organic vapors with very low concentration can be detected by the as-prepared sensor. • The as-prepared sensor shows impressive short exposure and recovery time. • The response to different organic vapors can be tailored by changing polymer matrix. - Abstract: Gas sensing composites were fabricated using polybenzoxazine-based activated carbon aerogel as a conductive filler. The activated carbon aerogel is a nano-porous material, which has high pore volume of 0.57 cm{sup 3}/g and surface area of 917 m{sup 2}/g. The activated carbon aerogel/polybutadiene composite displayed good response of 11.2 and 6.7 to toluene and n-hexane, respectively, compared to those of graphite/polybutadiene composite. The activated carbon aerogel/polybutadiene composite also showed high sensitivity of 3.09 × 10{sup 2} ppm{sup −1} to toluene. However, the sensitivity of activated carbon aerogel/polybutadiene composite drastically decreased to 1.99 ppm{sup −1} and zero when exposed to acetone and water, respectively. Contrarily, when polyvinyl alcohol was used as a matrix, the sensitivity was about 4.19 ppm{sup −1} to water. While the composite was found to be not sensitive to toluene. The activated carbon aerogel/polybutadiene composite also showed good recovery as the electrical resistance came back to the original value within minutes when exposed to nitrogen gas.

  17. Highly sensitive room temperature organic vapor sensor based on polybenzoxazine-derived carbon aerogel thin film composite

    International Nuclear Information System (INIS)

    Thubsuang, Uthen; Sukanan, Darunee; Sahasithiwat, Somboon; Wongkasemjit, Sujitra; Chaisuwan, Thanyalak

    2015-01-01

    Graphical abstract: - Highlights: • Activated carbon aerogel with high surface area can be prepared from polybenzoxazine. • Activated carbon aerogel enhances the adsorption capacity of gas sensor. • Organic vapors with very low concentration can be detected by the as-prepared sensor. • The as-prepared sensor shows impressive short exposure and recovery time. • The response to different organic vapors can be tailored by changing polymer matrix. - Abstract: Gas sensing composites were fabricated using polybenzoxazine-based activated carbon aerogel as a conductive filler. The activated carbon aerogel is a nano-porous material, which has high pore volume of 0.57 cm 3 /g and surface area of 917 m 2 /g. The activated carbon aerogel/polybutadiene composite displayed good response of 11.2 and 6.7 to toluene and n-hexane, respectively, compared to those of graphite/polybutadiene composite. The activated carbon aerogel/polybutadiene composite also showed high sensitivity of 3.09 × 10 2 ppm −1 to toluene. However, the sensitivity of activated carbon aerogel/polybutadiene composite drastically decreased to 1.99 ppm −1 and zero when exposed to acetone and water, respectively. Contrarily, when polyvinyl alcohol was used as a matrix, the sensitivity was about 4.19 ppm −1 to water. While the composite was found to be not sensitive to toluene. The activated carbon aerogel/polybutadiene composite also showed good recovery as the electrical resistance came back to the original value within minutes when exposed to nitrogen gas

  18. New properties of a fiber optic sensor in application of a composite fence for critical infrastructure protection

    Science.gov (United States)

    Zyczkowski, M.; Szustakowski, M.; Markowski, P.

    2015-09-01

    This paper presents a new solution of using the composite fence with a novel fiber optic modalmetric sensor integrated within its structure. The modalmetric sensor is based on changes in a transverse modal field which is generated at the output of a multimode fiber. By a spatial limitation of the transverse modal field observation to its fragment thereof, changes' transformation in the modal distribution into changes of the output signal amplitude is made. Due to a constant analysis of the structure output signal, detection of an external disorder is possible. Integration of optical fibers with the fence structure allows for an accurate reproduction of the fence movement onto the optical fiber by significantly improving sensitivity of the modalmetric fiber sensor structure.

  19. An amperometric biosensor based on acetylcholinesterase immobilized onto iron oxide nanoparticles/multi-walled carbon nanotubes modified gold electrode for measurement of organophosphorus insecticides

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Nidhi [Department of Biochemistry, M.D. University, Rohtak 124001, Haryana (India); Pundir, Chandra Shekhar, E-mail: pundircs@rediffmail.com [Department of Biochemistry, M.D. University, Rohtak 124001, Haryana (India)

    2011-09-02

    Graphical abstract: The stepwise amperometric biosensor fabrication process and immobilized acetylcholinesterase inhibition in pesticide solution. Highlights: {center_dot} Constructed a novel composite material using Fe{sub 3}O{sub 4}NP and c-MWCNT at Au electrode for electrocatalysis. {center_dot} The properties of nanoparticles modified electrodes were studied by SEM, FTIR, CVs and EIS. {center_dot} The biosensor exhibited good sensitivity (0.475 mA {mu}M{sup -1}) {center_dot} The half life of electrode was 2 months. {center_dot} The sensor was suitable for trace detection of OP pesticide residues in milk and water. - Abstract: An acetylcholinesterase (AChE) purified from maize seedlings was immobilized covalently onto iron oxide nanoparticles (Fe{sub 3}O{sub 4}NP) and carboxylated multi walled carbon nanotubes (c-MWCNT) modified Au electrode. An organophosphorus (OP) biosensor was fabricated using this AChE/Fe{sub 3}O{sub 4}/c-MWCNT/Au electrode as a working electrode, Ag/AgCl as standard and Pt wire as an auxiliary electrode connected through a potentiostat. The biosensor was based on inhibition of AChE by OP compounds/insecticides. The properties of nanoparticles modified electrodes were studied by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), cyclic voltammograms (CVs) and electrochemical impedance spectroscopy (EIS). The synergistic action of Fe{sub 3}O{sub 4}NP and c-MWCNT showed excellent electrocatalytic activity at low potential (+0.4 V). The optimum working conditions for the sensor were pH 7.5, 35 deg. C, 600 {mu}M substrate concentration and 10 min for inhibition by pesticide. Under optimum conditions, the inhibition rates of OP pesticides were proportional to their concentrations in the range of 0.1-40 nM, 0.1-50 nM, 1-50 nM and 10-100 nM for malathion, chlorpyrifos, monocrotophos and endosulfan respectively. The detection limits were 0.1 nM for malathion and chlorpyrifos, 1 nM for monocrotophos and 10 nM for endosulfan. The

  20. Open Circuit Resonant (SansEC) Sensor Technology for Lightning Mitigation and Damage Detection and Diagnosis for Composite Aircraft Applications

    Science.gov (United States)

    Szatkowski, George N.; Dudley, Kenneth L.; Smith, Laura J.; Wang, Chuantong; Ticatch, Larry A.

    2014-01-01

    Traditional methods to protect composite aircraft from lightning strike damage rely on a conductive layer embedded on or within the surface of the aircraft composite skin. This method is effective at preventing major direct effect damage and minimizes indirect effects to aircraft systems from lightning strike attachment, but provides no additional benefit for the added parasitic weight from the conductive layer. When a known lightning strike occurs, the points of attachment and detachment on the aircraft surface are visually inspected and checked for damage by maintenance personnel to ensure continued safe flight operations. A new multi-functional lightning strike protection (LSP) method has been developed to provide aircraft lightning strike protection, damage detection and diagnosis for composite aircraft surfaces. The method incorporates a SansEC sensor array on the aircraft exterior surfaces forming a "Smart skin" surface for aircraft lightning zones certified to withstand strikes up to 100 kiloamperes peak current. SansEC sensors are open-circuit devices comprised of conductive trace spiral patterns sans (without) electrical connections. The SansEC sensor is an electromagnetic resonator having specific resonant parameters (frequency, amplitude, bandwidth & phase) which when electromagnetically coupled with a composite substrate will indicate the electrical impedance of the composite through a change in its resonant response. Any measureable shift in the resonant characteristics can be an indication of damage to the composite caused by a lightning strike or from other means. The SansEC sensor method is intended to diagnose damage for both in-situ health monitoring or ground inspections. In this paper, the theoretical mathematical framework is established for the use of open circuit sensors to perform damage detection and diagnosis on carbon fiber composites. Both computational and experimental analyses were conducted to validate this new method and system for

  1. Scalable fabrication of immunosensors based on carbon nanotube polymer composites

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza, Ernest; Gonzalez-Guerrero, Ana B [Institut Catala de Nanotecnologia, Campus Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Orozco, Jahir; Jimenez-Jorquera, Cecilia; Fernandez-Sanchez, Cesar [Instituto de Microelectronica de Barcelona, CNM-IMB (CSIC), Campus Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Calle, Ana; Lechuga, Laura M [Instituto de Microelectronica de Madrid, CNM-IMM (CSIC), Isaac Newton 8, 28760 Tres Cantos, Madrid (Spain)], E-mail: Ernest.Mendoza.icn@uab.es

    2008-02-20

    In this work we present the fabrication and characterization of immunosensors based on polystyrene (PS)-multiwalled carbon nanotube (MWCNT) composites. The electrochemical properties of the sensors have been investigated and show that the surface area is increased upon addition of the MWCNT-PS layer. Furthermore, a plasma activation process is used to partially remove the PS and expose the MWCNTs. This results in a huge increase in the electrochemical area and opens up the possibility of binding biomolecules to the MWCNT wall. The MWCNTs have been functionalized covalently with a model antibody (rabbit IgG). The biosensors have been tested using amperometric techniques and show detection limits comparable to standard techniques such as ELISA.

  2. Dynamic Strain Measurements on Automotive and Aeronautic Composite Components by Means of Embedded Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Alfredo Lamberti

    2015-10-01

    Full Text Available The measurement of the internal deformations occurring in real-life composite components is a very challenging task, especially for those components that are rather difficult to access. Optical fiber sensors can overcome such a problem, since they can be embedded in the composite materials and serve as in situ sensors. In this article, embedded optical fiber Bragg grating (FBG sensors are used to analyze the vibration characteristics of two real-life composite components. The first component is a carbon fiber-reinforced polymer automotive control arm; the second is a glass fiber-reinforced polymer aeronautic hinge arm. The modal parameters of both components were estimated by processing the FBG signals with two interrogation techniques: the maximum detection and fast phase correlation algorithms were employed for the demodulation of the FBG signals; the Peak-Picking and PolyMax techniques were instead used for the parameter estimation. To validate the FBG outcomes, reference measurements were performed by means of a laser Doppler vibrometer. Sensors 2015, 15 27175 The analysis of the results showed that the FBG sensing capabilities were enhanced when the recently-introduced fast phase correlation algorithm was combined with the state-of-the-art PolyMax estimator curve fitting method. In this case, the FBGs provided the most accurate results, i.e. it was possible to fully characterize the vibration behavior of both composite components. When using more traditional interrogation algorithms (maximum detection and modal parameter estimation techniques (Peak-Picking, some of the modes were not successfully identified.

  3. Highly sensitive amperometric biosensor based on electrochemically-reduced graphene oxide-chitosan/hemoglobin nanocomposite for nitromethane determination.

    Science.gov (United States)

    Wen, Yunping; Wen, Wei; Zhang, Xiuhua; Wang, Shengfu

    2016-05-15

    Nitromethane (CH3NO2) is an important organic chemical raw material with a wide variety of applications as well as one of the most common pollutants. Therefore it is pretty important to establish a simple and sensitive detection method for CH3NO2. In our study, a novel amperometric biosensor for nitromethane (CH3NO2) based on immobilization of electrochemically-reduced graphene oxide (rGO), chitosan (CS) and hemoglobin (Hb) on a glassy carbon electrode (GCE) was constructed. Scanning electron microscopy, infrared spectroscopy and electrochemical methods were used to characterize the Hb-CS/rGO-CS composite film. The effects of scan rate and pH of phosphate buffer on the biosensor have been studied in detail and optimized. Due to the graphene and chitosan nanocomposite, the developed biosensor demonstrating direct electrochemistry with faster electron-transfer rate (6.48s(-1)) and excellent catalytic activity towards CH3NO2. Under optimal conditions, the proposed biosensor exhibited fast amperometric response (<5s) to CH3NO2 with a wide linear range of 5 μM~1.46 mM (R=0.999) and a low detection limit of 1.5 μM (S/N=3). In addition, the biosensor had high selectivity, reproducibility and stability, providing the possibility for monitoring CH3NO2 in complex real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Double electrolyte sensor for monitoring hydrogen permeation rate in steels

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang, Y.J. [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Department of Chemistry and Chemical Engineering, Huaihua College, Huaihua 418008 (China); Yu, G., E-mail: yuganghnu@163.co [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Ou, A.L.; Hu, L.; Xu, W.J. [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

    2011-06-15

    Highlights: {yields} Designed an amperometric hydrogen sensor with double electrolytes. {yields} Explained the principle of determining hydrogen permeation rate. {yields} Verified good stability, reproducibility and correctness of the developed sensor. {yields} Field on-line monitoring the susceptivity of hydrogen induced cracks. - Abstract: An amperometric hydrogen sensor with double electrolytes composed of a gelatiniform electrolyte and KOH solution has been developed to determine the permeation rate of hydrogen atoms in steel equipment owing to hydrogen corrosion. The gelatiniform electrolyte was made of sodium polyacrylate (PAAS), carboxyl methyl cellulose (CMC) and 0.2 mol dm{sup -3} KOH solution. The results show that the gelatiniform electrolyte containing 50 wt.% polymers has suitable viscosity and high electrical conductivity. The consistent permeation curves were detected by the sensor of the double electrolyte and single liquid KOH electrolyte, respectively. The developed sensor has good stability and reproducibility at room temperature.

  5. Double electrolyte sensor for monitoring hydrogen permeation rate in steels

    International Nuclear Information System (INIS)

    Ouyang, Y.J.; Yu, G.; Ou, A.L.; Hu, L.; Xu, W.J.

    2011-01-01

    Highlights: → Designed an amperometric hydrogen sensor with double electrolytes. → Explained the principle of determining hydrogen permeation rate. → Verified good stability, reproducibility and correctness of the developed sensor. → Field on-line monitoring the susceptivity of hydrogen induced cracks. - Abstract: An amperometric hydrogen sensor with double electrolytes composed of a gelatiniform electrolyte and KOH solution has been developed to determine the permeation rate of hydrogen atoms in steel equipment owing to hydrogen corrosion. The gelatiniform electrolyte was made of sodium polyacrylate (PAAS), carboxyl methyl cellulose (CMC) and 0.2 mol dm -3 KOH solution. The results show that the gelatiniform electrolyte containing 50 wt.% polymers has suitable viscosity and high electrical conductivity. The consistent permeation curves were detected by the sensor of the double electrolyte and single liquid KOH electrolyte, respectively. The developed sensor has good stability and reproducibility at room temperature.

  6. Large Scale Applications Using FBG Sensors: Determination of In-Flight Loads and Shape of a Composite Aircraft Wing

    Directory of Open Access Journals (Sweden)

    Matthew J. Nicolas

    2016-06-01

    Full Text Available Technological advances have enabled the development of a number of optical fiber sensing methods over the last few years. The most prevalent optical technique involves the use of fiber Bragg grating (FBG sensors. These small, lightweight sensors have many attributes that enable their use for a number of measurement applications. Although much literature is available regarding the use of FBGs for laboratory level testing, few publications in the public domain exist of their use at the operational level. Therefore, this paper gives an overview of the implementation of FBG sensors for large scale structures and applications. For demonstration, a case study is presented in which FBGs were used to determine the deflected wing shape and the out-of-plane loads of a 5.5-m carbon-composite wing of an ultralight aerial vehicle. The in-plane strains from the 780 FBG sensors were used to obtain the out-of-plane loads as well as the wing shape at various load levels. The calculated out-of-plane displacements and loads were within 4.2% of the measured data. This study demonstrates a practical method in which direct measurements are used to obtain critical parameters from the high distribution of FBG sensors. This procedure can be used to obtain information for structural health monitoring applications to quantify healthy vs. unhealthy structures.

  7. Resistance pressure sensor based on Ag/Cu/sub 2/O-PEPC-NiPc/Al composite

    International Nuclear Information System (INIS)

    Khan, A.; Karimov, K.S.; Shah, M.

    2011-01-01

    This work reports on the fabrication and investigation of pressure sensor based on Ag/Cu/sub 2/O-PEPC-NiPc/Al composite. The active layer of the composite was deposited by drop-casting of the blend Cu/sub 2/O-PEPC-NiPc on flexible substrate. The thin film of the blend consist of cuprous oxide (Cu/sub 2/O) micropowder, (5 wt. %), poly-N-epoxypropyl carbazole (PEPC), (2 wt. %) and nickel phthalocyanine (NiPc) micropowder, (3 wt. %) in benzol (1 ml). The film thickness of the composite is in the range of 20-30 mu m. It is found that the fabricated sensor is sensitive to pressure and showed good repeatability. The decrease in resistance of the sensor is observed 10 times by increasing the external uniaxial pressure up to 11.7 kNm/sup -2/. The experimentally obtained results are compared with the simulated results and showed reasonable agreement with each other. (author)

  8. Novel amperometric glucose biosensor based on MXene nanocomposite

    KAUST Repository

    Rakhi, R. B.

    2016-11-10

    A biosensor platform based on Au/MXene nanocomposite for sensitive enzymatic glucose detection is reported. The biosensor leverages the unique electrocatalytic properties and synergistic effects between Au nanoparticles and MXene sheets. An amperometric glucose biosensor is fabricated by the immobilization of glucose oxidase (GOx) enzyme on Nafion solubilized Au/ MXene nanocomposite over glassy carbon electrode (GCE). The biomediated Au nanoparticles play a significant role in facilitating the electron exchange between the electroactive center of GOx and the electrode. The GOx/Au/MXene/Nafion/GCE biosensor electrode displayed a linear amperometric response in the glucose concentration range from 0.1 to 18 mM with a relatively high sensitivity of 4.2 μAmM−1 cm−2 and a detection limit of 5.9 μM (S/N = 3). Furthermore, the biosensor exhibited excellent stability, reproducibility and repeatability. Therefore, the Au/MXene nanocomposite reported in this work is a potential candidate as an electrochemical transducer in electrochemical biosensors.

  9. Novel amperometric glucose biosensor based on MXene nanocomposite

    KAUST Repository

    Baby, Rakhi Raghavan; Nayuk, Pranati; Xia, Chuan; Alshareef, Husam N.

    2016-01-01

    A biosensor platform based on Au/MXene nanocomposite for sensitive enzymatic glucose detection is reported. The biosensor leverages the unique electrocatalytic properties and synergistic effects between Au nanoparticles and MXene sheets. An amperometric glucose biosensor is fabricated by the immobilization of glucose oxidase (GOx) enzyme on Nafion solubilized Au/ MXene nanocomposite over glassy carbon electrode (GCE). The biomediated Au nanoparticles play a significant role in facilitating the electron exchange between the electroactive center of GOx and the electrode. The GOx/Au/MXene/Nafion/GCE biosensor electrode displayed a linear amperometric response in the glucose concentration range from 0.1 to 18 mM with a relatively high sensitivity of 4.2 μAmM−1 cm−2 and a detection limit of 5.9 μM (S/N = 3). Furthermore, the biosensor exhibited excellent stability, reproducibility and repeatability. Therefore, the Au/MXene nanocomposite reported in this work is a potential candidate as an electrochemical transducer in electrochemical biosensors.

  10. An Effective Amperometric Biosensor Based on Gold Nanoelectrode Arrays

    Directory of Open Access Journals (Sweden)

    Zhu Yingchun

    2008-01-01

    Full Text Available Abstract A sensitive amperometric biosensor based on gold nanoelectrode array (NEA was investigated. The gold nanoelectrode array was fabricated by template-assisted electrodeposition on general electrodes, which shows an ordered well-defined 3D structure of nanowires. The sensitivity of the gold NEA to hydrogen peroxide is 37 times higher than that of the conventional electrode. The linear range of the platinum NEA toward H2O2is from 1 × 10−6to 1 × 10−2 M, covering four orders of magnitudes with detection limit of 1 × 10−7 M and a single noise ratio (S/N of four. The enzyme electrode exhibits an excellent response performance to glucose with linear range from 1 × 10−5to 1 × 10−2 M and a fast response time within 8 s. The Michaelis–Menten constantkm and the maximum current densityi maxof the enzyme electrode were 4.97 mM and 84.60 μA cm−2, respectively. This special nanoelectrode may find potential application in other biosensors based on amperometric signals.

  11. Amperometric immunosensor for rapid detection of Mycobacterium tuberculosis

    International Nuclear Information System (INIS)

    Hiraiwa, Morgan; Lee, Hyun-Boo; Inoue, Shinnosuke; Chung, Jae-Hyun; Kim, Jong-Hoon; Becker, Annie L; Weigel, Kris M; Cangelosi, Gerard A; Lee, Kyong-Hoon

    2015-01-01

    Tuberculosis (TB) has been a major public health problem, which can be better controlled by using accurate and rapid diagnosis in low-resource settings. A simple, portable, and sensitive detection method is required for point-of-care (POC) settings. This paper studies an amperometric biosensor using a microtip immunoassay for a rapid and low-cost detection of Mycobacterium tuberculosis (MTB) in sputum. MTB in sputum is specifically captured on the functionalized microtip surface and detected by electric current. According to the numerical study, the current signal on the microtip surface is linearly changed with increasing immersion depth. Using a reference microtip, the immersion depth is compensated for a sensing microtip. On the microtip surface, target bacteria are concentrated and organized by a coffee-ring effect, which amplifies the electric current. To enhance the signal-to-noise ratio, both the sample processing and rinsing steps are presented with the use of deionized water as a medium for the amperometric measurement. When applied to cultured MTB cells spiked into human sputum, the detection limit was 100 CFU mL −1 , comparable to a more labor-intensive fluorescence detection method reported previously. (paper)

  12. Amperometric immunosensor for rapid detection of Mycobacterium tuberculosis

    Science.gov (United States)

    Hiraiwa, Morgan; Kim, Jong-Hoon; Lee, Hyun-Boo; Inoue, Shinnosuke; Becker, Annie L.; Weigel, Kris M.; Cangelosi, Gerard A.; Lee, Kyong-Hoon; Chung, Jae-Hyun

    2015-05-01

    Tuberculosis (TB) has been a major public health problem, which can be better controlled by using accurate and rapid diagnosis in low-resource settings. A simple, portable, and sensitive detection method is required for point-of-care (POC) settings. This paper studies an amperometric biosensor using a microtip immunoassay for a rapid and low-cost detection of Mycobacterium tuberculosis (MTB) in sputum. MTB in sputum is specifically captured on the functionalized microtip surface and detected by electric current. According to the numerical study, the current signal on the microtip surface is linearly changed with increasing immersion depth. Using a reference microtip, the immersion depth is compensated for a sensing microtip. On the microtip surface, target bacteria are concentrated and organized by a coffee-ring effect, which amplifies the electric current. To enhance the signal-to-noise ratio, both the sample processing and rinsing steps are presented with the use of deionized water as a medium for the amperometric measurement. When applied to cultured MTB cells spiked into human sputum, the detection limit was 100 CFU mL-1, comparable to a more labor-intensive fluorescence detection method reported previously.

  13. Toward a hydrogen peroxide sensor for exhaled breath analysis

    NARCIS (Netherlands)

    Wiedemair, Justyna; van Dorp, Henriëtte; Olthuis, Wouter; van den Berg, Albert

    2011-01-01

    In this contribution a chip-integrated amperometric sensor for the detection of H2O2 in exhaled breath condensate (EBC) is reported. The electrode chip is characterized, and detection of H2O2 in an aqueous phase is shown by means of cyclic voltammetry (CV) and amperometry. Variation of conditions

  14. Amperometric biosensor based on carbon nanotubes coated with polyaniline/dendrimer-encapsulated Pt nanoparticles for glucose detection

    International Nuclear Information System (INIS)

    Xu Lihuan; Zhu Yihua; Yang Xiaoling; Li Chunzhong

    2009-01-01

    A novel amperometric glucose biosensor based on the nanocomposites of multi-wall carbon nanotubes (CNT) coated with polyaniline (PANI) and dendrimer-encapsulated Pt nanoparticles (Pt-DENs) is prepared. CNT coated with protonated PANI is in situ synthesized and Pt-DENs is absorbed on PANI/CNT composite surface by self-assembly method. Then Glucose oxidase (GOx) is crosslink-immobilizated onto Pt-DENs/PANI/CNT composite film. The results show that the fabricated GOx/Pt-DENs/PANI/CNT electrode exhibits excellent response performance to glucose, such as low detection limit (0.5 μM), wide linear range (1 μM-12 mM), short response time (about 5 s), high sensitivity (42.0 μA mM -1 cm -2 ) and stability (83% remains after 3 weeks).

  15. Amperometric biosensor for hydrogen peroxide based on hemoglobin entrapped in titania sol-gel film

    International Nuclear Information System (INIS)

    Yu Jiuhong; Ju Huangxian

    2003-01-01

    Hemoglobin (Hb) was entrapped in a titania sol-gel matrix and used as a mimetic peroxidase to construct a novel amperometric biosensor for hydrogen peroxide. The Hb entrapped titania sol-gel film was obtained with a vapor deposition method, which simplified the traditional sol-gel process for protein immobilization. The morphologies of both titania sol-gel and the Hb films were characterized using scanning electron microscopy (SEM) and proved to be chemically clean, porous, homogeneous. This matrix provided a biocompatible microenvironment for retaining the native structure and activity of the entrapped Hb and a very low mass transport barrier to the substrates. H 2 O 2 could be reduced by the catalysis of the entrapped hemoglobin at -300 mV without any mediator. The reagentless H 2 O 2 sensor exhibited a fast response (less than 5 s) and sensitivity as high as 1.29 mA mM -1 cm -2 . The linear range for H 2 O 2 determination was from 5.0x10 -7 to 5.4x10 -5 M with a detection limit of 1.2x10 -7 M. The apparent Michaelis-Menten constant of the encapsulated hemoglobin was calculated to be 0.18±0.02 mM. The stability of the biosensor was also evaluated

  16. [Properties of modified amperometric biosensors based on methanol dehydrogenase and Methylobacterium nodulans cells].

    Science.gov (United States)

    Kuznetsova, T A; Beschastnyĭ, A P; Alferov, S V; Trotsenko, Iu A

    2013-01-01

    The properties of amperometric biosensors based on methanol dehydrogenase (MDH), Methylobacterium nodulans cells, and the ferrocene-modified carbon paste electrode were investigated. It was shown that the addition ofhydroxyapatite (HA) to a carbon paste increased the sensitivity and operating stability of MDH biosensors. The linear range of the electrode was 0.0135-0.5 and 0.032-1.5 mM for methanol and formaldehyde, respectively. The detection limit of methanol and formaldehyde was 4.5 and 11.0 microM, respectively. The loss of activity of the electrode within 10 days of storage in the presence of 2.0 mM KCN did not exceed 12%. Cyanide (10 mM) completely inhibited the sensor responses to formaldehyde (1.0 mM), which allowed for the selective determination of methanol in the presence of formaldehyde. The biosensor based on cells exhibited lower stability and sensitivity toward methanol and formaldehyde; the sensitivity coefficients were 980 and 21 nA/mM, respectively.

  17. Flow injection analysis using carbon film resistor electrodes for amperometric determination of ambroxol.

    Science.gov (United States)

    Felix, Fabiana S; Brett, Christopher M A; Angnes, Lúcio

    2008-06-30

    Flow injection analysis (FIA) using a carbon film sensor for amperometric detection was explored for ambroxol analysis in pharmaceutical formulations. The specially designed flow cell designed in the lab generated sharp and reproducible current peaks, with a wide linear dynamic range from 5x10(-7) to 3.5x10(-4) mol L(-1), in 0.1 mol L(-1) sulfuric acid electrolyte, as well as high sensitivity, 0.110 Amol(-1) L cm(-2) at the optimized flow rate. A detection limit of 7.6x10(-8) mol L(-1) and a sampling frequency of 50 determinations per hour were achieved, employing injected volumes of 100 microL and a flow rate of 2.0 mL min(-1). The repeatability, expressed as R.S.D. for successive and alternated injections of 6.0x10(-6) and 6.0x10(-5) mol L(-1) ambroxol solutions, was 3.0 and 1.5%, respectively, without any noticeable memory effect between injections. The proposed method was applied to the analysis of ambroxol in pharmaceutical samples and the results obtained were compared with UV spectrophotometric and acid-base titrimetric methods. Good agreement between the results utilizing the three methods and the labeled values was achieved, corroborating the good performance of the proposed electrochemical methodology for ambroxol analysis.

  18. Electrooxidation and amperometric determination of vorinostat on hierarchical leaf-like gold nanolayers.

    Science.gov (United States)

    Vais, R Dehdari; Karimian, K; Heli, H

    2018-02-01

    Hierarchical leaf-like gold nanolayers were electrodeposited using choline chloride as a shape directing agent and characterized using field emission scanning electron microscopy. The electrooxidation behavior of vorinostat was then studied on the nanolayers and the kinetic parameters of the electrodic process were obtained by voltammetric measurements in a phosphate buffer solution at pH 7.40. Vorinostat was electrooxidized on the nanolayers' surface at a lower potential and with a higher rate, compared to a polycrystalline smooth gold surface, through an irreversible process. Based on the results, an amperometric sensor was designed using the hierarchical leaf-like gold nanolayers for the determination of vorinostat. A linear dynamic range of 4.0-52μmol L -1 with a calibration sensitivity of 7.7mAmol -1 L, and a detection limit of 1.40μmolL -1 were obtained. The amperometry method was also applied to the analysis of vorinostat capsules. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. [Amperometric biosensor for ethanol analysis in wines and grape must during wine fermentation].

    Science.gov (United States)

    Shkotova, L V; Slast'ia, E A; Zhyliakova, T A; Soldatkin, O P; Schuhmann, W; Dziadevych, S V

    2005-01-01

    The amperometric biosensor for ethanol determination based on alcohol oxidase immobilised by the method of electrochemical polymerization has been developed. The industrial screen-printed platinum electrodes were used as transducers for creation of amperometric alcohol biosensor. Optimal conditions for electrochemical deposition of an active membrane with alcohol oxidase has been determined. Biosensors are characterised by good reproducibility and operational stability with minimal detection limit of ethanol 8 x 10(-5) M. The good correlation of results for ethanol detection in wine and during wine fermentation by using the developed amperometric biosensor with the data obtained by the standard methods was shown (r = 0.995).

  20. Microfiber Bragg grating hydrogen sensor base on co-sputtered Pd/Ni composite film

    Science.gov (United States)

    Wang, Gaopeng; Yang, Minghong; Dai, Jixiang; Cheng, Cheng; Yuan, Yinqian

    2015-07-01

    A novel hydrogen sensor based on Pd/Ni co-sputtered coating on micro fiber Bragg grating (MFBG) is proposed and experimentally demonstrated. The microfiber is stretched uniformly and the Bragg grating is directly inscribed on the microfiber without hydrogen loading using 193 nm ArF excimer laser and a phase mask. Palladium and nickel coatings are co-sputtered on the micro fiber Bragg grating for hydrogen sensing. The MFBG hydrogen sensors are characterized concerning their response to the hydrogen, ambient temperature and ambient refractive index, respectively. The performance of the proposed MFBG hydrogen sensor is obviously enhanced, especially when compared to standard FBG hydrogen sensors.

  1. Currently Commercially Available Chemical Sensors Employed for Detection of Volatile Organic Compounds in Outdoor and Indoor Air

    OpenAIRE

    Bartosz Szulczyński; Jacek Gębicki

    2017-01-01

    The paper presents principle of operation and design of the most popular chemical sensors for measurement of volatile organic compounds (VOCs) in outdoor and indoor air. It describes the sensors for evaluation of explosion risk including pellistors and IR-absorption sensors as well as the sensors for detection of toxic compounds such as electrochemical (amperometric), photoionization and semiconductor with solid electrolyte ones. Commercially available sensors for detection of VOCs and their ...

  2. Manufacturing and testing of active composite panels with embedded piezoelectric sensors and actuators: wires out by molded-in holes

    Science.gov (United States)

    Ghasemi-Nejhad, Mehrdad N.; Pourjalali, Saeid

    2003-08-01

    This work presents manufacturing and testing of active composite panels (ACPs) with embedded piezoelectric sensors and actuators. The composite material employed here is a plain weave carbon epoxy prepreg fabric with about 0.33 mm ply thickness. The piezoelectric patches employed here are Continuum Control Corporation, CCC, (recently Continuum Photonics, Inc) active fiber composite patches with 0.33 mm thickness, i.e. close to the composite ply thickness. Composite cut-out layers are used to fill the space around the embedded piezoelectric patches to minimize the problems associated with ply drops in composites. The piezoelectric patches were embedded inside the composite laminate. High-temperature wires were soldered to the piezoelectric leads, insulated from the carbon substructure by high-temperature materials, and were taken out of the composite laminates employing a molded-in hole technique that reduces the stress concentration as opposed to a drilled hole, and thereby enhancing the performance of the composite structure. The laminated ACP"s were co-cured inside an autoclave employing the cure cycle recommended by the composite material supplier. The curie temperature of the embedded piezoelectric patches should be well above the curing temperature of the composite materials as was the case here. The manufactured ACP beams and plates were trimmed and then tested for their functionality. Vibration suppression as well as simultaneous vibration suppression and precision positioning tests, using PID control as well as Hybrid Adaptive Control techniques were successfully conducted on the manufactured ACP beams and their functionality were demonstrated. Recommendations on the use of this embedding technique for ACPs are provided.

  3. Low-potential sensitive H2O2 detection based on composite micro tubular Te adsorbed on platinum electrode.

    Science.gov (United States)

    Guascito, M R; Chirizzi, D; Malitesta, C; Mazzotta, E; M Siciliano; Siciliano, T; Tepore, A; Turco, A

    2011-04-15

    In this work a new original amperometric sensor for H(2)O(2) detection based on a Pt electrode modified with Te-microtubes was developed. Te-microtubes, synthesized by the simple thermal evaporation of Te powder, have a tubular structure with a hexagonal cross-section and are open ended. Modified electrode was prepared by direct drop casting of the mixture of Te-microtubes dispersed in ethanol on Pt surface. The spectroscopic characterization of synthesized Te-microtubes and Pt/Te-microtubes modified electrodes was performed by scanning electron microscopy (SEM), energy-dispersive X-rays microanalysis (EDX), X-ray diffraction analysis (XRD) and X-ray photoelectron spectroscopy (XPS). Moreover a complete electrochemical characterization of the new composite material Pt/Te-microtubes was performed by cyclic voltammetry (CV) and cronoamperometry (CA) in phosphate buffer solution (PBS) at pH 7. Electrochemical experiments showed that the presence of Te-microtubes on modified electrode was responsible for an increment of both cathodic and anodic currents in presence of H(2)O(2) with respect to bare Pt. Specifically, data collected from amperometric experiments at -150 mV vs. SCE in batch and -200 mV vs. SCE in flow injection analysis (FIA) experiments show a remarkable increment of the cathodic current. The electrochemical performances of tested sensors make them suitable for the quantitative determination of H(2)O(2) substrate both in batch and in FIA. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. A comparative assessment of different frequency based damage detection in unidirectional composite plates using MFC sensors

    Science.gov (United States)

    de Medeiros, Ricardo; Sartorato, Murilo; Vandepitte, Dirk; Tita, Volnei

    2016-11-01

    The basic concept of the vibration based damage identification methods is that the dynamic behaviour of a structure can change if damage occurs. Damage in a structure can alter the structural integrity, and therefore, the physical properties like stiffness, mass and/or damping may change. The dynamic behaviour of a structure is a function of these physical properties and will, therefore, directly be affected by the damage. The dynamic behaviour can be described in terms of time, frequency and modal domain parameters. The changes in these parameters (or properties derived from these parameters) are used as indicators of damage. Hence, this work has two main objectives. The first one is to provide an overview of the structural vibration based damage identification methods. For this purpose, a fundamental description of the structural vibration based damage identification problem is given, followed by a short literature overview of the damage features, which are commonly addressed. The second objective is to create a damage identification method for detection of the damage in composite structures. To aid in this process, two basic principles are discussed, namely the effect of the potential damage case on the dynamic behaviour, and the consequences involved with the information reduction in the signal processing. Modal properties from the structural dynamic output response are obtained. In addition, experimental and computational results are presented for the application of modal analysis techniques applied to composite specimens with and without damage. The excitation of the structures is performed using an impact hammer and, for measuring the output data, accelerometers as well as piezoelectric sensors. Finite element models are developed by shell elements, and numerical results are compared to experimental data, showing good correlation for the response of the specimens in some specific frequency range. Finally, FRFs are analysed using suitable metrics, including a

  5. A novel solid-state electrochemiluminescence quenching sensor for detection of aniline based on luminescent composite nanofibers

    International Nuclear Information System (INIS)

    Wang, Xiaoying; Yang, Yu; Gao, Huiwen

    2014-01-01

    A novel solid-state electrochemiluminescence (ECL) quenching sensor based on the luminescent composite nanofibers for detection of aniline has been developed. The gold nanoparticles (AuNPs) and Ruthenium (II) tris-(bipyridine) (Ru(bpy) 3 2+ ) doped nylon 6 (PA6) luminescent composite nanofibers (Ru–AuNPs–PA6) were successfully deposited to the bare glassy carbon (GC) electrode by a one-step electrospinning technique. The Ru–AuNPs–PA6 nanofibers maintained the photoelectric properties of the Ru(bpy) 3 2+ ions completely and exhibited excellent ECL behaviors. A high quenching effect on the ECL signal of the Ru–AuNPs–PA6/C 2 O 4 2− system was obtained with the presence of low concentration aniline compounds. The potential of analytical application was explored by use of the inhibited ECL. The quenching efficiencies of the five kinds of aniline compounds were compared by monitoring the aniline-dependent ECL intensity change. The magnitude of quenching depended linearly upon the concentration of aniline in the investigated concentration range of 10–10 µM. The detection limit for aniline is 5.0 nM, which is comparable or better than that in the reported assays. The solid-state ECL quenching sensor exhibited high sensitivity and good stability. This study may provide new insight into the design of advanced electrospun nanofibers-based ECL sensors for detection and analysis of a variety of active molecules. - Highlights: • The Ru–AuNPs–PA6 nanofibers were first prepared by one-step electrospinning technique. • The Ru–AuNPs–PA6 nanofibers exhibited excellent ECL behaviors on GC electrodes. • It is the first solid-state ECL sensor based on nanofibers for aniline detection. • The quenching efficiencies of the five kinds of aniline compounds were compared. • The strategy could be extended to develop various nanofibers-based ECL sensors

  6. 3D printing of highly elastic strain sensors using polyurethane/multiwall carbon nanotube composites

    Science.gov (United States)

    Christ, Josef F.; Hohimer, Cameron J.; Aliheidari, Nahal; Ameli, Amir; Mo, Changki; Pötschke, Petra

    2017-04-01

    As the desire for wearable electronics increases and the soft robotics industry advances, the need for novel sensing materials has also increased. Recently, there have been many attempts at producing novel materials, which exhibit piezoresistive behavior. However, one of the major shortcomings in strain sensing technologies is in the fabrication of such sensors. While there is significant research and literature covering the various methods for developing piezoresistive materials, fabricating complex sensor platforms is still a manufacturing challenge. Here, we report a facile method to fabricate multidirectional embedded strain sensors using additive manufacturing technology. Pure thermoplastic polyurethane (TPU) and TPU/multiwall carbon nanotubes (MWCNT) nanocomposites were 3D printed in tandem using a low-cost multi-material FDM printer to fabricate uniaxial and biaxial strain sensors with conductive paths embedded within the insulative TPU platform. The sensors were then subjected to a series of cyclic strain loads. The results revealed excellent piezoresistive responses of the sensors with cyclic repeatability in both the axial and transverse directions and in response to strains as high as 50%. Further, while strain-softening did occur in the embedded printed strain sensors, it was predictable and similar to the results found in the literature for bulk polymer nanocomposites. This works demonstrates the possibility of manufacturing embedded and multidirectional flexible strain sensors using an inexpensive and versatile method, with potential applications in soft robotics and flexible electronics and health monitoring.

  7. Highly Stable and Flexible Pressure Sensors with Modified Multi-Walled Carbon Nanotube/Polymer Composites for Human Monitoring.

    Science.gov (United States)

    He, Yin; Ming, Yue; Li, Wei; Li, Yafang; Wu, Maoqi; Song, Jinzhong; Li, Xiaojiu; Liu, Hao

    2018-04-26

    A facile method for preparing an easy processing, repeatable and flexible pressure sensor was presented via the synthesis of modified multi-walled carbon nanotubes (m-MWNTs) and polyurethane (PU) films. The surface modification of multi-walled carbon nanotubes (MWNTs) simultaneously used a silane coupling agent (KH550) and sodium dodecyl benzene sulfonate (SDBS) to improve the dispersibility and compatibility of the MWNTs in a polymer matrix. The electrical property and piezoresistive behavior of the m-MWNT/PU composites were compared with raw multi-walled carbon nanotube (raw MWNT)/PU composites. Under linear uniaxial pressure, the m-MWNT/PU composite exhibited 4.282%kPa −1 sensitivity within the pressure of 1 kPa. The nonlinear error, hysteresis error and repeatability error of the piezoresistivity of m-MWNT/PU decreased 9%, 16.72% and 54.95% relative to raw MWNT/PU respectively. Therefore, the piezoresistive response of m-MWNT/PU had better stability than that of raw MWNT/PU composites. The m-MWNT/PU sensors could be utilized in wearable devices for body movement detection, monitoring of respiration and pressure detection in garments.

  8. Amperometric Determination of Glucose at Parts per Million Levels with Immobilized Glucose Oxidase.

    Science.gov (United States)

    Sittampalam, G.; Wilson, G. S.

    1982-01-01

    An experiment on the operation and utility of an amperometric immobilized enzyme electrode (or probe) is described, including advantages of the experiment, equipment, reagents, preparation of phosphate buffer, enzyme immobilization techniques, laboratory procedures, precautions, and discussion of experimental results. (SK)

  9. Evaluation of permselective membranes for optimization of intracerebral amperometric glutamate biosensors

    NARCIS (Netherlands)

    Wahono, N.; Qin, S.; Oomen, P.; Cremers, T. I. F.; de Vries, M. G.; Westerink, B. H. C.

    2012-01-01

    Monitoring of extracellular brain glutamate concentrations by intracerebral biosensors is a promising approach to further investigate the role of this important neurotransmitter. However, amperometric biosensors are typically hampered by Faradaic interference caused by the presence of other

  10. The procedure of ethanol determination in wine by enzyme amperometric biosensor

    Directory of Open Access Journals (Sweden)

    Dzyadevych S. V.

    2009-08-01

    Full Text Available Aim. Development of the procedure of ethanol determination in wine by an enzyme amperometric biosensor. Methods. The amperometric biosensor method of ethanol analysis has been used in this work. Results. The paper presents comparative analysis of two methods of alcohol oxidase (AO immobilization for development of amperometric biosensor for ethanol determination in wine. The method of AO immobilization in glutaraldehyde vapour was chosen as optimal for this purpose. The selectivity, operational and storage stability, and pH-optimum for operation of the created biosensor were determined. The procedure of ethanol determination in wine by amperometric biosensor on the basis of platinum printed electrode SensLab and AO was optimized. The analysis of ethanol concentration in wine and must samples was carried out using the developed high-stable biosensor. A good correlation between the data obtained by the biosensor and densitometry methods was shown. Conclusion. The proposed method of ethanol analysis could be used in wine production

  11. Composite multi-modal vibration control for a stiffened plate using non-collocated acceleration sensor and piezoelectric actuator

    International Nuclear Information System (INIS)

    Li, Shengquan; Li, Juan; Mo, Yueping; Zhao, Rong

    2014-01-01

    A novel active method for multi-mode vibration control of an all-clamped stiffened plate (ACSP) is proposed in this paper, using the extended-state-observer (ESO) approach based on non-collocated acceleration sensors and piezoelectric actuators. Considering the estimated capacity of ESO for system state variables, output superposition and control coupling of other modes, external excitation, and model uncertainties simultaneously, a composite control method, i.e., the ESO based vibration control scheme, is employed to ensure the lumped disturbances and uncertainty rejection of the closed-loop system. The phenomenon of phase hysteresis and time delay, caused by non-collocated sensor/actuator pairs, degrades the performance of the control system, even inducing instability. To solve this problem, a simple proportional differential (PD) controller and acceleration feed-forward with an output predictor design produce the control law for each vibration mode. The modal frequencies, phase hysteresis loops and phase lag values due to non-collocated placement of the acceleration sensor and piezoelectric patch actuator are experimentally obtained, and the phase lag is compensated by using the Smith Predictor technology. In order to improve the vibration control performance, the chaos optimization method based on logistic mapping is employed to auto-tune the parameters of the feedback channel. The experimental control system for the ACSP is tested using the dSPACE real-time simulation platform. Experimental results demonstrate that the proposed composite active control algorithm is an effective approach for suppressing multi-modal vibrations. (paper)

  12. Hydrogen peroxide sensor based on modified vitreous carbon with multiwall carbon nanotubes and composites of Pt nanoparticles-dopamine

    Energy Technology Data Exchange (ETDEWEB)

    Guzman, C.; Orozco, G. [Electrochemistry Department, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica S.C., P.O. Box 064, C.P. 76700, Pedro Escobedo, Queretaro (Mexico); Verde, Y. [Instituto Tecnologico de Cancun, Av. Kabah Km. 3, C.P. 77500, Cancun, Quintana Roo (Mexico); Jimenez, S. [Unidad Queretaro Centro de Investigacion y de Estudios Avanzados del I.P.N., Juriquilla, Santiago de Queretaro (Mexico); Godinez, Luis A. [Electrochemistry Department, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica S.C., P.O. Box 064, C.P. 76700, Pedro Escobedo, Queretaro (Mexico); Juaristi, E. [Chemistry Department, Centro de Investigacion y de Estudios Avanzados del I.P.N., P.O. Box 14-740, C.P. 07360 Mexico, D.F. (Mexico); Bustos, E. [Electrochemistry Department, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica S.C., P.O. Box 064, C.P. 76700, Pedro Escobedo, Queretaro (Mexico); Chemistry Department, Centro de Investigacion y de Estudios Avanzados del I.P.N., P.O. Box 14-740, C.P. 07360 Mexico, D.F. (Mexico)], E-mail: ebustos@cideteq.mx

    2009-02-15

    Sensors using nanostructured materials have been under development in the last decade due to their selectivity for the detection and quantification of different compounds. The physical and chemical characteristics of carbon nanotubes provide significant advantages when used as electrodes for electronic devices, fuel cells and electrochemical sensors. This paper presents preliminary results on the modification of vitreous carbon electrodes with Multiwall Carbon Nanotubes (MWCNTs) and composites of Pt nanoparticles-dopamine (DA) as electro-catalytic materials for the hydrogen peroxide (H{sub 2}O{sub 2}) reaction. Chemical pre-treatment and consequent functionalization of MWCNTs with carboxylic groups was necessary to increase the distribution of the composites. In addition, the presence of DA was important to protect the active sites and eliminate the pasivation of the surface after the electro-oxidation of H{sub 2}O{sub 2} takes place. The proposed H{sub 2}O{sub 2} sensor exhibited a linear response in the 0-5 mM range, with detection and quantification limits of 0.3441 mM and 1.1472 mM, respectively.

  13. Hydrogen peroxide sensor based on modified vitreous carbon with multiwall carbon nanotubes and composites of Pt nanoparticles-dopamine

    International Nuclear Information System (INIS)

    Guzman, C.; Orozco, G.; Verde, Y.; Jimenez, S.; Godinez, Luis A.; Juaristi, E.; Bustos, E.

    2009-01-01

    Sensors using nanostructured materials have been under development in the last decade due to their selectivity for the detection and quantification of different compounds. The physical and chemical characteristics of carbon nanotubes provide significant advantages when used as electrodes for electronic devices, fuel cells and electrochemical sensors. This paper presents preliminary results on the modification of vitreous carbon electrodes with Multiwall Carbon Nanotubes (MWCNTs) and composites of Pt nanoparticles-dopamine (DA) as electro-catalytic materials for the hydrogen peroxide (H 2 O 2 ) reaction. Chemical pre-treatment and consequent functionalization of MWCNTs with carboxylic groups was necessary to increase the distribution of the composites. In addition, the presence of DA was important to protect the active sites and eliminate the pasivation of the surface after the electro-oxidation of H 2 O 2 takes place. The proposed H 2 O 2 sensor exhibited a linear response in the 0-5 mM range, with detection and quantification limits of 0.3441 mM and 1.1472 mM, respectively

  14. Composite Sr- and V-doped LaCrO3/YSZ sensor electrode operating at low oxygen levels

    DEFF Research Database (Denmark)

    Lund, Anders; Jacobsen, Torben; Hansen, Karin Vels

    2012-01-01

    A porous composite electrode of La0.8Sr0.2Cr0.97V0.03O3 -delta (LSCV) and yttria-stabilised zirconia (YSZ) was evaluated as a possible candidate for high-temperature potentiometric oxygen sensor measuring electrodes. The oxygen processes at the electrode were characterised by performing electroch....... The relatively low response time at 700º C at an oxygen partial pressure of around 5x10-6 bar and an inlet gas flow rate of 8 L h-1 makes the LSCV/YSZ electrode suitable for use as an potentiometric oxygen sensor electrodes.......A porous composite electrode of La0.8Sr0.2Cr0.97V0.03O3 -delta (LSCV) and yttria-stabilised zirconia (YSZ) was evaluated as a possible candidate for high-temperature potentiometric oxygen sensor measuring electrodes. The oxygen processes at the electrode were characterised by performing...... and 400 nm. At oxygen partial pressures around 0.2 bar at 700º C, the oxygen reaction is dominated by solid-state diffusion of oxide ions and surface reaction kinetics. At oxygen partial pressures around 10-5 bar above 800º C, gas phase mass transport processes dominate the impedance spectra...

  15. Amperometric glucose biosensor based on glucose oxidase dispersed in multiwalled carbon nanotubes/graphene oxide hybrid biocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Palanisamy, Selvakumar; Cheemalapati, Srikanth; Chen, Shen-Ming, E-mail: smchen78@ms15.hinet.net

    2014-01-01

    An amperometric glucose biosensor based on enhanced and fast direct electron transfer (DET) of glucose oxidase (GOx) at enzyme dispersed multiwalled carbon nanotubes/graphene oxide (MWCNT/GO) hybrid biocomposite was developed. The fabricated hybrid biocomposite was characterized by transmission electron microscopy (TEM), Raman and infrared spectroscopy (IR). The TEM image of hybrid biocomposite reveals that a thin layer of GOx was covered on the surface of MWCNT/GO hybrid composite. IR results validate that the hybrid biocomposite was formed through the electrostatic interactions between GOx and MWCNT/GO hybrid composite. Further, MWCNT/GO hybrid composite has also been characterized by TEM and UV–visible spectroscopy. A pair of well-defined redox peak was observed for GOx immobilized at the hybrid biocomposite electrode than that immobilized at the MWCNT modified electrode. The electron transfer rate constant (K{sub s}) of GOx at the hybrid biocomposite was calculated to be 11.22 s{sup −1}. The higher K{sub s} value revealed that fast DET of GOx occurred at the electrode surface. Moreover, fabricated biosensor showed a good sensitivity towards glucose oxidation over a linear range 0.05–23.2 mM. The limit of detection (LOD) was estimated to be 28 μM. The good features of the proposed biosensor could be used for the accurate detection of glucose in the biological samples. - Highlights: • An amperometric glucose biosensor has been developed at MWCNT/GO hybrid biocomposite. • Enhanced and fast direct electron transfer kinetics of glucose oxidase has been achieved at hybrid biocomposite. • Hybrid biocomposite has been characterized by TEM, IR and Raman spectroscopy. • Highly sensitive and selective for glucose determination.

  16. Amperometric glucose biosensor based on glucose oxidase dispersed in multiwalled carbon nanotubes/graphene oxide hybrid biocomposite

    International Nuclear Information System (INIS)

    Palanisamy, Selvakumar; Cheemalapati, Srikanth; Chen, Shen-Ming

    2014-01-01

    An amperometric glucose biosensor based on enhanced and fast direct electron transfer (DET) of glucose oxidase (GOx) at enzyme dispersed multiwalled carbon nanotubes/graphene oxide (MWCNT/GO) hybrid biocomposite was developed. The fabricated hybrid biocomposite was characterized by transmission electron microscopy (TEM), Raman and infrared spectroscopy (IR). The TEM image of hybrid biocomposite reveals that a thin layer of GOx was covered on the surface of MWCNT/GO hybrid composite. IR results validate that the hybrid biocomposite was formed through the electrostatic interactions between GOx and MWCNT/GO hybrid composite. Further, MWCNT/GO hybrid composite has also been characterized by TEM and UV–visible spectroscopy. A pair of well-defined redox peak was observed for GOx immobilized at the hybrid biocomposite electrode than that immobilized at the MWCNT modified electrode. The electron transfer rate constant (K s ) of GOx at the hybrid biocomposite was calculated to be 11.22 s −1 . The higher K s value revealed that fast DET of GOx occurred at the electrode surface. Moreover, fabricated biosensor showed a good sensitivity towards glucose oxidation over a linear range 0.05–23.2 mM. The limit of detection (LOD) was estimated to be 28 μM. The good features of the proposed biosensor could be used for the accurate detection of glucose in the biological samples. - Highlights: • An amperometric glucose biosensor has been developed at MWCNT/GO hybrid biocomposite. • Enhanced and fast direct electron transfer kinetics of glucose oxidase has been achieved at hybrid biocomposite. • Hybrid biocomposite has been characterized by TEM, IR and Raman spectroscopy. • Highly sensitive and selective for glucose determination

  17. A sensitive electrochemical sensor for in vitro detection of parathyroid hormone based on a MoS2-graphene composite

    Science.gov (United States)

    Kim, Hyeong-U.; Kim, Hye Youn; Kulkarni, Atul; Ahn, Chisung; Jin, Yinhua; Kim, Yeongseok; Lee, Kook-Nyung; Lee, Min-Ho; Kim, Taesung

    2016-10-01

    This paper reports a biosensor based on a MoS2-graphene (MG) composite that can measure the parathyroid hormone (PTH) concentration in serum samples from patients. The interaction between PTH and MG was analysed via an electrochemical sensing technique. The MG was functionalized using L-cysteine. Following this, PTH could be covalently immobilized on the MG sensing electrode. The properties of MG were evaluated using scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectrometry. Following optimization of immobilized materials—such as MG, PTH, and alkaline phosphatase (ALP)—the performance of the MG sensor was investigated via cyclic voltammetry, to assess its linearity, repeatability, and reproducibility. Electrochemical impedance spectroscopy was performed on graphene oxide (GO) and MG-modified electrodes to confirm the capture of a monoclonal antibody (MAb) targeting PTH. Furthermore, the ALP-PTH-MG sensor exhibits a linear response towards PTH from artificial serum over a range of 1-50 pg mL-1. Moreover, patient sera (n = 30) were evaluated using the ALP-PTH-MG sensor and compared using standard equipment (Roche E 170). The P-value is less than 0.01 when evaluated with a t-test using Welch’s correction. This implies that the fabricated sensor can be deployed for medical diagnosis.

  18. A green synthetic strategy of nickel hexacyanoferrate nanoparticals supported on the graphene substrate and its non-enzymatic amperometric sensing application

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Zhonghua, E-mail: xzh@nwnu.edu.cn [Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, College of Chemistry & Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); He, Nan [Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, College of Chemistry & Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Rao, Honghong [College of Chemistry and Chemical Engineering, Lanzhou City University, Lanzhou, 730070 (China); Hu, Chenxian; Wang, Xiaofen; Wang, Hui; Liu, Xiuhui [Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, College of Chemistry & Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Lu, Xiaoquan, E-mail: luxq@nwnu.edu.cn [Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, College of Chemistry & Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China)

    2017-02-28

    Highlights: • A sensitive non-enzymatic glucose sensor was explored by using a facile and green strategy. • Well dispersed and uniform NiHCF nanoparticles can be effectively produced by the introduction of electrochemical reduction graphene oxide films. • Metal hexacyanoferrate as a potential electron mediator was proposed and applied into non-enzymatic sensing. - Abstract: Rapid glucose detection is a key requirement for both diagnosis and treatment of diabetes. A facile and green strategy to achieve spherical-shaped nickel hexacyanoferrate (NiHCF) nanoparticals supported on electrochemical reduction graphene oxide by using electrochemical cyclic voltammetry is explored. As a sensing substrate, electrochemical reduction graphene oxide deposited on a glassy carbon electrode surface exhibited obvious positive effect on the electrodeposition of NiHCF nanoparticals with spherical structure and thus effectively improved the electrical conductivity and electrochemical sensing of the proposed amperometric sensor. Proof-concept experiments demonstrated that the proposed nanocomposites modified electrode exhibited excellent sensitivity toward glucose oxidation as well as with a satisfying detection limit of 0.11 μM. More importantly, we also explore that as a simple, green and facile method, electrochemical technology can be employed and provide a new strategy for developing GO and metal hexacyanoferrate based amperometric sensing platform toward glucose and other biomolecules.

  19. A green synthetic strategy of nickel hexacyanoferrate nanoparticals supported on the graphene substrate and its non-enzymatic amperometric sensing application

    International Nuclear Information System (INIS)

    Xue, Zhonghua; He, Nan; Rao, Honghong; Hu, Chenxian; Wang, Xiaofen; Wang, Hui; Liu, Xiuhui; Lu, Xiaoquan

    2017-01-01

    Highlights: • A sensitive non-enzymatic glucose sensor was explored by using a facile and green strategy. • Well dispersed and uniform NiHCF nanoparticles can be effectively produced by the introduction of electrochemical reduction graphene oxide films. • Metal hexacyanoferrate as a potential electron mediator was proposed and applied into non-enzymatic sensing. - Abstract: Rapid glucose detection is a key requirement for both diagnosis and treatment of diabetes. A facile and green strategy to achieve spherical-shaped nickel hexacyanoferrate (NiHCF) nanoparticals supported on electrochemical reduction graphene oxide by using electrochemical cyclic voltammetry is explored. As a sensing substrate, electrochemical reduction graphene oxide deposited on a glassy carbon electrode surface exhibited obvious positive effect on the electrodeposition of NiHCF nanoparticals with spherical structure and thus effectively improved the electrical conductivity and electrochemical sensing of the proposed amperometric sensor. Proof-concept experiments demonstrated that the proposed nanocomposites modified electrode exhibited excellent sensitivity toward glucose oxidation as well as with a satisfying detection limit of 0.11 μM. More importantly, we also explore that as a simple, green and facile method, electrochemical technology can be employed and provide a new strategy for developing GO and metal hexacyanoferrate based amperometric sensing platform toward glucose and other biomolecules.

  20. Modelling of Amperometric Biosensor Used for Synergistic Substrates Determination

    Directory of Open Access Journals (Sweden)

    Dainius Simelevicius

    2012-04-01

    Full Text Available In this paper the operation of an amperometric biosensor producing a chemically amplified signal is modelled numerically. The chemical amplification is achieved by using synergistic substrates. The model is based on non-stationary reaction-diffusion equations. The model involves three layers (compartments: a layer of enzyme solution entrapped on the electrode surface, a dialysis membrane covering the enzyme layer and an outer diffusion layer which is modelled by the Nernst approach. The equation system is solved numerically by using the finite difference technique. The biosensor response and sensitivity are investigated by altering the model parameters influencing the enzyme kinetics as well as the mass transport by diffusion. The biosensor action was analyzed with a special emphasis to the effect of the chemical amplification. The simulation results qualitatively explain and confirm the experimentally observed effect of the synergistic substrates conversion on the biosensor response.

  1. Amperometric and impedance monitoring systems for biomedical applications

    CERN Document Server

    Punter-Villagrasa, Jaime; del Campo, Francisco J; Miribel, Pere

    2017-01-01

    The book presents the conception and realization of a pervasive electronic architecture for electrochemical applications, focusing on electronic instrumentation design and device development, particularly in electrochemical Point-of-Care and Lab-on-a-Chip devices, covering examples based on amperometric (DC) and impedance detection (AC) techniques. The presented electronics combine tailored front-end instrumentation and back-end data post-processing, enabling applications in different areas, and across a variety of techniques, analytes, transducers and environments. It addresses how the electronics are designed and implemented with special interest in the flow process: starting from electronic circuits and electrochemical biosensor design to a final validation and implementation for specific applications. Similarly, other important aspects are discussed throughout the book, such as electrochemical techniques, different analytes, targets, electronics reliability and robustness. The book also describes the use ...

  2. Photonic Sensor for Nondestructive Testing of Composite Overwrapped Pressure Vessels, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Los Gatos Research proposes to develop a photonic sensor instrumentation, capable of monitoring distributed load and acoustic emission (AE) for rapid inspection of...

  3. Wide-Bandwidth, Ultra-Accurate, Composite Inertial Reference Sensor, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Applied Technology Associates (ATA) proposes to develop a new inertial sensor by combining two sensing phenomena in a single device. ATA has patented an advanced...

  4. Development of a bifunctional sensor using haptenized acetylcholinesterase and application for the detection of cocaine and organophosphates

    NARCIS (Netherlands)

    Teller, Carsten; Halamek, J.; Žeravík, Jiri; Stöcklein, Walter F.M.; Scheller, Frieder W.

    2008-01-01

    We developed a dual piezoelectric/amperometric sensor for the detection of two unrelated analytes in one experiment that uses propidium to anchor acetylcholinesterases (AChE) at the surface. This mass-sensitive sensor does not only allow the examination of the interaction between AChE and the

  5. A new amperometric glucose biosensor based on screen printed carbon electrodes with rhenium(IV - oxide as a mediator

    Directory of Open Access Journals (Sweden)

    ALBANA VESELI

    2012-11-01

    Full Text Available Rhenium(IV-oxide, ReO2, was used as a mediator for carbon paste (CPE and screen printed carbon (SPCE electrodes for the catalytic amperometric determination of hydro-gen peroxide, whose overpotential for the reduction could be lowered to -0.1 V vs. Ag/AgCl in flow injection analysis (FIA using phosphate buffer (0.1 M, pH=7.5 as a carrier. For hydrogen peroxide a detection limit (3σ of 0.8 mg L-1 could be obtained.ReO2-modified SPCEs were used to design biosensors with a template enzyme, i.e. glucose oxidase, entrapped in a Nafion membrane. The resulting glucose sensor showed a linear dynamic range up to 200 mg L-1 glucose with a detection limit (3σ of 0.6 mg L-1. The repeatability was 2.1 % RSD (n = 5 measurements, the reproducibility 5.4 % (n = 5 sensors. The sensor could be applied for the determination of glucose in blood serum in good agreement with a reference method.

  6. Determination of plutonium and neptunium in various materials by coulometric titration with amperometric indicating

    International Nuclear Information System (INIS)

    Moiseev, I.V.; Kuperman, A.Ya.; Borodina, N.N.; Galkina, V.N.; Nikitskaya, V.N.

    1976-01-01

    Coulometric methods of determining Pu and Np in the products of complex composition containing, in addition to Pu and Np, Cr and Nn have been developed. The methods are based on titration of Pusup((6)) and Npsup((6)) to tetravalent state in H 2 SO 4 -H 3 PO 4 with iron (2) ions generated continuously. A new variant of amperometric method has been proposed for determining end-point of titration. The methods of preparing Pusup((6)) and Npsup((6)) solutions have been developed. It has been shown that, upon dissolution of PuO 2 and NpO 2 by boiling with a mixture of nitric and perchloric acids Pusup((4)) and Npsup((4)) are oxidized quantitatively to Pusup((6)) and Npsup((6)) while Cl 2 , Crsup((6)) and Mnsup((7,4,3)) in the solution obtained are selectively reduced by CHOOH and CH 2 (COOH) 2 . In 6-8 M in terms of H 2 SO 4 solution, ammonium bichromate oxidizes Npsup((4)) to Npsup((6)), Pusup((3)) to Pusup((4)), and Mnsup((2)) to Mnsup((3)). Oxidized Mn and excess of Crsup((6)) are selectively reduced by CHOOH and H 2 C 2 O 4 in 4M in terms of H 2 SO 4 solution

  7. Using a magnetite/thermoplastic composite in 3D printing of direct replacements for commercially available flow sensors

    International Nuclear Information System (INIS)

    Leigh, S J; Purssell, C P; Billson, D R; Hutchins, D A

    2014-01-01

    Flow sensing is an essential technique required for a wide range of application environments ranging from liquid dispensing to utility monitoring. A number of different methodologies and deployment strategies have been devised to cover the diverse range of potential application areas. The ability to easily create new bespoke sensors for new applications is therefore of natural interest. Fused deposition modelling is a 3D printing technology based upon the fabrication of 3D structures in a layer-by-layer fashion using extruded strands of molten thermoplastic. The technology was developed in the late 1980s but has only recently come to more wide-scale attention outside of specialist applications and rapid prototyping due to the advent of low-cost 3D printing platforms such as the RepRap. Due to the relatively low-cost of the printers and feedstock materials, these printers are ideal candidates for wide-scale installation as localized manufacturing platforms to quickly produce replacement parts when components fail. One of the current limitations with the technology is the availability of functional printing materials to facilitate production of complex functional 3D objects and devices beyond mere concept prototypes. This paper presents the formulation of a simple magnetite nanoparticle-loaded thermoplastic composite and its incorporation into a 3D printed flow-sensor in order to mimic the function of a commercially available flow-sensing device. Using the multi-material printing capability of the 3D printer allows a much smaller amount of functional material to be used in comparison to the commercial flow sensor by only placing the material where it is specifically required. Analysis of the printed sensor also revealed a much more linear response to increasing flow rate of water showing that 3D printed devices have the potential to at least perform as well as a conventionally produced sensor. (paper)

  8. A glassy carbon electrode modified with a polyaniline doped with silicotungstic acid and carbon nanotubes for the sensitive amperometric determination of ascorbic acid

    International Nuclear Information System (INIS)

    Zhang, X.; Lai, G.; Zhang, H.; Yu, A.

    2013-01-01

    We report on an electrochemical sensor for the sensitive amperometric determination of ascorbic acid (AA). Aniline containing suspended silicotungstic acid and carbon nanotubes was electropolymerized on the surface of a glassy carbon electrode in a single step which provides a simple and controllable method and greatly improves the electrocatalytic oxidation of AA. The effects of scan rate, solution pH and working potential were studied. A linear relationship exists between the current measured and the concentration of AA in the range from 1 μM to 10 μM and 0.01 mM to 9 mM, with a limit of detection as low as 0.51 μM (S/N = 3). The sensor is selective, stable and satisfyingly reliable in real sample experiments. In our eyes, it has a large potential for practical applications. (author)

  9. Cytosine-assisted synthesis of gold nanochains and gold nanoflowers for the construction of a microperoxidase-11 based amperometric biosensor for hydrogen peroxide

    International Nuclear Information System (INIS)

    Zhang, Qian-Li; Zhou, Dan-Ling; Wang, Ai-Jun; Qin, Su-Fang; Feng, Jiu-Ju; Li, Yong-Fang

    2014-01-01

    A simple method was developed for synthesis of network-like gold nanochains and gold nanoflowers in the presence of cytosine by reduction of tetrachloroauric acid with sodium borohydride and ascorbic acid, respectively. The resulting gold nanocrystals were coated with microperoxidase-11 via electrostatic interactions. Electrodes modified with protein-coated gold nanochains or nanoflowers display well-defined and quasi reversible redox peaks and enhanced high electrocatalytic activity toward the reduction of H 2 O 2 that is due to direct electron transfer to the protein. The effects were exploited for the amperometric detection of H 2 O 2 with a linear response from 0.5 μM to 0.13 mM (for the gold nanochains) and from 1.0 μM to 0.11 mM (for the gold nanoflowers), respectively. The sensor shows lower detection limit and faster response time than sensors based on the use of spherical gold nanoparticles. (author)

  10. Composite Cure Process Modeling and Simulations using COMPRO(Registered Trademark) and Validation of Residual Strains using Fiber Optics Sensors

    Science.gov (United States)

    Sreekantamurthy, Thammaiah; Hudson, Tyler B.; Hou, Tan-Hung; Grimsley, Brian W.

    2016-01-01

    Composite cure process induced residual strains and warping deformations in composite components present significant challenges in the manufacturing of advanced composite structure. As a part of the Manufacturing Process and Simulation initiative of the NASA Advanced Composite Project (ACP), research is being conducted on the composite cure process by developing an understanding of the fundamental mechanisms by which the process induced factors influence the residual responses. In this regard, analytical studies have been conducted on the cure process modeling of composite structural parts with varied physical, thermal, and resin flow process characteristics. The cure process simulation results were analyzed to interpret the cure response predictions based on the underlying physics incorporated into the modeling tool. In the cure-kinetic analysis, the model predictions on the degree of cure, resin viscosity and modulus were interpreted with reference to the temperature distribution in the composite panel part and tool setup during autoclave or hot-press curing cycles. In the fiber-bed compaction simulation, the pore pressure and resin flow velocity in the porous media models, and the compaction strain responses under applied pressure were studied to interpret the fiber volume fraction distribution predictions. In the structural simulation, the effect of temperature on the resin and ply modulus, and thermal coefficient changes during curing on predicted mechanical strains and chemical cure shrinkage strains were studied to understand the residual strains and stress response predictions. In addition to computational analysis, experimental studies were conducted to measure strains during the curing of laminated panels by means of optical fiber Bragg grating sensors (FBGs) embedded in the resin impregnated panels. The residual strain measurements from laboratory tests were then compared with the analytical model predictions. The paper describes the cure process

  11. Buckling control of morphing composite airfoil structure using multi-stable laminate by piezoelectric sensors/actuators

    Science.gov (United States)

    Zareie, Shahin; Zabihollah, Abolghassem; Azizi, Aydin

    2011-04-01

    In the present work, an unsymmetric laminated plate with surface bonded piezoelectric sensors, and actuators has been considered. Piezoelectric sensor were used to monitor the load and deformation bifurcation occurs. Monitoring the shape and load of a morphing structure is essential to ascertain that the structure is properly deployed and it is not loaded excessively ,thus, preventing structural to failure. A piezoceramic actuator is used to provide activation load and to force the structure to change its stability state from one to another. A non-linear finite element model based on the layerwise displacement theory considering the electro-mechanical coupling effects of piezoelectric elements has been developed for simulation purposes. A control mechanism is also employed to actively control the shape of the structure. It is observed that, utilizing multistable composite to design a morphing structure may significantly reduce the energy required for changing the shape. Further controlling the buckling phenomena using piezoelectric sensor and actuator along with an ON/OFF controller can effectively and efficiency enhance the performance of the morphing structure during manoeuver.

  12. Development of Meandering Winding Magnetometer (MWM (Register Trademark)) Eddy Current Sensors for the Health Monitoring, Modeling and Damage Detection of High Temperature Composite Materials

    Science.gov (United States)

    Russell, Richard; Washabaugh, Andy; Sheiretov, Yanko; Martin, Christopher; Goldfine, Neil

    2011-01-01

    The increased use of high-temperature composite materials in modern and next generation aircraft and spacecraft have led to the need for improved nondestructive evaluation and health monitoring techniques. Such technologies are desirable to improve quality control, damage detection, stress evaluation and temperature measurement capabilities. Novel eddy current sensors and sensor arrays, such as Meandering Winding Magnetometers (MWMs) have provided alternate or complimentary techniques to ultrasound and thermography for both nondestructive evaluation (NDE) and structural health monitoring (SHM). This includes imaging of composite material quality, damage detection and .the monitoring of fiber temperatures and multidirectional stresses. Historically, implementation of MWM technology for the inspection of the Space Shuttle Orbiter Reinforced Carbon-Carbon Composite (RCC) leading edge panels was developed by JENTEK Sensors and was subsequently transitioned by NASA as an operational pre and post flight in-situ inspection at the Kennedy Space Center. A manual scanner, which conformed'automatically to the curvature of the RCC panels was developed and used as a secondary technique if a defect was found during an infrared thermography screening, During a recent proof of concept study on composite overwrapped pressure vessels (COPV's), three different MWM sensors were tested at three orientations to demonstrate the ability of the technology to measure stresses at various fiber orientations and depths. These results showed excellent correlation with actual surface strain gage measurements. Recent advancements of this technology have been made applying MWM sensor technology for scanning COPVs for mechanical damage. This presentation will outline the recent advance in the MWM.technology and the development of MWM techniques for NDE and SHM of carbon wraped composite overwrapped pressure vessels (COPVs) including the measurement of internal stresses via a surface mounted sensor

  13. Effect of degree of crosslinking and polymerization of 3D printable polymer/ionic liquid composites on performance of stretchable piezoresistive sensors

    Science.gov (United States)

    Lee, Jeongwoo; Faruk Emon, Md Omar; Vatani, Morteza; Choi, Jae-Won

    2017-03-01

    Ionic liquid (IL)/polymer composites (1-ethyl-3-methyl-imidazolium tetrafluoroborate (EMIMBF4)/2-[[(butylamino)carbonyl]oxy]ethyl acrylate (BACOEA)) were fabricated to use as sensing materials for stretchable piezoresistive tactile sensors. The detectability of the IL/polymer composites was enhanced because the ionic transport properties of EMIMBF4 in the composites were improved by the synergic actions between the coordinate sites generated by the local motion of BACOEA chain segments under enough activation energy. The performance of the piezoresistive sensors was investigated with the degree of crosslinking and polymerization of the IL/polymer composites. As the compressive strain was increased, the distance between two electrodes decreased, and the motion of polymer chains and IL occurred, resulting in a decrease in the electrical resistance of the sensors. We have confirmed that the sensitivity of the sensors are affected by the degree of crosslink and polymerization of the IL/polymer composites. In addition, all of the materials (skins, sensing material, and electrode) used in this study are photo-curable, and thus the stretchable piezoresistive tactile sensors can be successfully fabricated by 3D printing.

  14. Crack growth monitoring in composite materials using embedded optical Fiber Bragg Grating sensor

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira; Mikkelsen, Lars Pilgaard; McGugan, Malcolm

    2015-01-01

    In this paper a novel method to assess a crack growing/damage event in fiber reinforced plastic, or adhesive using Fiber Bragg Grating (FBG) sensors embedded in a host material is shown. Different features of the crack mechanism that induce a change in the FBG response were identified. Double...

  15. New Textile Sensors for In Situ Structural Health Monitoring of Textile Reinforced Thermoplastic Composites Based on the Conductive Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) Polymer Complex.

    Science.gov (United States)

    Jerkovic, Ivona; Koncar, Vladan; Grancaric, Ana Marija

    2017-10-10

    Many metallic structural and non-structural parts used in the transportation industry can be replaced by textile-reinforced composites. Composites made from a polymeric matrix and fibrous reinforcement have been increasingly studied during the last decade. On the other hand, the fast development of smart textile structures seems to be a very promising solution for in situ structural health monitoring of composite parts. In order to optimize composites' quality and their lifetime all the production steps have to be monitored in real time. Textile sensors embedded in the composite reinforcement and having the same mechanical properties as the yarns used to make the reinforcement exhibit actuating and sensing capabilities. This paper presents a new generation of textile fibrous sensors based on the conductive polymer complex poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) developed by an original roll to roll coating method. Conductive coating for yarn treatment was defined according to the preliminary study of percolation threshold of this polymer complex. The percolation threshold determination was based on conductive dry films' electrical properties analysis, in order to develop highly sensitive sensors. A novel laboratory equipment was designed and produced for yarn coating to ensure effective and equally distributed coating of electroconductive polymer without distortion of textile properties. The electromechanical properties of the textile fibrous sensors confirmed their suitability for in situ structural damages detection of textile reinforced thermoplastic composites in real time.

  16. Primary response of high-aspect-ratio thermoresistive sensors

    Science.gov (United States)

    Majlesein, H. R.; Mitchell, D. L.; Bhattacharya, Pradeep K.; Singh, A.; Anderson, James A.

    1997-07-01

    There is a growing need for sensors in monitoring performance in modern quality products such as in electronics to monitor heat build up, substrate delaminations, and thermal runaway. In processing instruments, intelligent sensors are needed to measure deposited layer thickness and resistivities for process control, and in environmental electrical enclosures, they are used for climate monitoring and control. A yaw sensor for skid prevention utilizes very fine moveable components, and an automobile engine controller blends a microprocessor and sensor on the same chip. An Active-Pixel Image Sensor is integrated with a digital readout circuit to perform most of the functions in a video camera. Magnetostrictive transducers sense and damp vibrations. Improved acoustic sensors will be used in flow detection of air and other fluids, even at subsonic speeds. Optoelectronic sensor systems are being developed for installation on rocket engines to monitor exhaust gases for signs of wear in the engines. With new freon-free coolants being available the problems of A/C system corrosion have gone up in automobiles and need to be monitored more frequently. Defense cutbacks compel the storage of hardware in safe-custody for an indeterminate period of time, and this makes monitoring more essential. Just-in-time customized manufacturing in modern industries also needs dramatic adjustment in productivity of various selected items, leaving some manufacturing equipment idle for a long time, and therefore, it will be prone to more corrosion, and corrosion sensors are needed. In the medical device industry, development of implantable medical devices using both potentiometric and amperometric determination of parameters has, until now, been used with insufficient micro miniaturization, and thus, requires surgical implantation. In many applications, high-aspect- ratio devices, made possible by the use of synchrotron radiation lithography, allow more useful devices to be produced. High

  17. Development and implementation of an automatic integration system for fibre optic sensors in the braiding process with the objective of online-monitoring of composite structures

    Science.gov (United States)

    Hufenbach, W.; Gude, M.; Czulak, A.; Kretschmann, Martin

    2014-04-01

    Increasing economic, political and ecological pressure leads to steadily rising percentage of modern processing and manufacturing processes for fibre reinforced polymers in industrial batch production. Component weights beneath a level achievable by classic construction materials, which lead to a reduced energy and cost balance during product lifetime, justify the higher fabrication costs. However, complex quality control and failure prediction slow down the substitution by composite materials. High-resolution fibre-optic sensors (FOS), due their low diameter, high measuring point density and simple handling, show a high applicability potential for an automated sensor-integration in manufacturing processes, and therefore the online monitoring of composite products manufactured in industrial scale. Integrated sensors can be used to monitor manufacturing processes, part tests as well as the component structure during product life cycle, which simplifies allows quality control during production and the optimization of single manufacturing processes.[1;2] Furthermore, detailed failure analyses lead to a enhanced understanding of failure processes appearing in composite materials. This leads to a lower wastrel number and products of a higher value and longer product life cycle, whereby costs, material and energy are saved. This work shows an automation approach for FOS-integration in the braiding process. For that purpose a braiding wheel has been supplemented with an appliance for automatic sensor application, which has been used to manufacture preforms of high-pressure composite vessels with FOS-networks integrated between the fibre layers. All following manufacturing processes (vacuum infiltration, curing) and component tests (quasi-static pressure test, programmed delamination) were monitored with the help of the integrated sensor networks. Keywords: SHM, high-pressure composite vessel, braiding, automated sensor integration, pressure test, quality control, optic

  18. On the Electrooxidation and Amperometric Detection of NO Gas at the Pt/Nafion® Electrode

    Directory of Open Access Journals (Sweden)

    Jin-Cherng Yang

    2003-08-01

    Full Text Available The electrochemical oxidation of nitric oxide (NO gas at the Pt/Nafion® electrode has been studied at a concentration of 500 ppm. The electrooxidation of NO taking place over a wide potential range can be described by a transcendental equation, from which the half-wave potential of the reaction can be determined. For NO oxidation with appreciable overpotentials but negligible mass-transfer effects, the Tafel kinetics applies. The obtained charge transfer coefficient (a and the exchange current density (io are 0.77 and 14 mA/cm2, respectively. An amperometric NO gas sensor based on the Pt/Nafion® electrode has been fabricated and tested over the NO concentration range from 0 to 500 ppm. The Pt/Nafion® electrode was used as an anode at a fixed potential, preferably 1.15 V (vs. Ag/AgCl/sat. KCl, which assures current limitation by diffusion only. The sensitivity of the electrochemical sensor was found to be 1.86 mA/ppm/cm2. The potential interference by other gases, such as nitrogen dioxide (NO2 and carbon monoxide (CO, was also studied in the range 0-500 ppm. Both sensitivity for NO and selectivity of NO over NO2/CO show significant enhancement upon using a cyclic voltammetric (CV activation, or cleaning procedure.

  19. Mediatorless amperometric bienzyme glucose biosensor based on horseradish peroxidase and glucose oxidase cross-linked to multiwall carbon nanotubes

    International Nuclear Information System (INIS)

    Xu, Shuxia; Zhou, Shiyi; Zhang, Xinfeng; Qi, Honglan; Zhang, Chengxiao

    2014-01-01

    We report on a bienzyme-channeling sensor for sensing glucose without the aid of mediator. It was fabricated by cross-linking horseradish peroxidase (HRP) and glucose oxidase (GOx) on a glassy carbon electrode modified with multiwalled carbon nanotubes (MWNTs). The bienzyme was cross-linked with the MWNTs by glutaraldehyde and bovine serum albumin. The MWNTs were employed to accelerate the electron transfer between immobilized HRP and electrode. Glucose was sensed by amperometric reduction of enzymatically generated H 2 O 2 at an applied voltage of −50 mV (vs. Ag/AgCl). Factors influencing the preparation and performance of the bienzyme electrode were investigated in detail. The biosensor exhibited a fast and linear response to glucose in the concentration range from 0.4 to 15 mM, with a detection limit of 0.4 mM. The sensor exhibited good selectivity and durability, with a long-term relative standard deviation of <5 %. Analysis of glucose-spiked human serum samples yielded recoveries between 96 and 101 %. (author)

  20. Amperometric Microsensors Monitoring Glutamate-Evoked In Situ Responses of Nitric Oxide and Carbon Monoxide from Live Human Neuroblastoma Cells

    Directory of Open Access Journals (Sweden)

    Yejin Ha

    2017-07-01

    Full Text Available In the brain, nitric oxide (NO and carbon monoxide (CO are important signaling gases which have multifaceted roles, such as neurotransmitters, neuromodulators, and vasodilators. Even though it is difficult to measure NO and CO in a living system due to their high diffusibility and extremely low release levels, electrochemical sensors are promising tools to measure in vivo and in vitro NO and CO gases. In this paper, using amperometric dual and septuple NO/CO microsensors, real-time NO and CO changes evoked by glutamate were monitored simultaneously for human neuroblastoma (SH-SY5Y cells. In cultures, the cells were differentiated and matured into functional neurons by retinoic acid and brain-derived neurotrophic factor. When glutamate was administrated to the cells, both NO and CO increases and subsequent decreases returning to the basal levels were observed with a dual NO/CO microsensor. In order to facilitate sensor’s measurement, a flower-type septuple NO/CO microsensor was newly developed and confirmed in terms of the sensitivity and selectivity. The septuple microsensor was employed for the measurements of NO and CO changes as a function of distances from the position of glutamate injection. Our sensor measurements revealed that only functionally differentiated cells responded to glutamate and released NO and CO.

  1. Detection and quantification of new psychoactive substances (NPSs) within the evolved "legal high" product, NRG-2, using high performance liquid chromatography-amperometric detection (HPLC-AD).

    Science.gov (United States)

    Zuway, Khaled Y; Smith, Jamie P; Foster, Christopher W; Kapur, Nikil; Banks, Craig E; Sutcliffe, Oliver B

    2015-09-21

    The global increase in the production and abuse of cathinone-derived New Psychoactive Substances (NPSs) has developed the requirement for rapid, selective and sensitive protocols for their separation and detection. Electrochemical sensing of these compounds has been demonstrated to be an effective method for the in-field detection of these substances, either in their pure form or in the presence of common adulterants, however, the technique is limited in its ability to discriminate between structurally related cathinone-derivatives (for example: (±)-4′-methylmethcathinone (4-MMC, 2a) and (±)-4′-methyl-N-ethylmethcathinone (4-MEC, 2b) when they are both present in a mixture. In this paper we demonstrate, for the first time, the combination of HPLC-UV with amperometric detection (HPLC-AD) for the qualitative and quantitative analysis of 4-MMC and 4-MEC using either a commercially available impinging jet (LC-FC-A) or custom-made iCell channel (LC-FC-B) flow-cell system incorporating embedded graphite screen-printed macroelectrodes. The protocol offers a cost-effective, reproducible and reliable sensor platform for the simultaneous HPLC-UV and amperometric detection of the target analytes. The two systems have similar limits of detection, in terms of amperometric detection [LC-FC-A: 14.66 μg mL(-1) (2a) and 9.35 μg mL(-1) (2b); LC-FC-B: 57.92 μg mL(-1) (2a) and 26.91 μg mL(-1) (2b)], to the previously reported oxidative electrochemical protocol [39.8 μg mL(-1) (2a) and 84.2 μg mL(-1) (2b)], for two synthetic cathinones, prevalent on the recreational drugs market. Though not as sensitive as standard HPLC-UV detection, both flow cells show a good agreement, between the quantitative electroanalytical data, thereby making them suitable for the detection and quantification of 4-MMC and 4-MEC, either in their pure form or within complex mixtures. Additionally, the simultaneous HPLC-UV and amperometric detection protocol detailed herein shows a marked improvement

  2. Composite cavity based fiber optic Fabry–Perot strain sensors demodulated by an unbalanced fiber optic Michelson interferometer with an electrical scanning mirror

    International Nuclear Information System (INIS)

    Zhang, Jianzhong; Yang, Jun; Sun, Weimin; Yuan, Libo; Jin, Wencai; Peng, G D

    2008-01-01

    A composite cavity based fiber optic Fabry–Perot strain sensor system, interrogated by a white light source and demodulated by an unbalanced fiber optic Michelson interferometer with an electrical scanning mirror, is proposed and demonstrated. Comparing with the traditional extrinsic fiber optic Fabry–Perot strain sensor, the potential multiplexing capability and the dynamic measurement range are improved simultaneously. At the same time, the measurement stability of the electrical scanning mirror system is improved by the self-referenced signal of the sensor structure

  3. Construction of a non-enzymatic sensor based on the poly(o-phenylenediamine)/Ag-NPs composites for detecting glucose in blood

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jinxiang; Wang, Meirong [College of Chemistry and Chemical Engineering, Jiangsu Key Laboratory of Environmental Engineering and Monitoring, Yangzhou University, 180 Si–Wang–Ting Road, Yangzhou 225002 (China); Guan, Jun [Clinical Medical College of Yangzhou University, Subei People' s Hospital of Jiangsu Province, Yangzhou 225002 (China); Wang, Chengyin, E-mail: wangcy@yzu.edu.cn [College of Chemistry and Chemical Engineering, Jiangsu Key Laboratory of Environmental Engineering and Monitoring, Yangzhou University, 180 Si–Wang–Ting Road, Yangzhou 225002 (China); Wang, Guoxiu [School of Mathematical and Physical Sciences, University of Technology Sydney, City Campus, Broadway, Sydney, NSW 2007 (Australia)

    2017-02-01

    A non-enzymatic glucose sensor, based on the silver nanoparticles (Ag-NPs)/poly (o-phenylenediamine) (PoPD) composites, is developed by the electrochemical polymerization of o-phenylenediamine and electrodeposition of silver nanoparticles on an indium tin oxide electrode. The Ag-NPs/PoPD composites are characterized by atomic force microscopy, scanning electronic microscopy and energy dispersive spectrometer. Under the optimized experimental conditions, the proposed glucose sensor demonstrates a wide linear range from 0.15 to 13 mmol L{sup −1} with a correlation coefficient of 0.998. The proposed glucose sensor can be used to detect glucose in blood sample with a satisfactory result. In addition, the proposed sensor presents the advantages, such as facile preparation, low cost, high sensitivity and fast response time. It also exhibits good anti-interference performance and stability. - Highlights: • A facile AgNPs/PoPD/ITO modified sensor was developed for the first time. • The non-enzymatic sensor can detect glucose in human blood directly with a wide detection range. • This sensor is of rapid response, low cost, high sensitivity, and long-time stability.

  4. Atrazine analysis using an amperometric immunosensor based on single-chain antibody fragments and regeneration-free multi-calibrant measurement

    International Nuclear Information System (INIS)

    Grennan, Kathleen; Strachan, Gillian; Porter, Andrew J.; Killard, Anthony J.; Smyth, Malcolm R.

    2003-01-01

    This work describes the development of an electrochemical immunosensor for the analysis of atrazine using recombinant single-chain antibody (scAb) fragments. The sensors are based on carbon paste screen-printed electrodes incorporating the conducting polymer polyaniline (PANI)/poly(vinylsulphonic acid) (PVSA), which enables direct mediatorless coupling to take place between the redox centres of antigen-labelled horseradish peroxidase (HRP) and the electrode surface. Competitive immunoassays can be performed in real-time using this separation-free system. Analytical measurements based on the pseudo-linear relationship between the slope of a real-time amperometric signal and the concentration of analyte, yield a novel immunosensor set-up capable of regenerationless amperometric analysis. Multiple, sequential measurements of standards and samples can be performed on a single scAb-modified surface in a matter of minutes. No separation of bound and unbound species was necessary prior to detection. The system is capable of measuring atrazine to a detection limit of 0.1 ppb (0.1 μg l -1 ). This system offers the potential for rapid, cost-effective immunosensing for the analysis of samples of environmental, medical and pharmaceutical significance

  5. Polypyrrole Composite Film for Highly Sensitive and Selective Electrochemical Determination Sensors

    International Nuclear Information System (INIS)

    Zheng, Xiangli; Tian, Dong; Duan, Shuo; Wei, Maochao; Liu, Shan; Zhou, Changli; Li, Qing; Wu, Gang

    2014-01-01

    In this paper, polypyrrole (PPy) and benz[a]anthracene-7,12-dione (BaD) were electro-polymerized onto a pyrolytic graphite electrode (PGE), constructing a novel BaD/PPy/PGE platform for electrochemical sensoring. The morphology and electrochemical properties of the fabricated BaD/PPy/PGE were characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Furthermore, the electrochemical behavior of benzo[k]fluoranthene (BkF) at the BaD/PPy/PGE was investigated. Due to the specific interactions between BkF and BaD, a wide linear range of BkF detection from 1.0 × 10 −12 to 1.0 × 10 −9 M with good linearity (R 2 = 0.9962) and a low detection limit (1.0 × 10 −13 M, S/N = 3) were demonstrated. Importantly, other similar aromatics which had one ring or more than two rings, such as benzo[a]anthracene, benzo[a]pyrene, pyrene, benzo[ghi]peryle, anthracene, phenanthrene, naphthalene and parachlorophenol, showed insignificant interference on BkF detection. Consequently, this novel BaD/PPy/PGE with excellent stability and selectivity holds promise as an effective BkF electrochemical sensor in aqueous solution. As an example for its practical application, the newly developed sensor was applied to quantitative determination of BkF in waste water samples obtained from a coking plant with satisfactory sensitivity, selectivity, and reversibility

  6. Cyclic voltammetry deposition of copper nanostructure on MWCNTs modified pencil graphite electrode: An ultra-sensitive hydrazine sensor

    Energy Technology Data Exchange (ETDEWEB)

    Heydari, Hamid [Faculty of Sciences, Razi University, Kermanshah (Iran, Islamic Republic of); Gholivand, Mohammad B., E-mail: mbgholivand@razi.ac.ir [Faculty of Sciences, Razi University, Kermanshah (Iran, Islamic Republic of); Abdolmaleki, Abbas [Department of Chemistry, Malek Ashtar University of Technology, Tehran (Iran, Islamic Republic of)

    2016-09-01

    In this study, Copper (Cu) nanostructures (CuNS) were electrochemically deposited on a film of multiwall carbon nanotubes (MWCNTs) modified pencil graphite electrode (MWCNTs/PGE) by cyclic voltammetry method to fabricate a CuNS–MWCNTs composite sensor (CuNS–MWCNT/PGE) for hydrazine detection. Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX) were used for the characterization of CuNS on the MWCNTs matrix. The composite of CuNS-MWCNTs was characterized with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The preliminary studies showed that the proposed sensor have a synergistic electrocatalytic activity for the oxidation of hydrazine in phosphate buffer. The catalytic currents of square wave voltammetry had a linear correlation with the hydrazine concentration in the range of 0.1 to 800 μM with a low detection limit of 70 nM. Moreover, the amperometric oxidation current exhibited a linear correlation with hydrazine concentration in the concentration range of 50–800 μM with the detection limit of 4.3 μM. The proposed electrode was used for the determination of hydrazine in real samples and the results were promising. Empirical results also indicated that the sensor had good reproducibility, long-term stability, and the response of the sensor to hydrazine was free from interferences. Moreover, the proposed sensor benefits from simple preparation, low cost, outstanding sensitivity, selectivity, and reproducibility for hydrazine determination. - Highlights: • The Copper nanostructures (CuNS) were prepared by cyclic voltammetry deposition. • The CuNS-MWCNT/PGE sensor shows high activity toward hydrazine (N{sub 2}H{sub 4}). • The proposed sensor exhibits a wide linear range (0.1 to 800 μM), low detection limit (70 nM), high sensitivity and stability for hydrazine.

  7. Construction of ferrocene modified conducting polymer based amperometric urea biosensor.

    Science.gov (United States)

    Dervisevic, Muamer; Dervisevic, Esma; Senel, Mehmet; Cevik, Emre; Yildiz, Huseyin Bekir; Camurlu, Pınar

    2017-07-01

    Herein, an electrochemical urea sensing bio-electrode is reported that has been constructed by firstly electropolymerizing 4-(2,5-Di(thiophen-2-yl)-1H-pyrrol-1-yl)aniline monomer (SNS-Aniline) on Pencil Graphite Electrode (PGE), then modifying the polymer coated electrode surface with di-amino-Ferrocene (DAFc) as the mediator, and lastly Urease enzyme through glutaraldehyde crosslinking. The effect of pH, temperature, polymer thickness, and applied potential on the electrode current response was investigated besides performing storage and operational stability experiments with the interference studies. The resulting urea biosensor's amperometric response was linear in the range of 0.1-8.5mM with the sensitivity of 0.54μA/mM, detection limit of 12μM, and short response time of 2s. The designed bio-electrode was tested with real human blood and urine samples where it showed excellent analytical performance with insignificant interference. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Wireless Amperometric Neurochemical Monitoring Using an Integrated Telemetry Circuit

    Science.gov (United States)

    Roham, Masoud; Halpern, Jeffrey M.; Martin, Heidi B.; Chiel, Hillel J.

    2015-01-01

    An integrated circuit for wireless real-time monitoring of neurochemical activity in the nervous system is described. The chip is capable of conducting high-resolution amperometric measurements in four settings of the input current. The chip architecture includes a first-order ΔΣ modulator (ΔΣM) and a frequency-shift-keyed (FSK) voltage-controlled oscillator (VCO) operating near 433 MHz. It is fabricated using the AMI 0.5 μm double-poly triple-metal n-well CMOS process, and requires only one off-chip component for operation. Measured dc current resolutions of ~250 fA, ~1.5 pA, ~4.5 pA, and ~17 pA were achieved for input currents in the range of ±5, ±37, ±150, and ±600 nA, respectively. The chip has been interfaced with a diamond-coated, quartz-insulated, microneedle, tungsten electrode, and successfully recorded dopamine concentration levels as low as 0.5 μM wirelessly over a transmission distance of ~0.5 m in flow injection analysis experiments. PMID:18990633

  9. A new amperometric enzyme electrode for alcohol determination.

    Science.gov (United States)

    Gülce, H; Gülce, A; Kavanoz, M; Coşkun, H; Yildiz, A

    2002-06-01

    A new enzyme electrode for the determination of alcohols was developed by immobilizing alcohol oxidase in polvinylferrocenium matrix coated on a Pt electrode surface. The amperometric response due to the electrooxidation of enzymatically generated H(2)O(2) was measured at a constant potential of +0.70 V versus SCE. The effects of substrate, buffer and enzyme concentrations, pH and temperature on the response of the electrode were investigated. The optimum pH was found to be pH 8.0 at 30 degrees C. The steady-state current of this enzyme electrode was reproducible within +/-5.0% of the relative error. The sensitivity of the enzyme electrode decreased in the following order: methanol>ethanol>n-butanol>benzyl alcohol. The linear response was observed up to 3.7 mM for methanol, 3.0 mM for ethanol, 6.2 mM for n-butanol, and 5.2 mM for benzyl alcohol. The apparent Michaelis-Menten constant (K(Mapp)) value and the activation energy, E(a), of this immobilized enzyme system were found to be 5.78 mM and 38.07 kJ/mol for methanol, respectively.

  10. Wireless amperometric neurochemical monitoring using an integrated telemetry circuit.

    Science.gov (United States)

    Roham, Masoud; Halpern, Jeffrey M; Martin, Heidi B; Chiel, Hillel J; Mohseni, Pedram

    2008-11-01

    An integrated circuit for wireless real-time monitoring of neurochemical activity in the nervous system is described. The chip is capable of conducting high-resolution amperometric measurements in four settings of the input current. The chip architecture includes a first-order Delta Sigma modulator (Delta Sigma M) and a frequency-shift-keyed (FSK) voltage-controlled oscillator (VCO) operating near 433 MHz. It is fabricated using the AMI 0.5 microm double-poly triple-metal n-well CMOS process, and requires only one off-chip component for operation. Measured dc current resolutions of approximately 250 fA, approximately 1.5 pA, approximately 4.5 pA, and approximately 17 pA were achieved for input currents in the range of +/-5, +/-37, +/-150, and +/-600 nA, respectively. The chip has been interfaced with a diamond-coated, quartz-insulated, microneedle, tungsten electrode, and successfully recorded dopamine concentration levels as low as 0.5 microM wirelessly over a transmission distance of approximately 0.5 m in flow injection analysis experiments.

  11. Solid Amalgam Composite Electrode as a New Sensor for the Determination of Biologically Active Compounds

    Czech Academy of Sciences Publication Activity Database

    Josypčuk, Bohdan; Navrátil, Tomáš; Lukina, A.; Pecková, K.; Barek, J.

    2007-01-01

    Roč. 52, č. 6 (2007), s. 897-910 ISSN 0009-2223 R&D Projects: GA ČR GA203/07/1195; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z40400503 Keywords : solid composite electrode * solid amalgam electrodes * solid amalgam composite electrode * voltammetry Subject RIV: CG - Electrochemistry Impact factor: 0.529, year: 2007

  12. Development of a novel biosensor based on a polypyrrole-dodecylbenzene sulphonate (PPy-DBS) film for the determination of amperometric cholesterol.

    Science.gov (United States)

    Özer, Bayram Oğuz; Çete, Servet

    2017-06-01

    Herein a novel amperometric biosensor based on a conducting polymer with anionic dopant modified electrode was successfully developed for detection of cholesterol. Polypyrrole is deposited on a platinum surface and the sodium dodecylbenzene sulphonate (DBS) ion-doped polypyrrole film was electrochemically prepared by scanning the electrode potential between -0.8 and +0.8 V at a scan rate of 20 mV/s. The present electrochemical biosensor was optimized in terms of working potential, number of cycles, concentrations of monomer, and anionic dopant. Cholesterol oxidase (ChOx) was physically entrapped in PPy-DBS to construct an amperometric cholesterol biosensor. Amperometric determination is based on the electrochemical detection of H 2 O 2 generated in the enzymatic reaction of cholesterol. Kinetic parameters, operational and storage stabilities, pH, and temperature dependencies were determined. Km and Imax were calculated as 0.11 μM and 0.967 nM/min, respectively. The operational stability results showed that 90.0% of the response current was retained after 30 activity assays. Morphology of electrodes was characterized by SEM and AFM. Additionally, contact angle measurements were made with 1 μL water of polymer film and enzyme electrode. As a result, the cholesterol biosensor suggested in this study is easy to prepare and is highly cost-effective. This composite (PPy-DBS) can supply a biocompatible and electrochemical microenvironment for immobilization of the enzyme, making this material a good candidate for the fabrication of highly sensitive and selective cholesterol biosensors.

  13. New Textile Sensors for In Situ Structural Health Monitoring of Textile Reinforced Thermoplastic Composites Based on the Conductive Poly(3,4-ethylenedioxythiophene-poly(styrenesulfonate Polymer Complex

    Directory of Open Access Journals (Sweden)

    Ivona Jerkovic

    2017-10-01

    Full Text Available Many metallic structural and non-structural parts used in the transportation industry can be replaced by textile-reinforced composites. Composites made from a polymeric matrix and fibrous reinforcement have been increasingly studied during the last decade. On the other hand, the fast development of smart textile structures seems to be a very promising solution for in situ structural health monitoring of composite parts. In order to optimize composites’ quality and their lifetime all the production steps have to be monitored in real time. Textile sensors embedded in the composite reinforcement and having the same mechanical properties as the yarns used to make the reinforcement exhibit actuating and sensing capabilities. This paper presents a new generation of textile fibrous sensors based on the conductive polymer complex poly(3,4-ethylenedioxythiophene-poly(styrenesulfonate developed by an original roll to roll coating method. Conductive coating for yarn treatment was defined according to the preliminary study of percolation threshold of this polymer complex. The percolation threshold determination was based on conductive dry films’ electrical properties analysis, in order to develop highly sensitive sensors. A novel laboratory equipment was designed and produced for yarn coating to ensure effective and equally distributed coating of electroconductive polymer without distortion of textile properties. The electromechanical properties of the textile fibrous sensors confirmed their suitability for in situ structural damages detection of textile reinforced thermoplastic composites in real time.

  14. Amperometric cell for subcutaneous detection of hydrogen sulfide in anesthetized experimental animals

    International Nuclear Information System (INIS)

    Nagy, L; Nagy, G; Filotás, D; Boros, M; Pozsgai, G; Pintér, E

    2014-01-01

    Hydrogen sulfide (H 2 S) is a toxic gas. It has been recognized that H 2 S evolving in biochemical reactions in living organisms has an important role in different physiologic processes. Nowadays, H 2 S is known as an endogenous messenger molecule. Natural sulfurous spring water has been proved beneficial in the therapy of diseases of the skin and other organs (Boros et al 2013). In vivo real-time detection of local H 2 S concentration is an important but challenging task. We developed a two-electrode amperometric cell for selective subcutaneous detection of H 2 S in anesthetized mice. The cell is a small size implantable gas sensor containing a platinum disc anode and a silver cathode. The selectivity is provided by a membrane permeable only by gases. There is a buffered reversible electrochemical mediator solution in an oxidized form inside the cell. As gaseous H 2 S penetrates into the cell the mediator is reduced, and +0.4 V versus the reference is employed on the platinum working electrode. The reduced mediator is oxidized on the anode surface. The current provides an analytical signal representing the concentration of H 2 S. Appropriate shape, size and membrane material were selected, and optimal working parameters—such as mediator concentration, pH and cell voltage—were determined in vitro. The lower limit of detection in the stirred sample solution at pH = 5.5 was as small as 9.4  ×  10 −7  M and a dynamic concentration range of 0–6  ×  10 –4  M could be achieved. The detecting surfaces of the cell were covered with freshly dissected mouse skin to test dermal H 2 S permeability. In other experiments, the cell was implanted subcutaneously in an anesthetized mouse and the animal was submerged in a buffer solution containing different concentrations of H 2 S so that the skin surface over the sensor was covered by the solution. Measurements of subcutaneous H 2 S concentration were taken. The experiments clearly proved that H 2 S

  15. Influence of Methacrylic-Acrylic Copolymer Composition on Plasticiser-free Optode Films for pH Sensors

    Directory of Open Access Journals (Sweden)

    Musa Ahmad

    2003-03-01

    Full Text Available In this work we have examined the use of plasticiser-free polymeric films incorporating a proton selective chromoionophore for optical pH sensor. Four types of methacrylic-acrylic copolymers containing different compositions of n-butyl acrylate (nBA and methyl methacrylate (MMA were synthesised for use as optical sensor films. The copolymers were mixed with appropriate amounts of chromoionophore (ETH5294 and a lipophilic salt before spin coated on glass slides to form films for the evaluation of pH response using spectrophotometry. Co-polymer films with high nBA content gave good response and the response time depended on the film thickness. A preliminary evaluation of the optical films of high nBA content with pHs from 2 - 14 showed distinguishable responses from pH 5 - 9. However, the adhesion of the pH sensitive film was good for copolymers with higher content of MMA but not for films with high nBA.

  16. Operating modes of electrochemical H-concentration probes for tritium sensors

    International Nuclear Information System (INIS)

    Juhera, E.; Colominas, S.; Abellà, J.

    2015-01-01

    Highlights: • Synthesis and chemical characterization of Sr(Ce_0_._9–Zr_0_._1)_0_._9_5Yb_0_._0_5O_3_−_α proton conductor ceramic. • Evaluation of the sensor performance at different hydrogen concentrations. • Two different operating modes of the sensors: amperometric and potentiometric. • In amperometric mode sensor sensitivity can be tuned by changing the applied voltage. - Abstract: Potentiometric hydrogen sensors using different solid-state electrolytes have been designed and tested at the Electrochemical Methods Lab at Institut Quimic de Sarria (IQS). The most promising element (Sr(Ce_0_._9–Zr_0_._1)_0_._9_5Yb_0_._0_5O_3_−_α) has been selected for this work in order to evaluate the sensor performance at different hydrogen concentrations in two different operating modes: amperometric and potentiometric. In addition, the sensor response has been evaluated at different working temperatures (500, 575 and 650 °C). The experiments performed proved that when the sensor was used in a potentiometric mode, there is a threshold hydrogen concentration that the sensor can detect depending on the working conditions; 15 mbar at 575 °C and 10 mbar 650 °C. At 500 °C the minimum working temperature of this ceramic has not been achieved, so large deviations between experimental data and theoretical calculations has been obtained. When the sensor was used in an amperometric mode the obtained currents increased as a function of the applied voltage. At a fixed potential, the higher the temperature the higher the current was. So the sensor sensitivity can be tuned by changing the applied voltage at a fixed temperature and hydrogen concentration.

  17. Femtosecond Laser Ablated FBG with Composite Microstructure for Hydrogen Sensor Application

    Directory of Open Access Journals (Sweden)

    Meng Zou

    2016-12-01

    Full Text Available A composite microstructure in fiber Bragg grating (FBG with film deposition for hydrogen detection is presented. Through ablated to FBG cladding by a femtosecond laser, straight-trenches and spiral micro-pits are formed. A Pd–Ag film is sputtered on the surface of the laser processed FBG single mode fiber, and acts as hydrogen sensing transducer. The demonstrated experimental outcomes show that a composite structure produced the highest sensitivity of 26.3 pm/%H, nearly sevenfold more sensitive compared with original standard FBG. It offers great potential in engineering applications for its good structure stability and sensitivity.

  18. Waste Composite Sensor Designed by Cellulose and Activated Carbon as Ethylene Absorber

    Directory of Open Access Journals (Sweden)

    S. Ummartyotin

    2016-01-01

    Full Text Available Activated carbon was successfully derived from scrap tile waste from thermochemical conversion. Chemical and physical modifications were therefore employed to modify the specific surface area and porosity of activated carbon. Cellulose was successfully extracted from palm front. Designation of waste composite was prepared by cellulose and activated carbon. Less than 30 wt% of activated carbon was integrated into cellulose sheet matrix. It was important to note that there is no change in mechanical and morphological properties. Small amount of activated carbon was well dispersed. In order to investigate the feasibility of composite as active packaging, oxygen permeation rate and ethylene gas adsorption ability were preliminary investigated.

  19. CO gas sensing properties of In_4Sn_3O_1_2 and TeO_2 composite nanoparticle sensors

    International Nuclear Information System (INIS)

    Mirzaei, Ali; Park, Sunghoon; Sun, Gun-Joo; Kheel, Hyejoon; Lee, Chongmu

    2016-01-01

    Highlights: • In4Sn3O12–TeO2 composite nanoparticles were synthesized via a facile hydrothermal route. • The response of the In4Sn3O12–TeO2 composite sensor to CO was stronger than the pristine In4Sn3O12 sensor. • The response of the In4Sn3O12–TeO2 composite sensor to CO was faster than the pristine In4Sn3O12 sensor. • The improved sensing performance of the In4Sn3O12–TeO2 nanocomposite sensor is discussed in detail. • The In4Sn3O12-based nanoparticle sensors showed selectivity to CO over NH3, HCHO and H2. - Abstract: A simple hydrothermal route was used to synthesize In_4Sn_3O_1_2 nanoparticles and In_4Sn_3O_1_2–TeO_2 composite nanoparticles, with In(C_2H_3O_2)_3, SnCl_4, and TeCl_4 as the starting materials. The structure and morphology of the synthesized nanoparticles were examined by X-ray diffraction and scanning electron microscopy (SEM), respectively. The gas-sensing properties of the pure and composite nanoparticles toward CO gas were examined at different concentrations (5–100 ppm) of CO gas at different temperatures (100–300 °C). SEM observation revealed that the composite nanoparticles had a uniform shape and size. The sensor based on the In_4Sn_3O_1_2–TeO_2 composite nanoparticles showed stronger response to CO than its pure In_4Sn_3O_1_2 counterpart. The response of the In_4Sn_3O_1_2–TeO_2 composite-nanoparticle sensor to 100 ppm of CO at 200 °C was 10.21, whereas the maximum response of the In_4Sn_3O_1_2 nanoparticle sensor was 2.78 under the same conditions. Furthermore, the response time of the composite sensor was 19.73 s under these conditions, which is less than one-third of that of the In_4Sn_3O_1_2 sensor. The improved sensing performance of the In_4Sn_3O_1_2–TeO_2 nanocomposite sensor is attributed to the enhanced modulation of the potential barrier height at the In_4Sn_3O_1_2–TeO_2 interface, the stronger oxygen adsorption of p-type TeO_2, and the formation of preferential adsorption sites.

  20. Plain to point network reduced graphene oxide - activated carbon composites decorated with platinum nanoparticles for urine glucose detection

    Science.gov (United States)

    Hossain, Mohammad Faruk; Park, Jae Y.

    2016-02-01

    In this study, a hydrothermal technique was applied to synthesize glucose-treated reduced graphene oxide-activated carbon (GRGO/AC) composites. Platinum nanoparticles (PtNP) were electrochemically deposited on the modified GRGO/AC surface, and chitosan-glucose oxidase (Chit-GOx) composites and nafion were integrated onto the modified surface of the working electrode to prepare a highly sensitive glucose sensor. The fabricated biosensor exhibited a good amperometric response to glucose in the detection range from 0.002 mM to 10 mM, with a sensitivity of 61.06 μA/mMcm2, a short response time (4 s) and a low detection limit of 2 μM (signal to noise ratio is 3). The glucose sensor exhibited a negligible response to interference and good stability. In addition, the glucose levels in human urine were tested in order to conduct a practical assessment of the proposed sensor, and the results indicate that the sensor had superior urine glucose recognition. These results thus demonstrate that the noble nano-structured electrode with a high surface area and electrocatalytic activity offers great promise for use in urine glucose sensing applications.

  1. Nanostructured progesterone immunosensor using a tyrosinase-colloidal gold-graphite-Teflon biosensor as amperometric transducer

    Energy Technology Data Exchange (ETDEWEB)

    Carralero, Veronica [Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, 28040 Madrid (Spain); Gonzalez-Cortes, Araceli [Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, 28040 Madrid (Spain); Yanez-Sedeno, Paloma [Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, 28040 Madrid (Spain)]. E-mail: yseo@quim.ucm.es; Pingarron, Jose M. [Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, 28040 Madrid (Spain)

    2007-07-16

    A novel progesterone immunosensor using a colloidal gold-graphite-Teflon-tyrosinase composite biosensor as amperometric transducer is reported. A sequential competitive configuration between the analyte and progesterone labelled with alkaline phosphatase (AP) was used. Phenyl phosphate was employed as the AP-substrate and the enzyme reaction product, phenol, was oxidized by tyrosinase to o-quinone, which is subsequently reduced at -0.1 V at the biocomposite electrode. Variables such as the concentration of phenyl phosphate, the amount of antibody attached to the electrode surface, immersion time in a 2% BSA solution, working pH and incubation times in progesterone and AP conjugate were optimized. A linear calibration graph for progesterone was obtained between 0 and 40 ng mL{sup -1} with a slope value of -82.3 nA ng{sup -1} mL, and a detection limit of 0.43 ng mL{sup -1}. The time needed to reach the steady-state current from the addition of phenyl phosphate was 30-40 s. These analytical characteristics improve substantially those reported for other progesterone immunosensors. A lifetime of 14 days with no need to apply any regeneration procedure was also achieved. The usefulness of the immunosensor was evaluated by determining progesterone in milk samples spiked with the analyte at 5.0 and 1.5 ng mL{sup -1} concentration levels. Following a very simple procedure, involving only sample dilution, mean recoveries (n = 7) of 98 {+-} 3% and 99 {+-} 3%, respectively, were obtained.

  2. Nanostructured progesterone immunosensor using a tyrosinase-colloidal gold-graphite-Teflon biosensor as amperometric transducer

    International Nuclear Information System (INIS)

    Carralero, Veronica; Gonzalez-Cortes, Araceli; Yanez-Sedeno, Paloma; Pingarron, Jose M.

    2007-01-01

    A novel progesterone immunosensor using a colloidal gold-graphite-Teflon-tyrosinase composite biosensor as amperometric transducer is reported. A sequential competitive configuration between the analyte and progesterone labelled with alkaline phosphatase (AP) was used. Phenyl phosphate was employed as the AP-substrate and the enzyme reaction product, phenol, was oxidized by tyrosinase to o-quinone, which is subsequently reduced at -0.1 V at the biocomposite electrode. Variables such as the concentration of phenyl phosphate, the amount of antibody attached to the electrode surface, immersion time in a 2% BSA solution, working pH and incubation times in progesterone and AP conjugate were optimized. A linear calibration graph for progesterone was obtained between 0 and 40 ng mL -1 with a slope value of -82.3 nA ng -1 mL, and a detection limit of 0.43 ng mL -1 . The time needed to reach the steady-state current from the addition of phenyl phosphate was 30-40 s. These analytical characteristics improve substantially those reported for other progesterone immunosensors. A lifetime of 14 days with no need to apply any regeneration procedure was also achieved. The usefulness of the immunosensor was evaluated by determining progesterone in milk samples spiked with the analyte at 5.0 and 1.5 ng mL -1 concentration levels. Following a very simple procedure, involving only sample dilution, mean recoveries (n = 7) of 98 ± 3% and 99 ± 3%, respectively, were obtained

  3. Amperometric glucose biosensor based on glucose oxidase dispersed in multiwalled carbon nanotubes/graphene oxide hybrid biocomposite.

    Science.gov (United States)

    Palanisamy, Selvakumar; Cheemalapati, Srikanth; Chen, Shen-Ming

    2014-01-01

    An amperometric glucose biosensor based on enhanced and fast direct electron transfer (DET) of glucose oxidase (GOx) at enzyme dispersed multiwalled carbon nanotubes/graphene oxide (MWCNT/GO) hybrid biocomposite was developed. The fabricated hybrid biocomposite was characterized by transmission electron microscopy (TEM), Raman and infrared spectroscopy (IR). The TEM image of hybrid biocomposite reveals that a thin layer of GOx was covered on the surface of MWCNT/GO hybrid composite. IR results validate that the hybrid biocomposite was formed through the electrostatic interactions between GOx and MWCNT/GO hybrid composite. Further, MWCNT/GO hybrid composite has also been characterized by TEM and UV-visible spectroscopy. A pair of well-defined redox peak was observed for GOx immobilized at the hybrid biocomposite electrode than that immobilized at the MWCNT modified electrode. The electron transfer rate constant (Ks) of GOx at the hybrid biocomposite was calculated to be 11.22s(-1). The higher Ks value revealed that fast DET of GOx occurred at the electrode surface. Moreover, fabricated biosensor showed a good sensitivity towards glucose oxidation over a linear range 0.05-23.2mM. The limit of detection (LOD) was estimated to be 28μM. The good features of the proposed biosensor could be used for the accurate detection of glucose in the biological samples. © 2013.

  4. Piezoelectric and dielectric properties of polymer-ceramic composites for sensors

    NARCIS (Netherlands)

    James, N.K.

    2015-01-01

    The main objective of this PhD thesis is to develop new routes and concepts for manufacturing piezoelectric ceramic-polymer composites with adequate piezoelectric properties while retaining ease of manufacturing and mechanical flexibility and explore new possibilities to maximize especially the

  5. Multi-sensor data fusion for estimating forest species composition and abundance in northern Minnesota

    Science.gov (United States)

    Peter P. Wolter; Phillip A. Townsend

    2011-01-01

    The magnitude, duration, and frequency of forest disturbance caused by the spruce budworm and forest tent caterpillar in northern Minnesota and neighboring Ontario, Canada have increased over the last century due to a shift in forest species composition linked to historical fire suppression, forest management, and pesticide application that has fostered increased...

  6. Developing an electrochemical sensor based on a carbon paste electrode modified with nano-composite of reduced graphene oxide and CuFe2O4 nanoparticles for determination of hydrogen peroxide.

    Science.gov (United States)

    Benvidi, Ali; Nafar, Mohammad Taghi; Jahanbani, Shahriar; Tezerjani, Marzieh Dehghan; Rezaeinasab, Masoud; Dalirnasab, Sudabeh

    2017-06-01

    In this paper, a highly sensitive voltammetric sensor based on a carbon paste electrode with CuFe 2 O 4 nanoparticle (RGO/CuFe 2 O 4 /CPE) was designed for determination of hydrogen peroxide (H 2 O 2 ). The electrocatalytic reduction of H 2 O 2 was examined using various techniques such as cyclic voltammetry (CV), chronoamperometry, amperometry and differential pulse voltammetry (DPV). CuFe 2 O 4 nanoparticles were synthesized by co-precipitation method and characterized with scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) techniques. Then, a high conductive platform based on a carbon paste electrode modified with RGO and CuFe 2 O 4 nanoparticles was prepared as a suitable platform for determination of hydrogen peroxide. Under the optimum conditions (pH5), the modified electrode indicated a fast amperometric response of determination of hydrogen peroxide. Also, the peak current of differential pulse voltammetry (DPV) of hydrogen peroxide is increased linearly with its concentration in the ranges of 2 to 10μM and 10 to 1000μM. The obtained detection limit for hydrogen peroxide was evaluated to be 0.064μM by DPV. The designed sensor was successfully applied for the assay of hydrogen peroxide in biological and pharmaceutical samples such as milk, green tea, and hair dye cream and mouthwash solution. Copyright © 2017. Published by Elsevier B.V.

  7. Reengineered glucose oxidase for amperometric glucose determination in diabetes analytics.

    Science.gov (United States)

    Arango Gutierrez, Erik; Mundhada, Hemanshu; Meier, Thomas; Duefel, Hartmut; Bocola, Marco; Schwaneberg, Ulrich

    2013-12-15

    Glucose oxidase is an oxidoreductase exhibiting a high β-D-glucose specificity and high stability which renders glucose oxidase well-suited for applications in diabetes care. Nevertheless, GOx activity is highly oxygen dependent which can lead to inaccuracies in amperometric β-D-glucose determinations. Therefore a directed evolution campaign with two rounds of random mutagenesis (SeSaM followed by epPCR), site saturation mutagenesis studies on individual positions, and one simultaneous site saturation library (OmniChange; 4 positions) was performed. A diabetes care well suited mediator (quinone diimine) was selected and the GOx variant (T30V I94V) served as starting point. For directed GOx evolution a microtiter plate detection system based on the quinone diimine mediator was developed and the well-known ABTS-assay was applied in microtiter plate format to validate oxygen independency of improved GOx variants. Two iterative rounds of random diversity generation and screening yielded to two subsets of amino acid positions which mainly improved activity (A173, A332) and oxygen independency (F414, V560). Simultaneous site saturation of all four positions with a reduced subset of amino acids using the OmniChange method yielded finally variant V7 with a 37-fold decreased oxygen dependency (mediator activity: 7.4 U/mg WT, 47.5 U/mg V7; oxygen activity: 172.3 U/mg WT, 30.1 U/mg V7). V7 is still highly β-D-glucose specific, highly active with the quinone diimine mediator and thermal resistance is retained (prerequisite for GOx coating of diabetes test stripes). The latter properties and V7's oxygen insensitivity make V7 a very promising candidate to replace standard GOx in diabetes care applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Development of a Telemetric, Miniaturized Electrochemical Amperometric Analyzer.

    Science.gov (United States)

    Jung, Jaehyo; Lee, Jihoon; Shin, Siho; Kim, Youn Tae

    2017-10-23

    In this research, we developed a portable, three-electrode electrochemical amperometric analyzer that can transmit data to a PC or a tablet via Bluetooth communication. We performed experiments using an indium tin oxide (ITO) glass electrode to confirm the performance and reliability of the analyzer. The proposed analyzer uses a current-to-voltage (I/V) converter to convert the current generated by the reduction-oxidation (redox) reaction of the buffer solution to a voltage signal. This signal is then digitized by the processor. The configuration of the power and ground of the printed circuit board (PCB) layer is divided into digital and analog parts to minimize the noise interference of each part. The proposed analyzer occupies an area of 5.9 × 3.25 cm² with a current resolution of 0.4 nA. A potential of 0~2.1 V can be applied between the working and the counter electrodes. The results of this study showed the accuracy of the proposed analyzer by measuring the Ruthenium(III) chloride ( Ru III ) concentration in 10 mM phosphate-buffered saline (PBS) solution with a pH of 7.4. The measured data can be transmitted to a PC or a mobile such as a smartphone or a tablet PC using the included Bluetooth module. The proposed analyzer uses a 3.7 V, 120 mAh lithium polymer battery and can be operated for 60 min when fully charged, including data processing and wireless communication.

  9. Development of a Telemetric, Miniaturized Electrochemical Amperometric Analyzer

    Directory of Open Access Journals (Sweden)

    Jaehyo Jung

    2017-10-01

    Full Text Available In this research, we developed a portable, three-electrode electrochemical amperometric analyzer that can transmit data to a PC or a tablet via Bluetooth communication. We performed experiments using an indium tin oxide (ITO glass electrode to confirm the performance and reliability of the analyzer. The proposed analyzer uses a current-to-voltage (I/V converter to convert the current generated by the reduction-oxidation (redox reaction of the buffer solution to a voltage signal. This signal is then digitized by the processor. The configuration of the power and ground of the printed circuit board (PCB layer is divided into digital and analog parts to minimize the noise interference of each part. The proposed analyzer occupies an area of 5.9 × 3.25 cm2 with a current resolution of 0.4 nA. A potential of 0~2.1 V can be applied between the working and the counter electrodes. The results of this study showed the accuracy of the proposed analyzer by measuring the Ruthenium(III chloride ( Ru III concentration in 10 mM phosphate-buffered saline (PBS solution with a pH of 7.4. The measured data can be transmitted to a PC or a mobile such as a smartphone or a tablet PC using the included Bluetooth module. The proposed analyzer uses a 3.7 V, 120 mAh lithium polymer battery and can be operated for 60 min when fully charged, including data processing and wireless communication.

  10. Development of an enzyme free glucose sensor based on copper oxide-graphene composite by using green reducing agent ascorbic acid

    Science.gov (United States)

    Palve, Yogesh Pandit; Jha, Neetu

    2018-05-01

    In this research work we have developed high sensitive and selective glucose sensor based on copper oxide-graphene composite which is prepared by green synthesis method and used for nonenzymatic glucose sensor. In present paper we report that present method highly selective, simple, efficient, accurate, ecofriendly, less toxic. The prepared composite were characterized by material characterization like SEM, XRD and also by electrochemical characterization like CV, chronoamperometry represents that copper oxide-graphene shows excellent electrocatalytic activity towards glucose, exhibiting a good sensitivity of 103.84 µA mM-1 cm-2, a fast response time 2s, a low detection limit 0.00033µM and linear range from 10 µM-3000 µM. The present sensor can successfully apply for determination of glucose concentration in human blood sample.

  11. A built-in sensor with carbon nanotubes coated by Ag clusters for deformation monitoring of glass fibre/epoxy composites

    Science.gov (United States)

    Slobodian, P.; Riha, P.; Matyas, J.; Olejnik, R.; Lloret Pertegás, S.; Schledjewski, R.; Kovar, M.

    2018-03-01

    A multiwalled carbon nanotube network embedded in a polyurethane membrane was integrated into a glass fibre reinforced epoxy composite by means of vacuum infusion to become a part of the composite and has been serving for a strain self-sensing functionality. Besides the pristine nanotubes also nanotubes with Ag nanoparticles attached to their surfaces were used to increase strain sensing. Moreover, the design of the carbon nanotube/polyurethane sensor allowed formation of network micro-sized cracks which increased its reversible electrical resistance resulted in an enhancement of strain sensing. The resistance sensitivity, quantified by a gauge factor, increased more than hundredfold in case of a pre-strained sensor with Ag decorated nanotubes in comparison with the sensor with pristine nanotubes.

  12. Construction of a new functional platform by grafting poly(4-vinylpyridine) in multi-walled carbon nanotubes for complexing copper ions aiming the amperometric detection of L-cysteine

    International Nuclear Information System (INIS)

    Carvalho Castro e Silva, Cecília de; Breitkreitz, Márcia Cristina; Santhiago, Murilo; Crispilho Corrêa, Cátia; Tatsuo Kubota, Lauro

    2012-01-01

    Highlights: ► Construction of new nanostructured platform based on MWCNTs–PVP to complex copper(II) ions. ► Development of an amperometric sensor for highly selective determination of Cys in food supplement samples. ► Combination of nanocomposite and the copper(II) ions causes a dramatic enhancement in the sensitivity of Cys quantification at low overpotential. - Abstract: This work describes the preparation of an amperometric sensor for electrocatalytical detection of L-cysteine (Cys). The developed sensor is based on a functional platform to complex copper ions on multi-walled carbon nanotubes (MWCNTs) modified with poly-4-vinylpyridine (PVP) through an in situ polymerization. The obtained values for the kinetic constants of heterogeneous electron transfer rate (k s ) and for chemical reaction (k obs ) between Cu 2+ and cysteine were 5.78 s −1 and 6.96 L mol −1 s −1 , respectively. The analytical curve showed a linear response range for detecting L-cysteine in concentrations from 5 to 60 μmol L −1 . The detection and quantification limits obtained were 1.50 and 5.00 μmol L −1 , respectively with a response time of 0.10 s at an applied potential of 150 mV vs SCE.

  13. Prediction of wastewater quality using amperometric bioelectronic tongues

    DEFF Research Database (Denmark)

    Czolkos, Ilja; Dock, Eva; Tonning, Erik

    2016-01-01

    regression (PLS-R), we could link the sensor responses to the Microtox (R) toxicity parameter, as well as to global organic pollution parameters (COD, BOD, and TOC). From investigating the influences of individual sensors in the array, it was found that the best models were in most cases obtained when all...

  14. Multi-sensor system for in situ shape monitoring and damage identification of high-speed composite rotors

    Science.gov (United States)

    Philipp, K.; Filippatos, A.; Kuschmierz, R.; Langkamp, A.; Gude, M.; Fischer, A.; Czarske, J.

    2016-08-01

    Glass fibre-reinforced polymer (GFRP) composites offer a higher stiffness-to-weight ratio than conventional rotor materials used in turbomachinery. However, the material behaviour of GFRP high-speed rotors is difficult to predict due to the complexity of the composite material and the dynamic loading conditions. Consequently dynamic expansion measurements of GRFP rotors are required in situ and with micron precision. However, the whirling motion amplitude is about two orders of magnitude higher than the desired precision. To overcome this problem, a multi-sensor system capable of separating rotor expansion and whirling motion is proposed. High measurement rates well above the rotational frequency and micron uncertainty are achieved at whirling amplitudes up to 120μm and surface velocities up to 300 m/s. The dynamic elliptical expansion of a GFRP rotor is investigated in a rotor loading test rig under vacuum conditions. In situ measurements identified not only the introduced damage but also damage initiation and propagation.

  15. Remote monitoring of bond line defects between a composite panel and a stiffener using distributed piezoelectric sensors

    Science.gov (United States)

    Yu, Xudong; Fan, Zheng; Puliyakote, Sreedhar; Castaings, Michel

    2018-03-01

    Structural health monitoring (SHM) using ultrasonic guided waves has proven to be attractive for the identification of damage in composite plate-like structures, due to its realization of both significant propagation distances and reasonable sensitivity to defects. However, topographical features such as bends, lap joints, and bonded stiffeners are often encountered in these structures, and they are susceptible to various types of defects as a consequence of stress concentration and cyclic loading during the service life. Therefore, the health condition of such features has to be assessed effectively to ensure the safe operation of the entire structure. This paper proposes a novel feature guided wave (FGW) based SHM strategy, in which proper FGWs are exploited as a screening tool to rapidly interrogate the representative stiffener-adhesive bond-composite skin assembly. An array of sensors permanently attached to the vicinity of the feature is used to capture scattered waves from the localized damage occurring in the bond line. This technique is combined with an imaging approach, and the damage reconstruction is achieved by the synthetic focusing algorithm using these scattered signals. The proposed SHM scheme is implemented in both the 3D finite element simulation and the experiment, and the results are in good agreement, demonstrating the feasibility of such SHM strategy.

  16. A Flexible Multifunctional Sensor Based on Carbon Nanotube/Polyurethane Composite

    Czech Academy of Sciences Publication Activity Database

    Slobodian, P.; Říha, Pavel; Benlikaya, R.; Svoboda, P.; Petráš, D.

    2013-01-01

    Roč. 13, č. 10 (2013), s. 4045-4048 ISSN 1530-437X Grant - others:GA MŠk(CZ) ED2.1.00/03.0111; UTB Zlín(CZ) iga/ft/2012/022 Institutional research plan: CEZ:AV0Z20600510 Institutional support: RVO:67985874 Keywords : carbon nanotubes * chemical vapor sensing * deformation sensing * polymer composite Subject RIV: BK - Fluid Dynamics Impact factor: 1.852, year: 2013

  17. Multifunctional Carbon Nanotube-Based Sensors for Damage Detection and Self Healing in Structural Composites

    Science.gov (United States)

    2010-10-29

    established based on the concept of equipotential surface . The effect of nanotube length on the critical charge level is plotted in Fig. 17. Fig...walled carbon nanotubes was used to develop composites with agglomerated regions of nanotubes at the fiber surface [3]. An image of the nanotube...coating on the surface of two E-glass fibers is shown in Fig. 5. Fig. 5. (a) Carbon nanotube agglomerates on the surface of glass fibers in the

  18. Mechanical and Vibration Testing of Carbon Fiber Composite Material with Embedded Piezoelectric Sensors

    Science.gov (United States)

    Duffy, Kirsten P.; Lerch, Bradley A.; Wilmoth, Nathan G.; Kray, Nicholas; Gemeinhardt, Gregory

    2012-01-01

    Piezoelectric materials have been proposed as a means of decreasing turbomachinery blade vibration either through a passive damping scheme, or as part of an active vibration control system. For polymer matrix fiber composite (PMFC) blades, the piezoelectric elements could be embedded within the blade material, protecting the brittle piezoceramic material from the airflow and from debris. Before implementation of a piezoelectric element within a PMFC blade, the effect on PMFC mechanical properties needs to be understood. This study attempts to determine how the inclusion of a packaged piezoelectric patch affects the material properties of the PMFC. Composite specimens with embedded piezoelectric patches were tested in four-point bending, short beam shear, and flatwise tension configurations. Results show that the embedded piezoelectric material does decrease the strength of the composite material, especially in flatwise tension, attributable to failure at the interface or within the piezoelectric element itself. In addition, the sensing properties of the post-cured embedded piezoelectric materials were tested, and performed as expected. The piezoelectric materials include a non-flexible patch incorporating solid piezoceramic material, and two flexible patch types incorporating piezoelectric fibers. The piezoceramic material used in these patches was Navy Type-II PZT.

  19. Amperometric sensing of nitrite using a glassy carbon electrode modified with a multilayer consisting of carboxylated nanocrystalline cellulose and poly(diallyldimethyl ammonium) ions in a PEDOT host

    International Nuclear Information System (INIS)

    Xu, Guiyun; Liang, Shaoping; Sheng, Ge; Luo, Xiliang; Fan, Jinshi

    2016-01-01

    Negatively charged carboxylated nanocrystalline cellulose (CNCC) and positively charged poly(diallyldimethyl ammonium chloride) (PDDA) were alternatingly assembled on the surface of a glassy carbon electrode to form a relatively uniform polyelectrolyte multilayer nanocomposite (CNCC/PDDA)n. It was then incorporated into a matrix of conducting poly(3,4-ethylenedioxythiophene) (PEDOT) electrodeposited on the surface of the electrode. The nanocomposites were prepared in various ratios of PEDOT and (CNCC/PDDA), and then characterized by transmission electron microscopy, scanning electron microscopy, electrochemical impedance spectroscopy, cyclic voltammetry, and differential pulse voltammetry. The PEDOT/(CNCC/PDDA)4 nanocomposite showed the lowest electrochemical impedance and best electrocatalytic activity towards the oxidation of nitrite. Based on these findings, an amperometric sensor was developed which, if operated at 0.80 V (vs. SCE), can detect nitrite in the 0.2 μM to 1.73 mM concentration range with a 57 nM detection limit. (author)

  20. Design and development of amperometric biosensor for the detection of lead and mercury ions in water matrix-a permeability approach.

    Science.gov (United States)

    Gumpu, Manju Bhargavi; Krishnan, Uma Maheswari; Rayappan, John Bosco Balaguru

    2017-07-01

    Intake of water contaminated with lead (Pb 2+ ) and mercury (Hg 2+ ) ions leads to various toxic effects and health issues. In this context, an amperometric urease inhibition-based biosensor was developed to detect Pb 2+ and Hg 2+ ions in water matrix. The modified Pt/CeO 2 /urease electrode was fabricated by immobilizing CeO 2 nanoparticles and urease using a semi-permeable adsorption layer of nafion. With urea as a substrate, urease catalytic activity was examined through cyclic voltammetry. Further, maximum amperometric inhibitive response of the modified Pt/CeO 2 /urease electrode was observed in the presence of Pb 2+ and Hg 2+ ions due to the urease inhibition at specific potentials of -0.03 and 0 V, respectively. The developed sensor exhibited a detection limit of 0.019 ± 0.001 μM with a sensitivity of 89.2 × 10 -3  μA μM -1 for Pb 2+ ions. A detection limit of 0.018 ± 0.003 with a sensitivity of 94.1 × 10 -3  μA μM -1 was achieved in detecting Hg 2+ ions. The developed biosensor showed a fast response time (<1 s) with a linear range of 0.5-2.2 and 0.02-0.8 μM for Pb 2+ and Hg 2+ ions, respectively. The modified electrode offered a good stability for 20 days with a good repeatability and reproducibility. The developed sensor was used to detect Pb 2+ and Hg 2+ ions contaminating Cauvery river water and the observed results were in good co-ordination with atomic absorption spectroscopic data.

  1. Increasing amperometric biosensor sensitivity by length fractionated single-walled carbon nanotubes

    DEFF Research Database (Denmark)

    Tasca, Federico; Gorton, Lo; Wagner, Jakob Birkedal

    2008-01-01

    In this work the sensitivity-increasing effect of single-walled carbon nanotubes (SWCNTs) in amperometric biosensors, depending on their average length distribution, was studied. For this purpose the SWCNTs were oxidatively shortened and subsequently length separated by size exclusion...

  2. Estimation of Curvature Changes for Steel-Concrete Composite Bridge Using Fiber Bragg Grating Sensors

    OpenAIRE

    Kang, Donghoon; Chung, Wonseok

    2013-01-01

    This study is focused on the verification of the key idea of a newly developed steel-concrete composite bridge. The key idea of the proposed bridge is to reduce the design moment by applying vertical prestressing force to steel girders, so that a moment distribution of a continuous span bridge is formed in a simple span bridge. For the verification of the key technology, curvature changes of the bridge should be monitored sequentially at every construction stage. A pair of multiplexed FBG sen...

  3. Indirect amperometric sensing of dopamine using a redox-switchable naphthoquinone-terminated self-assembled monolayer on gold electrode

    International Nuclear Information System (INIS)

    Hammami, Asma; Raouafi, Noureddine; Sahli, Rihab

    2016-01-01

    We report on the design of a simple yet sensitive and selective electrode for amperometric determination of dopamine at a cathodic potential as low as −0.30 V vs. Ag/AgCl. The electrode was obtained by self-assembly of ω-mercaptopropyl naphthoquinone (NQ-SAM) on the surface of a polycrystalline gold electrode. The presence of dopamine induces an increase of the reduction current peak at −0.30 V corresponding to the reduction of naphthoquinone to hydronaphthoquinone. Dopamine and dopamine-quinone accumulate on the surface to form a 3D network linked by hydrogen bonds. Raman and infrared spectroscopy as well as atomic force microscopy confirmed the multilayer formation. The method allows dopamine to be indirectly detected at a working potential that is lower by 0.50 V than the standard oxidation potential at a bare gold electrode. The sensor shows distinct oxidation potentials for dopamine (120 mV), ascorbic acid (280 mV) and uric acid (520 mV) which makes the method fairly selective. The analytical range extends from 1 to 100 μM concentrations of dopamine, and the limits of detection and quantification are 0.040 and 0.134 μM, respectively. (author)

  4. Direct electrodeposition of highly ordered gold nanotube arrays for use in non-enzymatic amperometric sensing of glucose

    International Nuclear Information System (INIS)

    Tian, Taolei; Dong, Junping; Xu, Jiaqiang

    2016-01-01

    The authors describe vertically aligned gold nanotube arrays (Au-NTAs) and gold nanowire arrays (Au-NWAs) that were directly grown in alumina oxide templates by galvanostatic deposition. The morphology of the gold arrays can be controlled by adjusting the pH value of the plating bath. Scanning electron microscopy shows the nanoarrays to be highly ordered (with an average length of around 2 μm), and the opening width of the gold nanotube arrays to be uniform (with diameters of around 50 nm). The electrocatalytic activities of the Au-NTAs and Au-NWAs deposited on a glassy carbon electrode toward glucose oxidation were compared by cyclic voltammetry and amperometry at pH 7.2. The Au-NTAs yield higher amperometric currents. The respective glucose sensor, when operated at a working potential of 0.25 V (vs. SCE), exhibits a linear range that extends from 5 μM to 16.4 mM concentrations of glucose, a sensitivity of 44.2 μA mM"−"1 cm"−"2, and a detection limit of 2.1 μM (at an S/N ratio of 3). The excellent sensing performance is attributed to the large surface area and the fast electron transfer rate for the one-dimensional gold nanoarrays (author)

  5. Magnetic polymer-silica composites as bioluminescent sensors for bilirubin detection

    Energy Technology Data Exchange (ETDEWEB)

    Timin, Alexander S., E-mail: a_timin@mail.ru [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000, Ivanovo (Russian Federation); RASA Center in Tomsk, Tomsk Polytechnic University, pros. Lenina, 30, Tomsk (Russian Federation); Solomonov, Alexey V. [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000, Ivanovo (Russian Federation); Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 7610001 (Israel); Kumagai, Akiko; Miyawaki, Atsushi [Cell Function Dynamics, Brain Science Institute RIKEN, 2-1 Hirosawa, Wako-city, Saitama, 351-0198 (Japan); Khashirova, Svetlana Yu; Zhansitov, Azamat [Kabardino-Balkar State University, 173 Chernyshevskogo St., Nal' chik, 360004, Kabardino-Balkaria (Russian Federation); Rumyantsev, Evgeniy V. [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000, Ivanovo (Russian Federation)

    2016-11-01

    The synthesis of multifunctional nano-sized materials is leading to the rapid development of key application, including improved drug delivery, bioimaging and protein separation. In this work, magnetic silica particles modified with novel guanidine containing co-polymers were manufactured via sol-gel method. To evaluate the chemical composition of our prepared samples, FT-IR spectroscopy and thermogravimetry were conducted. Scanning electron microscopy was used in order to investigate the morphology of final products after modification by guanidine containing co-polymers and iron nanoparticles. In addition, the surface of polymer-silica composites was functionalized by the novel bilirubin-inducible fluorescent protein UnaG. In an aqueous bilirubin solution, the silica particles decorated with the polymer-UnaG have showed bright fluorescence. Synthesis and characterization of these hybrid materials allow developing of new multifunctional nano-sized materials, which will be used for detection and separation of bilirubin, a lipophilic heme catabolite that is a clinical diagnostic for liver function. - Highlights: • Novel magnetic silicas grafted by guanidine containing co-polymers were prepared. • Unag protein was effectively loaded into polymer coated silicas. • The fluorescent properties depend on content of bilirubin.

  6. Predicting the Composition of Red Wine Blends Using an Array of Multicomponent Peptide-Based Sensors

    Directory of Open Access Journals (Sweden)

    Eman Ghanem

    2015-05-01

    Full Text Available Differential sensing using synthetic receptors as mimics of the mammalian senses of taste and smell is a powerful approach for the analysis of complex mixtures. Herein, we report on the effectiveness of a cross-reactive, supramolecular, peptide-based sensing array in differentiating and predicting the composition of red wine blends. Fifteen blends of Cabernet Sauvignon, Merlot and Cabernet Franc, in addition to the mono varietals, were used in this investigation. Linear Discriminant Analysis (LDA showed a clear differentiation of blends based on tannin concentration and composition where certain mono varietals like Cabernet Sauvignon seemed to contribute less to the overall characteristics of the blend. Partial Least Squares (PLS Regression and cross validation were used to build a predictive model for the responses of the receptors to eleven binary blends and the three mono varietals. The optimized model was later used to predict the percentage of each mono varietal in an independent test set composted of four tri-blends with a 15% average error. A partial least square regression model using the mouth-feel and taste descriptive sensory attributes of the wine blends revealed a strong correlation of the receptors to perceived astringency, which is indicative of selective binding to polyphenols in wine.

  7. Predicting the composition of red wine blends using an array of multicomponent Peptide-based sensors.

    Science.gov (United States)

    Ghanem, Eman; Hopfer, Helene; Navarro, Andrea; Ritzer, Maxwell S; Mahmood, Lina; Fredell, Morgan; Cubley, Ashley; Bolen, Jessica; Fattah, Rabia; Teasdale, Katherine; Lieu, Linh; Chua, Tedmund; Marini, Federico; Heymann, Hildegarde; Anslyn, Eric V

    2015-05-20

    Differential sensing using synthetic receptors as mimics of the mammalian senses of taste and smell is a powerful approach for the analysis of complex mixtures. Herein, we report on the effectiveness of a cross-reactive, supramolecular, peptide-based sensing array in differentiating and predicting the composition of red wine blends. Fifteen blends of Cabernet Sauvignon, Merlot and Cabernet Franc, in addition to the mono varietals, were used in this investigation. Linear Discriminant Analysis (LDA) showed a clear differentiation of blends based on tannin concentration and composition where certain mono varietals like Cabernet Sauvignon seemed to contribute less to the overall characteristics of the blend. Partial Least Squares (PLS) Regression and cross validation were used to build a predictive model for the responses of the receptors to eleven binary blends and the three mono varietals. The optimized model was later used to predict the percentage of each mono varietal in an independent test set composted of four tri-blends with a 15% average error. A partial least square regression model using the mouth-feel and taste descriptive sensory attributes of the wine blends revealed a strong correlation of the receptors to perceived astringency, which is indicative of selective binding to polyphenols in wine.

  8. Magnetic polymer-silica composites as bioluminescent sensors for bilirubin detection

    International Nuclear Information System (INIS)

    Timin, Alexander S.; Solomonov, Alexey V.; Kumagai, Akiko; Miyawaki, Atsushi; Khashirova, Svetlana Yu; Zhansitov, Azamat; Rumyantsev, Evgeniy V.

    2016-01-01

    The synthesis of multifunctional nano-sized materials is leading to the rapid development of key application, including improved drug delivery, bioimaging and protein separation. In this work, magnetic silica particles modified with novel guanidine containing co-polymers were manufactured via sol-gel method. To evaluate the chemical composition of our prepared samples, FT-IR spectroscopy and thermogravimetry were conducted. Scanning electron microscopy was used in order to investigate the morphology of final products after modification by guanidine containing co-polymers and iron nanoparticles. In addition, the surface of polymer-silica composites was functionalized by the novel bilirubin-inducible fluorescent protein UnaG. In an aqueous bilirubin solution, the silica particles decorated with the polymer-UnaG have showed bright fluorescence. Synthesis and characterization of these hybrid materials allow developing of new multifunctional nano-sized materials, which will be used for detection and separation of bilirubin, a lipophilic heme catabolite that is a clinical diagnostic for liver function. - Highlights: • Novel magnetic silicas grafted by guanidine containing co-polymers were prepared. • Unag protein was effectively loaded into polymer coated silicas. • The fluorescent properties depend on content of bilirubin.

  9. Neural network approach to modelling the behaviour of quantum tunnelling composites as multifunctional sensors

    International Nuclear Information System (INIS)

    Lantada, Andrés Díaz; Morgado, Pilar Lafont; Otero, Javier Echavarri; Munoz-Guijosa, Juan Manuel; Sanz, José Luis Muñoz

    2010-01-01

    Quantum tunnelling composites, or 'QTCs', are composites with an elastomeric polymer matrix and a metal particle filling (usually nickel). At rest, these metal particles do not touch each other and the polymer acts as an insulator. When the material is suitably deformed, however, the particles come together (without actually touching) and the quantum tunnelling effect is promoted, which causes the electrical resistance to fall drastically. This paper contains a detailed description of neural networks for a faster, simpler and more accurate modelling and simulation of QTC behaviour that is based on properly training these neural models with the help of data from characterization tests. Instead of using analytical equations that integrate different quantum and thermomechanical effects, neural networks are used here due to the notable nonlinearity of the aforementioned effects, which involve developing analytical models that are too complex to be of practical use. By conducting tests under different pressures and temperatures that encompass a wide range of operating conditions for these materials, different neural networks are trained and compared as the number of neurons is increased. The results of these tests have also enabled certain previously described phenomena to be simulated with more accuracy, especially those involving the response of QTCs to changes in pressure and temperature

  10. Soft sensor based composition estimation and controller design for an ideal reactive distillation column.

    Science.gov (United States)

    Vijaya Raghavan, S R; Radhakrishnan, T K; Srinivasan, K

    2011-01-01

    In this research work, the authors have presented the design and implementation of a recurrent neural network (RNN) based inferential state estimation scheme for an ideal reactive distillation column. Decentralized PI controllers are designed and implemented. The reactive distillation process is controlled by controlling the composition which has been estimated from the available temperature measurements using a type of RNN called Time Delayed Neural Network (TDNN). The performance of the RNN based state estimation scheme under both open loop and closed loop have been compared with a standard Extended Kalman filter (EKF) and a Feed forward Neural Network (FNN). The online training/correction has been done for both RNN and FNN schemes for every ten minutes whenever new un-trained measurements are available from a conventional composition analyzer. The performance of RNN shows better state estimation capability as compared to other state estimation schemes in terms of qualitative and quantitative performance indices. Copyright © 2010 ISA. Published by Elsevier Ltd. All rights reserved.

  11. Amperometric immunosensor based on multiwalled carbon nanotubes/Prussian blue/nanogold-modified electrode for determination of α-fetoprotein.

    Science.gov (United States)

    Jiang, Wen; Yuan, Ruo; Chai, Ya-Qin; Yin, Bing

    2010-12-01

    In this article, a conspicuously simple and highly sensitive amperometric immunosensor based on the sequential electrodeposition of Prussian blue (PB) and gold nanoparticles (GNPs) on multiwalled carbon nanotube (MWCNT)-modified glassy carbon electrode (GCE) surface is proposed for the detection of α-fetoprotein (AFP). By comparison with PB, the MWCNT/PB composite film had been proven to show much better electrochemical stability and a larger response current. The electrodeposited GNP film can be used not only to immobilize biomolecules but also to avoid the leakage of PB and to prevent shedding of MWCNT/PB composite film from the electrode surface. The performance and factors influencing the performance of the immunosensor were investigated. Under optimal experimental conditions, the proposed immunosensor for AFP was observed with an ultralow limit of detection (LOD) equal to 3 pg/ml (at 3δ), and the linear working range spanned the concentrations of AFP from 0.01 to 300 ng/ml. Moreover, the immunosensor, as well as a commercially available kit, was examined for use in the determination of AFP in real human serum specimens. More significant, the assay mentioned here is simpler than the traditional enzyme-linked immunosorbent assay (ELISA), and an excellent correlation of levels of AFP measured was obtained, indicating that the developed immunoassay could be a promising alternative approach for detection of AFP and other tumor markers in the clinical diagnosis. Copyright © 2010 Elsevier Inc. All rights reserved.

  12. Amperometric catechol biosensor based on laccase immobilized on nitrogen-doped ordered mesoporous carbon (N-OMC)/PVA matrix

    International Nuclear Information System (INIS)

    Guo, Meiqing; Wang, Hefeng; Huang, Di; Han, Zhijun; Wang, Xiaojun; Li, Qiang; Chen, Jing

    2014-01-01

    A functionalized nitrogen-containing ordered mesoporous carbon (N-OMC), which shows good electrical properties, was synthesized by the carbonization of polyaniline inside a SBA-15 mesoporous silica template. Based on this, through entrapping laccase onto the N-OMC/polyvinyl alcohol (PVA) film a facilely fabricated amperometric biosensor was developed. Laccase from Trametes versicolor was assembled on a composite film of a N-OMC/PVA modified Au electrode and the electrochemical behavior was investigated. The results indicated that the N-OMC modified electrode exhibits electrical properties towards catechol. The optimum experimental conditions of a biosensor for the detection of catechol were studied in detail. Under the optimal conditions, the sensitivity of the biosensor was 0.29 A*M −1 with a detection limit of 0.31 μM and a linear detection range from 0.39 μM to 8.98 μM for catechol. The calibration curve followed the Michaelis–Menten kinetics and the apparent Michaelis–Menten (K M app ) was 6.28 μM. This work demonstrated that the N-OMC/PVA composite provides a suitable support for laccase immobilization and the construction of a biosensor. (papers)

  13. Robust, Brillouin Active Embedded Fiber-Is-The-Sensor System in Smart Composite Structures

    Science.gov (United States)

    Yu, Chung

    1996-01-01

    Extensive review of our proposed sensing scheme, based mainly on the forward Guided Acoustic Wave Brillouin Scattering (GAWBS) with backward stimulated Brillouin scattering (sBs) as an auxiliary scheme for system fault tolerance has been completed during this project period. This preliminary study is conducted for a number of reasons. The most significant reasons lie in the essential capability of the system to measure temperature and pressure. These two measurands have been proposed to be sensed by sBs in our proposal. Temperature and pressure/strain are important measurands in structural monitoring, so that the effectiveness of sensing by sBs needs to be further examined. It has been pointed out initially that sBs shift will be dependent on temperature and pressure/strain simultaneously. The shift versus temperature or strain is linear. Now, the question is how can these two measurands be separated when sBs is used to sense an environment, in which both temperature and strain are changing simultaneously. Typical sBs shift plotted versus strain and varying temperature is shown in Fig. 1. As is clear, a fiber initially stressed will relax with rising temperature. This is verified by a displacement to the right with rising temperature of the sBs shift vs strain curves in the figure. A way to circumvent this ambiguity is by employing two fibers, one pre-stressed and the other is a free fiber. The latter will measure temperature and subtracting data in the latter fiber from those of the former will give us net strain readings. This is a laborious approach, since it involves the use of two identical fibers, and this is hard to accomplish, especially when many sensors are needed. Additional multiplexing of the data stream for data subtraction becomes a necessity.

  14. Currently Commercially Available Chemical Sensors Employed for Detection of Volatile Organic Compounds in Outdoor and Indoor Air

    Directory of Open Access Journals (Sweden)

    Bartosz Szulczyński

    2017-03-01

    Full Text Available The paper presents principle of operation and design of the most popular chemical sensors for measurement of volatile organic compounds (VOCs in outdoor and indoor air. It describes the sensors for evaluation of explosion risk including pellistors and IR-absorption sensors as well as the sensors for detection of toxic compounds such as electrochemical (amperometric, photoionization and semiconductor with solid electrolyte ones. Commercially available sensors for detection of VOCs and their metrological parameters—measurement range, limit of detection, measurement resolution, sensitivity and response time—were presented. Moreover, development trends and prospects of improvement of the metrological parameters of these sensors were highlighted.

  15. Numerical and Experimental Characterization of Fiber-Reinforced Thermoplastic Composite Structures with Embedded Piezoelectric Sensor-Actuator Arrays for Ultrasonic Applications

    Directory of Open Access Journals (Sweden)

    Klaudiusz Holeczek

    2016-02-01

    Full Text Available The paper presents preliminary numerical and experimental studies of active textile-reinforced thermoplastic composites with embedded sensor-actuator arrays. The goal of the investigations was the assessment of directional sound wave generation capability using embedded sensor-actuator arrays and developed a wave excitation procedure for ultrasound measurement tasks. The feasibility of the proposed approach was initially confirmed in numerical investigations assuming idealized mechanical and geometrical conditions. The findings were validated in real-life conditions on specimens of elementary geometry. Herein, the technological aspects of unique automated assembly of thermoplastic films containing adapted thermoplastic-compatible piezoceramic modules and conducting paths were described.

  16. An electrochemical sensor for warfarin determination based on covalent immobilization of quantum dots onto carboxylated multiwalled carbon nanotubes and chitosan composite film modified electrode

    International Nuclear Information System (INIS)

    Gholivand, Mohammad Bagher; Mohammadi-Behzad, Leila

    2015-01-01

    A method is described for the construction of a novel electrochemical warfarin sensor based on covalent immobilization of CdS-quantum dots (CdS-QDs) onto carboxylated multiwalled carbon nanotubes/chitosan (CS) composite film on the surface of a glassy carbon electrode. The CdS-QDs/CS/MWCNTs were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, XRD analysis and electrochemical impedance spectroscopy (EIS). The sensor showed optimum anodic stripping response within 90 s at an accumulation potential of 0.75 V. The modified electrode was used to detect the concentration of warfarin with a wide linear range of 0.05–80 μM and a detection limit (S/N = 3) of 8.5 nM. The proposed sensor has good storage stability, repeatability and reproducibility and was successfully applied for the determination of warfarin in real samples such as urine, serum and milk. - Highlights: • A new sensitive sensor for warfarin determination was developed. • The sensor was constructed based on covalent immobilization of CdS-QDs on the chitosan/MWCNTs/GCE. • The parameters affecting the stripping analysis of warfarin were optimized. • The proposed sensor is used for trace determination of warfarin in urine, serum and milk

  17. An electrochemical sensor for warfarin determination based on covalent immobilization of quantum dots onto carboxylated multiwalled carbon nanotubes and chitosan composite film modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Gholivand, Mohammad Bagher, E-mail: mbgholivand2013@gmail.com; Mohammadi-Behzad, Leila

    2015-12-01

    A method is described for the construction of a novel electrochemical warfarin sensor based on covalent immobilization of CdS-quantum dots (CdS-QDs) onto carboxylated multiwalled carbon nanotubes/chitosan (CS) composite film on the surface of a glassy carbon electrode. The CdS-QDs/CS/MWCNTs were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, XRD analysis and electrochemical impedance spectroscopy (EIS). The sensor showed optimum anodic stripping response within 90 s at an accumulation potential of 0.75 V. The modified electrode was used to detect the concentration of warfarin with a wide linear range of 0.05–80 μM and a detection limit (S/N = 3) of 8.5 nM. The proposed sensor has good storage stability, repeatability and reproducibility and was successfully applied for the determination of warfarin in real samples such as urine, serum and milk. - Highlights: • A new sensitive sensor for warfarin determination was developed. • The sensor was constructed based on covalent immobilization of CdS-QDs on the chitosan/MWCNTs/GCE. • The parameters affecting the stripping analysis of warfarin were optimized. • The proposed sensor is used for trace determination of warfarin in urine, serum and milk.

  18. Molecularly imprinted poly(4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid) modified glassy carbon electrode as an electrochemical theophylline sensor.

    Science.gov (United States)

    Aswini, K K; Vinu Mohan, A M; Biju, V M

    2016-08-01

    Theophylline is an inexpensive drug employed in asthma and chronic obstructive pulmonary disorder medications and is toxic at higher concentration. The development of a molecularly imprinted polymer based theophylline electrochemical sensor on glassy carbon electrode by the electropolymerization of 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid is being discussed in this work. The MIP modification enhances the theophylline recognition ability and the electron transfer kinetics of the bare electrode. The parameters, controlling the performance of the imprinted polymer based sensor, like number of electropolymerization cycles, composition of the pre-polymerization mixture, pH and immersion time were investigated and optimized. The interaction energy and the most stable conformation of the template-monomer complex in the pre-polymerization mixture were determined computationally using ab initio calculations based on density functional theory. The amperometric measurements showed that the developed sensor has a method detection limit of 0.32μM for the dynamic range of 0.4 to 17μM, at optimized conditions. The transducer possesses appreciable selectivity in the presence of structurally similar interferents such as theobromine, caffeine and doxofylline. The developed sensor showed remarkable stability and reproducibility and was also successfully employed in theophylline detection from commercially available tablets. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Underwater thrust and power generation using flexible piezoelectric composites: an experimental investigation toward self-powered swimmer-sensor platforms

    International Nuclear Information System (INIS)

    Erturk, Alper; Delporte, Ghislain

    2011-01-01

    Fiber-based flexible piezoelectric composites offer several advantages to use in energy harvesting and biomimetic locomotion. These advantages include ease of application, high power density, effective bending actuation, silent operation over a range of frequencies, and light weight. Piezoelectric materials exhibit the well-known direct and converse piezoelectric effects. The direct piezoelectric effect has received growing attention for low-power generation to use in wireless electronic applications while the converse piezoelectric effect constitutes an alternative to replace the conventional actuators used in biomimetic locomotion. In this paper, underwater thrust and electricity generation are investigated experimentally by focusing on biomimetic structures with macro-fiber composite piezoelectrics. Fish-like bimorph configurations with and without a passive caudal fin (tail) are fabricated and compared. The favorable effect of having a passive caudal fin on the frequency bandwidth is reported. The presence of a passive caudal fin is observed to bring the second bending mode close to the first one, yielding a wideband behavior in thrust generation. The same smart fish configuration is tested for underwater piezoelectric power generation in response to harmonic excitation from its head. Resonant piezohydroelastic actuation is reported to generate milli-newton level hydrodynamic thrust using milli-watt level actuation power input. The average actuation power requirement for generating a mean thrust of 19 mN at 6 Hz using a 10 g piezoelastic fish with a caudal fin is measured as 120 mW. This work also discusses the feasibility of thrust generation using the harvested energy toward enabling self-powered swimmer-sensor platforms with comparisons based on the capacity levels of structural thin-film battery layers as well as harvested solar and vibrational energy

  20. Elaboration of new method of enzyme adsorption on silicalite and nano beta zeolite for amperometric biosensor creation

    Directory of Open Access Journals (Sweden)

    Soldatkin O. O.

    2014-07-01

    Full Text Available Aim. Optimization of a new method of enzyme immobilization for amperometric biosensor creation. Methods. The amperometric biosensor with glucose oxidase immobilized on zeolites as bioselective elements and platinum disk electrode as transducers of biochemical signal into the electric one was used in the work. Results. The biosensors based on glucose oxidase adsorbed on zeolites were characterized by a higher sensitivity to glucose and a better inter-reproducibility. The best analytical characteristics were obtained for the biosensors based on nano beta zeolite. It has been found that an increase in the amount of zeolite on the surface of amperometric transducer may change such biosensor parameters as sensitivity to the substrate and duration of the analysis. Conclusions. The proposed method of enzyme immobilization by adsorption on zeolites is shown to be quite promising in the development of amperometric biosensors and therefore should be further investigated.

  1. A Resistive Humidity Sensor Based on Nanostructured WO3-ZnO Composites

    Directory of Open Access Journals (Sweden)

    Karunesh Tiwari

    2011-11-01

    Full Text Available Paper reports morphological and humidity sensing studies of WO3 and WO3-ZnO composite pellets prepared in the weight % ratio of 10:1, 4:1 and 2:1 by solid-state reaction route. The pellets have been annealed at temperatures of 300-500 °C. XRD pattern shows peaks of ZnWO4 formed due to solid state reaction between WO3 and ZnO. SEM micrographs show that the sensing elements manifest porous structure. Granulation and tendency to agglomerate seen in the SEM micrograph are due to the presence of zinc ions in ZnWO4. Nanoparticles are having their sizes in the range 37-182 nm. The average Kelvin radius at 20˚C room temperature is 27 Ả. Humidity sensing application of the pellets has been studied in a humidity control cabinet. It is observed that as relative humidity increases, there is decrease in the resistance of pellets in the range 10-85 % RH. Sensing element of WO3-ZnO in 2:1 weight % ratio shows best results in 10-85 % relative humidity range. The average sensitivity of this sample is 1.25 MΩ/%RH. This sensing element shows good reproducibility, low hysteresis and less effect of aging.

  2. Parametric and Wavelet Analyses of Acoustic Emission Signals for the Identification of Failure Modes in CFRP Composites Using PZT and PVDF Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Prasopchaichana, Kritsada; Kwon, Oh Yang [Inha University, Incheon (Korea, Republic of)

    2007-12-15

    Combination of the parametric and the wavelet analyses of acoustic emission (AE) signals was applied to identify the failure modes in carbon fiber reinforced plastic (CFRP) composite laminates during tensile testing. AE signals detected by surface mounted lead-zirconate-titanate (PZT) and polyvinylidene fluoride (PVDF) sensors were analyzed by parametric analysis based on the time of occurrence which classifies AE signals corresponding to failure modes. The frequency band level-energy analysis can distinguish the dominant frequency band for each failure mode. It was observed that the same type of failure mechanism produced signals with different characteristics depending on the stacking sequences and the type of sensors. This indicates that the proposed method can identify the failure modes of the signals if the stacking sequences and the sensors used are known

  3. Continued Development of Meandering Winding Magnetometer (MWM (Register Trademark)) Eddy Current Sensors for the Health Monitoring, Modeling and Damage Detection of Composite Overwrapped Pressure Vessels

    Science.gov (United States)

    Russell, Richard; Wincheski, Russell; Jablonski, David; Washabaugh, Andy; Sheiretov, Yanko; Martin, Christopher; Goldfine, Neil

    2011-01-01

    Composite Overwrapped Pressure Vessels (COPVs) are used in essentially all NASA spacecraft, launch. vehicles and payloads to contain high-pressure fluids for propulsion, life support systems and science experiments. Failure of any COPV either in flight or during ground processing would result in catastrophic damage to the spacecraft or payload, and could lead to loss of life. Therefore, NASA continues to investigate new methods to non-destructively inspect (NDE) COPVs for structural anomalies and to provide a means for in-situ structural health monitoring (SHM) during operational service. Partnering with JENTEK Sensors, engineers at NASA, Kennedy Space Center have successfully conducted a proof-of-concept study to develop Meandering Winding Magnetometer (MWM) eddy current sensors designed to make direct measurements of the stresses of the internal layers of a carbon fiber composite wrapped COPV. During this study three different MWM sensors were tested at three orientations to demonstrate the ability of the technology to measure stresses at various fiber orientations and depths. These results showed good correlation with actual surface strain gage measurements. MWM-Array technology for scanning COPVs can reliably be used to image and detect mechanical damage. To validate this conclusion, several COPVs were scanned to obtain a baseline, and then each COPV was impacted at varying energy levels and then rescanned. The baseline subtracted images were used to demonstrate damage detection. These scans were performed with two different MWM-Arrays. with different geometries for near-surface and deeper penetration imaging at multiple frequencies and in multiple orientations of the linear MWM drive. This presentation will include a review of micromechanical models that relate measured sensor responses to composite material constituent properties, validated by the proof of concept study, as the basis for SHM and NDE data analysis as well as potential improvements including

  4. Ultra-Precision Measurement and Control of Angle Motion in Piezo-Based Platforms Using Strain Gauge Sensors and a Robust Composite Controller

    Science.gov (United States)

    Liu, Lei; Bai, Yu-Guang; Zhang, Da-Li; Wu, Zhi-Gang

    2013-01-01

    The measurement and control strategy of a piezo-based platform by using strain gauge sensors (SGS) and a robust composite controller is investigated in this paper. First, the experimental setup is constructed by using a piezo-based platform, SGS sensors, an AD5435 platform and two voltage amplifiers. Then, the measurement strategy to measure the tip/tilt angles accurately in the order of sub-μrad is presented. A comprehensive composite control strategy design to enhance the tracking accuracy with a novel driving principle is also proposed. Finally, an experiment is presented to validate the measurement and control strategy. The experimental results demonstrate that the proposed measurement and control strategy provides accurate angle motion with a root mean square (RMS) error of 0.21 μrad, which is approximately equal to the noise level. PMID:23860316

  5. Ultra-Precision Measurement and Control of Angle Motion in Piezo-Based Platforms Using Strain Gauge Sensors and a Robust Composite Controller

    Directory of Open Access Journals (Sweden)

    Zhi-Gang Wu

    2013-07-01

    Full Text Available The measurement and control strategy of a piezo-based platform by using strain gauge sensors (SGS and a robust composite controller is investigated in this paper. First, the experimental setup is constructed by using a piezo-based platform, SGS sensors, an AD5435 platform and two voltage amplifiers. Then, the measurement strategy to measure the tip/tilt angles accurately in the order of sub-μrad is presented. A comprehensive composite control strategy design to enhance the tracking accuracy with a novel driving principle is also proposed. Finally, an experiment is presented to validate the measurement and control strategy. The experimental results demonstrate that the proposed measurement and control strategy provides accurate angle motion with a root mean square (RMS error of 0.21 μrad, which is approximately equal to the noise level.

  6. Composites

    International Nuclear Information System (INIS)

    Kasen, M.B.

    1983-01-01

    This chapter discusses the roles of composite laminates and aggregates in cryogenic technology. Filamentary-reinforced composites are emphasized because they are the most widely used composite materials. Topics considered include composite systems and terminology, design and fabrication, composite failure, high-pressure reinforced plastic laminates, low-pressure reinforced plastics, reinforced metals, selectively reinforced structures, the effect of cryogenic temperatures, woven-fabric and random-mat composites, uniaxial fiber-reinforced composites, composite joints in cryogenic structures, joining techniques at room temperature, radiation effects, testing laminates at cryogenic temperatures, static and cyclic tensile testing, static and cyclic compression testing, interlaminar shear testing, secondary property tests, and concrete aggregates. It is suggested that cryogenic composite technology would benefit from the development of a fracture mechanics model for predicting the fitness-for-purpose of polymer-matrix composite structures

  7. Structural health monitoring method for wind turbine trailing edge: Crack growth detection using Fibre Bragg Grating sensor embedded in composite materials

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira; Mikkelsen, Lars Pilgaard; McGugan, Malcolm

    2015-01-01

    In this article a novel method to assess a crack growing/damage event in composite material using Fibre Bragg Grating (FBG) sensors embedded in a host material and its application into a composite material structure, Wind Turbine Trailing Edge, is presented. A Structure-Material-FBG model......, such as compression fields ahead the crack or non-uniform strain fields, and then identify the presence of such damage in the structure. Experimental tests were conducted to fully characterize this concept and support the model. Double Cantilever Beams (DCB), made with two glass fibre beams glued with structural...

  8. Layer-by-layer construction of graphene/cobalt phthalocyanine composite film on activated GCE for application as a nitrite sensor

    International Nuclear Information System (INIS)

    Cui, Lili; Pu, Tao; Liu, Ying; He, Xingquan

    2013-01-01

    Graphical abstract: A novel nitrite sensor was prepared by using LBL technique which for the first time used the activated positively charged glassy carbon electrode (A-GCE) as the substrate. The nitrite sensor shows super stability for consecutive CV testing and rather low detection limit. -- Abstract: In this paper, a novel graphene/cobalt phthalocyanine composite film was prepared by layer-by-layer (LBL) technique which for the first time used the activated positively charged glassy carbon electrode (A-GCE) as the substrate. The surface morphology of graphene/cobalt phthalocyanine composite film was characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM). It is found that graphene/cobalt phthalocyanine composite film modified GCE exhibits good catalytic activity toward the oxidation of nitrite. The oxidation current barely decreases in consecutive CV test. Furthermore, the modified GCE shows long-term stability after 70 days. The super good stability can be attributed to the immobilization and dispersion of electroactive cobalt phthalocyanine by graphene, and using A-GCE as substrate which can enhance the interaction force between GCE and electroactive cobalt phthalocyanine. The nitrite sensor shows rather low detection limit of 0.084 μM at a signal-to-noise ratio = 3 (S/N = 3)

  9. Carbon Nanotube Modified Screen Printed Electrodes: Pyranose Oxidase Immobilization Platform for Amperometric Enzyme Sensors

    Directory of Open Access Journals (Sweden)

    Dilek ODACI DEMIRKOL

    2017-03-01

    Full Text Available Here, a novel enzymatic biosensor was developed using multiwalled carbon nanotube including screen printed electrodes (MWCNT-SPE. Pyranose oxidase (PyOx was immobilized on the electrode surface by way of gelatin membrane and then cross-linked using glutaraldehyde. Glucose was detected at -0.7 V (vs. Ag/AgCl by watching consumed oxygen in enzymatic reaction after addition substrate. After optimization of pH and enzyme loading, the linearity was found in the range of 0.1–1.0 mM of glucose. After that, the effect of MCNT on the current was tested. Also the enzymatic biosensor including glucose oxidase instead of pyranose oxidase was prepared and the biosensor response followed for glucose. Furthermore, this system was tested for glucose analysis in soft drinks.

  10. Amperometric Sensor for Heparin: Sensing Mechanism and Application in Human Blood Plasma Analysis

    Czech Academy of Sciences Publication Activity Database

    Langmaier, Jan; Olšák, J.; Samcová, E.; Samec, Zdeněk; Trojánek, Antonín

    2006-01-01

    Roč. 18, 13-14 (2006), s. 1329-1338 ISSN 1040-0397 R&D Projects: GA ČR GA203/04/0424 Institutional research plan: CEZ:AV0Z40400503 Keywords : heparin * amperometry * PVC membrane electrode * sensing mechanism * human blood plasma Subject RIV: CG - Electrochemistry Impact factor: 2.444, year: 2006

  11. Amperometric Sensor Used for Determination of Thiocyanate with a Silver Nanoparticles Modified Electrode

    OpenAIRE

    Wang, Guang-Feng; Li, Mao-Guo; Gao, Ying-Chun; Fang, Bin

    2004-01-01

    Abstract: A novel electrode modified with silver nanoparticles was fabricated. It is found that the reducibility of silver nanoparticles is higher than for bulk silver by comparing a silver nanoparticles modified electrode with a silver micro-disk electrode. When SCN- was added, a new oxidation peak occurred and the anodic peak current of silver nanoparticles decreased. The new anodic peak current is proportional to the thiocyanate concentration in the range of 5.0×10-7~4.0×10-4 mol/L i...

  12. Flow-injection amperometric determination of glucose using a biosensor based on immobilization of glucose oxidase onto Au seeds decorated on core Fe₃O₄ nanoparticles.

    Science.gov (United States)

    Samphao, Anchalee; Butmee, Preeyanut; Jitcharoen, Juthamas; Švorc, Ľubomír; Raber, Georg; Kalcher, Kurt

    2015-09-01

    An amperometric biosensor based on chemisorption of glucose oxidase (GOx) on Au seeds decorated on magnetic core Fe3O4 nanoparticles (Fe3O4@Au) and their immobilization on screen-printed carbon electrode bulk-modified with manganese oxide (SPCE{MnO2}) was designed for the determination of glucose. The Fe3O4@Au/GOx modified SPCE{MnO2} was used in a flow-injection analysis (FIA) arrangement. The experimental conditions were investigated in amperometric mode with the following optimized parameters: flow rate 1.7 mL min(-1), applied potential +0.38 V, phosphate buffer solution (PBS; 0.1 mol L(-1), pH 7.0) as carrier and 3.89 unit mm(-2) enzyme glucose oxidase loading on the active surface of the SPCE. The designed biosensor in FIA arrangement yielded a linear dynamic range for glucose from 0.2 to 9.0 mmol L(-1) with a sensitivity of 2.52 µA mM(-1) cm(-2), a detection limit of 0.1 mmol L(-1) and a quantification limit of 0.3 mmol L(-1). Moreover, a good repeatability of 2.8% (number of measurements n=10) and a sufficient reproducibility of 4.0% (number of sensors n=3) were achieved. It was found that the studied system Fe3O4@Au facilitated not only a simpler enzyme immobilization but also provided wider linear range. The practical application of the proposed biosensor for FIA quantification of glucose was tested in glucose sirup samples, honeys and energy drinks with the results in good accordance with those obtained by an optical glucose meter and with the contents declared by the producers. Copyright © 2015. Published by Elsevier B.V.

  13. Amperometric detection of nitrite based on Dawson-type vanodotungstophosphate and carbon nanotubes

    International Nuclear Information System (INIS)

    Zhang, Di; Ma, Huiyuan; Chen, Yanyan; Pang, Haijun; Yu, Yan

    2013-01-01

    Graphical abstract: A composite film has been constructed by vanodotungstophosphate α 2 -K 7 P 2 VW 17 O 62 ·18H 2 O (P 2 W 17 V) and carbon nanotubes (CNTs) using the layer-by-layer self-assembly method. The incorporation of CNTs and P 2 W 17 V into the composite film endowed the modified electrode fast electron transfer rate and high electrocatalytic activity of toward nitrite oxidation. This nitrite sensor shows broad linear range, low detection limit, and high sensitivity and stability. Also it did not show any interference with other potential interfering species, and was successfully employed for determination of nitrite in real samples. -- Highlights: •A composite film was constructed by a vanodotungstophosphate and carbon nanotubes. •The composite film showed fast electron transfer rate and high electrocatalytic activity of toward nitrite oxidation. •The proposed sensor can amperometricially detect nitrite with high sensitivity and selectivity. -- Abstract: A nitrite sensor based on Dawson vanodotungstophosphates α 2 -K 7 P 2 VW 17 O 62 ·18H 2 O (P 2 W 17 V) and carbon nanotubes (CNTs) was prepared by electrostatic layer-by-layer self-assembly technique. The sensor {PEI/PSS/[PDDA/P 2 W 17 V-CNTs] n } was characterized by UV–vis spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray photoelectron spectra (XPS). The electron transfer and sensing ability of this sensor were explored using cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) technology. The results show that the incorporation of CNTs and P 2 W 17 V into the composite film endowed the modified electrode with fast transfer rate and high electrocatalytic activity towards oxidation of nitrite. This nitrite sensor with 10 bilayers has a broad linear range of 5 × 10 −8 to 2.13 × 10 −3 M, a low detection limit of 0.0367 μM (S N −1 = 3), a high sensitivity of 0.35 mA mM −1 NO 2 − , an excellent anti-interference property in the

  14. A reagentless amperometric immunosensor based on nano-au and ...

    African Journals Online (AJOL)

    In this paper, carboxyl-ferrocene (Fc-COOH) was explored to label alphafetoprotein antibody (anti-AFP), which was then mixed with AU nanoparticles (nano-Au) and multi-walled carbon nanotubes (MWCNTs) dispersed by chitosan (CS) to form the nano-Au/MWCNTs/anti-AFP-Fc chitosan composite. After that, the composite ...

  15. A novel electrochemical sensor of bisphenol A based on stacked graphene nanofibers/gold nanoparticles composite modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Niu, Xiuli; Yang, Wu; Wang, Guoying; Ren, Jie; Guo, Hao; Gao, Jinzhang

    2013-01-01

    In this paper, a novel and convenient electrochemical sensor based on stacked graphene nanofibers (SGNF) and gold nanoparticles (AuNPs) composite modified glassy carbon electrode (GCE) was developed for the determination of bisphenol A (BPA). The AuNPs/SGNF modified electrode showed an efficient electrocatalytic role for the oxidation of BPA, and the oxidation overpotentials of BPA were decreased significantly and the peak current increased greatly compared with bare GCE and other modified electrode. The transfer electron number (n) and the charge transfer coefficient (α) were calculated with the result as n = 4, α = 0.52 for BPA, which indicated the electrochemical oxidation of BPA on AuNPs/SGNF modified electrode was a four-electron and four-proton process. The effective surface areas of AuNPs/SGNF/GCE increased for about 1.7-fold larger than that of the bare GCE. In addition, the kinetic parameters of the modified electrode were calculated and the apparent heterogeneous electron transfer rate constant (k s ) was 0.51 s −1 . Linear sweep voltammetry was applied as a sensitive analytical method for the determination of BPA and a good linear relationship between the peak current and BPA concentration was obtained in the range from 0.08 to 250 μM with a detection limit of 3.5 × 10 −8 M. The modified electrode exhibited a high sensitivity, long-term stability and remarkable reproducible analytical performance and was successfully applied for the determination of BPA in baby bottles with satisfying results

  16. A Reagentless Amperometric Formaldehyde-Selective Chemosensor Based on Platinized Gold Electrodes

    OpenAIRE

    Demkiv, Olha; Smutok, Oleh; Gonchar, Mykhailo; Nisnevitch, Marina

    2017-01-01

    Fabrication and characterization of a new amperometric chemosensor for accurate formaldehyde analysis based on platinized gold electrodes is described. The platinization process was performed electrochemically on the surface of 4 mm gold planar electrodes by both electrolysis and cyclic voltamperometry. The produced electrodes were characterized using scanning electron microscopy and X-ray spectral analysis. Using a low working potential (0.0 V vs. Ag/AgCl) enabled an essential increase in th...

  17. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2011-01-01

    Strategies are open compositions to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them in full...

  18. Composition

    DEFF Research Database (Denmark)

    2014-01-01

    Memory Pieces are open compositions to be realised solo by an improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them...

  19. Analogs of N-cynnamoylphenylhydroxylamine as reagents for amperometric determination of scandium

    International Nuclear Information System (INIS)

    Shvedene, N.V.; Gallaj, Z.A.; Sheina, N.M.; Zujkova, N.V.

    1978-01-01

    To decrease the detection limit of scandium and increase selectivity of amperometric determination, oxidation of 2-furylacryloyl-N-p-chlorophenylhydroxylamine (FACPhHA) and 3-styrylacryloyl-N-phenylhydroxylamine (SAPhHA) on a graphite electrode has been studied by volt-amperometry. The possibility has been established of using the oxidation current of the reagent for plotting the titration curves. The solubility of scandium complexes with FACPhHA and SAPhHA under conditions of titration against the background with pH 6.0 has been determined and equals (2.1+-0.3)x10 -6 and (5.3+-0.3)x10 -7 , respectively. The methods have been developed of amperometric determination of scandium with the use of the considered reagents against backgrounds with pH 5.5-6.5. The use of SAPhHA has decreased the limit of scandium detection down to 0.1 mgk/ml. Besides, the amperometric method makes it possible to titrate in turbid and coloured media what is an advantage of this method. The developed method is used for determination of scandium in scandium silicide

  20. Load sensor

    OpenAIRE

    Van den Ende, D.; Almeida, P.M.R.; Dingemans, T.J.; Van der Zwaag, S.

    2007-01-01

    The invention relates to a load sensor comprising a polymer matrix and a piezo-ceramic material such as PZT, em not bedded in the polymer matrix, which together form a compos not ite, wherein the polymer matrix is a liquid crystalline resin, and wherein the piezo-ceramic material is a PZT powder forming 30-60% by volume of the composite, and wherein the PZT powder forms 40-50% by volume of the composite.

  1. Synthesis of the cactus-like silicon nanowires/tungsten oxide nanowires composite for room-temperature NO{sub 2} gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Weiyi, E-mail: zhangweiyi@tju.edu.cn [School of Electronic Information Engineering, Tianjin University, Tianjin, 300072 (China); Hu, Ming [School of Electronic Information Engineering, Tianjin University, Tianjin, 300072 (China); Key Laboratory for Advanced Ceramics and Machining Technology, Ministry of Education, School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Liu, Xing; Wei, Yulong; Li, Na [School of Electronic Information Engineering, Tianjin University, Tianjin, 300072 (China); Qin, Yuxiang, E-mail: qinyuxiang@tju.edu.cn [School of Electronic Information Engineering, Tianjin University, Tianjin, 300072 (China); Key Laboratory for Advanced Ceramics and Machining Technology, Ministry of Education, School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)

    2016-09-15

    In the present work, the tungsten oxide (WO{sub 3}) nanowires functionalized silicon nanowires (SiNWs) with cactus-like structure has been successfully synthesized for room-temperature NO{sub 2} detection. The novel nanocomposite was fabricated by metal-assisted chemical etching (MACE) and thermal annealing of tungsten film. The WO{sub 3} nanowires were evenly distributed from the upper to the lower part of the SiNWs, indicating excellent uniformity which is conducive to adsorption and desorption of gas molecules. The gas-sensing properties have been examined by measuring the resistance change towards 0.25–5 ppm NO{sub 2} gas. At room temperature, which is the optimum working temperature, the SiNWs/WO{sub 3} nanowires composite showed two-times higher NO{sub 2} response than that of the bare SiNWs at 2 ppm NO{sub 2}. On the contrary, the responses of composite sensors to high concentrations of other reducing gases were very low, indicating excellent selectivity. Simultaneously, the composite sensors exhibited good sensing repeatability and stability. The enhancement in gas sensing properties may be attributed to the change in width of the space charge region, which is similar to the behavior of p-n junctions under forward bias, in the high-density p-n heterojunction structure formed between SiNWs and WO{sub 3} nanowires. - Highlights: • SiNWs/WO{sub 3} nanowires composite with cactus-like structure is synthesized. • The morphology of WO{sub 3} nanowires depends on the thermal annealing temperature. • The nanocomposite sensor exhibit better gas response than that of bare SiNWs. • The gas sensing mechanism is discussed using p-n heterojunction theory.

  2. Vesicle Motion during Sustained Exocytosis in Chromaffin Cells: Numerical Model Based on Amperometric Measurements.

    Directory of Open Access Journals (Sweden)

    Daungruthai Jarukanont

    Full Text Available Chromaffin cells release catecholamines by exocytosis, a process that includes vesicle docking, priming and fusion. Although all these steps have been intensively studied, some aspects of their mechanisms, particularly those regarding vesicle transport to the active sites situated at the membrane, are still unclear. In this work, we show that it is possible to extract information on vesicle motion in Chromaffin cells from the combination of Langevin simulations and amperometric measurements. We developed a numerical model based on Langevin simulations of vesicle motion towards the cell membrane and on the statistical analysis of vesicle arrival times. We also performed amperometric experiments in bovine-adrenal Chromaffin cells under Ba2+ stimulation to capture neurotransmitter releases during sustained exocytosis. In the sustained phase, each amperometric peak can be related to a single release from a new vesicle arriving at the active site. The amperometric signal can then be mapped into a spike-series of release events. We normalized the spike-series resulting from the current peaks using a time-rescaling transformation, thus making signals coming from different cells comparable. We discuss why the obtained spike-series may contain information about the motion of all vesicles leading to release of catecholamines. We show that the release statistics in our experiments considerably deviate from Poisson processes. Moreover, the interspike-time probability is reasonably well described by two-parameter gamma distributions. In order to interpret this result we computed the vesicles' arrival statistics from our Langevin simulations. As expected, assuming purely diffusive vesicle motion we obtain Poisson statistics. However, if we assume that all vesicles are guided toward the membrane by an attractive harmonic potential, simulations also lead to gamma distributions of the interspike-time probability, in remarkably good agreement with experiment. We

  3. Vesicle Motion during Sustained Exocytosis in Chromaffin Cells: Numerical Model Based on Amperometric Measurements.

    Science.gov (United States)

    Jarukanont, Daungruthai; Bonifas Arredondo, Imelda; Femat, Ricardo; Garcia, Martin E

    2015-01-01

    Chromaffin cells release catecholamines by exocytosis, a process that includes vesicle docking, priming and fusion. Although all these steps have been intensively studied, some aspects of their mechanisms, particularly those regarding vesicle transport to the active sites situated at the membrane, are still unclear. In this work, we show that it is possible to extract information on vesicle motion in Chromaffin cells from the combination of Langevin simulations and amperometric measurements. We developed a numerical model based on Langevin simulations of vesicle motion towards the cell membrane and on the statistical analysis of vesicle arrival times. We also performed amperometric experiments in bovine-adrenal Chromaffin cells under Ba2+ stimulation to capture neurotransmitter releases during sustained exocytosis. In the sustained phase, each amperometric peak can be related to a single release from a new vesicle arriving at the active site. The amperometric signal can then be mapped into a spike-series of release events. We normalized the spike-series resulting from the current peaks using a time-rescaling transformation, thus making signals coming from different cells comparable. We discuss why the obtained spike-series may contain information about the motion of all vesicles leading to release of catecholamines. We show that the release statistics in our experiments considerably deviate from Poisson processes. Moreover, the interspike-time probability is reasonably well described by two-parameter gamma distributions. In order to interpret this result we computed the vesicles' arrival statistics from our Langevin simulations. As expected, assuming purely diffusive vesicle motion we obtain Poisson statistics. However, if we assume that all vesicles are guided toward the membrane by an attractive harmonic potential, simulations also lead to gamma distributions of the interspike-time probability, in remarkably good agreement with experiment. We also show that

  4. Sub-parts per million NO2 chemi-transistor sensors based on composite porous silicon/gold nanostructures prepared by metal-assisted etching.

    Science.gov (United States)

    Sainato, Michela; Strambini, Lucanos Marsilio; Rella, Simona; Mazzotta, Elisabetta; Barillaro, Giuseppe

    2015-04-08

    Surface doping of nano/mesostructured materials with metal nanoparticles to promote and optimize chemi-transistor sensing performance represents the most advanced research trend in the field of solid-state chemical sensing. In spite of the promising results emerging from metal-doping of a number of nanostructured semiconductors, its applicability to silicon-based chemi-transistor sensors has been hindered so far by the difficulties in integrating the composite metal-silicon nanostructures using the complementary metal-oxide-semiconductor (CMOS) technology. Here we propose a facile and effective top-down method for the high-yield fabrication of chemi-transistor sensors making use of composite porous silicon/gold nanostructures (cSiAuNs) acting as sensing gate. In particular, we investigate the integration of cSiAuNs synthesized by metal-assisted etching (MAE), using gold nanoparticles (NPs) as catalyst, in solid-state junction-field-effect transistors (JFETs), aimed at the detection of NO2 down to 100 parts per billion (ppb). The chemi-transistor sensors, namely cSiAuJFETs, are CMOS compatible, operate at room temperature, and are reliable, sensitive, and fully recoverable for the detection of NO2 at concentrations between 100 and 500 ppb, up to 48 h of continuous operation.

  5. The Effect of Zeolite Composition and Grain Size on Gas Sensing Properties of SnO2/Zeolite Sensor

    Directory of Open Access Journals (Sweden)

    Yanhui Sun

    2018-01-01

    Full Text Available In order to improve the sensing properties of tin dioxide gas sensor, four kinds of different SiO2/Al2O3 ratio, different particle size of MFI type zeolites (ZSM-5 were coated on the SnO2 to prepared zeolite modified gas sensors, and the gas sensing properties were tested. The measurement results showed that the response values of ZSM-5 zeolite (SiO2/Al2O3 = 70, grain size 300 nm coated SnO2 gas sensors to formaldehyde vapor were increased, and the response to acetone decreased compared with that of SnO2 gas sensor, indicating an improved selectivity property. The other three ZSM-5 zeolites with SiO2/Al2O3 70, 150 and 470, respectively, and grain sizes all around 1 μm coated SnO2 sensors did not show much difference with SnO2 sensor for the response properties to both formaldehyde and acetone. The sensing mechanism of ZSM-5 modified sensors was briefly analyzed.

  6. Comparison between amperometric and true potentiometric end-point detection in the determination of water by the Karl Fischer method.

    Science.gov (United States)

    Cedergren, A

    1974-06-01

    A rapid and sensitive method using true potentiometric end-point detection has been developed and compared with the conventional amperometric method for Karl Fischer determination of water. The effect of the sulphur dioxide concentration on the shape of the titration curve is shown. By using kinetic data it was possible to calculate the course of titrations and make comparisons with those found experimentally. The results prove that the main reaction is the slow step, both in the amperometric and the potentiometric method. Results obtained in the standardization of the Karl Fischer reagent showed that the potentiometric method, including titration to a preselected potential, gave a standard deviation of 0.001(1) mg of water per ml, the amperometric method using extrapolation 0.002(4) mg of water per ml and the amperometric titration to a pre-selected diffusion current 0.004(7) mg of water per ml. Theories and results dealing with dilution effects are presented. The time of analysis was 1-1.5 min for the potentiometric and 4-5 min for the amperometric method using extrapolation.

  7. Platinum decorated carbon nanotubes for highly sensitive amperometric glucose sensing

    International Nuclear Information System (INIS)

    Xie Jining; Wang Shouyan; Aryasomayajula, L; Varadan, V K

    2007-01-01

    Fine platinum nanoparticles (1-5 nm in diameter) were deposited on functionalized multi-walled carbon nanotubes (MWNTs) through a decoration technique. A novel type of enzymatic Pt/MWNTs paste-based mediated glucose sensor was fabricated. Electrochemical measurements revealed a significantly improved sensitivity (around 52.7 μA mM -1 cm -2 ) for glucose sensing without using any picoampere booster or Faraday cage. In addition, the calibration curve exhibited a good linearity in the range of 1-28 mM of glucose concentration. Transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS) were performed to investigate the nanoscale structure and the chemical bonding information of the Pt/MWNTs paste-based sensing material, respectively. The improved sensitivity of this novel glucose sensor could be ascribed to its higher electroactive surface area, enhanced electron transfer, efficient enzyme immobilization, unique interaction in nanoscale and a synergistic effect on the current signal from possible multi-redox reactions

  8. Identification of minute damage in composite bridge structures equipped with fiber optic sensors using the location of neutral axis and finite element analysis

    Science.gov (United States)

    Li, Xi; Glisic, Branko

    2016-04-01

    By definition, the neutral axis of a loaded composite beam structure is the curve along which the section experiences zero bending strain. When no axial loading is present, the location of the neutral axis passes through the centroid of stiffness of the beam cross-section. In the presence of damage, the centroid of stiffness, as well as the neutral axis, shift from the healthy position. The concept of neutral axis can be widely applied to all beam-like structures. According to literature, a change in location of the neutral axis can be associated with damage in the corresponding cross-section. In this paper, the movement of neutral axis near locations of minute damage in a composite bridge structure was studied using finite element analysis and experimental results. The finite element model was developed based on a physical scale model of a composite simply-supported structure with controlled minute damage in the reinforced concrete deck. The structure was equipped with long-gauge fiber optic strain and temperature sensors at a healthy reference location as well as two locations of damage. A total of 12 strain sensors were installed during construction and used to monitor the structure during various loading events. This paper aims to explain previous experimental results which showed that the observed positions of neutral axis near damage locations were higher than the predicted healthy locations in some loading events. Analysis has shown that finite element analysis has potential to simulate and explain the physical behavior of the test structure.

  9. Durability Evaluation of a Thin Film Sensor System With Enhanced Lead Wire Attachments on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Lei, Jih-Fen; Kiser, J. Douglas; Singh, Mrityunjay; Cuy, Mike; Blaha, Charles A.; Androjna, Drago

    2000-01-01

    An advanced thin film sensor system instrumented on silicon carbide (SiC) fiber reinforced SiC matrix ceramic matrix composites (SiC/SiC CMCs), was evaluated in a Mach 0.3 burner rig in order to determine its durability to monitor material/component surface temperature in harsh environments. The sensor system included thermocouples in a thin film form (5 microns thick), fine lead wires (75 microns diameter), and the bonds between these wires and the thin films. Other critical components of the overall system were the heavy, swaged lead wire cable (500 microns diameter) that contained the fine lead wires and was connected to the temperature readout, and ceramic attachments which were bonded onto the CMCs for the purpose of securing the lead wire cables, The newly developed ceramic attachment features a combination of hoops made of monolithic SiC or SiC/SiC CMC (which are joined to the test article) and high temperature ceramic cement. Two instrumented CMC panels were tested in a burner rig for a total of 40 cycles to 1150 C (2100 F). A cycle consisted of rapid heating to 1150 C (2100 F), a 5 minute hold at 1150 C (2100 F), and then cooling down to room temperature in 2 minutes. The thin film sensor systems provided repeatable temperature measurements for a maximum of 25 thermal cycles. Two of the monolithic SiC hoops debonded during the sensor fabrication process and two of the SiC/SiC CMC hoops failed during testing. The hoops filled with ceramic cement, however, showed no sign of detachment after 40 thermal cycle test. The primary failure mechanism of this sensor system was the loss of the fine lead wire-to-thin film connection, which either due to detachment of the fine lead wires from the thin film thermocouples or breakage of the fine wire.

  10. Combining Electrochemical Sensors with Miniaturized Sample Preparation for Rapid Detection in Clinical Samples

    Science.gov (United States)

    Bunyakul, Natinan; Baeumner, Antje J.

    2015-01-01

    Clinical analyses benefit world-wide from rapid and reliable diagnostics tests. New tests are sought with greatest demand not only for new analytes, but also to reduce costs, complexity and lengthy analysis times of current techniques. Among the myriad of possibilities available today to develop new test systems, amperometric biosensors are prominent players—best represented by the ubiquitous amperometric-based glucose sensors. Electrochemical approaches in general require little and often enough only simple hardware components, are rugged and yet provide low limits of detection. They thus offer many of the desirable attributes for point-of-care/point-of-need tests. This review focuses on investigating the important integration of sample preparation with (primarily electrochemical) biosensors. Sample clean up requirements, miniaturized sample preparation strategies, and their potential integration with sensors will be discussed, focusing on clinical sample analyses. PMID:25558994

  11. An Electrochemical Sensor Based on Nanostructured Hollandite-type Manganese Oxide for Detection of Potassium Ions

    Directory of Open Access Journals (Sweden)

    Alex S. Lima

    2009-08-01

    Full Text Available The participation of cations in redox reactions of manganese oxides provides an opportunity for development of chemical sensors for non-electroactive ions. A sensor based on a nanostructured hollandite-type manganese oxide was investigated for voltammetric detection of potassium ions. The detection is based on the measurement of anodic current generated by oxidation of Mn(III to Mn(IV at the surface of the electrode and the subsequent extraction of the potassium ions into the hollandite structure. In this work, an amperometric procedure at an operating potential of 0.80 V (versus SCE is exploited for amperometric monitoring. The current signals are linearly proportional to potassium ion concentration in the range 4.97 × 10−5 to 9.05 × 10−4 mol L−1, with a correlation coefficient of 0.9997.

  12. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2014-01-01

    Cue Rondo is an open composition to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound/video files will in some cases only provide a few minutes' sample, or the visuals will not appear at all....... Please DOWNLOAD them to see/hear them in full length! This work is licensed under a Creative Commons "by-nc" License. You may for non-commercial purposes use and distribute it, performance instructions as well as specially designated recordings, as long as the author is mentioned. Please see http...

  13. Separation and determination of alditols and sugars by high-pH anion-exchange chromatography with pulsed amperometric detection

    DEFF Research Database (Denmark)

    Andersen, Rikke; Sørensen, A.

    2000-01-01

    Carbohydrates such as alditols (polyols or sugar alcohols), monosaccharides and disaccharides are separated as anions by anion-exchange chromatography with a sodium hydroxide eluent, MA1 CarboPac column and pulsed amperometric detection. We report a high-pH anion-exchange chromatographic-pulsed a......Carbohydrates such as alditols (polyols or sugar alcohols), monosaccharides and disaccharides are separated as anions by anion-exchange chromatography with a sodium hydroxide eluent, MA1 CarboPac column and pulsed amperometric detection. We report a high-pH anion-exchange chromatographic......-pulsed amperometric detection (HPAEC-PAD) method that determines all the polyols used as food additives in food products and the most commonly found mono- and disaccharides on a routine basis. The linearity, repeatability, internal reproducibility and accuracy are described. The applicability of the method has been...

  14. Glucose oxidase-modified carbon-felt-reactor coupled with peroxidase-modified carbon-felt-detector for amperometric flow determination of glucose

    International Nuclear Information System (INIS)

    Wang Yue; Hasebe, Yasushi

    2012-01-01

    Glucose oxidase (GOx) and horseradish peroxidase (HRP) were covalently immobilized on a porous carbon-felt (CF) by using cyanuric chloride (CC) as a linking reagent. The resulting GOx-modified-CF (GOx-ccCF) was used as column-type enzyme reactor and placed on upstream of the HRP-ccCF-based H 2 O 2 flow-detector to fabricate amperometric flow-biosensor for glucose. Sensor setting conditions and the operational conditions were optimized, and the analytical performance characteristics of the resulting flow-biosensor were evaluated. The chemical modification of the GOx via CC was found to be effective to obtain larger catalytic activity as compared with the physical adsorption. Under the optimized conditions (i.e., volume ratio of the GOx-ccCF-reactor to the HRP-ccCF-detector is 1.0; applied potential is − 0.12 V vs. Ag/AgCl; carrier pH is 6.5; and carrier flow rate is 4.3 ml/min), highly selective and quite reproducible peak current responses toward glucose were obtained: the RSD for 30 consecutive injections of 3 mM glucose was 1.04%, and no serious interferences were observed for fructose, ethanol, uric acid, urea and tartaric acid for the amperometric measurements of glucose. The magnitude of the cathodic peak currents for glucose was linear up to 5 mM (sensitivity, 6.38 ± 0.32 μA/μM) with the limit detection of 9.4 μM (S/N = 3, noise level, 20 nA). The present GOx-ccCF-reactor and HRP-ccCF-detector-coupled flow-glucose biosensor was utilized for the determination of glucose in beverages and liquors, and the analytical results by the sensor were in fairly good agreement with those by the conventional spectrophotometry. - Highlights: ► Glucose oxidase (GOx) and peroxidase (HRP) were modified on carbon-felt. ► GOx-CF reactor and HRP-CF detector-coupled flow glucose biosensor was developed. ► This flow biosensor enabled the determination of glucose in beverages and liquors.

  15. Glucose oxidase-modified carbon-felt-reactor coupled with peroxidase-modified carbon-felt-detector for amperometric flow determination of glucose

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yue [School of Chemical Engineering, University of Science and Technology LiaoNing, 185 Qianshan Middle Road, High-tech Zone, Anshan, LiaoNing, 114501 (China); Hasebe, Yasushi, E-mail: hasebe@sit.ac.jp [Department of Life Science and Green Chemistry, Faculty of Engineering, Saitama Institute of Technology, 1690, Fusaiji, Fukaya, Saitama 369-0293 (Japan)

    2012-04-01

    Glucose oxidase (GOx) and horseradish peroxidase (HRP) were covalently immobilized on a porous carbon-felt (CF) by using cyanuric chloride (CC) as a linking reagent. The resulting GOx-modified-CF (GOx-ccCF) was used as column-type enzyme reactor and placed on upstream of the HRP-ccCF-based H{sub 2}O{sub 2} flow-detector to fabricate amperometric flow-biosensor for glucose. Sensor setting conditions and the operational conditions were optimized, and the analytical performance characteristics of the resulting flow-biosensor were evaluated. The chemical modification of the GOx via CC was found to be effective to obtain larger catalytic activity as compared with the physical adsorption. Under the optimized conditions (i.e., volume ratio of the GOx-ccCF-reactor to the HRP-ccCF-detector is 1.0; applied potential is - 0.12 V vs. Ag/AgCl; carrier pH is 6.5; and carrier flow rate is 4.3 ml/min), highly selective and quite reproducible peak current responses toward glucose were obtained: the RSD for 30 consecutive injections of 3 mM glucose was 1.04%, and no serious interferences were observed for fructose, ethanol, uric acid, urea and tartaric acid for the amperometric measurements of glucose. The magnitude of the cathodic peak currents for glucose was linear up to 5 mM (sensitivity, 6.38 {+-} 0.32 {mu}A/{mu}M) with the limit detection of 9.4 {mu}M (S/N = 3, noise level, 20 nA). The present GOx-ccCF-reactor and HRP-ccCF-detector-coupled flow-glucose biosensor was utilized for the determination of glucose in beverages and liquors, and the analytical results by the sensor were in fairly good agreement with those by the conventional spectrophotometry. - Highlights: Black-Right-Pointing-Pointer Glucose oxidase (GOx) and peroxidase (HRP) were modified on carbon-felt. Black-Right-Pointing-Pointer GOx-CF reactor and HRP-CF detector-coupled flow glucose biosensor was developed. Black-Right-Pointing-Pointer This flow biosensor enabled the determination of glucose in beverages and

  16. Using membrane composition to fine-tune the pKa of an optical liposome pH sensor.

    Science.gov (United States)

    Clear, Kasey J; Virga, Katelyn; Gray, Lawrence; Smith, Bradley D

    2016-04-14

    Liposomes containing membrane-anchored pH-sensitive optical probes are valuable sensors for monitoring pH in various biomedical samples. The dynamic range of the sensor is maximized when the probe p K a is close to the expected sample pH. While some biomedical samples are close to neutral pH there are several circumstances where the pH is 1 or 2 units lower. Thus, there is a need to fine-tune the probe p K a in a predictable way. This investigation examined two lipid-conjugated optical probes, each with appended deep-red cyanine dyes containing indoline nitrogen atoms that are protonated in acid. The presence of anionic phospholipids in the liposomes stabilized the protonated probes and increased the probe p K a values by sensor for optimal pH sensing performance.

  17. A laser-based sensor for measurement of off-gas composition and temperature in basic oxygen steelmaking

    International Nuclear Information System (INIS)

    Ottesen, D.; Allendorf, S.; Ludowise, P.; Hardesty, D.; Miller, T.; Goldstein, D.; Smith, C.; Bonin, M.

    1999-01-01

    We are developing an optical sensor for process control in basic oxygen steelmaking. The sensor measures gas temperature and relative CO/CO 2 concentration ratios in the furnace off-gas by transmitting the laser probe beam directly above the furnace lip and below the exhaust hood during oxygen blowing. Dynamic off-gas information is being evaluated for optimizing variables such as lance height, oxygen flow, post-combustion control, and prediction of final melt-carbon content. The non-invasive nature of the optical sensor renders it robust and relatively maintenance-free. Additional potential applications of the method are process control for electric arc furnace and bottom-blown oxygen steelmaking processes. (author)

  18. Alginate copper oxide nano-biocomposite as a novel material for amperometric glucose biosensing

    International Nuclear Information System (INIS)

    Buk, Vuslat; Emregul, Emel; Emregul, Kaan Cebesoy

    2017-01-01

    A novel amperometric glucose biosensor based on alginate-CuO nano-biocomposite and glucose oxidase (GOD) film was developed and characterized. The properties of the alginate-CuO-GOD film were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Amperometric measurements were employed to characterize the analytical performance of the biosensor. Several parameters including amount of alginate, concentration of GOD and cross-linkers, amount of CuO nanoparticles, and effect of pH were studied and optimized. Under optimal conditions, the developed alginate-CuO-GOD biosensor was shown to have two linear ranges; from 0.04 mM to 3 mM (with a correlation coefficient of 0.9996 and the sensitivity of 30.443 μA mM −1 cm −2 ) and from 4 mM to 35 mM (with a correlation coefficient of 0.9994 and the sensitivity of 7.205 μA mM −1 cm −2 ). The overall detection limit was estimated to be 1.6 μM (signal-to-noise ratio of 3) and the K m value of 2.82 mM. The biosensor exhibited rather good performance with long-term stability (remainder of activity is 78% after 15 days) and significant specificity for glucose when compared to possible interfering molecules such as ascorbic acid, uric acid and acetaminophen. - Highlights: • An amperometric biosensor was constructed by using Alginate-CuO nano-biocomposite complexed with Glucose Oxidase • Glucose Oxidase immobilized to the surface via cross-linking. • Alginate-CuO film was characterized by SEM and FTIR. • The biosensor exhibits excellent analytical performance to glucose with a wide linear range and high sensitivity.

  19. Alginate copper oxide nano-biocomposite as a novel material for amperometric glucose biosensing

    Energy Technology Data Exchange (ETDEWEB)

    Buk, Vuslat [Ankara University, Department of Chemistry, Science Faculty, Tandoğan, Ankara 06100 (Turkey); Tyndall National Institute, University College Cork, Dyke Parade, Cork (Ireland); Emregul, Emel, E-mail: eemregul@yahoo.com [Ankara University, Department of Chemistry, Science Faculty, Tandoğan, Ankara 06100 (Turkey); Emregul, Kaan Cebesoy [Ankara University, Department of Chemistry, Science Faculty, Tandoğan, Ankara 06100 (Turkey)

    2017-05-01

    A novel amperometric glucose biosensor based on alginate-CuO nano-biocomposite and glucose oxidase (GOD) film was developed and characterized. The properties of the alginate-CuO-GOD film were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Amperometric measurements were employed to characterize the analytical performance of the biosensor. Several parameters including amount of alginate, concentration of GOD and cross-linkers, amount of CuO nanoparticles, and effect of pH were studied and optimized. Under optimal conditions, the developed alginate-CuO-GOD biosensor was shown to have two linear ranges; from 0.04 mM to 3 mM (with a correlation coefficient of 0.9996 and the sensitivity of 30.443 μA mM{sup −1} cm{sup −2}) and from 4 mM to 35 mM (with a correlation coefficient of 0.9994 and the sensitivity of 7.205 μA mM{sup −1} cm{sup −2}). The overall detection limit was estimated to be 1.6 μM (signal-to-noise ratio of 3) and the K{sub m} value of 2.82 mM. The biosensor exhibited rather good performance with long-term stability (remainder of activity is 78% after 15 days) and significant specificity for glucose when compared to possible interfering molecules such as ascorbic acid, uric acid and acetaminophen. - Highlights: • An amperometric biosensor was constructed by using Alginate-CuO nano-biocomposite complexed with Glucose Oxidase • Glucose Oxidase immobilized to the surface via cross-linking. • Alginate-CuO film was characterized by SEM and FTIR. • The biosensor exhibits excellent analytical performance to glucose with a wide linear range and high sensitivity.

  20. Underwater tracking of a moving dipole source using an artificial lateral line: algorithm and experimental validation with ionic polymer–metal composite flow sensors

    International Nuclear Information System (INIS)

    Abdulsadda, Ahmad T; Tan, Xiaobo

    2013-01-01

    Motivated by the lateral line system of fish, arrays of flow sensors have been proposed as a new sensing modality for underwater robots. Existing studies on such artificial lateral lines (ALLs) have been mostly focused on the localization of a fixed underwater vibrating sphere (dipole source). In this paper we examine the problem of tracking a moving dipole source using an ALL system. Based on an analytical model for the moving dipole-generated flow field, we formulate a nonlinear estimation problem that aims to minimize the error between the measured and model-predicted magnitudes of flow velocities at the sensor sites, which is subsequently solved with the Gauss–Newton scheme. A sliding discrete Fourier transform (SDFT) algorithm is proposed to efficiently compute the evolving signal magnitudes based on the flow velocity measurements. Simulation indicates that it is adequate and more computationally efficient to use only the signal magnitudes corresponding to the dipole vibration frequency. Finally, experiments conducted with an artificial lateral line consisting of six ionic polymer–metal composite (IPMC) flow sensors demonstrate that the proposed scheme is able to simultaneously locate the moving dipole and estimate its vibration amplitude and traveling speed with small errors. (paper)

  1. Amperometric titration of thorium and some lanthanoids in acetic-acid medium using two indicator electrodes

    International Nuclear Information System (INIS)

    Khadeev, V.A.; Gevorgyan, A.M.; Talipov, Sh.T.; Kostylev, V.S.

    1979-01-01

    The votammetric behaviour of nitriletrimethylphosphonic acid (NTMP) in the medium of anhydrous acetic acid with different backgrounds in the anode region of polarization of a platinum microdisk electrode, is studied. The optimal conditions are found for the amperometric titration with two indicator electrodes of thorium and same lanthanides by a NTMP solution in anhydrous acetic medium. The influence of foreign anions and cations on the results of titration by the NTPM solution in anhydrous acetic acid is studied. The selectivity of titration in anhydrous medium is higher than in aqueous

  2. Creation of a Databank for Content of Antioxidants in Food Products by an Amperometric Method

    Directory of Open Access Journals (Sweden)

    Polina A. Fedina

    2010-10-01

    Full Text Available Oxidative stress, i.e. excessive content of reactionary, oxygen, and nitrogen compounds (ROAC, including free radicals, is one of the causes of various dangerous diseases as well as premature aging. The adverse effect of free radicals can be neutralized by antioxidants. In order to carry out antioxidant therapy, one needs to know the contents of antioxidants in food products. We have created the databank for the contents of antioxidants in 1,140 food products, beverages, etc. Apart from water-soluble antioxidants, fat-soluble antioxidants in dairy and fish products, cacao, chocolate, nuts etc. were determined for the first time using an amperometric method.

  3. Enzyme-free hydrogen peroxide sensor based on Au@Ag@C core-double shell nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yancai, E-mail: liyancai@mnnu.edu.cn [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China); Zhang, Yayun; Zhong, Yanmei [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Li, Shunxing [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China)

    2015-08-30

    Graphical abstract: - Highlights: • A facile method was designed to synthesize Au@Ag@C core-double shell nanocomposites. • Carbon nanomaterials at the outermost layer could protect Au and Ag nanoparticles from oxidation and aggregation. • The Au@Ag@C core-double shell nanocomposites showed high sensitivity and selectivity to electrocatalytic reduction of hydrogen peroxide. • The hydrogen peroxide sensor has a wide linear range of 5.0 μM to 4.75 mM and a limit of detection as low as 0.14 μM. - Abstract: The well-designed Au@Ag@C core-double shell nanocomposites were synthesized via a facile method, and were used to fabricate an enzyme-free amperometric hydrogen peroxide (H{sub 2}O{sub 2}) sensor. The size, shape, elementary composition and structure of the nanocomposites were characterized by transmission electron microscope (TEM), energy-dispersed spectrum (EDS) and X-ray diffraction (XRD). The outermost layer of the nanocomposites was amorphous carbon, the second layer was Ag and the core was Au. The Au@Ag@C core-double shell nanocomposites exhibit attractive activity for electrocatalytic reduction of H{sub 2}O{sub 2} according to the electrochemical experiments. It also demonstrates the H{sub 2}O{sub 2} sensor possess well performance with a wide linear range of 5.0 μM to 4.75 mM and a limit of detection (LOD) as low as 0.14 μM (S/N = 3). Furthermore, the interference from the common interfering species, such as glucose, ascorbic acid, dopamine and uric acid can be effectively avoided. In a word, the Au@Ag@C nanocomposites are promising candidates for enzyme-free H{sub 2}O{sub 2} sensor.

  4. Monolithic Composite “Pressure + Acceleration + Temperature + Infrared” Sensor Using a Versatile Single-Sided “SiN/Poly-Si/Al” Process-Module

    Directory of Open Access Journals (Sweden)

    Xinxin Li

    2013-01-01

    Full Text Available We report a newly developed design/fabrication module with low-cost single-sided “low-stress-silicon-nitride (LS-SiN/polysilicon (poly-Si/Al” process for monolithic integration of composite sensors for sensing-network-node applications. A front-side surface-/bulk-micromachining process on a conventional Si-substrate is developed, featuring a multifunctional SiN/poly-Si/Al layer design for diverse sensing functions. The first “pressure + acceleration + temperature + infrared” (PATIR composite sensor with the chip size of 2.5 mm × 2.5 mm is demonstrated. Systematic theoretical design and analysis methods are developed. The diverse sensing components include a piezoresistive absolute-pressure sensor (up to 700 kPa, with a sensitivity of 49 mV/MPa under 3.3 V supplied voltage, a piezoresistive accelerometer (±10 g, with a sensitivity of 66 μV/g under 3.3 V and a −3 dB bandwidth of 780 Hz, a thermoelectric infrared detector (with a responsivity of 45 V/W and detectivity of 3.6 × 107 cm·Hz1/2/W and a thermistor (−25–120 °C. This design/fabrication module concept enables a low-cost monolithically-integrated “multifunctional-library” technique. It can be utilized as a customizable tool for versatile application-specific requirements, which is very useful for small-size, low-cost, large-scale sensing-network node developments.

  5. Carbon Nanotubes/Gold Nanoparticles Composite Film for the Construction of a Novel Amperometric Choline Biosensor

    Directory of Open Access Journals (Sweden)

    Baoyan Wu

    2011-01-01

    Full Text Available This study develops a facile method to fabricate a novel choline biosensor based on multiwalled carbon nanotubes (MWCNTs and gold nanoparticles (AuNPs. Chitosan, a natural biocompatible polymer, was used to solubilize MWCNTs for constructing the aqueous Chit-MWCNTs solution. Then Chit-MWCNTs were first dropped on the surface of a cleaned platinum electrode. Finally, a thiolated silica sol containing AuNPs and choline oxidase (ChOx was immobilized on the surface of the Chit-MWCNTs-modified electrode. The MWCNTs/AuNPs/Pt electrode showed excellent electrocatalytic activity for choline. The resulting choline biosensor showed high sensitivity of choline (3.56 μA/mM, and wide linear range from 0.05 to 0.8 mM with the detection limit of 15 μM. In addition, good reproducibility and stability were obtained.

  6. An Amperometric Immunosensor Based on Graphene Composite Film and Protein a for Chlorpyrifos Detection

    Directory of Open Access Journals (Sweden)

    Xiangyou Wang

    2014-09-01

    Full Text Available In this paper, an immunosensor was designed for chlorpyrifos detection, which was based on graphene-multi-walled carbon nanotubes-gold nanoparticle-chitosan (GR-MWCNTs-AuNPs- CHIT nanocomposite film. Protein A (SPA can combine with gold nanoparticles, which made anti- chlorpyrifos antibody immobilized orientedly, eventually the modified immunosensor was developed for the detection of chlorpyrifos residues. Under the optimized conditions, a regression equation: y=9.5676 lgC (ng/mL +18.164 (R2=0.9976 was obtained with a detection limit as low as 0.037 ng/mL. The proposed chlorpyrifos immunosensor exhibited high reproducibility, stability, and good selectivity and regeneration, it has the potential of real sample detection.

  7. Sensitive amperometric biosensor for phenolic compounds based on graphene-silk peptide/tyrosinase composite nanointerface.

    Science.gov (United States)

    Qu, Ying; Ma, Ming; Wang, Zhengguo; Zhan, Guoqing; Li, Buhai; Wang, Xian; Fang, Huaifang; Zhang, Huijuan; Li, Chunya

    2013-06-15

    New graphene-silk peptide (Gr-SP) nanosheets were prepared and successfully fabricated with tyrosinase (Tyr) as a novel biosensor for the determination of phenolic compounds. The Gr-SP nanosheets were fully characterized with transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, UV/Vis and FTIR spectra. The developed biosensors were also characterized with scanning electronic microscopy and electrochemical impedance spectroscopy. Using bisphenol A (BPA) as a model substrate in the sensing system, a number of key factors including the volume of Gr-SP-Tyr solution, the applied potential, pH values, temperature, and the Tyr/Gr-SP ratio that influence the analytical performance of the biosensor were investigated. The biosensor gave a linear response on the concentration ranges of 0.001-16.91 μM for catechol with the sensitivity of 7634 mA M(-1)cm(-2), 0.0015-21.12 μM for phenol with the sensitivity of 4082 mA M(-1)cm(-2), and 0.002-5.48 μM for BPA with the sensitivity of 2511 mA M(-1)cm(-2). The low detection limits were estimated to be 0.23, 0.35 and 0.72 nM (S/N=3) for catechol, phenol and BPA, respectively. The biosensors also exhibit good repeatability and long-term stability. The practical application of the biosensor was also demonstrated by the determination of BPA leaching from commercial plastic drinking bottles. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Highly Stretchable Potentiometric pH Sensor Fabricated via Laser Carbonization and Machining of Carbon-Polyaniline Composite.

    Science.gov (United States)

    Rahimi, Rahim; Ochoa, Manuel; Tamayol, Ali; Khalili, Shahla; Khademhosseini, Ali; Ziaie, Babak

    2017-03-15

    The development of stretchable sensors has recently attracted considerable attention. These sensors have been used in wearable and robotics applications, such as personalized health-monitoring, motion detection, and human-machine interfaces. Herein, we report on a highly stretchable electrochemical pH sensor for wearable point-of-care applications that consists of a pH-sensitive working electrode and a liquid-junction-free reference electrode, in which the stretchable conductive interconnections are fabricated by laser carbonizing and micromachining of a polyimide sheet bonded to an Ecoflex substrate. This method produces highly porous carbonized 2D serpentine traces that are subsequently permeated with polyaniline (PANI) as the conductive filler, binding material, and pH-sensitive membrane. The experimental and simulation results demonstrate that the stretchable serpentine PANI/C-PI interconnections with an optimal trace width of 0.3 mm can withstand elongations of up to 135% and are robust to more than 12 000 stretch-and-release cycles at 20% strain without noticeable change in the resistance. The pH sensor displays a linear sensitivity of -53 mV/pH (r 2 = 0.976) with stable performance in the physiological range of pH 4-10. The sensor shows excellent stability to applied longitudinal and transverse strains up to 100% in different pH buffer solutions with a minimal deviation of less than ±4 mV. The material biocompatibility is confirmed with NIH 3T3 fibroblast cells via PrestoBlue assays.

  9. Sensor Access to the Cellular Microenvironment Using the Sensing Cell Culture Flask.

    Science.gov (United States)

    Kieninger, Jochen; Tamari, Yaara; Enderle, Barbara; Jobst, Gerhard; Sandvik, Joe A; Pettersen, Erik O; Urban, Gerald A

    2018-04-26

    The Sensing Cell Culture Flask (SCCF) is a cell culture monitoring system accessing the cellular microenvironment in 2D cell culture using electrochemical microsensors. The system is based on microfabricated sensor chips embedded in standard cell culture flasks. Ideally, the sensor chips could be equipped with any electrochemical sensor. Its transparency allows optical inspection of the cells during measurement. The surface of the sensor chip is in-plane with the flask surface allowing undisturbed cell growth on the sensor chip. A custom developed rack system allows easy usage of multiple flasks in parallel within an incubator. The presented data demonstrates the application of the SCCF with brain tumor (T98G) and breast cancer (T-47D) cells. Amperometric oxygen sensors were used to monitor cellular respiration with different incubation conditions. Cellular acidification was accessed with potentiometric pH sensors using electrodeposited iridium oxide films. The system itself provides the foundation for electrochemical monitoring systems in 3D cell culture.

  10. Novel Non-Stoichiometric Manganese – Cobalt – Nickel – Oxide Composite as Humidity Sensor Through Solid-State Electrical Conductivity Measurements

    Directory of Open Access Journals (Sweden)

    R. Sundaram

    2006-08-01

    Full Text Available Equimolar amounts of manganese(II chloride, cobalt(III nitrate and nickel(II chloride in aqueous solution were reacted with ammonia and the resulting precipitate of hydroxides was heated to 7500 C in 6h to yield a non stoichiometric oxides having a composition of Mn0.06Co0.6Ni0.6O2.5 as analyzed by atomic absorption spectroscopy to a pellet and sintered at 6000 C. Characterization of the material has been made with AAS, Far-IR, TG-DTA, XRD, SEM, VSM and electrical conductance measurement. The far-IR spectra indicated the presence of metal-oxygen bonds and the discrete nature of the oxide was established from power X-ray diffraction pattern recorded at room temperature. The thermogravimetric data indicated the successive loss and gain of fraction of oxygen atoms, a specific feature of non-stoichiometric metal oxides. It was subjected to solid-state DC electrical conductivity measurements at room temperature. The current increases linearly with applied field and exponentially with increase in temperature showing conformance to ohmic law and semiconducting nature. The scanning electron microscopy (SEM studies were carried out to study the surface and pores structure of the sensor materials. The Brunauer-Emmett-Teller (BET surface adsorption studies showed that the radiuses of the pore sizes were found to be distributed from 10-45A with the pore specific volume being 0.01 cm3 g-1. As the composites having micropores are preferred for humidity sensing properties, the material was subjected to water vapour of different humidity achieved by various water buffers at room temperature and the electrical conductivity was measured as a function of relative humidity (RH. The electrical resistivity drastically decreases with increase in humidity, proving the material to be a good water vapour sensor. The sensitivity factor (Sf was 55000 in the range 5–98% RH, meaning the resistivity falls by a factor of 5.5 x 104 when the atmospheric RH increases from 5

  11. Molecularly imprinted poly(4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid) modified glassy carbon electrode as an electrochemical theophylline sensor

    International Nuclear Information System (INIS)

    Aswini, K.K.; Vinu Mohan, A.M.; Biju, V.M.

    2016-01-01

    Theophylline is an inexpensive drug employed in asthma and chronic obstructive pulmonary disorder medications and is toxic at higher concentration. The development of a molecularly imprinted polymer based theophylline electrochemical sensor on glassy carbon electrode by the electropolymerization of 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid is being discussed in this work. The MIP modification enhances the theophylline recognition ability and the electron transfer kinetics of the bare electrode. The parameters, controlling the performance of the imprinted polymer based sensor, like number of electropolymerization cycles, composition of the pre-polymerization mixture, pH and immersion time were investigated and optimized. The interaction energy and the most stable conformation of the template–monomer complex in the pre-polymerization mixture were determined computationally using ab initio calculations based on density functional theory. The amperometric measurements showed that the developed sensor has a method detection limit of 0.32 μM for the dynamic range of 0.4 to 17 μM, at optimized conditions. The transducer possesses appreciable selectivity in the presence of structurally similar interferents such as theobromine, caffeine and doxofylline. The developed sensor showed remarkable stability and reproducibility and was also successfully employed in theophylline detection from commercially available tablets. - Highlights: • Molecularly imprinted polymer based theophylline sensor was developed. • Imprinted poly(4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid) was electrodeposited. • Most stable template-monomer complex was assigned by computational analysis. • Possessed remarkable selectivity in the presence of structurally similar interferents • Employed for theophylline detection from commercially available tablets

  12. Molecularly imprinted poly(4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid) modified glassy carbon electrode as an electrochemical theophylline sensor

    Energy Technology Data Exchange (ETDEWEB)

    Aswini, K.K., E-mail: aswinikk@ymail.com; Vinu Mohan, A.M.; Biju, V.M., E-mail: vmbiju@ymail.com

    2016-08-01

    Theophylline is an inexpensive drug employed in asthma and chronic obstructive pulmonary disorder medications and is toxic at higher concentration. The development of a molecularly imprinted polymer based theophylline electrochemical sensor on glassy carbon electrode by the electropolymerization of 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid is being discussed in this work. The MIP modification enhances the theophylline recognition ability and the electron transfer kinetics of the bare electrode. The parameters, controlling the performance of the imprinted polymer based sensor, like number of electropolymerization cycles, composition of the pre-polymerization mixture, pH and immersion time were investigated and optimized. The interaction energy and the most stable conformation of the template–monomer complex in the pre-polymerization mixture were determined computationally using ab initio calculations based on density functional theory. The amperometric measurements showed that the developed sensor has a method detection limit of 0.32 μM for the dynamic range of 0.4 to 17 μM, at optimized conditions. The transducer possesses appreciable selectivity in the presence of structurally similar interferents such as theobromine, caffeine and doxofylline. The developed sensor showed remarkable stability and reproducibility and was also successfully employed in theophylline detection from commercially available tablets. - Highlights: • Molecularly imprinted polymer based theophylline sensor was developed. • Imprinted poly(4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid) was electrodeposited. • Most stable template-monomer complex was assigned by computational analysis. • Possessed remarkable selectivity in the presence of structurally similar interferents • Employed for theophylline detection from commercially available tablets.

  13. A Reagentless Amperometric Formaldehyde-Selective Chemosensor Based on Platinized Gold Electrodes.

    Science.gov (United States)

    Demkiv, Olha; Smutok, Oleh; Gonchar, Mykhailo; Nisnevitch, Marina

    2017-05-06

    Fabrication and characterization of a new amperometric chemosensor for accurate formaldehyde analysis based on platinized gold electrodes is described. The platinization process was performed electrochemically on the surface of 4 mm gold planar electrodes by both electrolysis and cyclic voltamperometry. The produced electrodes were characterized using scanning electron microscopy and X-ray spectral analysis. Using a low working potential (0.0 V vs. Ag/AgCl) enabled an essential increase in the chemosensor's selectivity for the target analyte. The sensitivity of the best chemosensor prototype to formaldehyde is uniquely high (28180 A·M -1 ·m -2 ) with a detection limit of 0.05 mM. The chemosensor remained stable over a one-year storage period. The formaldehye-selective chemosensor was tested on samples of commercial preparations. A high correlation was demonstrated between the results obtained by the proposed chemosensor, chemical and enzymatic methods ( R = 0.998). The developed formaldehyde-selective amperometric chemosensor is very promising for use in industry and research, as well as for environmental control.

  14. Bromopyrogallol red: a new microanalytical reagent for amperometric estimation of Dy (III) and Gd (III)

    International Nuclear Information System (INIS)

    Sahu, G.P.; Lavale, S.C.

    2000-01-01

    Bromopyrogallol red (BPR) has been extensively used as an indicator but its electro-reducibility has proved it to be a very useful amperometric reagent. BPR reduces on a DME in KNO 3 in the entire pH range 2.4 to 9.5. It produces single stage reduction wave below pH 4, but a two stage reduction wave in the basic range. Progressive ionization of hydroxyl group and distinct colour species of BPR, have also been studied using a Bausch and Lomb spectronic-20 spectrophotometer in order to support electroanalytical studies. On performing amperometric titrations of Dy(III) and Gd(III) with BPR at its plateau potential 1.0 V at pH 2.6 and μ = 0.4, reversed L-shaped titration curves have been observed indicating metal to BPR ratio 1:1 and the colour changes from claret red to orange yellow. The reagents have been tested in presence of various diverse ions and tolerance limits have been computed. Na + , K + , Li + , Cl - , ClO 4 - , CH 3 COO - , Pd 2+ , Fe 3+ ions did not interfere in the titrimetric procedure. However, small amounts of Bi 3+ , Pb 2+ , Ni 2+ , Co 2+ , Cd 2+ , Mg 2+ and rare earth metals have hampered the titrimetric estimations. (author)

  15. Amperometric magnetoimmunoassay for the direct detection of tumor necrosis factor alpha biomarker in human serum

    Energy Technology Data Exchange (ETDEWEB)

    Eletxigerra, U. [Micro-NanoFabrication Unit, IK4-Tekniker, Eibar (Spain); CIC microGUNE, Arrasate-Mondragón (Spain); Martinez-Perdiguero, J. [CIC microGUNE, Arrasate-Mondragón (Spain); Merino, S. [Micro-NanoFabrication Unit, IK4-Tekniker, Eibar (Spain); CIC microGUNE, Arrasate-Mondragón (Spain); Villalonga, R.; Pingarrón, J.M. [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, Madrid (Spain); Campuzano, S., E-mail: susanacr@quim.ucm.es [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, Madrid (Spain)

    2014-08-01

    Highlights: • Electrochemical magnetoimmunosensor for tumor necrosis factor alpha (TNFα) biomarker. • Sensitive and selective detection of TNFα in undiluted serum. • LOD achieved lower than the cut-off value established for relevant illnesses. • Useful and affordable alternative to ELISAs for TNFα determination in serum. - Abstract: An amperometric immunoassay for the determination of tumor necrosis factor alpha (TNFα) protein biomarker in human serum based on the use of magnetic microbeads (MBs) and disposable screen-printed carbon electrodes (SPCEs) has been developed. The specifically modified microbeads were magnetically captured on the working electrode surface and the amperometric responses were measured at −0.20 V (vs. Ag pseudo-reference electrode), upon addition of hydroquinone (HQ) as electron transfer mediator and H{sub 2}O{sub 2} as the enzyme substrate. After a thorough optimization of the assay, extremely low limits of detection were achieved: 2.0 pg mL{sup −1} (36 fM) and 5.8 pg mL{sup −1} (105 fM) for standard solutions and spiked human serum, respectively. The simplicity, robustness and this clinically interesting LOD proved the developed TNFα immunoassay as a good contender for real clinical application.

  16. Amperometric magnetoimmunoassay for the direct detection of tumor necrosis factor alpha biomarker in human serum

    International Nuclear Information System (INIS)

    Eletxigerra, U.; Martinez-Perdiguero, J.; Merino, S.; Villalonga, R.; Pingarrón, J.M.; Campuzano, S.

    2014-01-01

    Highlights: • Electrochemical magnetoimmunosensor for tumor necrosis factor alpha (TNFα) biomarker. • Sensitive and selective detection of TNFα in undiluted serum. • LOD achieved lower than the cut-off value established for relevant illnesses. • Useful and affordable alternative to ELISAs for TNFα determination in serum. - Abstract: An amperometric immunoassay for the determination of tumor necrosis factor alpha (TNFα) protein biomarker in human serum based on the use of magnetic microbeads (MBs) and disposable screen-printed carbon electrodes (SPCEs) has been developed. The specifically modified microbeads were magnetically captured on the working electrode surface and the amperometric responses were measured at −0.20 V (vs. Ag pseudo-reference electrode), upon addition of hydroquinone (HQ) as electron transfer mediator and H 2 O 2 as the enzyme substrate. After a thorough optimization of the assay, extremely low limits of detection were achieved: 2.0 pg mL −1 (36 fM) and 5.8 pg mL −1 (105 fM) for standard solutions and spiked human serum, respectively. The simplicity, robustness and this clinically interesting LOD proved the developed TNFα immunoassay as a good contender for real clinical application

  17. Silver nanowire/polymer composite soft conductive film fabricated by large-area compatible coating for flexible pressure sensor array

    Science.gov (United States)

    Chen, Sujie; Li, Siying; Peng, Sai; Huang, Yukun; Zhao, Jiaqing; Tang, Wei; Guo, Xiaojun

    2018-01-01

    Soft conductive films composed of a silver nanowire (AgNW) network, a neutral-pH PEDOT:PSS over-coating layer and a polydimethylsiloxane (PDMS) elastomer substrate are fabricated by large area compatible coating processes. The neutral-pH PEDOT:PSS layer is shown to be able to significantly improve the conductivity, stretchability and air stability of the conductive films. The soft conductive films are patterned using a simple maskless patterning approach to fabricate an 8 × 8 flexible pressure sensor array. It is shown that such soft conductive films can help to improve the sensitivity and reduce the signal crosstalk over the pressure sensor array. Project supported by the Science and Technology Commission of Shanghai Municipality (No. 16JC1400603).

  18. Evaluation of different disinfectants on the performance of an on-meter dosed amperometric glucose-oxidase-based glucose meter.

    Science.gov (United States)

    Sarmaga, Don; Dubois, Jeffrey A; Lyon, Martha E

    2011-11-01

    Off-meter dosed photometric glucose-oxidase-based glucose meters have been reported to be susceptible to interference by hydrogen-peroxide-based disinfecting agents. The objective of this study was to determine if a single application of hydrogen-peroxide-containing Accel® wipe to disinfect an on-meter dosed amperometric glucose-oxidase-based glucose meter will influence its performance. The performance of five on-meter dosed amperometric glucose-oxidase-based glucose meters was determined before and after disinfecting the devices with a single application of either CaviWipes® (14.3% isopropanol and 0.23% diisobutyl-phenoxy-ethoxyethyl dimethyl benzyl ammonium chloride) or Accel (0.5% hydrogen peroxide) wipes. Replicate glucose measurements were conducted before disinfecting the devices, immediately after disinfecting, and then 1 and 2 min postdisinfecting, with measurements in triplicate. Analysis was sequentially completed for five different meters. Results were analyzed by a two-way analysis of variance (Analyze-it software). No clinical ( .05) in glucose concentration were detected when the on-meter dosed amperometric glucose-oxidase-based glucose meters were disinfected with either CaviWipes or Accel wipes and measured immediately or 1 or 2 min postdisinfecting. No clinically significant difference in glucose concentration was detected between meters (glucose oxidase amperometric-based glucose meters are not analytically susceptible to interference by a single application of hydrogen-peroxide-containing Accel disinfectant wipes. © 2011 Diabetes Technology Society.

  19. In vivo continuous and simultaneous monitoring of brain energy substrates with a multiplex amperometric enzyme-based biosensor device

    NARCIS (Netherlands)

    De Lima Braga Lopes Cordeiro, Carlos; de Vries, M.G.; Ngabi, W; Oomen, P.E.; Cremers, T.I.F.H.; Westerink, B.H.C.

    2015-01-01

    Enzyme-based amperometric biosensors are widely used for monitoring key biomarkers. In experimental neuroscience there is a growing interest in in vivo continuous and simultaneous monitoring of metabolism-related biomarkers, like glucose, lactate and pyruvate. The use of multiplex biosensors will

  20. Isolation and characterization of mutated alcohol oxidases from the yeast Hansenula polymorpha with decreased affinity toward substrates and their use as selective elements of an amperometric biosensor

    Directory of Open Access Journals (Sweden)

    Schuhmann Wolfgang

    2007-06-01

    Full Text Available Abstract Background Accurate, rapid, and economic on-line analysis of ethanol is very desirable. However, available biosensors achieve saturation at very low ethanol concentrations and thus demand the time and labour consuming procedure of sample dilution. Results Hansenula polymorpha (Pichia angusta mutant strains resistant to allyl alcohol in methanol medium were selected. Such strains possessed decreased affinity of alcohol oxidase (AOX towards methanol: the KM values for AOX of wild type and mutant strains CA2 and CA4 are shown to be 0.62, 2.48 and 1.10 mM, respectively, whereas Vmax values are increased or remain unaffected. The mutant AOX alleles from H. polymorpha mutants CA2 and CA4 were isolated and sequenced. Several point mutations in the AOX gene, mostly different between the two mutant alleles, have been identified. Mutant AOX forms were isolated and purified, and some of their biochemical properties were studied. An amperometric biosensor based on the mutated form of AOX from the strain CA2 was constructed and revealed an extended linear response to the target analytes, ethanol and formaldehyde, as compared to the sensor based on the native AOX. Conclusion The described selection methodology opens up the possibility of isolating modified forms of AOX with further decreased affinity toward substrates without reduction of the maximal velocity of reaction. It can help in creation of improved ethanol biosensors with a prolonged linear response towards ethanol in real samples of wines, beers or fermentation liquids.

  1. Amperometric Biosensor Based on Diamine Oxidase/Platinum Nanoparticles/Graphene/Chitosan Modified Screen-Printed Carbon Electrode for Histamine Detection.

    Science.gov (United States)

    Apetrei, Irina Mirela; Apetrei, Constantin

    2016-03-24

    This work describes the development and optimization studies of a novel biosensor employed in the detection and quantification of histamine in freshwater fish samples. The proposed biosensor is based on a modified carbon screen-printed electrode with diamineoxidase, graphene and platinum nanoparticles, which detects the hydrogen peroxide formed by the chemical process biocatalysed by the enzyme diamine oxidase and immobilized onto the nanostructurated surface of the receptor element. The amperometric measurements with the biosensor have been implemented in buffer solution of pH 7.4, applying an optimal low potential of +0.4 V. The novel biosensor shows high sensitivity (0.0631 μA·μM), low detection limit (2.54 × 10(-8) M) and a broad linear domain from 0.1 to 300 μM. The applicability in natural complex samples and the analytical parameters of this enzyme sensor have been performed in the quantification of histamine in freshwater fish. An excellent correlation among results achieved with the developed biosensor and results found with the standard method for all freshwater fish samples has been achieved.

  2. Compositions of graphene materials with metal nanostructures and microstructures and methods of making and using including pressure sensors

    KAUST Repository

    Chen, Ye; Khashab, Niveen M.; Tao, Jing

    2017-01-01

    Composition comprising at least one graphene material and at least one metal. The metal can be in the form of nanoparticles as well as microflakes, including single crystal microflakes. The metal can be intercalated in the graphene sheets

  3. The quest for highly sensitive QCM humidity sensors: the coating of CNT/MOF composite sensing films as case study

    KAUST Repository

    Chappanda, Karumbaiah. N.; Shekhah, Osama; Yassine, Omar; Patole, Shashikant P.; Eddaoudi, Mohamed; Salama, Khaled N.

    2017-01-01

    coating technique on a quartz-crystal microbalance (QCM) and a comparison of their shift in resonance frequencies to adsorbed water vapor (5 to 75% relative humidity) is presented. Through optimization of the CNT and HKUST-1 composition, we could

  4. Immobilization of glucose oxidase on graphene and cobalt phthalocyanine composite and its application for the determination of glucose.

    Science.gov (United States)

    Mani, Veerappan; Devasenathipathy, Rajkumar; Chen, Shen-Ming; Huang, Sheng-Tung; Vasantha, V S

    2014-11-01

    We described a simple and facile chemical reduction strategy for the preparation of graphene (GR)-cobalt phthalocyanine (CoPc) composite and explored it for the enzymatic determination of glucose. CoPc is an active mediator and electrocatalysts for the immobilization of GOx and determination of glucose. However, it is not stable on the electrode surface and also suffers from lack of conductivity. Here, we have employed GR as the suitable support to stabilize CoPc through simple chemical reduction method and the resulting composite has been used for the glucose biosensor application. Scanning electron microscopy, X-ray diffraction and Energy-dispersive X-ray spectroscopy studies confirmed the successful formation of composite. Direct electron transfer of glucose oxidase (GOx) was observed with well defined redox peaks at the formal potential of -0.44 V. The amount of electroactive GOx (Г) and electron transfer rate constant (ks) were calculated to be 3.77×10(-10) mol cm(-2) and 3.57 s(-1), respectively. The fabricated amperometric biosensor detects glucose in wide linear concentration range from 10 μM to 14.8 mM with high sensitivity of 5.0 9μA mM(-1) cm(-2). The sensor offered very low detection limit (LOD) of 1.6 μM. In addition, practical feasibility of the sensor has been explored in screen printing carbon electrode with accurate determination of glucose present in human blood serum and urine samples. Furthermore, the sensor exhibited appreciable stability, repeatability and reproducibility results. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Amperometric immunosensor for {alpha}-fetoprotein antigen in human serum based on co-immobilizing dinuclear copper complex and gold nanoparticle doped chitosan film

    Energy Technology Data Exchange (ETDEWEB)

    Gan Ning; Meng Linghua; Wang Feng [State Key Laboratory Base of Novel Functional Materials and Preparation science, Faculty of Material Science and Chemical Engineering of Ninbo University, Ningbo, 315211 (China)], E-mail: ganning@nbu.edu.cn

    2009-09-01

    A sensitive amperometric immunosensor for {alpha}-fetoprotein (AFP), a tumor marker for the diagnosis of hepatocellular carcinoma (HCC), was constructed, The immunosensor is prepared by co-immobilizing [Cu{sub 2}(phen){sub 2}Cl{sub 2}] ({mu}-Cl){sub 2} (CuL), nano-Au/Chitosan(Chit) composite, horseradish peroxidase (HRP) and AFP antibody(anti-AFP) on a glassy carbon electrode (GCE). Firstly, CuL was irreversibly absorb on GCE electrode through {pi}-{pi} stacking interaction; then nano-Au/Chit composite was immobilized onto the electrode because of its excellent membrane-forming ability, finally HRP and anti-AFP was adsorbed onto the surface of the gold nanoparticles to construct GCE | CuL/nanoAu-chit/HRP/anti-AFP immunosensor. The preparation procedure of the electrode was characterized by electrochemical and spectroscopy method. The results showed that this immunosensor exhibited an excellent electrocatalytic response to the reduction of hydrogen peroxide (H{sub 2}O{sub 2}) without the aid of an electron mediator, offers a high-sensitivity (1710 nA {center_dot} ng{sup -1} {center_dot} ml{sup -1}) for the detection of AFP and has good correlation for detection of AFP in the range of 0.2 to 120.0 ng/ml with a detection limit of 0.05 ng/ml. The biosensor showed high selectivity as well as good stability and reproductivity.

  6. The Design of Dual-Emissive Composite Material [Zn2(HL)3]+@MOF-5 as Self-Calibrating Luminescent Sensors of Al3+ Ions and Monoethanolamine.

    Science.gov (United States)

    Wu, Meng-Meng; Wang, Jiao-Yang; Sun, Rui; Zhao, Cui; Zhao, Jiong-Peng; Che, Guang-Bo; Liu, Fu-Chen

    2017-08-21

    Introducing another chromophore into a luminescent MOF is a potential way to assembling novel dual-emissive luminescent materials. Putting the chromophore, for which luminescence can be enhanced by Zn 2+ ion, into MOF-5 by the "bottle around ship" strategy is a simple but efficient synthesis method to realize such dual-emissive materials. According to this strategy, a novel dual-emissive luminescent composite material [Zn 2 (HL) 3 ] + @MOF-5 was constructed by loading the [La 3 (HL) 2 L 2 (NO 3 ) 3 H 2 O] (1) (H 2 L = 7,7'-(ethane-1,1'-diyl)8-hydro-quinoline) into MOF-5, in which the [Zn 2 (HL) 3 ] + anions were transformed from 1 with the existence of Zn 2+ . The dual-emissive composite materials show excellent luminescence with two emissions of MOF-5 at 410 nm and [Zn 2 (HL) 3 ] + at 524 nm. Furthermore, by combining characteristics of MOF-5 and the guest chromophore, the composite material is highly selectively sensitive toward Al 3+ and monoethanolamine, which makes [Zn 2 (HL) 3 ] + @MOF-5 a potential self-calibrated fluorescence sensor.

  7. Applications research in ultrasonic testing of carbon fiber composite based on an optical fiber F-p sensor

    Science.gov (United States)

    Shan, Ning

    2016-10-01

    Carbon fiber composite is widely applied to the field of aerospace engineering because of its excellent performance. But it will be able to form more defects in the process of manufacturing inevitably on account of unique manufacturing process. Meanwhile it has sophisticated structure and services in the bad environment long time. The existence of defects will be able to cause the sharp decline in component's performance when the defect accumulates to a certain degree. So the reliability and safety test demand of carbon fiber composite is higher and higher. Ultrasonic testing technology is the important means used for characteristics of component inspection of composite materials. Ultrasonic information detection uses acoustic transducer generally. It need coupling agent and is higher demand for the surface of sample. It has narrow frequency band and low test precision. The extrinsic type optical fiber F-P interference cavity structure is designed to this problem. Its optical interference model is studied. The initial length of F-P cavity is designed. The realtime online detection system of carbon fiber composite is established based on optical fiber F-P Ultrasound sensing technology. Finally, the testing experiment study is conducted. The results show that the system can realize real-time online detection of carbon fiber composite's defect effectively. It operates simply and realizes easily. It has low cost and is easy to practical engineering.

  8. Investigation of dosimetric characteristics of a core-shell quantum dots nano composite (CdTe/CdS/PMMA): fabrication of a new gamma sensor

    Science.gov (United States)

    Feizi, Shahzad; Zare, Hakimeh; Hoseinpour, Masoumeh

    2018-06-01

    CdTe/CdS-PMMA nanocomposite was prepared using dispersion of CdTe/CdS core-shell quantum dots (QDs) in poly methyl methacrylate (PMMA) polymer matrix. High-quality CdTe/CdS core/shell quantum dots were synthesized in aqueous solution and were transferred from water to chloroform using ligand-exchange process in the presence of 1-dodecanethiol (1-DDT). Transmission electron microscopy analysis reveals that the obtained nano-particles are highly crystalline nature with mean diameter of 3.6 nm. To prepare an ohmic contact detector, a conductive cell with two silver coated walls was designed and fabricated for exploring gamma detecting properties of the nano composite. New detector was assessed for the linearity of doserate response, angular dependence, sensitivity and repeatability. The results show that the dose rate response of the prepared sensor is linear in the dose rate range of 50-145 mGy/min. So this nanocomposite can be utilized as a potential gamma sensor in the medical radiation device design.

  9. Poly(malachite green) at nafion doped multi-walled carbon nanotube composite film for simple aliphatic alcohols sensor.

    Science.gov (United States)

    Umasankar, Yogeswaran; Periasamy, Arun Prakash; Chen, Shen-Ming

    2010-01-15

    Conductive composite film which contains nafion (NF) doped multi-walled carbon nanotubes (MWCNTs) along with the incorporation of poly(malachite green) (PMG) has been synthesized on glassy carbon electrode (GCE), gold and indium tin oxide (ITO) electrodes by potentiostatic methods. The presence of MWCNTs in the composite film (MWCNTs-NF-PMG) enhances surface coverage concentration (Gamma) of PMG to approximately 396%, and increases the electron transfer rate constant (k(s)) to approximately 305%. Similarly, electrochemical quartz crystal microbalance study reveals the enhancement in the deposition of PMG at MWCNTs-NF film. The surface morphology of the composite film deposited on ITO electrode has been studied using scanning electron microscopy (SEM) and scanning tunneling microscopy (STM). These two techniques reveal that the PMG incorporated on MWCNTs-NF film. The MWCNTs-NF-PMG composite film also exhibits promising enhanced electrocatalytic activity towards the simple aliphatic alcohols such as methanol, ethanol and propanol. The electroanalytical responses of analytes at NF-PMG and MWCNTs-NF-PMG films were measured using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). From electroanalytical studies, well defined voltammetric peaks have been obtained at MWCNTs-NF-PMG composite film for methanol, ethanol and propanol at Epa=609, 614 and 602mV respectively. The sensitivity of MWCNTs-NF-PMG composite film towards methanol, ethanol and propanol in CV technique are 0.59, 0.36 and 0.92microAmM(-1)cm(-2) respectively, which are higher than NF-PMG film. Further, the sensitivity values obtained using DPV are higher than the values obtained using CV technique.

  10. Preparation and characterization of green-nano-composite material based on polyaniline, multiwalled carbon nano tubes and carboxymethyl cellulose: For electrochemical sensor applications.

    Science.gov (United States)

    Gautam, Vineeta; Singh, Karan Pratap; Yadav, Vijay Laxmi

    2018-06-01

    In this paper, we are presenting the preparation and characterization of "polyaniline/multiwalled carbon nanotubes/carboxymethyl cellulose" based novel composite material. It's morphological, thermal, structural, and electrochemical properties were investigated by using different instrumental techniques. During the in-situ chemical polymerization of aniline in the aqueous suspension of CMC and MWCNTs, the particle size change in two different ways "top to bottom" (low molecular weight oligomers grows in size) and "bottom to top" (long fibers of CMC fragmented in the reaction mixture). The combination of these two processes facilitated the fabrication of an integrated green-nano-composite material. In addition, a little amount of conductive nanofillers (MWCNTs) boosts the electrical and electrocatalytic properties of the material. Electron-rich centers of benzenoid rings exhibited π-π stacking with sp 2 carbon of MWCNTs. CMC dominantly impact on the properties of PANI, negatively charged carboxylate group of CMC ionically bonded with protonated amine/imine. FTIR and Raman analysis confirmed that the material has dominated quinoid units and effective charge transfer. Hydroxyl and carboxyl groups and bonded water molecules of CMC results in a network of hydrogen bonds (which induced directional property). PANI/MWCNTs/CMC have nanobead-like structures (TEM analysis), large surface area, large pore volume, small pore diameter (BET and BJH studies) and good dispersion ability in the aqueous phase. Nanostructures of aligned PANI exhibited excellent electrochemical properties have attracted increasing attention. Modified carbon paste electrode was used for electrocatalytic detection of ascorbic acid (as a model analyte). The sensor exhibited a linear range 0.05 mM-5 mM, sensitivity 100.63 μA mM -1  cm -2 , and limit of detection 0.01 mM. PANI/MWCNTs/CMC is suitable nanocomposite material for apply electroactive/conducting ink and membrane (which could be

  11. A novel sensor made of Antimony Doped Tin Oxide-silica composite sol on a glassy carbon electrode modified by single-walled carbon nanotubes for detection of norepinephrine.

    Science.gov (United States)

    Wang, Zhao; Wang, Kai; Zhao, Lu; Chai, Shigan; Zhang, Jinzhi; Zhang, Xiuhua; Zou, Qichao

    2017-11-01

    In this study, we designed a novel molecularly imprinted polymer (MIP), Antimony Doped Tin Oxide (ATO)-silica composite sol, which was made using a sol-gel method. Then a sensitive and selective imprinted electrochemical sensor was constructed with the ATO-silica composite sol on a glassy carbon electrode modified by single-walled carbon nanotubes (SWNTs). The introduction of SWNTs increased the sensitivity of the MIP sensor. The surface morphology of the MIP and MIP/SWNTs were characterized by scanning electron microscopy (SEM), and the optimal conditions for detection were determined. The oxidative peak current increased linearly with the concentration of norepinephrine in the range of 9.99×10 -8 M to 1.50×10 -5 M, as detected by cyclic voltammetry (CV), the detection limit was 3.33×10 -8 M (S/N=3). In addition, the proposed electrochemical sensors were successfully applied to detect the norepinephrine concentration in human blood serum samples. The recoveries of the sensors varied from 99.67% to 104.17%, indicating that the sensor has potential for the determination of norepinephrine in clinical tests. Moreover, the imprinted electrochemical sensor was used to selectively detect norepinephrine. The analytical application was conducted successfully and yielded accurate and precise results. Copyright © 2017. Published by Elsevier B.V.

  12. Development of Multi-Sensor Global Cloud and Radiance Composites for DSCOVR EPIC Imager with Subpixel Definition

    Science.gov (United States)

    Khlopenkov, K. V.; Duda, D. P.; Thieman, M. M.; Sun-Mack, S.; Su, W.; Minnis, P.; Bedka, K. M.

    2017-12-01

    The Deep Space Climate Observatory (DSCOVR) is designed to study the daytime Earth radiation budget by means of onboard Earth Polychromatic Imaging Camera (EPIC) and National Institute of Standards and Technology Advanced Radiometer (NISTAR). EPIC imager observes in several shortwave bands (317-780 nm), while NISTAR measures the top-of-atmosphere (TOA) whole-disk radiance in shortwave and total broadband windows. Calculation of albedo and outgoing longwave flux requires a high-resolution scene identification such as the radiance observations and cloud property retrievals from low earth orbit and geostationary satellite imagers. These properties have to be co-located with EPIC imager pixels to provide scene identification and to select anisotropic directional models, which are then used to adjust the NISTAR-measured radiance and subsequently obtain the global daytime shortwave and longwave fluxes. This work presents an algorithm for optimal merging of selected radiances and cloud properties derived from multiple satellite imagers to obtain seamless global hourly composites at 5-km resolution. The highest quality observation is selected by means of an aggregated rating which incorporates several factors such as the nearest time relative to EPIC observation, lowest viewing zenith angle, and others. This process provides a smoother transition and avoids abrupt changes in the merged composite data. Higher spatial accuracy in the composite product is achieved by using the inverse mapping with gradient search during reprojection and bicubic interpolation for pixel resampling. The composite data are subsequently remapped into the EPIC-view domain by convolving composite pixels with the EPIC point spread function (PSF) defined with a half-pixel accuracy. Within every EPIC footprint, the PSF-weighted average radiances and cloud properties are computed for each cloud phase and then stored within five data subsets (clear-sky, water cloud, ice cloud, total cloud, and no

  13. Prussian blue-modified nanoporous gold film electrode for amperometric determination of hydrogen peroxide.

    Science.gov (United States)

    Ghaderi, Seyran; Mehrgardi, Masoud Ayatollahi

    2014-08-01

    In this manuscript, the electrocatalytic reduction of hydrogen peroxides on Prussian blue (PB) modified nanoporous gold film (NPGF) electrode is described. The PB/NPGF is prepared by simple anodizing of a smooth gold film followed by PB film electrodeposition method. The morphology of the PB/NPGF electrode is characterized using scanning el