WorldWideScience

Sample records for gas sensors operating

  1. Gas Sensor

    KAUST Repository

    Luebke, Ryan

    2015-01-22

    A gas sensor using a metal organic framework material can be fully integrated with related circuitry on a single substrate. In an on-chip application, the gas sensor can result in an area-efficient fully integrated gas sensor solution. In one aspect, a gas sensor can include a first gas sensing region including a first pair of electrodes, and a first gas sensitive material proximate to the first pair of electrodes, wherein the first gas sensitive material includes a first metal organic framework material.

  2. Gas Sensor

    KAUST Repository

    Luebke, Ryan; Eddaoudi, Mohamed; Omran, Hesham; Belmabkhout, Youssef; Shekhah, Osama; Salama, Khaled N.

    2015-01-01

    A gas sensor using a metal organic framework material can be fully integrated with related circuitry on a single substrate. In an on-chip application, the gas sensor can result in an area-efficient fully integrated gas sensor solution. In one aspect, a gas sensor can include a first gas sensing region including a first pair of electrodes, and a first gas sensitive material proximate to the first pair of electrodes, wherein the first gas sensitive material includes a first metal organic framework material.

  3. Gas sensor

    International Nuclear Information System (INIS)

    Dorogan, V.; Korotchenkov, Gh.; Vieru, T.; Prodan, I.

    2003-01-01

    The invention relates to the gas sensors on base of metal-oxide films (SnO, InO), which may be used for enviromental control, in the fireextinguishing systema etc. The gas includes an insulating substrate, an active layer, a resistive layer with ohmic contacts. The resistive layer has two or more regions with dofferent resistances , and on the active layer are two or more pairs of ohmic contacts

  4. Gas sensor

    Science.gov (United States)

    Schmid, Andreas K.; Mascaraque, Arantzazu; Santos, Benito; de la Figuera, Juan

    2014-09-09

    A gas sensor is described which incorporates a sensor stack comprising a first film layer of a ferromagnetic material, a spacer layer, and a second film layer of the ferromagnetic material. The first film layer is fabricated so that it exhibits a dependence of its magnetic anisotropy direction on the presence of a gas, That is, the orientation of the easy axis of magnetization will flip from out-of-plane to in-plane when the gas to be detected is present in sufficient concentration. By monitoring the change in resistance of the sensor stack when the orientation of the first layer's magnetization changes, and correlating that change with temperature one can determine both the identity and relative concentration of the detected gas. In one embodiment the stack sensor comprises a top ferromagnetic layer two mono layers thick of cobalt deposited upon a spacer layer of ruthenium, which in turn has a second layer of cobalt disposed on its other side, this second cobalt layer in contact with a programmable heater chip.

  5. Gas sensor based on photoconductive electrospun titania nanofibres operating at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zampetti, E., E-mail: emiliano.zampetti@artov.imm.cnr.it; Macagnano, A.; Bearzotti, A. [Consiglio Nazionale delle Ricerche, Istituto per la Microelettronica e Microsistemi (CNR IMM) (Italy)

    2013-04-15

    An important drawback of semiconductor gas sensors is their operating temperature that needs the use of heaters. To overcome this problem a prototyping sensor using titania nanofibres (with an average diameter of 50 nm) as sensitive membrane were fabricated by electrospinning directly on the transducer of the sensor. Exploiting the effect of titania photoconductivity, resistance variations upon gas interaction under continuous irradiation of ultra violet light were measured at room temperature. The resistive sensor response was evaluated towards ammonia, nitrogen dioxide and humidity. The sensor exhibited a higher response to ammonia than to nitrogen dioxide, especially for concentrations larger than 100 ppb. For 200 ppb of ammonia and nitrogen dioxide, the responses were {approx}2.8 and 1.5 %, respectively.

  6. Low Power Operation of Temperature-Modulated Metal Oxide Semiconductor Gas Sensors

    Directory of Open Access Journals (Sweden)

    Javier Burgués

    2018-01-01

    Full Text Available Mobile applications based on gas sensing present new opportunities for low-cost air quality monitoring, safety, and healthcare. Metal oxide semiconductor (MOX gas sensors represent the most prominent technology for integration into portable devices, such as smartphones and wearables. Traditionally, MOX sensors have been continuously powered to increase the stability of the sensing layer. However, continuous power is not feasible in many battery-operated applications due to power consumption limitations or the intended intermittent device operation. This work benchmarks two low-power, duty-cycling, and on-demand modes against the continuous power one. The duty-cycling mode periodically turns the sensors on and off and represents a trade-off between power consumption and stability. On-demand operation achieves the lowest power consumption by powering the sensors only while taking a measurement. Twelve thermally modulated SB-500-12 (FIS Inc. Jacksonville, FL, USA sensors were exposed to low concentrations of carbon monoxide (0–9 ppm with environmental conditions, such as ambient humidity (15–75% relative humidity and temperature (21–27 °C, varying within the indicated ranges. Partial Least Squares (PLS models were built using calibration data, and the prediction error in external validation samples was evaluated during the two weeks following calibration. We found that on-demand operation produced a deformation of the sensor conductance patterns, which led to an increase in the prediction error by almost a factor of 5 as compared to continuous operation (2.2 versus 0.45 ppm. Applying a 10% duty-cycling operation of 10-min periods reduced this prediction error to a factor of 2 (0.9 versus 0.45 ppm. The proposed duty-cycling powering scheme saved up to 90% energy as compared to the continuous operating mode. This low-power mode may be advantageous for applications that do not require continuous and periodic measurements, and which can tolerate

  7. Low Power Operation of Temperature-Modulated Metal Oxide Semiconductor Gas Sensors.

    Science.gov (United States)

    Burgués, Javier; Marco, Santiago

    2018-01-25

    Mobile applications based on gas sensing present new opportunities for low-cost air quality monitoring, safety, and healthcare. Metal oxide semiconductor (MOX) gas sensors represent the most prominent technology for integration into portable devices, such as smartphones and wearables. Traditionally, MOX sensors have been continuously powered to increase the stability of the sensing layer. However, continuous power is not feasible in many battery-operated applications due to power consumption limitations or the intended intermittent device operation. This work benchmarks two low-power, duty-cycling, and on-demand modes against the continuous power one. The duty-cycling mode periodically turns the sensors on and off and represents a trade-off between power consumption and stability. On-demand operation achieves the lowest power consumption by powering the sensors only while taking a measurement. Twelve thermally modulated SB-500-12 (FIS Inc. Jacksonville, FL, USA) sensors were exposed to low concentrations of carbon monoxide (0-9 ppm) with environmental conditions, such as ambient humidity (15-75% relative humidity) and temperature (21-27 °C), varying within the indicated ranges. Partial Least Squares (PLS) models were built using calibration data, and the prediction error in external validation samples was evaluated during the two weeks following calibration. We found that on-demand operation produced a deformation of the sensor conductance patterns, which led to an increase in the prediction error by almost a factor of 5 as compared to continuous operation (2.2 versus 0.45 ppm). Applying a 10% duty-cycling operation of 10-min periods reduced this prediction error to a factor of 2 (0.9 versus 0.45 ppm). The proposed duty-cycling powering scheme saved up to 90% energy as compared to the continuous operating mode. This low-power mode may be advantageous for applications that do not require continuous and periodic measurements, and which can tolerate slightly higher

  8. Microfabricated Formaldehyde Gas Sensors

    Directory of Open Access Journals (Sweden)

    Karen C. Cheung

    2009-11-01

    Full Text Available Formaldehyde is a volatile organic compound that is widely used in textiles, paper, wood composites, and household materials. Formaldehyde will continuously outgas from manufactured wood products such as furniture, with adverse health effects resulting from prolonged low-level exposure. New, microfabricated sensors for formaldehyde have been developed to meet the need for portable, low-power gas detection. This paper reviews recent work including silicon microhotplates for metal oxide-based detection, enzyme-based electrochemical sensors, and nanowire-based sensors. This paper also investigates the promise of polymer-based sensors for low-temperature, low-power operation.

  9. Sensitive resonant gas sensor operating in air with metal organic frameworks coating

    KAUST Repository

    Jaber, Nizar; Ilyas, Saad; Shekhah, Osama; Eddaoudi, Mohamed; Younis, Mohammad I.

    2017-01-01

    We report a practical resonant gas sensor that is uniformly coated with metal organic frameworks (MOFs) and excited near the higher order modes for a higher attained sensitivity. The resonator is based on an electrostatically excited clamped-clamped microbeam. The microbeam is fabricated from a polyimide layer coated from the top with Cr/Au and from the bottom with Cr/Au/Cr layer. The geometry of the resonator is optimized to reduce the effect of the squeeze film damping, thereby allowing operation under atmospheric pressure. The electrostatic force electrode is designed to enhance the excitation of the second mode of vibration with the minimum power required. Significant frequency shift (kHz) is demonstrated for the first time upon water vapor, acetone, and ethanol exposure due to the MOFs functionalization and the higher order modes excitation. Also, the adsorption dynamics and MOF selectivity is investigated by studying the decaying time constants of the response upon gas exposure.

  10. Sensitive resonant gas sensor operating in air with metal organic frameworks coating

    KAUST Repository

    Jaber, Nizar

    2017-08-09

    We report a practical resonant gas sensor that is uniformly coated with metal organic frameworks (MOFs) and excited near the higher order modes for a higher attained sensitivity. The resonator is based on an electrostatically excited clamped-clamped microbeam. The microbeam is fabricated from a polyimide layer coated from the top with Cr/Au and from the bottom with Cr/Au/Cr layer. The geometry of the resonator is optimized to reduce the effect of the squeeze film damping, thereby allowing operation under atmospheric pressure. The electrostatic force electrode is designed to enhance the excitation of the second mode of vibration with the minimum power required. Significant frequency shift (kHz) is demonstrated for the first time upon water vapor, acetone, and ethanol exposure due to the MOFs functionalization and the higher order modes excitation. Also, the adsorption dynamics and MOF selectivity is investigated by studying the decaying time constants of the response upon gas exposure.

  11. Smart Resonant Gas Sensor and Switch Operating in Air With Metal-Organic Frameworks Coating

    KAUST Repository

    Jaber, Nizar; Ilyas, Saad; Shekhah, Osama; Eddaoudi, Mohamed; Younis, Mohammad I.

    2017-01-01

    We report a resonant gas sensor, uniformly coated with a metal-organic framework (MOF), and excited it near the higher order modes for a higher attained sensitivity. Also, switching upon exceeding a threshold value is demonstrated by operating the resonator near the bifurcation point and the dynamic pull-in instabilities. The resonator is based on an electrostatically excited clamped-clamped microbeam. The microbeam is fabricated from a polyimide layer coated from the top with Cr/Au and from the bottom with Cr/Au/Cr layer. The geometry of the resonator is optimized to reduce the effect of squeeze film damping, thereby allowing operation under atmospheric pressure. The electrostatic electrode is designed to enhance the excitation of the second mode of vibration with the minimum power required. Significant frequency shift (kHz) is demonstrated for the first time upon water vapor, acetone, and ethanol exposure due to the MOF functionalization and the higher order modes excitation. Also, the adsorption dynamics and MOF selectivity is investigated by studying the decaying time constants of the response upon gas exposure.

  12. Smart Resonant Gas Sensor and Switch Operating in Air With Metal-Organic Frameworks Coating

    KAUST Repository

    Jaber, Nizar

    2017-11-03

    We report a resonant gas sensor, uniformly coated with a metal-organic framework (MOF), and excited it near the higher order modes for a higher attained sensitivity. Also, switching upon exceeding a threshold value is demonstrated by operating the resonator near the bifurcation point and the dynamic pull-in instabilities. The resonator is based on an electrostatically excited clamped-clamped microbeam. The microbeam is fabricated from a polyimide layer coated from the top with Cr/Au and from the bottom with Cr/Au/Cr layer. The geometry of the resonator is optimized to reduce the effect of squeeze film damping, thereby allowing operation under atmospheric pressure. The electrostatic electrode is designed to enhance the excitation of the second mode of vibration with the minimum power required. Significant frequency shift (kHz) is demonstrated for the first time upon water vapor, acetone, and ethanol exposure due to the MOF functionalization and the higher order modes excitation. Also, the adsorption dynamics and MOF selectivity is investigated by studying the decaying time constants of the response upon gas exposure.

  13. Fiber optic gas sensor

    Science.gov (United States)

    Chen, Peng (Inventor); Buric, Michael P. (Inventor); Swinehart, Philip R. (Inventor); Maklad, Mokhtar S. (Inventor)

    2010-01-01

    A gas sensor includes an in-fiber resonant wavelength device provided in a fiber core at a first location. The fiber propagates a sensing light and a power light. A layer of a material is attached to the fiber at the first location. The material is able to absorb the gas at a temperature dependent gas absorption rate. The power light is used to heat the material and increases the gas absorption rate, thereby increasing sensor performance, especially at low temperatures. Further, a method is described of flash heating the gas sensor to absorb more of the gas, allowing the sensor to cool, thereby locking in the gas content of the sensor material, and taking the difference between the starting and ending resonant wavelengths as an indication of the concentration of the gas in the ambient atmosphere.

  14. A High-Sensitivity Gas Sensor Toward Methanol Using ZnO Microrods: Effect of Operating Temperature

    Science.gov (United States)

    Sinha, M.; Mahapatra, R.; Mondal, B.; Ghosh, R.

    2017-04-01

    In the present work, zinc oxide (ZnO) microrods with the average diameter of 350 nm have been synthesized on fluorine doped tin oxide (FTO) substrate using a hydrothermal reaction process at a low temperature of 90°C. The methanol gas sensing behaviour of as-synthesized ZnO microrods have been studied at different operating temperatures (100-300°C). The gas sensing results show that the ZnO microrods exhibit excellent sensitivity, selectivity, and stability toward methanol gas at 300°C. The as-grown ZnO microrods sensor also shows the good sensitivity for methanol even at a low operating temperature of 100°C. The ultra-high sensitivity of 4.41 × 104% [gas sensitivity, S g = ( I g - I a)/ I a × 100%] and 5.11 × 102% to 100 ppm methanol gas at a temperature of 300°C and 100°C, respectively, has been observed. A fast response time of 200 ms and 270 ms as well as a recovery time of 120 ms and 1330 ms to methanol gas have also been found at an operating temperature of 300°C and 100°C, respectively. The response and recovery time decreases with increasing operation temperature of the sensor.

  15. 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.

  16. Nanostructured ZrO2 Thick Film Resistors as H2-Gas Sensors Operable at Room Temperature

    Directory of Open Access Journals (Sweden)

    K. M. GARADKAR

    2009-11-01

    Full Text Available Nanostructured ZrO2 powder was synthesized by microwave assisted sol-gel method. The material was characterized by XRD and SEM techniques. X-Ray diffraction studies confirm that a combination of tetragonal and monoclinic zirconia nanoparticles is obtained by using microwave-assisted method. The nanopowder was calcined at an optimized temperature of 400 °C for 3 h. The prepared powder had crystalline size about 25 nm. Thick films of synthesized ZrO2 powder were prepared by screen printing technique. The gas sensing performances of these films for various gases were tested. Films showed highest response to H2 (50 ppm gas at room temperature with poor responses to others (1000 ppm. The quick response and fast recovery are the main features of this sensor. The effects of microstructure, operating temperature and gas concentration on the gas response, selectivity, response time and recovery time of the sensor in the presence of H2 gas and others were studied and discussed.

  17. The effect of noble metal additives on the optimum operating temperature of SnO2 gas sensors

    Science.gov (United States)

    Mohammad-Yousefi, S.; Rahbarpour, S.; Ghafoorifard, H.

    2017-12-01

    The effect of Pd and Au additives on gas sensing properties of SnO2 was investigated. SnO2 pallets were fabricated and sintered at 900 °C for 90 minutes. Several nanometer layers of Pd and Au were deposited on separate SnO2 pallets and were intentionally dispersed into the SnO2 pallets by long heat treatment (400 °C for 1 Day). All metal loaded samples showed significant enhancement in response level and optimum operating temperature compare to pure SnO2 gas sensors. The amount of enhancement was strongly dependent on the material and the thickness of deposited metal layer. Studying butanol response showed that increasing the thickness of metal causes the response level to increase. Further thickness increase caused contrary effect and decreased the performance of sensors. Best results were achieved at 10 nm-thick Au and 7 nm-thick Pd. Generally, Pd-SnO2 samples demonstrated better performance than Au-SnO2 ones, however, Au-SnO2 samples were proved to be good candidate to sense reducing gases with lower hydrogen atoms in their formula. Given experimental results were also good evidence of chemical activity of gold and simply confirms the relation between chemical activity and gold particle size. Results were qualitatively described by gas diffusion theory and surface reactions take place on metal particles.The first section in your paper

  18. Selectivity of the gas sensor based on the 50%In2O3-50%Ga2O3 thin film in dynamic mode of operation

    Science.gov (United States)

    Demin, I. E.; Kozlov, A. G.

    2018-01-01

    The article considers the gas sensor with the sensitive layer based on the 50%In2O3 -50%Ga2O3 thin film. The temperature and concentration dependencies of gas-induced resistance response of this sensor and the dynamical dependencies of its resistance response on the test gases in air are investigated. The test gases were ethanol, acetone, ammonia and liquefied petroleum gas. The information parameters of the sensor in the dynamical mode of operation were considered to improve its selectivity. The presented results show that the selectivity of the sensor in this mode may be improved by using the following information parameters: gas-induced resistance response in steady state, activation energy of the response and pre-exponential factor of the temperature dependence of the response time constant.

  19. Metal oxide gas sensors on the nanoscale

    Science.gov (United States)

    Plecenik, A.; Haidry, A. A.; Plecenik, T.; Durina, P.; Truchly, M.; Mosko, M.; Grancic, B.; Gregor, M.; Roch, T.; Satrapinskyy, L.; Moskova, A.; Mikula, M.; Kus, P.

    2014-06-01

    Low cost, low power and highly sensitive gas sensors operating at room temperature are very important devices for controlled hydrogen gas production and storage. One of the disadvantages of chemosensors is their high operating temperature (usually 200 - 400 °C), which excludes such type of sensors from usage in explosive environment. In this report, a new concept of gas chemosensors operating at room temperature based on TiO2 thin films is discussed. Integration of such sensor is fully compatible with sub-100 nm semiconductor technology and could be transferred directly from labor to commercial sphere.

  20. Gas stream analysis using voltage-current time differential operation of electrochemical sensors

    Science.gov (United States)

    Woo, Leta Yar-Li; Glass, Robert Scott; Fitzpatrick, Joseph Jay; Wang, Gangqiang; Henderson, Brett Tamatea; Lourdhusamy, Anthoniraj; Steppan, James John; Allmendinger, Klaus Karl

    2018-01-02

    A method for analysis of a gas stream. The method includes identifying an affected region of an affected waveform signal corresponding to at least one characteristic of the gas stream. The method also includes calculating a voltage-current time differential between the affected region of the affected waveform signal and a corresponding region of an original waveform signal. The affected region and the corresponding region of the waveform signals have a sensitivity specific to the at least one characteristic of the gas stream. The method also includes generating a value for the at least one characteristic of the gas stream based on the calculated voltage-current time differential.

  1. Chemoresistive gas sensor

    Science.gov (United States)

    Hirschfeld, T.B.

    1987-06-23

    A chemoresistive gas sensor is provided which has improved sensitivity. A layer of organic semiconductor is disposed between two electrodes which, in turn, are connected to a voltage source. High conductivity material is dispersed within the layer of organic semiconductor in the form of very small particles, or islands. The average interisland spacing is selected so that the predominant mode of current flow is by way of electron funneling. Adsorption of gaseous contaminant onto the layer of organic semiconductor modulates the tunneling current in a quantitative manner. 2 figs.

  2. Thermosensitive gas flow sensor

    International Nuclear Information System (INIS)

    Berlicki, T.; Osadnik, S.; Prociow, E.

    1997-01-01

    Results of investigations on thermal gas flow sensor have been presented. The sensor consists of three thin film resistors Si+Ta. The circuit was designed in the form of two bridges; one of them serves for measurement of the heater temperature, the second one for the measurement of temperature difference of peripheral resistors. The measurement of output voltage versus the rate of nitrogen flow at various power levels dissipated at the heater and various temperatures have been made. The measurements were carried out in three versions; (a) at constant temperature of the heater, (b) at constant power dissipated in the heater, controlled by the power of the heater, (c) at constant temperature of the heater controlled by the power dissipated in the peripheral resistors of the sensor. Due to measurement range it is advantageous to stabilize the temperature of the heater, especially by means of the power supplied to the peripheral resistors. In this case the wider measurement range can be obtained. (author)

  3. Temperature-programmed technique accompanied with high-throughput methodology for rapidly searching the optimal operating temperature of MOX gas sensors.

    Science.gov (United States)

    Zhang, Guozhu; Xie, Changsheng; Zhang, Shunping; Zhao, Jianwei; Lei, Tao; Zeng, Dawen

    2014-09-08

    A combinatorial high-throughput temperature-programmed method to obtain the optimal operating temperature (OOT) of gas sensor materials is demonstrated here for the first time. A material library consisting of SnO2, ZnO, WO3, and In2O3 sensor films was fabricated by screen printing. Temperature-dependent conductivity curves were obtained by scanning this gas sensor library from 300 to 700 K in different atmospheres (dry air, formaldehyde, carbon monoxide, nitrogen dioxide, toluene and ammonia), giving the OOT of each sensor formulation as a function of the carrier and analyte gases. A comparative study of the temperature-programmed method and a conventional method showed good agreement in measured OOT.

  4. Micro Coriolis Gas Density Sensor

    NARCIS (Netherlands)

    Sparreboom, Wouter; Ratering, Gijs; Kruijswijk, Wim; van der Wouden, E.J.; Groenesteijn, Jarno; Lötters, Joost Conrad

    2017-01-01

    In this paper we report on gas density measurements using a micro Coriolis sensor. The technology to fabricate the sensor is based on surface channel technology. The measurement tube is freely suspended and has a wall thickness of only 1 micron. This renders the sensor extremely sensitive to changes

  5. Multi-Gas Sensor

    Science.gov (United States)

    Sachse, Glenn W. (Inventor); Wang, Liang-Guo (Inventor); LeBel, Peter J. (Inventor); Steele, Tommy C. (Inventor); Rana, Mauro (Inventor)

    1999-01-01

    A multi-gas sensor is provided which modulates a polarized light beam over a broadband of wavelengths between two alternating orthogonal polarization components. The two orthogonal polarization components of the polarization modulated beam are directed along two distinct optical paths. At least one optical path contains one or more spectral discrimination element, with each spectral discrimination element having spectral absorption features of one or more gases of interest being measured. The two optical paths then intersect, and one orthogonal component of the intersected components is transmitted and the other orthogonal component is reflected. The combined polarization modulated beam is partitioned into one or more smaller spectral regions of interest where one or more gases of interest has an absorption band. The difference in intensity between the two orthogonal polarization components is then determined in each partitioned spectral region of interest as an indication of the spectral emission/absorption of the light beam by the gases of interest in the measurement path. The spectral emission/absorption is indicative of the concentration of the one or more gases of interest in the measurement path. More specifically, one embodiment of the present invention is a gas filter correlation radiometer which comprises a polarizer, a polarization modulator, a polarization beam splitter, a beam combiner, wavelength partitioning element, and detection element. The gases of interest are measured simultaneously and, further, can be measured independently or non-independently. Furthermore, optical or electronic element are provided to balance optical intensities between the two optical paths.

  6. Electrodes for Semiconductor Gas Sensors

    Science.gov (United States)

    Lee, Sung Pil

    2017-01-01

    The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and surface states of electrode–semiconductor interfaces on their characteristics is studied. This study describes that the gas interaction mechanism of the electrode–semiconductor interfaces should take into account the interfacial zone, surface states, image force, and tunneling effect. PMID:28346349

  7. A Rapid Process for Fabricating Gas Sensors

    Directory of Open Access Journals (Sweden)

    Chun-Ching Hsiao

    2014-07-01

    Full Text Available Zinc oxide (ZnO is a low-toxicity and environmentally-friendly material applied on devices, sensors or actuators for “green” usage. A porous ZnO film deposited by a rapid process of aerosol deposition (AD was employed as the gas-sensitive material in a CO gas sensor to reduce both manufacturing cost and time, and to further extend the AD application for a large-scale production. The relative resistance change (△R/R of the ZnO gas sensor was used for gas measurement. The fabricated ZnO gas sensors were measured with operating temperatures ranging from 110 °C to 180 °C, and CO concentrations ranging from 100 ppm to 1000 ppm. The sensitivity and the response time presented good performance at increasing operating temperatures and CO concentrations. AD was successfully for applied for making ZnO gas sensors with great potential for achieving high deposition rates at low deposition temperatures, large-scale production and low cost.

  8. Gas Sensors Based on Electrodeposited Polymers

    Directory of Open Access Journals (Sweden)

    Boris Lakard

    2015-07-01

    Full Text Available Electrochemically deposited polymers, also called “synthetic metals”, have emerged as potential candidates for chemical sensing due to their interesting and tunable chemical, electrical, and structural properties. In particular, most of these polymers (including polypyrrole, polyaniline, polythiophene and their derivatives can be used as the sensitive layer of conductimetric gas sensors because of their conducting properties. An important advantage of polymer-based gas sensors is their efficiency at room temperature. This characteristic is interesting since most of the commercially-available sensors, usually based on metal oxides, work at high temperatures (300–400 °C. Consequently, polymer-based gas sensors are playing a growing role in the improvement of public health and environment control because they can lead to gas sensors operating with rapid detection, high sensitivity, small size, and specificity in atmospheric conditions. In this review, the recent advances in electrodeposited polymer-based gas sensors are summarized and discussed. It is shown that the sensing characteristics of electrodeposited polymers can be improved by chemical functionalization, nanostructuration, or mixing with other functional materials to form composites or hybrid materials.

  9. Numerical Signal Analysis of Thermo-Cyclically Operated MOG Gas Sensor Arrays for Early Identification of Emissions from Overloaded Electric Cables

    Directory of Open Access Journals (Sweden)

    Rolf Seifert

    2015-10-01

    Full Text Available A thermo-cyclically operated multi metal oxide gas sensor (MOG array is introduced together with a novel signal analysis approach (SimSens for identifying the emissions from overheated isolation cable materials thereby detecting the fires originated in electrical cabinets at early stages. The MOG array can yield specific conductance signatures appropriate to specifically identify gases. The obtained results bear good capability for detection and identification of pyrolysis gas emissions at relatively low sample heating temperatures even before a visible color-change of the polyvinyl chloride (PVC-isolation material. The dynamic conductance signals were evaluated using SimSens, a numerical analysis tool designed for simultaneous evaluation of conductance profiles. The results show promising pyrolysis gas identification and concentration determination capabilities in relation to the conductance profile shapes of model gases like carbon monoxide (CO and propene.

  10. Nanowire-based gas sensors

    NARCIS (Netherlands)

    Chen, X.; Wong, C.K.Y.; Yuan, C.A.; Zhang, G.

    2013-01-01

    Gas sensors fabricated with nanowires as the detecting elements are powerful due to their many improved characteristics such as high surface-to-volume ratios, ultrasensitivity, higher selectivity, low power consumption, and fast response. This paper gives an overview on the recent process of the

  11. Potential use of gas sensors in beef manure nutrient content ...

    African Journals Online (AJOL)

    The purpose of this study was to develop a gas sensor array to estimate the manure nutrient contents. Three metal-oxide gas sensors including methane, ammonia and hydrogen sulfide were used. Forty manure samples were collected from four beef operations in Southwest North Dakota. Manure samples were sent to be ...

  12. Intelligent gas-mixture flow sensor

    NARCIS (Netherlands)

    Lammerink, Theodorus S.J.; Dijkstra, Fred; Houkes, Z.; van Kuijk, J.C.C.; van Kuijk, Joost

    A simple way to realize a gas-mixture flow sensor is presented. The sensor is capable of measuring two parameters from a gas flow. Both the flow rate and the helium content of a helium-nitrogen gas mixture are measured. The sensor exploits two measurement principles in combination with (local)

  13. Combustion Sensors: Gas Turbine Applications

    Science.gov (United States)

    Human, Mel

    2002-01-01

    This report documents efforts to survey the current research directions in sensor technology for gas turbine systems. The work is driven by the current and future requirements on system performance and optimization. Accurate real time measurements of velocities, pressure, temperatures, and species concentrations will be required for objectives such as combustion instability attenuation, pollutant reduction, engine health management, exhaust profile control via active control, etc. Changing combustor conditions - engine aging, flow path slagging, or rapid maneuvering - will require adaptive responses; the effectiveness of such will be only as good as the dynamic information available for processing. All of these issues point toward the importance of continued sensor development. For adequate control of the combustion process, sensor data must include information about the above mentioned quantities along with equivalence ratios and radical concentrations, and also include both temporal and spatial velocity resolution. Ultimately these devices must transfer from the laboratory to field installations, and thus must become low weight and cost, reliable and maintainable. A primary conclusion from this study is that the optics-based sensor science will be the primary diagnostic in future gas turbine technologies.

  14. Bimodular high temperature planar oxygen gas sensor

    Directory of Open Access Journals (Sweden)

    Xiangcheng eSun

    2014-08-01

    Full Text Available A bimodular planar O2 sensor was fabricated using NiO nanoparticles (NPs thin film coated yttria-stabilized zirconia (YSZ substrate. The thin film was prepared by radio frequency (r.f. magnetron sputtering of NiO on YSZ substrate, followed by high temperature sintering. The surface morphology of NiO nanoparticles film was characterized by atomic force microscopy (AFM and scanning electron microscopy (SEM. X-ray diffraction (XRD patterns of NiO NPs thin film before and after high temperature O2 sensing demonstrated that the sensing material possesses a good chemical and structure stability. The oxygen detection experiments were performed at 500 °C, 600 °C and 800 °C using the as-prepared bimodular O2 sensor under both potentiometric and resistance modules. For the potentiometric module, a linear relationship between electromotive force (EMF output of the sensor and the logarithm of O2 concentration was observed at each operating temperature, following the Nernst law. For the resistance module, the logarithm of electrical conductivity was proportional to the logarithm of oxygen concentration at each operating temperature, in good agreement with literature report. In addition, this bimodular sensor shows sensitive, reproducible and reversible response to oxygen under both sensing modules. Integration of two sensing modules into one sensor could greatly enrich the information output and would open a new venue in the development of high temperature gas sensors.

  15. Potential use of gas sensors in beef manure nutrient content ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-06-17

    Jun 17, 2009 ... manure samples were collected from four beef operations in Southwest North Dakota. Manure samples were sent to be ... cation rate at spreading time instead of waiting two or three weeks to receive the results ... Operation mechanism of metal-oxide gas sensors. The sensors used in this study were ...

  16. Compact portable QEPAS multi-gas sensor

    Science.gov (United States)

    Dong, Lei; Kosterev, Anatoliy A.; Thomazy, David; Tittel, Frank K.

    2011-01-01

    A quartz-enhanced photoacoustic spectroscopy (QEPAS) based multi-gas sensor was developed to quantify concentrations of carbon monoxide (CO), hydrogen cyanide (HCN), hydrogen chloride (HCl), and carbon dioxide (CO2) in ambient air. The sensor consists of a compact package of dimensions 25cm x 25cm x 10cm and was designed to operate at atmospheric pressure. The HCN, CO2, and HCl measurement channels are based on cw, C-band telecommunication-style packaged, fiber-coupled diode lasers, while the CO channel uses a TO can-packaged Sb diode laser as an excitation source. Moreover, the sensor incorporates rechargeable batteries and can operate on batteries for at least 8 hours. It can also operate autonomously or interact with another device (such as a computer) via a RS232 serial port. Trace gas detection limits of 7.74ppm at 4288.29cm-1 for CO, 450ppb at 6539.11 cm-1 for HCN, 1.48ppm at 5739.26 cm-1 for HCl and 97ppm at 6361.25 cm-1 for CO2 for a 1sec average time, were demonstrated.

  17. Laser-based gas sensors keep moisture out of pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2006-07-15

    Natural gas often contains contaminants that cause corrosion, and long-term deterioration, and must be cleaned and brought to pipeline standards before it can be delivered to high-pressure, long-distance pipelines. Many older sensors produce false data that can result in contaminated gas getting through. This article presented details of the SpectraSensor, a new laser-based sensor technology used by the El Paso Natural Gas Company (EPNG). The SpectraSensor is comprised of a tunable diode laser (TDL) based technology developed by the National American Space Agency (NASA). The gas analyzer provides non-contact measurement of moisture, carbon dioxide, and other corrosives in natural gas pipelines, and the tunable laser-based gas sensors are fast, accurate, and flexible. Producers can monitor El Paso's gas analyzer readings by capturing the electronic signal from El Paso's unit via a SCADA system and view the readings from control rooms. While initial purchase price is higher than more problematic surface-based gas sensors, an evaluation of the technology has indicated that maintenance savings alone may provide an almost immediate return on investments. Unlike electrochemical and crystal gas sensors, laser-based gas analyzers do not come into direct contact with any substances, a fact which practically eliminates maintenance and operational costs. Studies have shown that the cost of operating conventional electrochemical sensors can result in a cumulative annual expense exceeding $50,000 per unit including labour; recalibration and rebuilding; back-up sensor heads; and gas dehydration and tariffs. 1 fig.

  18. Carbon-Nanotube-Based Chemical Gas Sensor

    Science.gov (United States)

    Kaul, Arunpama B.

    2010-01-01

    Conventional thermal conductivity gauges (e.g. Pirani gauges) lend themselves to applications such as leak detectors, or in gas chromatographs for identifying various gas species. However, these conventional gauges are physically large, operate at high power, and have a slow response time. A single-walled carbon-nanotube (SWNT)-based chemical sensing gauge relies on differences in thermal conductance of the respective gases surrounding the CNT as it is voltage-biased, as a means for chemical identification. Such a sensor provides benefits of significantly reduced size and compactness, fast response time, low-power operation, and inexpensive manufacturing since it can be batch-fabricated using Si integrated-circuit (IC) process technology.

  19. Silicon microring refractometric sensor for atmospheric CO(2) gas monitoring.

    Science.gov (United States)

    Mi, Guangcan; Horvath, Cameron; Aktary, Mirwais; Van, Vien

    2016-01-25

    We report a silicon photonic refractometric CO(2) gas sensor operating at room temperature and capable of detecting CO(2) gas at atmospheric concentrations. The sensor uses a novel functional material layer based on a guanidine polymer derivative, which is shown to exhibit reversible refractive index change upon absorption and release of CO(2) gas molecules, and does not require the presence of humidity to operate. By functionalizing a silicon microring resonator with a thin layer of the polymer, we could detect CO(2) gas concentrations in the 0-500ppm range with a sensitivity of 6 × 10(-9) RIU/ppm and a detection limit of 20ppm. The microring transducer provides a potential integrated solution in the development of low-cost and compact CO(2) sensors that can be deployed as part of a sensor network for accurate environmental monitoring of greenhouse gases.

  20. Nano-Hydroxyapatite Thick Film Gas Sensors

    International Nuclear Information System (INIS)

    Khairnar, Rajendra S.; Mene, Ravindra U.; Munde, Shivaji G.; Mahabole, Megha P.

    2011-01-01

    In the present work pure and metal ions (Co and Fe) doped hydroxyapatite (HAp) thick films have been successfully utilized to improve the structural, morphological and gas sensing properties. Nanocrystalline HAp powder is synthesized by wet chemical precipitation route, and ion exchange process is employed for addition of Co and Fe ions in HAp matrix. Moreover, swift heavy ion irradiation (SHI) technique is used to modify the surface of pure and metal ion exchanged HAp with various ion fluence. The structural investigation of pure and metal ion exchanged HAp thick films are carried out using X-ray diffraction and the presence of functional group is observed by means FTIR spectroscopy. Furthermore, surface morphology is visualized by means of SEM and AFM analysis. CO gas sensing study is carried out for, pure and metal ions doped, HAp thick films with detail investigation on operating temperature, response/recovery time and gas uptake capacity. The surface modifications of sensor matrix by SHI enhance the gas response, response/recovery and gas uptake capacity. The significant observation is here to note that, addition of Co and Fe in HAp matrix and surface modification by SHI improves the sensing properties of HAp films drastically resulting in gas sensing at relatively lower temperatures.

  1. 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

  2. A high performance hydrogen sulfide gas sensor based on porous α-Fe{sub 2}O{sub 3} operates at room-temperature

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yanwu; Chen, Weimei; Zhang, Shouchao; Kuang, Zhong; Ao, Dongyi [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 (China); Alkurd, Nooraldeen Rafat; Zhou, Weilie [Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Liu, Wei [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 (China); Shen, Wenzhong [Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001 (China); Li, Zhijie, E-mail: zhijieli@uestc.edu.cn [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 (China)

    2015-10-01

    Highlights: • Novel porous α-Fe{sub 2}O{sub 3} nanoparticles were prepared by a facile hydrothermal method. • The sensor based on porous α-Fe{sub 2}O{sub 3} exhibits high sensitivity towards H{sub 2}S gas. • The detection limit towards H{sub 2}S gas was as low as 50 ppb at room temperature. • The sensor exhibits excellent selectivity against other toxic and noxious gases. - Abstract: Porous α-Fe{sub 2}O{sub 3} nanoparticles were synthesized by simple annealing of β-FeOOH precursor derived from a facile hydrothermal route, the structures and morphologies of the as-prepared product were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the average crystallite size of the obtained porous α-Fe{sub 2}O{sub 3} was 34 nm and exits numerous irregularly distributed pores with a diameter varying from 2 nm to 10 nm on the particle surface. The gas-sensing properties of the sensor based on porous α-Fe{sub 2}O{sub 3} nanoparticles were investigated, and the result showed that the sensor exhibited a high performance in hydrogen sulfide (H{sub 2}S) detection at room temperature. The highest sensitivity reached 38.4 for 100 ppm H{sub 2}S, and the detection limit was as low as 50 ppb. In addition, the response of the sensor towards other gases including C{sub 2}H{sub 5}OH, CO, H{sub 2} and NH{sub 3} indicates the sensor has an excellent selectivity to detection H{sub 2}S gas. Finally, the sensing mechanism of the sensor towards H{sub 2}S was also discussed.

  3. Ammonia gas sensors based on In2O3/PANI hetero-nanofibers operating at room temperature

    Directory of Open Access Journals (Sweden)

    Qingxin Nie

    2016-09-01

    Full Text Available Indium nitrate/polyvinyl pyrrolidone (In(NO33/PVP composite nanofibers were synthesized via electrospinning, and then hollow structure indium oxide (In2O3 nanofibers were obtained through calcination with PVP as template material. In situ polymerization was used to prepare indium oxide/polyaniline (In2O3/PANI composite nanofibers with different mass ratios of In2O3 to aniline. The structure and morphology of In(NO33/PVP, In2O3/PANI composite nanofibers and pure PANI were investigated by scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, transmission electron microscopy (TEM and current–voltage (I–V measurements. The gas sensing properties of these materials towards NH3 vapor (100 to 1000 ppm were measured at room temperature. The results revealed that the gas sensing abilities of In2O3/PANI composite nanofibers were better than pure PANI. In addition, the mass ratio of In2O3 to aniline and the p–n heterostructure between In2O3 and PANI influences the sensing performance of the In2O3/PANI composite nanofibers. In this paper, In2O3/PANI composite nanofibers with a mass ratio of 1:2 exhibited the highest response values, excellent selectivity, good repeatability and reversibility.

  4. Porous Silicon Structures as Optical Gas Sensors.

    Science.gov (United States)

    Levitsky, Igor A

    2015-08-14

    We present a short review of recent progress in the field of optical gas sensors based on porous silicon (PSi) and PSi composites, which are separate from PSi optochemical and biological sensors for a liquid medium. Different periodical and nonperiodical PSi photonic structures (bares, modified by functional groups or infiltrated with sensory polymers) are described for gas sensing with an emphasis on the device specificity, sensitivity and stability to the environment. Special attention is paid to multiparametric sensing and sensor array platforms as effective trends for the improvement of analyte classification and quantification. Mechanisms of gas physical and chemical sorption inside PSi mesopores and pores of PSi functional composites are discussed.

  5. 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

  6. Characterization of Polymeric Chemiresistors for Gas Sensor

    Directory of Open Access Journals (Sweden)

    Hendro Juwono

    2012-06-01

    Full Text Available Composite polymer-carbon has resistance change if come into contact with gas. Composite polymer-carbon can be used as a gas sensor. This research will be characterized the sensor composite polymer-carbon that has been made from 6 types of polymer, which are; PEG6000, PEG20M, PEG200, PEG1540, Silicon and Squelene. The 6 sensors will be tested by 9 types of gas, which are; Aceton, Aceton Nitril, Benzene, Etanol, Methanol, Ethyl Aceton, Chloroform, n-Hexan and Toluene. This characterization will be grouped into 4 claster of characteristics, which are; the selectivity (influence type of gas, the sensitivity (influence volume of gas, the influence of temperature and the influence of humidity. Test using method testing sensors that paleced in an isolated chamber which is connected with data acquisition. variations of temperature, humidity, type and volume of gas will be condition in the chamber. Correspondence analysis and regression will be used to process the data. Test results found that each sensor of type of polymers have different sensitivity and selectivity towards a particular type of gas. Resistance sensors increases with rising temperature and humidity environment with a polynomial equation of order-2 and order-3

  7. Integrated Microfluidic Gas Sensors for Water Monitoring

    Science.gov (United States)

    Zhu, L.; Sniadecki, N.; DeVoe, D. L.; Beamesderfer, M.; Semancik, S.; DeVoe, D. L.

    2003-01-01

    A silicon-based microhotplate tin oxide (SnO2) gas sensor integrated into a polymer-based microfluidic system for monitoring of contaminants in water systems is presented. This device is designed to sample a water source, control the sample vapor pressure within a microchannel using integrated resistive heaters, and direct the vapor past the integrated gas sensor for analysis. The sensor platform takes advantage of novel technology allowing direct integration of discrete silicon chips into a larger polymer microfluidic substrate, including seamless fluidic and electrical interconnects between the substrate and silicon chip.

  8. High resolution gas volume change sensor

    International Nuclear Information System (INIS)

    Dirckx, Joris J. J.; Aernouts, Jef E. F.; Aerts, Johan R. M.

    2007-01-01

    Changes of gas quantity in a system can be measured either by measuring pressure changes or by measuring volume changes. As sensitive pressure sensors are readily available, pressure change is the commonly used technique. In many physiologic systems, however, buildup of pressure influences the gas exchange mechanisms, thus changing the gas quantity change rate. If one wants to study the gas flow in or out of a biological gas pocket, measurements need to be done at constant pressure. In this article we present a highly sensitive sensor for quantitative measurements of gas volume change at constant pressure. The sensor is based on optical detection of the movement of a droplet of fluid enclosed in a capillary. The device is easy to use and delivers gas volume data at a rate of more than 15 measurements/s and a resolution better than 0.06 μl. At the onset of a gas quantity change the sensor shows a small pressure artifact of less than 15 Pa, and at constant change rates the pressure artifact is smaller than 10 Pa or 0.01% of ambient pressure

  9. First Fifty Years of Chemoresistive Gas Sensors

    Directory of Open Access Journals (Sweden)

    Giovanni Neri

    2015-01-01

    Full Text Available The first fifty years of chemoresistive sensors for gas detection are here reviewed, focusing on the main scientific and technological innovations that have occurred in the field over the course of these years. A look at advances made in fundamental and applied research and leading to the development of actual high performance chemoresistive devices is presented. The approaches devoted to the synthesis of novel semiconducting materials with unprecedented nanostructure and gas-sensing properties have been also presented. Perspectives on new technologies and future applications of chemoresistive gas sensors have also been highlighted.

  10. Planar Laser-Based QEPAS Trace Gas Sensor

    Directory of Open Access Journals (Sweden)

    Yufei Ma

    2016-06-01

    Full Text Available A novel quartz enhanced photoacoustic spectroscopy (QEPAS trace gas detection scheme is reported in this paper. A cylindrical lens was employed for near-infrared laser focusing. The laser beam was shaped as a planar line laser between the gap of the quartz tuning fork (QTF prongs. Compared with a spherical lens-based QEPAS sensor, the cylindrical lens-based QEPAS sensor has the advantages of easier laser beam alignment and a reduction of stringent stability requirements. Therefore, the reported approach is useful in long-term and continuous sensor operation.

  11. Solid state gas sensors. Industrial application

    Energy Technology Data Exchange (ETDEWEB)

    Fleischer, Maximilian [Siemens AG, Muenchen (Germany). Corporate Technology; Lehmann, Mirko (eds.) [Innovative Sensor Technology (IST) AG, Wattwil (Switzerland)

    2012-11-01

    Written by experts. Richly illustrated. Encourages future research and investments in the fascinating field of gas sensors. Gas sensor products are very often the key to innovations in the fields of comfort, security, health, environment, and energy savings. This compendium focuses on what the research community labels as solid state gas sensors, where a gas directly changes the electrical properties of a solid, serving as the primary signal for the transducer. It starts with a visionary approach to how life in future buildings can benefit from the power of gas sensors. The requirements for various applications, such as for example the automotive industry, are then discussed in several chapters. Further contributions highlight current trends in new sensing principles, such as the use of nanomaterials and how to use new sensing principles for innovative applications in e.g. meteorology. So as to bring together the views of all the different groups needed to produce new gas sensing applications, renowned industrial and academic representatives report on their experiences and expectations in research, applications and industrialisation.

  12. Gas Sensors Based on Molecular Imprinting Technology.

    Science.gov (United States)

    Zhang, Yumin; Zhang, Jin; Liu, Qingju

    2017-07-04

    Molecular imprinting technology (MIT); often described as a method of designing a material to remember a target molecular structure (template); is a technique for the creation of molecularly imprinted polymers (MIPs) with custom-made binding sites complementary to the target molecules in shape; size and functional groups. MIT has been successfully applied to analyze; separate and detect macromolecular organic compounds. Furthermore; it has been increasingly applied in assays of biological macromolecules. Owing to its unique features of structure specificity; predictability; recognition and universal application; there has been exploration of the possible application of MIPs in the field of highly selective gas sensors. In this present study; we outline the recent advances in gas sensors based on MIT; classify and introduce the existing molecularly imprinted gas sensors; summarize their advantages and disadvantages; and analyze further research directions.

  13. Porous Silicon Structures as Optical Gas Sensors

    Directory of Open Access Journals (Sweden)

    Igor A. Levitsky

    2015-08-01

    Full Text Available We present a short review of recent progress in the field of optical gas sensors based on porous silicon (PSi and PSi composites, which are separate from PSi optochemical and biological sensors for a liquid medium. Different periodical and nonperiodical PSi photonic structures (bares, modified by functional groups or infiltrated with sensory polymers are described for gas sensing with an emphasis on the device specificity, sensitivity and stability to the environment. Special attention is paid to multiparametric sensing and sensor array platforms as effective trends for the improvement of analyte classification and quantification. Mechanisms of gas physical and chemical sorption inside PSi mesopores and pores of PSi functional composites are discussed.

  14. Mechanical Drawing of Gas Sensors on Paper

    OpenAIRE

    Esser, Birgit; Mirica, Katherine; Weis, Jonathan Garrett; Schnorr, Jan Markus; Swager, Timothy Manning

    2012-01-01

    This communication describes a simple solvent-free method for fabricating chemoresistive gas sensors on the surface of paper. The method involves mechanical abrasion of compressed powders of sensing materials on the fibers of cellulose. We illustrate this approach by depositing conductive layers of several forms of carbon (e.g., single-walled carbon nanotubes [SWCNTs], multi-walled carbon nanotubes, and graphite) on the surface of different papers (Figure 1, Figure S1). The resulting sensors ...

  15. A Model of Solid State Gas Sensors

    Science.gov (United States)

    Woestman, J. T.; Brailsford, A. D.; Shane, M.; Logothetis, E. M.

    1997-03-01

    Solid state gas sensors are widely used to measure the concentrations of gases such as CO, CH_4, C_3H_6, H_2, C_3H8 and O2 The applications of these sensors range from air-to-fuel ratio control in combustion processes including those in automotive engines and industrial furnaces to leakage detection of inflammable and toxic gases in domestic and industrial environments. As the need increases to accurately measure smaller and smaller concentrations, problems such as poor selectivity, stability and response time limit the use of these sensors. In an effort to overcome some of these limitations, a theoretical model of the transient behavior of solid state gas sensors has been developed. In this presentation, a model for the transient response of an electrochemical gas sensor to gas mixtures containing O2 and one reducing species, such as CO, is discussed. This model accounts for the transport of the reactive species to the sampling electrode, the catalyzed oxidation/reduction reaction of these species and the generation of the resulting electrical signal. The model will be shown to reproduce the results of published steady state models and to agree with experimental steady state and transient data.

  16. Membrane gas sensors for fermentation monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Mandenius, C F

    1987-12-01

    Results of a study on membrane gas sensors are presented to show their general applicability to fermentation monitoring of volatiles, such as alcohols, organic acids and aldehydes under various process and reactor conditions. Permeable silicone (Noax AB) and teflon (fluorcarbon AB) are tested as material for a gas sensor. The silicone tubing method is mainly used and ethanolic fermentation is performed in the study. Investigation is made to determine the dependence of the sensitivity of the sensors on the temperature, pH, concentration and other properties of fermentation liquid. The effect of temperature on the ethanol response is investigated in the temperature range of 7-50/sup 0/C to reveal that the response time decreases while the sensor's sensitivity increases with an increasing temperature. Comparison among methanol, ethyl acetate, acetaldehyde and ethanol is made with respect to the effect of their concentration on the sensitivity of a sensor. Results of a three-month measurement with the sensor immersed in fermentation liquid are compared with those of GC analysis to investigate the correlation between the sensor's sensitivity and GC analysis data. (11 figs, 17 refs)

  17. Multi-electrode gas sensor system - MEGAS. Final report; Multi-Elektroden-Gassensorsystem - MEGAS. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Heidtkamp, C.

    2002-07-01

    A tungsten/titanium - mixed-oxide based sensor for selective exhaust gas measurement of e.g. diesel engines (NO{sub x}, CO, hydrocarbons, NH{sub 3},..) is described. The special design of the used sensors should allow operation at high ambient temperature with the potential of quantitative determination of different exhaust gas components with only one sensor. Several batches of sensor prototypes are characterised according to sensitivity and stability. (orig.)

  18. Signal processing circuitry for CMOS-based SAW gas sensors with low power and area

    International Nuclear Information System (INIS)

    Mohd-Yasin, F.; Tye, K.F.; Reaz, M.B.I.

    2009-06-01

    The design and development of interface circuitries for CMOS-based SAW gas sensor is presented in this paper. The SAW gas sensor devices typically run at RF, requiring most designs to have complex signal conditioning circuitry. The proposed approach attempts to design a simple architecture with reduced power consumption. The SAW gas sensors operate at 354MHz. Simulation data show that the interface circuitries are ten times smaller with lower power supply, comparing to existing work. (author)

  19. MAPLE activities and applications in gas sensors

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Miroslav; Remsa, Jan; Kocourek, Tomáš; Kubešová, B.; Schůrek, J.; Myslík, V.

    2011-01-01

    Roč. 105, č. 3 (2011), 643-649 ISSN 0947-8396 Institutional research plan: CEZ:AV0Z10100522 Keywords : MAPLE * gas sensors * biomedicine * thin films Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.630, year: 2011

  20. Smart gas sensors for mitigating environments

    International Nuclear Information System (INIS)

    Azad, A.M.

    1997-01-01

    From the viewpoint of industrial and automobile exhaust pollution control sensors capable of detecting and metering the concentration of harmful gasers such as carbon monoxide, hydrogen, hydrocarbons, NO sub x, SO sub x, etc, in the ambient are desired. Solid state gas sensors based on semiconducting metal oxides have been widely used for the detection and metering of a host of reducing gases, albeit with varying degrees of success. In this presentation, development aspects of new solid-state CO and H2 sensors are described. Benevolent effect of second phases and catalyst on the sensing characteristics, and the possible sensing mechanism are discussed. In the case of titania-based CO sensors, test results in a Ford V6 engine under programmed near-stoichiometric combustion conditions are also presented. Some new concepts in the area of reliable metering of humidity (water content) in the ambient are briefly highlighted. (author)

  1. MEMS device for mass market gas and chemical sensors

    Science.gov (United States)

    Kinkade, Brian R.; Daly, James T.; Johnson, Edward A.

    2000-08-01

    Gas and chemical sensors are used in many applications. Industrial health and safety monitors allow companies to meet OSHA requirements by detecting harmful levels of toxic or combustible gases. Vehicle emissions are tested during annual inspections. Blood alcohol breathalizers are used by law enforcement. Refrigerant leak detection ensures that the Earth's ozone layer is not being compromised. Industrial combustion emissions are also monitored to minimize pollution. Heating and ventilation systems watch for high levels of carbon dioxide (CO2) to trigger an increase in fresh air exchange. Carbon monoxide detectors are used in homes to prevent poisoning from poor combustion ventilation. Anesthesia gases are monitored during a patients operation. The current economic reality is that two groups of gas sensor technologies are competing in two distinct existing market segments - affordable (less reliable) chemical reaction sensors for consumer markets and reliable (expensive) infrared (IR) spectroscopic sensors for industrial, laboratory, and medical instrumentation markets. Presently high volume mass-market applications are limited to CO detectros and on-board automotive emissions sensors. Due to reliability problems with electrochemical sensor-based CO detectors there is a hesitancy to apply these sensors in other high volume applications. Applications such as: natural gas leak detection, non-invasive blood glucose monitoring, home indoor air quality, personal/portable air quality monitors, home fire/burnt cooking detector, and home food spoilage detectors need a sensor that is a small, efficient, accurate, sensitive, reliable, and inexpensive. Connecting an array of these next generation gas sensors to wireless networks that are starting to proliferate today creates many other applications. Asthmatics could preview the air quality of their destinations as they venture out into the day. HVAC systems could determine if fresh air intake was actually better than the air

  2. Magnesium ferrite nanoparticles: a rapid gas sensor for alcohol

    Science.gov (United States)

    Godbole, Rhushikesh; Rao, Pratibha; Bhagwat, Sunita

    2017-02-01

    Highly porous spinel MgFe2O4 nanoparticles with a high specific surface area have been successfully synthesized by a sintering free auto-combustion technique and characterized for their structural and surface morphological properties using XRD, BET, TEM and SEM techniques. Their sensing properties to alcohol vapors viz. ethanol and methanol were investigated. The site occupation of metal ions was investigated by VSM. The as-synthesized sample shows the formation of sponge-like porous material which is necessary for gas adsorption. The gas sensing characteristics were obtained by measuring the gas response as a function of operating temperature, concentration of the gas, and the response-recovery time. The response of magnesium ferrite to ethanol and methanol vapors was compared and it was revealed that magnesium ferrite is more sensitive and selective to ethanol vapor. The sensor operates at a substantially low vapor concentration of about 1 ppm of alcohol vapors, exhibits fantastic response reproducibility, long term reliability and a very fast response and recovery property. Thus the present study explored the possibility of making rapidly responding alcohol vapor sensor based on magnesium ferrite. The sensing mechanism has been discussed in co-relation with magnetic and morphological properties. The role of occupancy of Mg2+ ions in magnesium ferrite on its gas sensing properties has also been studied and is found to influence the response of magnesium ferrite ethanol sensor.

  3. Test Structures for Rapid Prototyping of Gas and Pressure Sensors

    Science.gov (United States)

    Buehler, M.; Cheng, L. J.; Martin, D.

    1996-01-01

    A multi-project ceramic substrate was used in developing a gas sensor and pressure sensor. The ceramic substrate cantained 36 chips with six variants including sensors, process control monitors, and an interconnect ship. Tha gas sensor is being developed as an air quality monitor and the pressure gauge as a barometer.

  4. Optimized Feature Extraction for Temperature-Modulated Gas Sensors

    Directory of Open Access Journals (Sweden)

    Alexander Vergara

    2009-01-01

    Full Text Available One of the most serious limitations to the practical utilization of solid-state gas sensors is the drift of their signal. Even if drift is rooted in the chemical and physical processes occurring in the sensor, improved signal processing is generally considered as a methodology to increase sensors stability. Several studies evidenced the augmented stability of time variable signals elicited by the modulation of either the gas concentration or the operating temperature. Furthermore, when time-variable signals are used, the extraction of features can be accomplished in shorter time with respect to the time necessary to calculate the usual features defined in steady-state conditions. In this paper, we discuss the stability properties of distinct dynamic features using an array of metal oxide semiconductors gas sensors whose working temperature is modulated with optimized multisinusoidal signals. Experiments were aimed at measuring the dispersion of sensors features in repeated sequences of a limited number of experimental conditions. Results evidenced that the features extracted during the temperature modulation reduce the multidimensional data dispersion among repeated measurements. In particular, the Energy Signal Vector provided an almost constant classification rate along the time with respect to the temperature modulation.

  5. Trusted Operations on Sensor Data †

    Directory of Open Access Journals (Sweden)

    Hassaan Janjua

    2018-04-01

    Full Text Available The widespread use of mobile devices has allowed the development of participatory sensing systems that capture various types of data using the existing or external sensors attached to mobile devices. Gathering data from such anonymous sources requires a mechanism to establish the integrity of sensor readings. In many cases, sensor data need to be preprocessed on the device itself before being uploaded to the target server while ensuring the chain of trust from capture to the delivery of the data. This can be achieved by a framework that provides a means to implement arbitrary operations to be performed on trusted sensor data, while guaranteeing the security and integrity of the data. This paper presents the design and implementation of a framework that allows the capture of trusted sensor data from both external and internal sensors on a mobile phone along with the development of trusted operations on sensor data while providing a mechanism for performing predefined operations on the data such that the chain of trust is maintained. The evaluation shows that the proposed system ensures the security and integrity of sensor data with minimal performance overhead.

  6. Gas sensor with multiple internal reference electrodes and sensing electrodes

    DEFF Research Database (Denmark)

    2016-01-01

    The invention relates to a potentiometric gas sensor, or potentiometric gas detection element, with multiple internal reference electrodes and multiple sensing electrodes for determining the concentrations of gas components in a gaseous mixture. The sensor for gas detection comprises: a solid...

  7. Sol-Gel Thin Films for Plasmonic Gas Sensors

    Science.gov (United States)

    Della Gaspera, Enrico; Martucci, Alessandro

    2015-01-01

    Plasmonic gas sensors are optical sensors that use localized surface plasmons or extended surface plasmons as transducing platform. Surface plasmons are very sensitive to dielectric variations of the environment or to electron exchange, and these effects have been exploited for the realization of sensitive gas sensors. In this paper, we review our research work of the last few years on the synthesis and the gas sensing properties of sol-gel based nanomaterials for plasmonic sensors. PMID:26184216

  8. Review of Small Commercial Sensors for Indicative Monitoring of Ambient Gas

    OpenAIRE

    ALEIXANDRE Manuel; GERBOLES Michel

    2012-01-01

    The traditional ambient gases monitor stations are expensive, big and of complex operation. So they are not suitable for a network of sensors that cover large areas. To cover large areas these traditional systems algorithms usually interpolates the measurements to calculate the gas concentrations in points far away of the physical sensors. Small commercial sensors represent a big opportunity for making sensor networks that monitor the ambient gases within large areas w...

  9. Proximity Operations and Docking Sensor Development

    Science.gov (United States)

    Howard, Richard T.; Bryan, Thomas C.; Brewster, Linda L.; Lee, James E.

    2009-01-01

    The Next Generation Advanced Video Guidance Sensor (NGAVGS) has been under development for the last three years as a long-range proximity operations and docking sensor for use in an Automated Rendezvous and Docking (AR&D) system. The first autonomous rendezvous and docking in the history of the U.S. Space Program was successfully accomplished by Orbital Express, using the Advanced Video Guidance Sensor (AVGS) as the primary docking sensor. That flight proved that the United States now has a mature and flight proven sensor technology for supporting Crew Exploration Vehicles (CEV) and Commercial Orbital Transport Systems (COTS) Automated Rendezvous and Docking (AR&D). NASA video sensors have worked well in the past: the AVGS used on the Demonstration of Autonomous Rendezvous Technology (DART) mission operated successfully in spot mode out to 2 km, and the first generation rendezvous and docking sensor, the Video Guidance Sensor (VGS), was developed and successfully flown on Space Shuttle flights in 1997 and 1998. 12 Parts obsolescence issues prevent the construction of more AVGS units, and the next generation sensor was updated to allow it to support the CEV and COTS programs. The flight proven AR&D sensor has been redesigned to update parts and add additional capabilities for CEV and COTS with the development of the Next Generation AVGS at the Marshall Space Flight Center. The obsolete imager and processor are being replaced with new radiation tolerant parts. In addition, new capabilities include greater sensor range, auto ranging capability, and real-time video output. This paper presents some sensor hardware trades, use of highly integrated laser components, and addresses the needs of future vehicles that may rendezvous and dock with the International Space Station (ISS) and other Constellation vehicles. It also discusses approaches for upgrading AVGS to address parts obsolescence, and concepts for minimizing the sensor footprint, weight, and power requirements

  10. Alpha-Particle Gas-Pressure Sensor

    Science.gov (United States)

    Buehler, M. C.; Bell, L. D.; Hecht, M. H.

    1996-01-01

    An approximate model was developed to establish design curves for the saturation region and a more complete model developed to characterize the current-voltage curves for an alpha-particle pressure sensor. A simple two-parameter current-voltage expression was developed to describe the dependence of the ion current on pressure. The parameters are the saturation-current pressure coefficient and mu/D, the ion mobility/diffusion coefficient. The sensor is useful in the pressure range between 0.1 and 1000 mb using a 1 - mu Ci(241) Am source. Experimental results, taken between 1 and up to 200 mb, show the sensor operates with an anode voltage of 5 V and a sensitivity of 20 fA/mb in nitrogen.

  11. Autonomous Mission Operations for Sensor Webs

    Science.gov (United States)

    Underbrink, A.; Witt, K.; Stanley, J.; Mandl, D.

    2008-12-01

    We present interim results of a 2005 ROSES AIST project entitled, "Using Intelligent Agents to Form a Sensor Web for Autonomous Mission Operations", or SWAMO. The goal of the SWAMO project is to shift the control of spacecraft missions from a ground-based, centrally controlled architecture to a collaborative, distributed set of intelligent agents. The network of intelligent agents intends to reduce management requirements by utilizing model-based system prediction and autonomic model/agent collaboration. SWAMO agents are distributed throughout the Sensor Web environment, which may include multiple spacecraft, aircraft, ground systems, and ocean systems, as well as manned operations centers. The agents monitor and manage sensor platforms, Earth sensing systems, and Earth sensing models and processes. The SWAMO agents form a Sensor Web of agents via peer-to-peer coordination. Some of the intelligent agents are mobile and able to traverse between on-orbit and ground-based systems. Other agents in the network are responsible for encapsulating system models to perform prediction of future behavior of the modeled subsystems and components to which they are assigned. The software agents use semantic web technologies to enable improved information sharing among the operational entities of the Sensor Web. The semantics include ontological conceptualizations of the Sensor Web environment, plus conceptualizations of the SWAMO agents themselves. By conceptualizations of the agents, we mean knowledge of their state, operational capabilities, current operational capacities, Web Service search and discovery results, agent collaboration rules, etc. The need for ontological conceptualizations over the agents is to enable autonomous and autonomic operations of the Sensor Web. The SWAMO ontology enables automated decision making and responses to the dynamic Sensor Web environment and to end user science requests. The current ontology is compatible with Open Geospatial Consortium (OGC

  12. Solid electrolyte gas sensors based on cyclic voltammetry with one active electrode

    Energy Technology Data Exchange (ETDEWEB)

    Jasinski, G; Jasinski, P, E-mail: gregor@biomed.eti.pg.gda.pl [Gdansk University of Technology, Faculty of Electronics, Telecommunication and Informatics, Narutowicza 11/12, 80-233 Gdansk (Poland)

    2011-10-29

    Solid state gas sensors are cost effective, small, rugged and reliable. Typically electrochemical solid state sensors operate in either potentiometric or amperometric mode. However, a lack of selectivity is sometimes a shortcoming of such sensors. It seems that improvements of selectivity can be obtained in case of the electrocatalytic sensors, which operate in cyclic voltammetry mode. Their working principle is based on acquisition of an electric current, while voltage ramp is applied to the sensor. The current-voltage response depends in a unique way on the type and concentration of ambient gas. Most electrocatalytic sensors have symmetrical structure. They are in a form of pellets with two electrodes placed on their opposite sides. Electrochemical reactions occur simultaneously on both electrodes. In this paper results for sensors with only one active electrode exposed to ambient gas are presented. The other electrode was isolated from ambient gas with dielectric sealing. This sensor construction allows application of advanced measuring procedures, which permit sensor regeneration acceleration. Experiments were conducted on Nasicon sensors. Properties of two sensors, one with one active electrode and second with symmetrical structure, used for the detection of mixtures of NO{sub 2} and synthetic air are compared.

  13. Utilizing the response patterns of a temperature modulated chemoresistive gas sensor for gas diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Amini, Amir [Jannatabad College, Sama Organization, Islamic Azad University, Tehran (Iran, Islamic Republic of); Ghafarinia, Vahid, E-mail: amir.amini.elec@gmail.com, E-mail: ghafarinia@ee.kntu.ac.ir [Electrical Engineering Department, K. N. Toosi University of Technology, Tehran (Iran, Islamic Republic of)

    2011-02-15

    The observed features in the temporal response patterns of a temperature-modulated chemoresistive gas sensor were used for gas diagnosis. The patterns were recorded for clean air and air contaminated with different levels of some volatile organic compounds while a staircase heating voltage waveform had been applied to the microheater of a tin oxide gas sensor that modulated its operating temperature. Combining the steady-state and transient parameters of the recorded responses in the 50-400 deg. C range resulted in discriminatory feature vectors which were utilized for contaminant classification. The information content of these feature vectors was proved sufficient for discrimination of methanol, ethanol, 1-butanol, and acetone contaminations in a wide concentration range.

  14. Utilizing the response patterns of a temperature modulated chemoresistive gas sensor for gas diagnosis

    International Nuclear Information System (INIS)

    Amini, Amir; Ghafarinia, Vahid

    2011-01-01

    The observed features in the temporal response patterns of a temperature-modulated chemoresistive gas sensor were used for gas diagnosis. The patterns were recorded for clean air and air contaminated with different levels of some volatile organic compounds while a staircase heating voltage waveform had been applied to the microheater of a tin oxide gas sensor that modulated its operating temperature. Combining the steady-state and transient parameters of the recorded responses in the 50-400 deg. C range resulted in discriminatory feature vectors which were utilized for contaminant classification. The information content of these feature vectors was proved sufficient for discrimination of methanol, ethanol, 1-butanol, and acetone contaminations in a wide concentration range.

  15. THE GAS SENSORS BASED ON ZINC OXIDE (THE REVIEW)

    OpenAIRE

    Bugayova, M. E.; Koval, V. M.; Lashkarev, G. V.; Lazorenko, V. I.; Karpina, V. A.; Khranovskyy, V. D.

    2017-01-01

    The wide range of gas sensor application, in particular, in a mining industry for detection of outflow of gases, the control of gas emissions over an atmosphere at the industrial enterprises, in housing and communal services, in home appliances makes actual the review. As the systematized analysis of gas sensor based on ZnO has not being carried out — this work is of interest for development of chemical sensors based on zinc compound with high sensitivity, selectivity and stability. The resis...

  16. INTEGRATED SENSOR EVALUATION CIRCUIT AND METHOD FOR OPERATING SAID CIRCUIT

    OpenAIRE

    Krüger, Jens; Gausa, Dominik

    2015-01-01

    WO15090426A1 Sensor evaluation device and method for operating said device Integrated sensor evaluation circuit for evaluating a sensor signal (14) received from a sensor (12), having a first connection (28a) for connection to the sensor and a second connection (28b) for connection to the sensor. The integrated sensor evaluation circuit comprises a configuration data memory (16) for storing configuration data which describe signal properties of a plurality of sensor control signals (26a-c). T...

  17. [A mobile sensor for remote detection of natural gas leakage].

    Science.gov (United States)

    Zhang, Shuai; Liu, Wen-qing; Zhang, Yu-jun; Kan, Rui-feng; Ruan, Jun; Wang, Li-ming; Yu, Dian-qiang; Dong, Jin-ting; Han, Xiao-lei; Cui, Yi-ben; Liu, Jian-guo

    2012-02-01

    The detection of natural gas pipeline leak becomes a significant issue for body security, environmental protection and security of state property. However, the leak detection is difficult, because of the pipeline's covering many areas, operating conditions and complicated environment. A mobile sensor for remote detection of natural gas leakage based on scanning wavelength differential absorption spectroscopy (SWDAS) is introduced. The improved soft threshold wavelet denoising was proposed by analyzing the characteristics of reflection spectrum. And the results showed that the signal to noise ratio (SNR) was increased three times. When light intensity is 530 nA, the minimum remote sensitivity will be 80 ppm x m. A widely used SWDAS can make quantitative remote sensing of natural gas leak and locate the leak source precisely in a faster, safer and more intelligent way.

  18. Low Power Greenhouse Gas Sensors for Unmanned Aerial Vehicles

    Directory of Open Access Journals (Sweden)

    David J. Lary

    2012-05-01

    Full Text Available We demonstrate compact, low power, lightweight laser-based sensors for measuring trace gas species in the atmosphere designed specifically for electronic unmanned aerial vehicle (UAV platforms. The sensors utilize non-intrusive optical sensing techniques to measure atmospheric greenhouse gas concentrations with unprecedented vertical and horizontal resolution (~1 m within the planetary boundary layer. The sensors are developed to measure greenhouse gas species including carbon dioxide, water vapor and methane in the atmosphere. Key innovations are the coupling of very low power vertical cavity surface emitting lasers (VCSELs to low power drive electronics and sensitive multi-harmonic wavelength modulation spectroscopic techniques. The overall mass of each sensor is between 1–2 kg including batteries and each one consumes less than 2 W of electrical power. In the initial field testing, the sensors flew successfully onboard a T-Rex Align 700E robotic helicopter and showed a precision of 1% or less for all three trace gas species. The sensors are battery operated and capable of fully automated operation for long periods of time in diverse sensing environments. Laser-based trace gas sensors for UAVs allow for high spatial mapping of local greenhouse gas concentrations in the atmospheric boundary layer where land/atmosphere fluxes occur. The high-precision sensors, coupled to the ease-of-deployment and cost effectiveness of UAVs, provide unprecedented measurement capabilities that are not possible with existing satellite-based and suborbital aircraft platforms.

  19. Self-Test Procedures for Gas Sensors Embedded in Microreactor Systems

    Science.gov (United States)

    Helwig, Andreas; Hackner, Angelika; Zappa, Dario; Sberveglieri, Giorgio

    2018-01-01

    Metal oxide (MOX) gas sensors sensitively respond to a wide variety of combustible, explosive and poisonous gases. However, due to the lack of a built-in self-test capability, MOX gas sensors have not yet been able to penetrate safety-critical applications. In the present work we report on gas sensing experiments performed on MOX gas sensors embedded in ceramic micro-reaction chambers. With the help of an external micro-pump, such systems can be operated in a periodic manner alternating between flow and no-flow conditions, thus allowing repetitive measurements of the sensor resistances under clean air, R0, and under gas exposure, Rgas, to be obtained, even under field conditions. With these pairs of resistance values, eventual drifts in the sensor baseline resistance can be detected and drift-corrected values of the relative resistance response Resp=(R0−Rgas)/R0 can be determined. Residual poisoning-induced changes in the relative resistance response can be detected by reference to humidity measurements taken with room-temperature-operated capacitive humidity sensors which are insensitive to the poisoning processes operative on heated MOX gas sensors. PMID:29401673

  20. Self-Test Procedures for Gas Sensors Embedded in Microreactor Systems.

    Science.gov (United States)

    Helwig, Andreas; Hackner, Angelika; Müller, Gerhard; Zappa, Dario; Sberveglieri, Giorgio

    2018-02-03

    Metal oxide (MOX) gas sensors sensitively respond to a wide variety of combustible, explosive and poisonous gases. However, due to the lack of a built-in self-test capability, MOX gas sensors have not yet been able to penetrate safety-critical applications. In the present work we report on gas sensing experiments performed on MOX gas sensors embedded in ceramic micro-reaction chambers. With the help of an external micro-pump, such systems can be operated in a periodic manner alternating between flow and no-flow conditions, thus allowing repetitive measurements of the sensor resistances under clean air, R 0 , and under gas exposure, R g a s , to be obtained, even under field conditions. With these pairs of resistance values, eventual drifts in the sensor baseline resistance can be detected and drift-corrected values of the relative resistance response R e s p = ( R 0 - R g a s ) / R 0 can be determined. Residual poisoning-induced changes in the relative resistance response can be detected by reference to humidity measurements taken with room-temperature-operated capacitive humidity sensors which are insensitive to the poisoning processes operative on heated MOX gas sensors.

  1. Zirconia-based solid state chemical gas sensors

    CERN Document Server

    Zhuiykov, S

    2000-01-01

    This paper presents an overview of chemical gas sensors, based on solid state technology, that are sensitive to environmental gases, such as O sub 2 , SO sub x , NO sub x , CO sub 2 and hydrocarbons. The paper is focussed on performance of electrochemical gas sensors that are based on zirconia as a solid electrolyte. The paper considers sensor structures and selection of electrode materials. Impact of interfaces on sensor performance is discussed. This paper also provides a brief overview of electrochemical properties of zirconia and their effect on sensor performance. Impact of auxiliary materials on sensors performance characteristics, such as sensitivity, selectivity, response time and recovery time, is also discussed. Dual gas sensors that can be applied for simultaneous monitoring of the concentration of both oxygen and other gas phase components, are briefly considered

  2. A smart microelectromechanical sensor and switch triggered by gas

    KAUST Repository

    Bouchaala, Adam M.; Jaber, Nizar; Shekhah, Osama; Chernikova, Valeriya; Eddaoudi, Mohamed; Younis, Mohammad I.

    2016-01-01

    device based on a single microstructure. Specifically, we demonstrate a smart resonant gas (mass) sensor, which in addition to being capable of quantifying the amount of absorbed gas, can be autonomously triggered as an electrical switch upon exceeding a

  3. Nanostructured ZnO films for potential use in LPG gas sensors

    Science.gov (United States)

    Latyshev, V. M.; Berestok, T. O.; Opanasyuk, A. S.; Kornyushchenko, A. S.; Perekrestov, V. I.

    2017-05-01

    The aim of the work was to obtain ZnO nanostructures with heightened surface area and to study relationship between formation method and gas sensor properties towards propane-butane mixture (LPG). In order to synthesize ZnO nanostructures chemical and physical formation methods have been utilized. The first one was chemical bath deposition technology and the second one magnetron sputtering of Zn followed by oxidation. Optimal method and technological parameters corresponding to formation of material with the highest sensor response have been determined experimentally. Dynamical gas sensor response at different temperature values and dependencies of the sensor sensitivity on the temperature at different LPG concentrations in air have been investigated. It has been found, that sensor response depends on the sample morphology and has the highest value for the structure consisting of thin nanowires. The factors that lead to the decrease in the gas sensor operating temperature have been determined.

  4. Selective Sensing of Gas Mixture via a Temperature Modulation Approach: New Strategy for Potentiometric Gas Sensor Obtaining Satisfactory Discriminating Features.

    Science.gov (United States)

    Li, Fu-An; Jin, Han; Wang, Jinxia; Zou, Jie; Jian, Jiawen

    2017-03-12

    A new strategy to discriminate four types of hazardous gases is proposed in this research. Through modulating the operating temperature and the processing response signal with a pattern recognition algorithm, a gas sensor consisting of a single sensing electrode, i.e., ZnO/In₂O₃ composite, is designed to differentiate NO₂, NH₃, C₃H₆, CO within the level of 50-400 ppm. Results indicate that with adding 15 wt.% ZnO to In₂O₃, the sensor fabricated at 900 °C shows optimal sensing characteristics in detecting all the studied gases. Moreover, with the aid of the principle component analysis (PCA) algorithm, the sensor operating in the temperature modulation mode demonstrates acceptable discrimination features. The satisfactory discrimination features disclose the future that it is possible to differentiate gas mixture efficiently through operating a single electrode sensor at temperature modulation mode.

  5. Synthesis and characterization of porous silicon gas sensors

    Science.gov (United States)

    abbas, Roaa A.; Alwan, Alwan M.; Abdulhamied, Zainab T.

    2018-05-01

    In this work, photo-electrochemical etching process of n-type Silicon of resistivity(10 Ω.cm) and (100) orientation, using two illumination sources IR and violet wavelength in HF acid have been used to produce PSi gas detection device. The fabrication process was carried out at a fixed etching current density of 25mA/cm2 and at different etching time (5, 10, 15 and 20) min and (8, 16, 24, and 30) min. Two configurations of gas sensor configuration planer and sandwich have been made and investigated. The morphological properties have been studied using SEM,the FTIR measurement show that the (Si-Hx) and (Si-O-Si) absorption peak were increases with increasing etching time,and Photoluminescence properties of PSi layer show decrease in the peak of PL peak toward the violet shift. The gas detection process is made on the CO2 gas at different operating temperature and fixed gas concentration. In the planner structure, the gas sensing was measured through, the change in the resistance readout as a function to the exposure time, while for sandwich structure J-V characteristic have been made to determine the sensitivity.

  6. Chemical Gas Sensors for Aerospace Applications

    Science.gov (United States)

    Hunter, Gary W.; Liu, C. C.

    1998-01-01

    Chemical sensors often need to be specifically designed (or tailored) to operate in a given environment. It is often the case that a chemical sensor that meets the needs of one application will not function adequately in another application. The more demanding the environment and specialized the requirement, the greater the need to adapt exiting sensor technologies to meet these requirements or, as necessary, develop new sensor technologies. Aerospace (aeronautic and space) applications are particularly challenging since often these applications have specifications which have not previously been the emphasis of commercial suppliers. Further, the chemical sensing needs of aerospace applications have changed over the years to reflect the changing emphasis of society. Three chemical sensing applications of particular interest to the National Aeronautics and Space Administration (NASA) which illustrate these trends are launch vehicle leak detection, emission monitoring, and fire detection. Each of these applications reflects efforts ongoing throughout NASA. As described in NASA's "Three Pillars for Success", a document which outlines NASA's long term response to achieve the nation's priorities in aerospace transportation, agency wide objectives include: improving safety and decreasing the cost of space travel, significantly decreasing the amount of emissions produced by aeronautic engines, and improving the safety of commercial airline travel. As will be discussed below, chemical sensing in leak detection, emission monitoring, and fire detection will help enable the agency to meet these objectives. Each application has vastly different problems associated with the measurement of chemical species. Nonetheless, the development of a common base technology can address the measurement needs of a number of applications.

  7. Advancement of Miniature Optic Gas Sensor (MOGS) Probe Technology

    Science.gov (United States)

    Chullen, Cinda

    2015-01-01

    Advancement of Miniature Optic Gas Sensor (MOGS) Probe Technology" project will investigate newly developed optic gas sensors delivered from a Small Business Innovative Research (SBIR) Phase II effort. A ventilation test rig will be designed and fabricated to test the sensors while integrated with a Suited Manikin Test Apparatus (SMTA). Once the sensors are integrated, a series of test points will be completed to verify that the sensors can withstand Advanced Suit Portable Life Support System (PLSS) environments and associated human metabolic profiles for changes in pressure and levels of Oxygen (ppO2), carbon dioxide (ppCO2), and humidity (ppH2O).

  8. A Smart Gas Sensor Insensitive to Humidity and Temperature Variations

    International Nuclear Information System (INIS)

    Hajmirzaheydarali, Mohammadreza; Ghafarinia, Vahid

    2011-01-01

    The accuracy of the quantitative sensing of volatile organic compounds by chemoresistive gas sensors suffers from the fluctuations in the background atmospheric conditions. This is caused by the drift-like terms introduced in the responses by these instabilities, which should be identified and compensated. Here, a mathematical model is presented for a specific chemoresistive gas sensor, which facilitates these identification and compensation processes. The resistive gas sensor was considered as a multi-input-single-output system. Along with the steady state value of the measured sensor resistance, the ambient humidity and temperature are the inputs to the system, while the concentration level of the target gas is the output. The parameters of the model were calculated based on the experimental database. The model was simulated by the utilization of an artificial neural network. This was connected to the sensor and could deliver the correct contamination level upon receiving the measured gas response, ambient humidity and temperature.

  9. 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.

  10. CO_2 gas sensors based on rare earth oxycarbonates

    International Nuclear Information System (INIS)

    Haensch, Alexander

    2016-01-01

    This title presents a new type of CO_2 gas sensor, that allows the measurement of CO_2 gas with very low effort. The measurement principle is based on two semiconducting materials. One the ''receptor'' and a ''transducer'' form a semiconductor junction. Electronic changes in the receptor change the electrical resistance in the transducer and therefor allow the easy electrical measurement. The reactivity and the reaction mechanism is thoroughly studied. In the first part the basics and resistance measurements are presented. A comparison between different mixtures is done. The main part studies the surface chemistry with operando DRIFT spectroscopy. The chemical reactivity of different target gases and background gases is studied thoroughly. The electronic properties of Oxycarbonates and the combination of oxycarbonate and tin oxide were studied using operando Kelvin probes measurements. The result is that CO_2 alters the electron affinity of the material. Once moisture is present, an additional band bending is visible. The band bending dominated in a humid atmosphere, the work function changes. The electronic connection of oxycarbonate and tin oxide, the work function change of Oxycarbonates can be transferred to the tin oxide. Using the collected data, a basic idea of the operation will be presented by a two-semiconductor materials gas sensor.

  11. Ce doped NiO nanoparticles as selective NO2 gas sensor

    Science.gov (United States)

    Gawali, Swati R.; Patil, Vithoba L.; Deonikar, Virendrakumar G.; Patil, Santosh S.; Patil, Deepak R.; Patil, Pramod S.; Pant, Jayashree

    2018-03-01

    Metal oxide gas sensors are promising portable gas detection devices because of their advantages such as low cost, easy production and compact size. The performance of such sensors is strongly dependent on material properties such as morphology, structure and doping. In the present study, we report the effect of cerium (Ce) doping on nickel oxide (NiO) nano-structured thin film sensors towards various gases. Bare NiO and Ce doped NiO nanoparticles (Ce:NiO) were synthesized by sol-gel method. To understand the effect of Ce doping in nickel oxide, various molar percentages of Ce with respect to nickel were incorporated. The structure, phase, morphology and band-gap energy of as-synthesized nanoparticles were studied by XRD, SEM, EDAX and UV-vis spectroscopy. Thin film gas sensors of all the samples were prepared and subjected to various gases such as LPG, NH3, CH3COCH3 and NO2. A systematic and comparative study reveals an enhanced gas sensing performance of Ce:NiO sensors towards NO2 gas. The maximum sensitivity for NO2 gas is around 0.719% per ppm at moderate operating temperature of 150 °C for 0.5% Ce:NiO thin film gas sensor. The enhanced gas sensing performance for Ce:NiO is attributed to the distortion of crystal lattice caused by doping of Ce into NiO.

  12. Some Spinel Oxide Compounds as Reducing Gas Sensors

    Directory of Open Access Journals (Sweden)

    Nicolae Rezlescu

    2007-04-01

    Full Text Available Four spinel ferrites, MFe2O4 (M = Cu, Cd, Zn and Ni, having various grain sizes (100 – 700 nm were prepared by sol-gel-selfcombustion and their sensing properties to reducing gases were investigated. The gas sensing characteristics were obtained by measuring the sensitivity as a function of various controlling factors, like operating temperature, composition and concentration of the gas, and finally the response time. The sensitivity of four ferrites to reducing gases like acetone, ethanol and LPG was been compared. It was revealed that CuFe2O4 is the most sensitive to LPG and ZnFe2O4 can be used as a sensor to selectively detect ethanol vapors in air. The strong interaction between ethanol and porous ZnFe2O4 can explain the selective sensitivity to ethanol and negligible sensitivity to the other reducing gases.

  13. The effects of two thick film deposition methods on tin dioxide gas sensor performance.

    Science.gov (United States)

    Bakrania, Smitesh D; Wooldridge, Margaret S

    2009-01-01

    This work demonstrates the variability in performance between SnO(2) thick film gas sensors prepared using two types of film deposition methods. SnO(2) powders were deposited on sensor platforms with and without the use of binders. Three commonly utilized binder recipes were investigated, and a new binder-less deposition procedure was developed and characterized. The binder recipes yielded sensors with poor film uniformity and poor structural integrity, compared to the binder-less deposition method. Sensor performance at a fixed operating temperature of 330 °C for the different film deposition methods was evaluated by exposure to 500 ppm of the target gas carbon monoxide. A consequence of the poor film structure, large variability and poor signal properties were observed with the sensors fabricated using binders. Specifically, the sensors created using the binder recipes yielded sensor responses that varied widely (e.g., S = 5 - 20), often with hysteresis in the sensor signal. Repeatable and high quality performance was observed for the sensors prepared using the binder-less dispersion-drop method with good sensor response upon exposure to 500 ppm CO (S = 4.0) at an operating temperature of 330 °C, low standard deviation to the sensor response (±0.35) and no signal hysteresis.

  14. The Effects of Two Thick Film Deposition Methods on Tin Dioxide Gas Sensor Performance

    Directory of Open Access Journals (Sweden)

    Smitesh D. Bakrania

    2009-08-01

    Full Text Available This work demonstrates the variability in performance between SnO2 thick film gas sensors prepared using two types of film deposition methods. SnO2 powders were deposited on sensor platforms with and without the use of binders. Three commonly utilized binder recipes were investigated, and a new binder-less deposition procedure was developed and characterized. The binder recipes yielded sensors with poor film uniformity and poor structural integrity, compared to the binder-less deposition method. Sensor performance at a fixed operating temperature of 330 ºC for the different film deposition methods was evaluated by exposure to 500 ppm of the target gas carbon monoxide. A consequence of the poor film structure, large variability and poor signal properties were observed with the sensors fabricated using binders. Specifically, the sensors created using the binder recipes yielded sensor responses that varied widely (e.g., S = 5 – 20, often with hysteresis in the sensor signal. Repeatable and high quality performance was observed for the sensors prepared using the binder-less dispersion-drop method with good sensor response upon exposure to 500 ppm CO (S = 4.0 at an operating temperature of 330 ºC, low standard deviation to the sensor response (±0.35 and no signal hysteresis.

  15. Incidents Associated with Gas Operation

    Directory of Open Access Journals (Sweden)

    Szer J.

    2017-06-01

    Full Text Available This article shows incidents associated with the use of gas as an energy carrier. It presents selected incidents which have occurred in Poland and around the world in recent decades. Based on this, consequences of gas and air mixture explosions were analysed as well. The article presents the main causes of gas incidents which have taken place, as per instances which are similar worldwide. Incidents associated with the use of gas are not frequent, but at the same time very tragic as they often lead to illness or even death. In Poland, in the last twenty years, construction area disasters caused by gas explosions account for only 5% of all which have occurred, but the number of fatalities resulting from these cases is approximately 14%. The number of individuals injured reached 39% of all construction disaster victims. Considering all these facts, it is necessary to undertake wide preventive measures in order to increase safety in the use of gaseous fuels.

  16. Microfabricated Chemical Gas Sensors and Sensor Arrays for Aerospace Applications

    Science.gov (United States)

    Hunter, Gary W.

    2005-01-01

    Aerospace applications require the development of chemical sensors with capabilities beyond those of commercially available sensors. In particular, factors such as minimal sensor size, weight, and power consumption are particularly important. Development areas which have potential aerospace applications include launch vehicle leak detection, engine health monitoring, and fire detection. Sensor development for these applications is based on progress in three types of technology: 1) Micromachining and microfabrication (Microsystem) technology to fabricate miniaturized sensors; 2) The use of nanocrystalline materials to develop sensors with improved stability combined with higher sensitivity; 3) The development of high temperature semiconductors, especially silicon carbide. This presentation discusses the needs of space applications as well as the point-contact sensor technology and sensor arrays being developed to address these needs. Sensors to measure hydrogen, hydrocarbons, nitrogen oxides (NO,), carbon monoxide, oxygen, and carbon dioxide are being developed as well as arrays for leak, fire, and emissions detection. Demonstrations of the technology will also be discussed. It is concluded that microfabricated sensor technology has significant potential for use in a range of aerospace applications.

  17. Soil Gas Sampling Operating Procedure

    Science.gov (United States)

    EPA Region 4 Science and Ecosystem Support Division (SESD) document that describes general and specific procedures, methods, and considerations when collecting soil gas samples for field screening or laboratory analysis.

  18. Chemical Gas Sensors for Aeronautic and Space Applications

    Science.gov (United States)

    Hunter, Gary W.; Chen, Liang-Yu; Neudeck, Philip G.; Knight, Dak; Liu, Chung-Chiun; Wu, Quing-Hai; Zhou, Huan-Jun

    1997-01-01

    Aeronautic and space applications require the development of chemical sensors with capabilities beyond those of commercially available sensors. Two areas of particular interest are safety monitoring and emission monitoring. In safety monitoring, detection of low concentrations of hydrogen at potentially low temperatures is important while for emission monitoring the detection of nitrogen oxides, hydrogen, hydrocarbons and oxygen is of interest. This paper discusses the needs of aeronautic and space applications and the point-contact sensor technology being developed to address these needs. The development of these sensors is based on progress in two types of technology: (1) Micromachining and microfabrication technology to fabricate miniaturized sensors. (2) The development of high temperature semiconductors, especially silicon carbide. The detection of each type of gas involves its own challenges in the fields of materials science and fabrication technology. The number of dual-use commercial applications of this microfabricated gas sensor technology make this general area of sensor development a field of significant interest.

  19. Chemical gas sensors and the characterization, monitoring and sensor technology needs of the US Department of Energy

    International Nuclear Information System (INIS)

    Bastiaans, G.J.; Haas, W.J. Jr.; Junk, G.A.

    1993-01-01

    The Office of Technology Development within the Dept. of Energy (DOE) has the responsibility of providing new technologies to aid the environmental restoration and waste management (ER/WM) activities of the DOE. There is a perception that application and judicious development of chemical sensor technologies could result in large cost savings and reduced risk to the health and safety of ER/WM personnel. A number of potential gas sensor applications which exist within DOE ER/WM operations are described. The capabilities of several chemical sensor technologies and their potential to meet the needs of ER/WM applications in the present or near term future are discussed

  20. Meso-/Nanoporous Semiconducting Metal Oxides for Gas Sensor Applications

    Directory of Open Access Journals (Sweden)

    Nguyen Duc Hoa

    2015-01-01

    Full Text Available Development and/or design of new materials and/or structures for effective gas sensor applications with fast response and high sensitivity, selectivity, and stability are very important issues in the gas sensor technology. This critical review introduces our recent progress in the development of meso-/nanoporous semiconducting metal oxides and their applications to gas sensors. First, the basic concepts of resistive gas sensors and the recent synthesis of meso-/nanoporous metal oxides for gas sensor applications are introduced. The advantages of meso-/nanoporous metal oxides are also presented, taking into account the crystallinity and ordered/disordered porous structures. Second, the synthesis methods of meso-/nanoporous metal oxides including the soft-template, hard-template, and temple-free methods are introduced, in which the advantages and disadvantages of each synthetic method are figured out. Third, the applications of meso-/nanoporous metal oxides as gas sensors are presented. The gas nanosensors are designed based on meso-/nanoporous metal oxides for effective detection of toxic gases. The sensitivity, selectivity, and stability of the meso-/nanoporous gas nanosensors are also discussed. Finally, some conclusions and an outlook are presented.

  1. Miniaturized Planar Room Temperature Ionic Liquid Electrochemical Gas Sensor for Rapid Multiple Gas Pollutants Monitoring.

    Science.gov (United States)

    Wan, Hao; Yin, Heyu; Lin, Lu; Zeng, Xiangqun; Mason, Andrew J

    2018-02-01

    The growing impact of airborne pollutants and explosive gases on human health and occupational safety has escalated the demand of sensors to monitor hazardous gases. This paper presents a new miniaturized planar electrochemical gas sensor for rapid measurement of multiple gaseous hazards. The gas sensor features a porous polytetrafluoroethylene substrate that enables fast gas diffusion and room temperature ionic liquid as the electrolyte. Metal sputtering was utilized for platinum electrodes fabrication to enhance adhesion between the electrodes and the substrate. Together with carefully selected electrochemical methods, the miniaturized gas sensor is capable of measuring multiple gases including oxygen, methane, ozone and sulfur dioxide that are important to human health and safety. Compared to its manually-assembled Clark-cell predecessor, this sensor provides better sensitivity, linearity and repeatability, as validated for oxygen monitoring. With solid performance, fast response and miniaturized size, this sensor is promising for deployment in wearable devices for real-time point-of-exposure gas pollutant monitoring.

  2. Gas sensing properties of indium–gallium–zinc–oxide gas sensors in different light intensity

    Directory of Open Access Journals (Sweden)

    Kuen-Lin Chen

    2015-06-01

    Full Text Available We have successfully observed the change in indium–gallium–zinc–oxide (IGZO gas sensor sensitivity by controlling the light emitting diode (LED power under the same gas concentrations. The light intensity dependence of sensor properties is discussed. Different LED intensities obviously affected the gas sensor sensitivity, which decays with increasing LED intensity. High LED intensity decreases not only gas sensor sensitivity but also the response time (T90, response time constant (τres and the absorption rate per second. Low intensity irradiated to sensor causes high sensitivity, but it needs larger response time. Similar results were also observed in other kinds of materials such as TiO2. According to the results, the sensing properties of gas sensors can be modulated by controlling the light intensity.

  3. Triboelectric Hydrogen Gas Sensor with Pd Functionalized Surface

    Directory of Open Access Journals (Sweden)

    Sung-Ho Shin

    2016-10-01

    Full Text Available Palladium (Pd-based hydrogen (H2 gas sensors have been widely investigated thanks to its fast reaction and high sensitivity to hydrogen. Various sensing mechanisms have been adopted for H2 gas sensors; however, all the sensors must be powered through an external battery. We report here an H2 gas sensor that can detect H2 by measuring the output voltages generated during contact electrification between two friction surfaces. When the H2 sensor, composed of Pd-coated ITO (indium tin oxide and PET (polyethylene Terephthalate film, is exposed to H2, its output voltage is varied in proportion to H2 concentration because the work function (WF of Pd-coated surface changes, altering triboelectric charging behavior. Specifically, the output voltage of the sensor is gradually increased as exposing H2 concentration increases. Reproducible and sensitive sensor response was observed up 1% H2 exposure. The approach introduced here can easily be adopted to development of triboelectric gas sensors detecting other gas species.

  4. CO Emissions from Gas Engines Operating on Biomass Producer Gas

    DEFF Research Database (Denmark)

    Ahrenfeldt, Jesper; Jensen, T. K.; Henriksen, Ulrik Birk

    2004-01-01

    High carbon monoxide (CO) emission from gas engines fueled by producer gas is a concerning problem in the struggle to make biomass gasification for heat and power production a success. CO emissions from engines operating on biomass producer gases are high, especially at very lean conditions where...

  5. Semiconductor device-based sensors for gas, chemical, and biomedical applications

    CERN Document Server

    Ren, Fan

    2011-01-01

    Sales of U.S. chemical sensors represent the largest segment of the multi-billion-dollar global sensor market, which includes instruments for chemical detection in gases and liquids, biosensors, and medical sensors. Although silicon-based devices have dominated the field, they are limited by their general inability to operate in harsh environments faced with factors such as high temperature and pressure. Exploring how and why these instruments have become a major player, Semiconductor Device-Based Sensors for Gas, Chemical, and Biomedical Applications presents the latest research, including or

  6. Chemical Gas Sensors for Aeronautic and Space Applications 2

    Science.gov (United States)

    Hunter, G. W.; Chen, L. Y.; Neudeck, P. G.; Knight, D.; Liu, C. C.; Wu, Q. H.; Zhou, H. J.; Makel, D.; Liu, M.; Rauch, W. A.

    1998-01-01

    Aeronautic and Space applications require the development of chemical sensors with capabilities beyond those of commercially available sensors. Areas of most interest include launch vehicle safety monitoring emission monitoring and fire detection. This paper discusses the needs of aeronautic and space applications and the point-contact sensor technology being developed to address these needs. The development of these sensor is based on progress two types of technology: 1) Micro-machining and micro-fabrication technology to fabricate miniaturized sensors. 2) The development of high temperature semiconductors, especially silicon carbide. Sensor development for each application involves its own challenges in the fields of materials science and fabrication technology. The number of dual-use commercial applications of this micro-fabricated gas sensor technology make this area of sensor development a field of significant interest.

  7. Chemical Gas Sensors for Aeronautics and Space Applications III

    Science.gov (United States)

    Hunter, G. W.; Neudeck, P. G.; Chen, L. Y.; Liu, C. C.; Wu, Q. H.; Sawayda, M. S.; Jin, Z.; Hammond, J.; Makel, D.; Liu, M.; hide

    1999-01-01

    Aeronautic and space applications require the development of chemical sensors with capabilities beyond those of commercially available sensors. Areas of interest include launch vehicle safety monitoring, emission monitoring, and fire detection. This paper discusses the needs of aeronautic and space applications and the point-contact sensor technology being developed to address these needs. The development of these sensors is based on progress in two types of technology: 1) Micromachining and microfabrication technology to fabricate miniaturized sensors. 2) The development of high temperature semiconductors, especially silicon carbide. Sensor development for each application involves its own challenges in the fields of materials science and fabrication technology. The number of dual-use commercial applications of this microfabricated gas sensor technology make this area of sensor development a field of significant interest.

  8. Redesigned Gas Mass Flow Sensors for Space Shuttle Pressure Control System and Fuel Cell System

    Science.gov (United States)

    1996-01-01

    A program was conducted to determine if a state of the art micro-machined silicon solid state flow sensor could be used to replace the existing space shuttle orbiter flow sensors. The rather aggressive goal was to obtain a new sensor which would also be a multi-gas sensor and operate over a much wider flow range and with a higher degree of accuracy than the existing sensors. Two types of sensors were tested. The first type was a venturi throat design and the second was a bypass design. The accuracy of venturi design was found to be marginally acceptable. The bypass sensor was much better although it still did not fully reach the accuracy goal. Two main problems were identified which would require further work.

  9. Conductivity modeling of gas sensors based on copper ...

    African Journals Online (AJOL)

    The main objective of this work is to study the electronic conductivity of copper ... applications, such as gas sensors [11 - 13], catalysts [14], solar cells [15], .... solid systems and adopted to examine the mechanism of the adsorption process [38].

  10. Noble Gas Concept Of Operation

    Energy Technology Data Exchange (ETDEWEB)

    Carrigan, C. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-01-20

    The intent of this document is to provide the reader with an understanding of a general approach to performing the noble gas component of an On Site Inspection or OSI. The authors of this document recognize that owing to the wide range of scenarios that are possible for carrying out an underground nuclear explosion, the diverse sets of information that might be available to the inspection team initially and the potential range of political and physical constraints imposed during the inspection, a satisfactory prescriptive approach to carrying out the noble gas component of an OSI is unlikely. Rather, the authors intend only to aid the reader in understanding what a reasonable course of actions or responses may be as performed by an inspection team (IT) during a general OSI. If this document helps to inform the intuition of the reader about addressing the challenges resulting from the inevitable deviations from this general scenario, it will have achieved its intent.

  11. Titanium dioxide thin films for high temperature gas sensors

    Energy Technology Data Exchange (ETDEWEB)

    Seeley, Zachary Mark; Bandyopadhyay, Amit; Bose, Susmita, E-mail: sbose@wsu.ed

    2010-10-29

    Titanium dioxide (TiO{sub 2}) thin film gas sensors were fabricated via the sol-gel method from a starting solution of titanium isopropoxide dissolved in methoxyethanol. Spin coating was used to deposit the sol on electroded aluminum oxide (Al{sub 2}O{sub 3}) substrates forming a film 1 {mu}m thick. The influence of crystallization temperature and operating temperature on crystalline phase, grain size, electronic conduction activation energy, and gas sensing response toward carbon monoxide (CO) and methane (CH{sub 4}) was studied. Pure anatase phase was found with crystallization temperatures up to 800 {sup o}C, however, rutile began to form by 900 {sup o}C. Grain size increased with increasing calcination temperature. Activation energy was dependent on crystallite size and phase. Sensing response toward CO and CH{sub 4} was dependent on both calcination and operating temperatures. Films crystallized at 650 {sup o}C and operated at 450 {sup o}C showed the best selectivity toward CO.

  12. Novel gas sensors based on carbon nanotube networks

    International Nuclear Information System (INIS)

    Sayago, I; Aleixandre, M; Horrillo, M C; Fernandez, M J; Gutierrez, J; Terrado, E; Lafuente, E; Maser, W K; Benito, A M; Martinez, M T; Munoz, E; Urriolabeitia, E P; Navarro, R

    2008-01-01

    Novel resistive gas sensors based on single-walled carbon nanotube (SWNT) networks as the active sensing element nave been investigated for gas detection. SWNTs networks were fabricated by airbrushing on alumina substrates. As-produced- and Pd-decorated SWNT materials were used as sensitive layers for the detection of NO 2 and H 2 , respectively. The studied sensors provided good response to NO 2 and H 2 as well as excellent selectivities to interfering gases.

  13. Temperature-modulated direct thermoelectric gas sensors: thermal modeling and results for fast hydrocarbon sensors

    International Nuclear Information System (INIS)

    Rettig, Frank; Moos, Ralf

    2009-01-01

    Direct thermoelectric gas sensors are a promising alternative to conductometric gas sensors. For accurate results, a temperature modulation technique in combination with a regression analysis is advantageous. However, the thermal time constant of screen-printed sensors is quite large. As a result, up to now the temperature modulation frequency (20 mHz) has been too low and the corresponding principle-related response time (50 s) has been too high for many applications. With a special design, respecting the physical properties of thermal waves and the use of signal processing similar to a lock-in-amplifier, it is possible to achieve response times of about 1 s. As a result, direct thermoelectric gas sensors with SnO 2 as a gas-sensitive material respond fast and are reproducible to the propane concentration in the ambient atmosphere. Due to the path-independent behavior of the thermovoltage and the temperature, the measured thermopower of two sensors is almost identical

  14. Pulse-driven micro gas sensor fitted with clustered Pd/SnO2 nanoparticles.

    Science.gov (United States)

    Suematsu, Koichi; Shin, Yuka; Ma, Nan; Oyama, Tokiharu; Sasaki, Miyuki; Yuasa, Masayoshi; Kida, Tetsuya; Shimanoe, Kengo

    2015-08-18

    Real-time monitoring of specific gas concentrations with a compact and portable gas sensing device is required to sense potential health risk and danger from toxic gases. For such purposes, we developed an ultrasmall gas sensor device, where a micro sensing film was deposited on a micro heater integrated with electrodes fabricated by the microelectromechanical system (MEMS) technology. The developed device was operated in a pulse-heating mode to significantly reduce the heater power consumption and make the device battery-driven and portable. Using clustered Pd/SnO2 nanoparticles, we succeeded in introducing mesopores ranging from 10 to 30 nm in the micro gas sensing film (area: ϕ 150 μm) to detect large volatile organic compounds (VOCs). The micro sensor showed quick, stable, and high sensor responses to toluene at ppm (parts per million) concentrations at 300 °C even by operating the micro heater in a pulse-heating mode where switch-on and -off cycles were repeated at one-second intervals. The high performance of the micro sensor should result from the creation of efficient diffusion paths decorated with Pd sensitizers by using the clustered Pd/SnO2 nanoparticles. Hence we demonstrate that our pulse-driven micro sensor using nanostructured oxide materials holds promise as a battery-operable, portable gas sensing device.

  15. Quartz crystal microbalance gas sensor with nanocrystalline diamond sensitive layer

    Czech Academy of Sciences Publication Activity Database

    Varga, Marián; Laposa, A.; Kulha, Pavel; Kroutil, J.; Husák, M.; Kromka, Alexander

    2015-01-01

    Roč. 252, č. 11 (2015), s. 2591-2597 ISSN 0370-1972 R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:68378271 Keywords : gas sensor * nanocrystalline diamond * quartz resonator * thickness shear mode Subject RIV: JB - Sensor s, Measurment, Regulation Impact factor: 1.522, year: 2015

  16. An electrochemical sensor for determining elemental iodine in gas media

    Energy Technology Data Exchange (ETDEWEB)

    Goffman, V.G.; Shaimerdinov, B.U.; Kotelkin, I.M. [Institute of New Chemical Problems, Moscow (Russian Federation)] [and others

    1993-12-01

    The possibility of using solid-electrolyte Ag, AgI/AgI/Au cells as sensors for determining the concentration of elemental iodine in gas media is investigated. It is established that the sensor parameters are independent of oxygen content and radiation dose at different relative humidities.

  17. A Review of Carbon Nanotubes-Based Gas Sensors

    Directory of Open Access Journals (Sweden)

    Yun Wang

    2009-01-01

    Full Text Available Gas sensors have attracted intensive research interest due to the demand of sensitive, fast response, and stable sensors for industry, environmental monitoring, biomedicine, and so forth. The development of nanotechnology has created huge potential to build highly sensitive, low cost, portable sensors with low power consumption. The extremely high surface-to-volume ratio and hollow structure of nanomaterials is ideal for the adsorption of gas molecules. Particularly, the advent of carbon nanotubes (CNTs has fuelled the inventions of gas sensors that exploit CNTs' unique geometry, morphology, and material properties. Upon exposure to certain gases, the changes in CNTs' properties can be detected by various methods. Therefore, CNTs-based gas sensors and their mechanisms have been widely studied recently. In this paper, a broad but yet in-depth survey of current CNTs-based gas sensing technology is presented. Both experimental works and theoretical simulations are reviewed. The design, fabrication, and the sensing mechanisms of the CNTs-based gas sensors are discussed. The challenges and perspectives of the research are also addressed in this review.

  18. Resistive Oxygen Gas Sensors for Harsh Environments

    Science.gov (United States)

    Moos, Ralf; Izu, Noriya; Rettig, Frank; Reiß, Sebastian; Shin, Woosuck; Matsubara, Ichiro

    2011-01-01

    Resistive oxygen sensors are an inexpensive alternative to the classical potentiometric zirconia oxygen sensor, especially for use in harsh environments and at temperatures of several hundred °C or even higher. This device-oriented paper gives a historical overview on the development of these sensor materials. It focuses especially on approaches to obtain a temperature independent behavior. It is shown that although in the past 40 years there have always been several research groups working concurrently with resistive oxygen sensors, novel ideas continue to emerge today with respect to improvements of the sensor response time, the temperature dependence, the long-term stability or the manufacture of the devices themselves using novel techniques for the sensitive films. Materials that are the focus of this review are metal oxides; especially titania, titanates, and ceria-based formulations. PMID:22163805

  19. A Micro CO2 Gas Sensor Based on Sensing of pH-Sensitive Hydrogel Swelling by Means of a Pressure Sensor

    NARCIS (Netherlands)

    Herber, S.; Bomer, Johan G.; Olthuis, Wouter; Bergveld, Piet; van den Berg, Albert

    2005-01-01

    In this paper a sensor is presented for the detection of carbon dioxide gas inside the stomach in order to diagnose gastrointestinal ischemia. The operational principle of the sensor is measuring the CO2 induced pressure generation of a confined pH-sensitive hydrogel by means of a micro pressure

  20. Operating a fuel cell using landfill gas

    Energy Technology Data Exchange (ETDEWEB)

    Trippel, C.E.; Preston, J.L. Jr.; Trocciola, J.; Spiegel, R.

    1996-12-31

    An ONSI PC25{trademark}, 200 kW (nominal capacity) phosphoric acid fuel cell operating on landfill gas is installed at the Town of Groton Flanders Road landfill in Groton, Connecticut. This joint project by the Connecticut Light & Power Company (CL&P) which is an operating company of Northeast Utilities, the Town of Groton, International Fuel Cells (IFC), and the US EPA is intended to demonstrate the viability of installing, operating and maintaining a fuel cell operating on landfill gas at a landfill site. The goals of the project are to evaluate the fuel cell and gas pretreatment unit operation, test modifications to simplify the GPU design and demonstrate reliability of the entire system.

  1. Approach for Self-Calibrating CO2 Measurements with Linear Membrane-Based Gas Sensors

    Directory of Open Access Journals (Sweden)

    Detlef Lazik

    2016-11-01

    Full Text Available Linear membrane-based gas sensors that can be advantageously applied for the measurement of a single gas component in large heterogeneous systems, e.g., for representative determination of CO2 in the subsurface, can be designed depending on the properties of the observation object. A resulting disadvantage is that the permeation-based sensor response depends on operating conditions, the individual site-adapted sensor geometry, the membrane material, and the target gas component. Therefore, calibration is needed, especially of the slope, which could change over several orders of magnitude. A calibration-free approach based on an internal gas standard is developed to overcome the multi-criterial slope dependency. This results in a normalization of sensor response and enables the sensor to assess the significance of measurement. The approach was proofed on the example of CO2 analysis in dry air with tubular PDMS membranes for various CO2 concentrations of an internal standard. Negligible temperature dependency was found within an 18 K range. The transformation behavior of the measurement signal and the influence of concentration variations of the internal standard on the measurement signal were shown. Offsets that were adjusted based on the stated theory for the given measurement conditions and material data from the literature were in agreement with the experimentally determined offsets. A measurement comparison with an NDIR reference sensor shows an unexpectedly low bias (<1% of the non-calibrated sensor response, and comparable statistical uncertainty.

  2. Approach for Self-Calibrating CO₂ Measurements with Linear Membrane-Based Gas Sensors.

    Science.gov (United States)

    Lazik, Detlef; Sood, Pramit

    2016-11-17

    Linear membrane-based gas sensors that can be advantageously applied for the measurement of a single gas component in large heterogeneous systems, e.g., for representative determination of CO₂ in the subsurface, can be designed depending on the properties of the observation object. A resulting disadvantage is that the permeation-based sensor response depends on operating conditions, the individual site-adapted sensor geometry, the membrane material, and the target gas component. Therefore, calibration is needed, especially of the slope, which could change over several orders of magnitude. A calibration-free approach based on an internal gas standard is developed to overcome the multi-criterial slope dependency. This results in a normalization of sensor response and enables the sensor to assess the significance of measurement. The approach was proofed on the example of CO₂ analysis in dry air with tubular PDMS membranes for various CO₂ concentrations of an internal standard. Negligible temperature dependency was found within an 18 K range. The transformation behavior of the measurement signal and the influence of concentration variations of the internal standard on the measurement signal were shown. Offsets that were adjusted based on the stated theory for the given measurement conditions and material data from the literature were in agreement with the experimentally determined offsets. A measurement comparison with an NDIR reference sensor shows an unexpectedly low bias (sensor response, and comparable statistical uncertainty.

  3. Fast response time alcohol gas sensor using nanocrystalline F ...

    Indian Academy of Sciences (India)

    been used in gas sensor applications, i.e. adsorption ability, catalytic ... sity, as well as grain boundary alteration (Yamazoe 1991;. 521 ... oxide surface using a catalyst layer or gas filter layer. Shukla .... mobility and sheet resistance were measured using resisti- .... ation considerably reduces the conversion efficiency in flat.

  4. A Miniaturized Optical Sensor with Integrated Gas Cell

    NARCIS (Netherlands)

    Ayerden, N.P.; Ghaderi, M.; De Graaf, G.; Wolffenbuttel, R.F.

    2015-01-01

    The design, fabrication and characterization of a highly integrated optical gas sensor is presented. The gas cell takes up most of the space in a microspectrometer and is the only component that has so far not been miniaturized. Using the tapered resonator cavity of a linear variable optical filter

  5. Operational monitoring of acoustic sensor networks

    Directory of Open Access Journals (Sweden)

    Boltenkov V.A.

    2015-06-01

    Full Text Available Acoustic sensor networks (ASN are widely used to monitor water leaks in the power generating systems. Since the ASN are used in harsh climatic conditions the failures of microphone elements of ASN are inevitable. That's why the failure detection of ASN elements is a problem of current interest. Two techniques of operational monitoring ASN are developed. Both of them are based on the placement of the test sound source within a network. The signal processing for ASN sensors had to detect the failed element. Techniques are based time difference of arrival (TDOA estimating at the each pair of ASN elements. TDOA estimates as argmaximum of cross-correlation function (CCF for signals on each microphone sensors pair. The M-sequence phase-shift keyed signal is applied as a test acoustic signal to ensure high accuracy of the CCF maximum estimation at low signal/noise ratio (SNR. The first technique is based on the isolation principle for TDOA sum at three points. It require to locate the test sound source in the far field. This is not always possible due to technological reasons. For the second proposed technique test sound source can be located near the ASN. It is based on a system of hyperbolic equations solving for each of the four elements of the ASN. Both techniques has been tested in the computer imitation experiment. It was found that for the SNR to –5 dB both techniques show unmistakable indicators of control quality. The second method requires significantly more time control.

  6. Corroles-Porphyrins: A Teamwork for Gas Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Rosamaria Capuano

    2015-04-01

    Full Text Available Porphyrins provide an excellent material for chemical sensors, and they have been used for sensing species both in air and solution. In the gas phase, the broad selectivity of porphyrins is largely dependant on molecular features, such as the metal ion complexed at the core of the aromatic ring and the peripheral substituents. Although these features have been largely exploited to design gas sensor arrays, so far, little attention has been devoted to modify the sensing properties of these macrocycles by variation of the molecular aromatic ring. In this paper, the gas sensing properties of a porphyrin analog, the corrole, are studied in comparison with those of the parent porphyrin. Results show that changes in the aromatic ring have important consequences on the sensitivity and selectivity of the sensors and that porphyrins and corroles can positively cooperate to enhance the performance of sensor arrays.

  7. Gas Detection Instrument Based on Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    ANSONG FENG

    2013-06-01

    Full Text Available The wireless sensor network is used to simulate poisonous gas generating system in the Fire-Fighting Simulated Training System. In the paper, we use the wireless signal to simulate the poisonous gas source and use received signal strength indicator (RSSI to simulate the distance between the fireman and the gas source. The gas detection instrument samples the temperature and sphygmus of the trainee and uses the wireless signal as poisonous gas signal. When the trainee enters into the poisonous gas area, the gas detection instrument warns with sound and light and sends the type, density value, the location of the poisonous gas and vital signs of the trainee to host. The paper discusses the software and hardware design of the gas detection instrument. The system has been used to the several of Fire-Fighting training systems.

  8. A miniaturized optical gas sensor for natural gas analysis

    NARCIS (Netherlands)

    Ayerden, N.P.

    2016-01-01

    The depletion of domestic reserves and the growing use of sustainable resources forces a transition from the locally produced natural gas with a well-known composition toward the ‘new’ gas with a more flexible composition in the Netherlands. For safe combustion and proper billing, the natural gas

  9. Hydrate Control for Gas Storage Operations

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey Savidge

    2008-10-31

    The overall objective of this project was to identify low cost hydrate control options to help mitigate and solve hydrate problems that occur in moderate and high pressure natural gas storage field operations. The study includes data on a number of flow configurations, fluids and control options that are common in natural gas storage field flow lines. The final phase of this work brings together data and experience from the hydrate flow test facility and multiple field and operator sources. It includes a compilation of basic information on operating conditions as well as candidate field separation options. Lastly the work is integrated with the work with the initial work to provide a comprehensive view of gas storage field hydrate control for field operations and storage field personnel.

  10. Low-level radioactive gas monitor for natural gas operations

    International Nuclear Information System (INIS)

    Armstrong, F.E.

    1969-11-01

    A portable radioactivity detection system for monitoring the tritium content of natural gas under field conditions has been developed. The sensing device employed is a complex proportional counting assembly operated without the use of massive shielding previously employed with such low-level radiation detectors. The practical limit of detection for the system is a tritium content of 10 -9 microcurie per cc of natural gas. All components of the system are packaged in three waterproof cases weighing slightly less than 30 kg each. Power requirement is 500 watts of 120 volt, 60 Hz current. Operation is fully automatic with a printed record produced at predetermined time intervals

  11. Nanocrystalline samarium oxide coated fiber optic gas sensor

    International Nuclear Information System (INIS)

    Renganathan, B.; Sastikumar, D.; Srinivasan, R.; Ganesan, A.R.

    2014-01-01

    Highlights: • This fiber optic gas sensor works at room temperature. • As-prepared and annealed Sm 2 O 3 nanoparticles are act as sensor materials. • Sm 2 O 3 clad modified fiber detect the ammonia, ethanol and methanol gases. • The response of evanescent wave loss has been studied for different concentrations. - Abstract: Nanocrystalline Sm 2 O 3 coated fiber optic sensor is proposed for detecting toxic gases such as ammonia, methanol and ethanol vapors. Sm 2 O 3 in the as prepared form as well as annealed form have been used as gas sensing materials, by making them as cladding of a PMMA fiber. The spectral characteristics of the Sm 2 O 3 gas sensor are presented for ammonia, methanol and ethanol gases with different concentrations ranging from 0 to 500 ppm. The sensor exhibits a linear variation in the output light intensity with the concentration. The enhanced gas sensitivity and selectivity of the sensor for ethanol is discussed briefly

  12. Gas Sensors Based on Semiconducting Nanowire Field-Effect Transistors

    Directory of Open Access Journals (Sweden)

    Ping Feng

    2014-09-01

    Full Text Available One-dimensional semiconductor nanostructures are unique sensing materials for the fabrication of gas sensors. In this article, gas sensors based on semiconducting nanowire field-effect transistors (FETs are comprehensively reviewed. Individual nanowires or nanowire network films are usually used as the active detecting channels. In these sensors, a third electrode, which serves as the gate, is used to tune the carrier concentration of the nanowires to realize better sensing performance, including sensitivity, selectivity and response time, etc. The FET parameters can be modulated by the presence of the target gases and their change relate closely to the type and concentration of the gas molecules. In addition, extra controls such as metal decoration, local heating and light irradiation can be combined with the gate electrode to tune the nanowire channel and realize more effective gas sensing. With the help of micro-fabrication techniques, these sensors can be integrated into smart systems. Finally, some challenges for the future investigation and application of nanowire field-effect gas sensors are discussed.

  13. Low-frequency noise characterization of single CuO nanowire gas sensor devices

    NARCIS (Netherlands)

    Steinhauer, S.; Köck, A.; Gspan, C.; Grogger, W.; Vandamme, L.K.J.; Pogany, D.

    2015-01-01

    Low-frequency noise properties of single CuO nanowire devices were investigated under gas sensor operation conditions in dry and humid synthetic air at 350¿°C. A 1/f noise spectrum was found with the normalized power spectral density of current fluctuations typically a factor of 2 higher for humid

  14. Small battery operated unattended radar sensor for security systems

    Science.gov (United States)

    Plummer, Thomas J.; Brady, Stephen; Raines, Robert

    2013-06-01

    McQ has developed, tested, and is supplying to Unattended Ground Sensor (UGS) customers a new radar sensor. This radar sensor is designed for short range target detection and classification. The design emphasis was to have low power consumption, totally automated operation, a very high probability of detection coupled with a very low false alarm rate, be able to locate and track targets, and have a price compatible with the UGS market. The radar sensor complements traditional UGS sensors by providing solutions for scenarios that are difficult for UGS. The design of this radar sensor and the testing are presented in this paper.

  15. Planar Indium Tin Oxide Heater for Improved Thermal Distribution for Metal Oxide Micromachined Gas Sensors

    Directory of Open Access Journals (Sweden)

    M. Cihan Çakır

    2016-09-01

    Full Text Available Metal oxide gas sensors with integrated micro-hotplate structures are widely used in the industry and they are still being investigated and developed. Metal oxide gas sensors have the advantage of being sensitive to a wide range of organic and inorganic volatile compounds, although they lack selectivity. To introduce selectivity, the operating temperature of a single sensor is swept, and the measurements are fed to a discriminating algorithm. The efficiency of those data processing methods strongly depends on temperature uniformity across the active area of the sensor. To achieve this, hot plate structures with complex resistor geometries have been designed and additional heat-spreading structures have been introduced. In this work we designed and fabricated a metal oxide gas sensor integrated with a simple square planar indium tin oxide (ITO heating element, by using conventional micromachining and thin-film deposition techniques. Power consumption–dependent surface temperature measurements were performed. A 420 °C working temperature was achieved at 120 mW power consumption. Temperature distribution uniformity was measured and a 17 °C difference between the hottest and the coldest points of the sensor at an operating temperature of 290 °C was achieved. Transient heat-up and cool-down cycle durations are measured as 40 ms and 20 ms, respectively.

  16. Planar Indium Tin Oxide Heater for Improved Thermal Distribution for Metal Oxide Micromachined Gas Sensors.

    Science.gov (United States)

    Çakır, M Cihan; Çalışkan, Deniz; Bütün, Bayram; Özbay, Ekmel

    2016-09-29

    Metal oxide gas sensors with integrated micro-hotplate structures are widely used in the industry and they are still being investigated and developed. Metal oxide gas sensors have the advantage of being sensitive to a wide range of organic and inorganic volatile compounds, although they lack selectivity. To introduce selectivity, the operating temperature of a single sensor is swept, and the measurements are fed to a discriminating algorithm. The efficiency of those data processing methods strongly depends on temperature uniformity across the active area of the sensor. To achieve this, hot plate structures with complex resistor geometries have been designed and additional heat-spreading structures have been introduced. In this work we designed and fabricated a metal oxide gas sensor integrated with a simple square planar indium tin oxide (ITO) heating element, by using conventional micromachining and thin-film deposition techniques. Power consumption-dependent surface temperature measurements were performed. A 420 °C working temperature was achieved at 120 mW power consumption. Temperature distribution uniformity was measured and a 17 °C difference between the hottest and the coldest points of the sensor at an operating temperature of 290 °C was achieved. Transient heat-up and cool-down cycle durations are measured as 40 ms and 20 ms, respectively.

  17. Nanocrystalline Pd:NiFe2O4 thin films: A selective ethanol gas sensor

    International Nuclear Information System (INIS)

    Rao, Pratibha; Godbole, R.V.; Bhagwat, Sunita

    2016-01-01

    In this work, Pd:NiFe 2 O 4 thin films were investigated for the detection of reducing gases. These films were fabricated using spray pyrolysis technique and characterized using X-ray diffraction (XRD) to confirm the crystal structure. The surface morphology was studied using scanning electron microscopy (SEM). Magnetization measurements were carried out using SQUID VSM, which shows ferrimagnetic behavior of the samples. These thin film sensors were tested against methanol, ethanol, hydrogen sulfide and liquid petroleum gas, where they were found to be more selective to ethanol. The fabricated thin film sensors exhibited linear response signal for all the gases with concentrations up to 5 w/o Pd. Reduction in optimum operating temperature and enhancement in response was also observed. Pd:NiFe 2 O 4 thin films exhibited faster response and recovery characteristic. These sensors have potential for industrial applications because of their long-term stability, low power requirement and low production cost. - Highlights: • Ethanol gas sensors based on Pd:NiFe 2 O 4 nanoparticle thin film were fabricated. • Pd incorporation in NiFe 2 O 4 matrix inhibits grain growth. • The sensors were more selective to ethanol gas. • Sensors exhibited fast response and recovery when doped with palladium. • Pd:NiFe 2 O 4 thin film sensor displays excellent long–term stability.

  18. Design and implementation of an integrated safety management system for compressed natural gas stations using ubiquitous sensor network

    International Nuclear Information System (INIS)

    Yang, Jae Mo; Ko, Byung Seok; Park, Chulhwan; Ko, Jae Wook; Yoo, Byungtae; Shin, Dongil

    2014-01-01

    To increase awareness of safety in facilities where hazards may exist, operators, managers, and executive officers on the site should be able to monitor such facilities. However, most compressed natural gas (CNG) service stations in Korea use only local-mode monitoring, with only on-site operators to monitor the facility. To complement this local-mode monitoring, an online safety management system called Ubiquitous-gas safety management system (U-GSMS) was developed. The U-GSMS consists largely of software and hardware. The software consists of systems that can manage safety and operations, while the hardware consists of sensors installed in the gas facility and wireless communication systems using a ubiquitous sensor network (USN) technology that facilitates communication between sensors as well as between sensors and other devices. As these systems are web-based, on-site operators as well as managers and executive officers at the headquarters can more effectively and efficiently perform monitoring and safety management

  19. Design and implementation of an integrated safety management system for compressed natural gas stations using ubiquitous sensor network

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jae Mo; Ko, Byung Seok; Park, Chulhwan; Ko, Jae Wook [Kwangwoon University, Seoul (Korea, Republic of); Yoo, Byungtae [National Disaster Management Institute, Seoul (Korea, Republic of); Shin, Dongil [Myongji University, Yongin (Korea, Republic of)

    2014-03-15

    To increase awareness of safety in facilities where hazards may exist, operators, managers, and executive officers on the site should be able to monitor such facilities. However, most compressed natural gas (CNG) service stations in Korea use only local-mode monitoring, with only on-site operators to monitor the facility. To complement this local-mode monitoring, an online safety management system called Ubiquitous-gas safety management system (U-GSMS) was developed. The U-GSMS consists largely of software and hardware. The software consists of systems that can manage safety and operations, while the hardware consists of sensors installed in the gas facility and wireless communication systems using a ubiquitous sensor network (USN) technology that facilitates communication between sensors as well as between sensors and other devices. As these systems are web-based, on-site operators as well as managers and executive officers at the headquarters can more effectively and efficiently perform monitoring and safety management.

  20. Highly Sensitive and Selective Hydrogen Gas Sensor Using the Mesoporous SnO2 Modified Layers

    Directory of Open Access Journals (Sweden)

    Niuzi Xue

    2017-10-01

    Full Text Available It is important to improve the sensitivities and selectivities of metal oxide semiconductor (MOS gas sensors when they are used to monitor the state of hydrogen in aerospace industry and electronic field. In this paper, the ordered mesoporous SnO2 (m-SnO2 powders were prepared by sol-gel method, and the morphology and structure were characterized by X-ray diffraction analysis (XRD, transmission electron microscope (TEM and Brunauer–Emmett–Teller (BET. The gas sensors were fabricated using m-SnO2 as the modified layers on the surface of commercial SnO2 (c-SnO2 by screen printing technology, and tested for gas sensing towards ethanol, benzene and hydrogen with operating temperatures ranging from 200 °C to 400 °C. Higher sensitivity was achieved by using the modified m-SnO2 layers on the c-SnO2 gas sensor, and it was found that the S(c/m2 sensor exhibited the highest response (Ra/Rg = 22.2 to 1000 ppm hydrogen at 400 °C. In this paper, the mechanism of the sensitivity and selectivity improvement of the gas sensors is also discussed.

  1. Sensing characteristics of nanocrystalline bismuth oxide clad-modified fiber optic gas sensor

    Science.gov (United States)

    Manjula, M.; Karthikeyan, B.; Sastikumar, D.

    2017-08-01

    Gas sensing properties of nanocrystalline bismuth oxide clad - modified fiber optic sensor is reported for ammonia, ethanol, methanol and acetone gasses at room temperature. The output of sensor increases or decreases for certain gasses when the concentration of the gas is increased. The sensor exhibits high response and good selectivity to methanol gas. Time response characteristics of the sensor are also reported.

  2. Sensors for online determination of CNG gas quality; Sensorer foer onlinebestaemnning av fordonsgaskvalitet

    Energy Technology Data Exchange (ETDEWEB)

    Stenlaaaas, Ola; Roedjegaard, Henrik

    2012-07-01

    Swedish automotive gas has until now been a very uniform, high quality automotive fuel. Elsewhere in Europe the quality of automotive gas varies significantly. Gas from different sources with different flammability require engine settings adjusted to the chosen gas' unique composition. The prospects for a vehicle-mounted sensor based on infrared technology for gas quality measurement has been studied and solutions are presented with questions that must be answered in a possible future work. The proposed vehicle mounted sensor is based on two channels, one of which measures the partial pressure of methane and the other measures the partial pressure of heavier hydrocarbons in 'equivalents of butane'. Ethane produces a signal of about 0.6 equivalents of butane and propane about 0.8 equivalents. The sensor can be accommodated in a cube with 5 cm side and should be equipped with nipple connections to the existing system. The sensor is expected to work throughout their entire lifetime without manual calibration, through continuous automatic calibration, so-called ABC (Automatic Baseline Compensation). The sensor will have to meet tough quality and environmental standards in which primarily contact ring, vibration and prevention of leakage are identified as extra difficult. Working temperatures and the electrical conditions of power supply and communication interface is considered less challenging. In one million volumes, the cost per sensor could be 200 to 300 SEK.

  3. Solid-State Gas Sensors: Sensor System Challenges in the Civil Security Domain

    Directory of Open Access Journals (Sweden)

    Gerhard Müller

    2016-01-01

    Full Text Available The detection of military high explosives and illicit drugs presents problems of paramount importance in the fields of counter terrorism and criminal investigation. Effectively dealing with such threats requires hand-portable, mobile and affordable instruments. The paper shows that solid-state gas sensors can contribute to the development of such instruments provided the sensors are incorporated into integrated sensor systems, which acquire the target substances in the form of particle residue from suspect objects and which process the collected residue through a sequence of particle sampling, solid-vapor conversion, vapor detection and signal treatment steps. Considering sensor systems with metal oxide gas sensors at the backend, it is demonstrated that significant gains in sensitivity, selectivity and speed of response can be attained when the threat substances are sampled in particle as opposed to vapor form.

  4. Solid-State Gas Sensors: Sensor System Challenges in the Civil Security Domain.

    Science.gov (United States)

    Müller, Gerhard; Hackner, Angelika; Beer, Sebastian; Göbel, Johann

    2016-01-20

    The detection of military high explosives and illicit drugs presents problems of paramount importance in the fields of counter terrorism and criminal investigation. Effectively dealing with such threats requires hand-portable, mobile and affordable instruments. The paper shows that solid-state gas sensors can contribute to the development of such instruments provided the sensors are incorporated into integrated sensor systems, which acquire the target substances in the form of particle residue from suspect objects and which process the collected residue through a sequence of particle sampling, solid-vapor conversion, vapor detection and signal treatment steps. Considering sensor systems with metal oxide gas sensors at the backend, it is demonstrated that significant gains in sensitivity, selectivity and speed of response can be attained when the threat substances are sampled in particle as opposed to vapor form.

  5. Chemical sensors and gas sensors for process control in biotechnology

    International Nuclear Information System (INIS)

    Williams, D.E.

    1988-04-01

    This paper is concerned with the possibilities for chemical measurement of the progress of biotechnological processes which are offered by devices already developed for other demanding applications. It considers the potential use of ultrasonic instrumentation originally developed for the nuclear industry, gas measurement methods from the fields of environmental monitoring and combustion control, nuclear instruments developed for the oil, mining and chemical industries, robotic systems and advanced control techniques. (author)

  6. Application of a sensor array based on capillary-attached conductive gas sensors for odor identification

    International Nuclear Information System (INIS)

    Bahraminejad, Behzad; Basri, Shahnor; Isa, Maryam; Hambali, Zarida

    2010-01-01

    An electronic nose based on an array of capillary-attached conductive gas sensors was fabricated. The identification ability of the developed structure was investigated by employing different categories of simple and complex odor databases. Feature data sets were generated from the dynamic and steady state responses of the sensor array to the applied odor databases. Combinations of different feature extraction and classification methods were used to detect target gases. Validation of each technique was evaluated. Achievements of the study proved high classification rates of the fabricated e-nose in odor identification. It was indicated that gas identification is possible by applying the early selected portion of transient responses of the developed sensor array. The ability of the mentioned structure in analyzing gas mixtures was also investigated. The results presented high accuracy in the classification of gas mixtures

  7. Indoor air quality inspection and analysis system based on gas sensor array

    Science.gov (United States)

    Gao, Xiang; Wang, Mingjiang; Fan, Binwen

    2017-08-01

    A detection and analysis system capable of measuring the concentration of four major gases in indoor air is designed. It uses four gas sensors constitute a gas sensor array, to achieve four indoor gas concentration detection, while the detection of data for further processing to reduce the cross-sensitivity between the gas sensor to improve the accuracy of detection.

  8. Benchmarking European Gas Transmission System Operators

    DEFF Research Database (Denmark)

    Agrell, Per J.; Bogetoft, Peter; Trinkner, Urs

    This is the final report for the pan-European efficiency benchmarking of gas transmission system operations commissioned by the Netherlands Authority for Consumers and Markets (ACM), Den Haag, on behalf of the Council of European Energy Regulators (CEER) under the supervision of the authors....

  9. Development of a detection sensor for lethal H2S gas.

    Science.gov (United States)

    Park, Young-Ho; Kim, Yong-Jae; Lee, Chang-Seop

    2012-07-01

    The gas which may be lethal to human body with short-term exposure in common industrial fields or workplaces in LAB may paralyze the olfactory sense and impose severe damages to central nervous system and lung. This study is concerned with the gas sensor which allows individuals to avoid the toxic gas that may be generated in the space with residues of organic wastes under 50 degrees C or above. This study investigates response and selectivity of the sensor to hydrogen sulfide gas with operating temperatures and catalysts. The thick-film semiconductor sensor for hydrogen sulfide gas detection was fabricated WO3/SnO2 prepared by sol-gel and precipitation methods. The nanosized SnO2 powder mixed with the various metal oxides (WO3, TiO2, and ZnO) and doped with transition metals (Au, Ru, Pd Ag and In). Particle sizes, specific surface areas and phases of sensor materials were investigated by SEM, BET and XRD analyses. The metal-WO3/SnO2 thick films were prepared by screen-printing method. The measured response to hydrogen sulfide gas is defined as the ratio (Ra/R,) of the resistance of WO3ISnO2 film in air to the resistance of WO3/SnO2 film in a hydrogen sulfide gas. It was shown that the highest response and selectivity of the sensor for hydrogen sulfide by doping with 1 wt% Ru and 10 wt% WO3 to SnO2 at the optimum operating temperature of 200 degrees C.

  10. Nanoparticle-based gas sensors and methods of using the same

    Science.gov (United States)

    Mickelson, William; Zettl, Alex

    2017-10-17

    Gas sensors are provided. The gas sensors include a gas sensing element having metal oxide nanoparticles and a thin-film heating element. Systems that include the gas sensors, as well as methods of using the gas sensors, are also provided. Embodiments of the present disclosure find use in a variety of different applications, including detecting whether an analyte is present in a gaseous sample.

  11. Sulfophenyl-Functionalized Reduced Graphene Oxide Networks on Electrospun 3D Scaffold for Ultrasensitive NO2 Gas Sensor

    OpenAIRE

    Zou, Bin; Guo, Yunlong; Shen, Nannan; Xiao, Anshan; Li, Mingjun; Zhu, Liang; Wan, Pengbo; Sun, Xiaoming

    2017-01-01

    Ultrasensitive room temperature real-time NO2 sensors are highly desirable due to potential threats on environmental security and personal respiratory. Traditional NO2 gas sensors with highly operated temperatures (200–600 °C) and limited reversibility are mainly constructed from semiconducting oxide-deposited ceramic tubes or inter-finger probes. Herein, we report the functionalized graphene network film sensors assembled on an electrospun three-dimensional (3D) nanonetwork skeleton for ultr...

  12. Electrocatalytic cermet gas detector/sensor

    Science.gov (United States)

    Vogt, Michael C.; Shoemarker, Erika L.; Fraioli, deceased, Anthony V.

    1995-01-01

    An electrocatalytic device for sensing gases. The gas sensing device includes a substrate layer, a reference electrode disposed on the substrate layer comprised of a nonstoichiometric chemical compound enabling oxygen diffusion therethrough, a lower reference electrode coupled to the reference electrode, a solid electrolyte coupled to the lower reference electrode and an upper catalytically active electrode coupled to the solid electrolyte.

  13. Field effect-gas sensor for hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Plihal, M [Siemens A.G., Muenchen (Germany, F.R.). Forschungslaboratorium

    1977-01-01

    MIS diodes with palladium gate can be used to detect and to measure quantitatively the hydrogen concentration in gas mixtures. The dependence of the differential capacitance of these diodes on the partial pressure of hydrogen in nitrogen, oxygen and air is investigated. A theoretical model is developed which gives satisfactory agreement with most of the experimental results.

  14. Nano Ag-Doped In2O3 Thick Film: A Low-Temperature H2S Gas Sensor

    Directory of Open Access Journals (Sweden)

    D. N. Chavan

    2011-01-01

    Full Text Available Thick films of AR grade In2O3 were prepared by standard screen-printing technique. The gas sensing performances of thick films were tested for various gases. It showed maximum sensitivity to ethanol vapour at 350°C for 80 ppm concentration. To improve the sensitivity and selectivity of the film towards a particular gas, In2O3 sensors were surface-modified by dipping them in a solution of 2% nanosilver for different intervals of time. Obtained results indicated that spherical nano-Ag grains are highly dispersed on the surface of In2O3sensor. The surface area of the nano-Ag/ In2O3 sensor is several times larger than that of pure In2O3 sensor. In comparison with pure In2O3 sensor, all of the nano-Ag-doped sensors showed better sensing performance in respect of response, selectivity, and optimum operating temperature. The surface-modified (30 min In2O3 sensor showed larger sensitivity to H2S gas (10 ppm at 100°C. Nano silver on the surface of the film shifts the reactivity of film from ethanol vapour to H2S gas. A systematic study of gas sensing performance of the sensor indicates the key role played by the nano silver species on the surface. The sensitivity, selectivity, response, and recovery time of the sensor were measured and presented.

  15. Electrospray-printed nanostructured graphene oxide gas sensors

    Science.gov (United States)

    Taylor, Anthony P.; Velásquez-García, Luis F.

    2015-12-01

    We report low-cost conductometric gas sensors that use an ultrathin film made of graphene oxide (GO) nanoflakes as transducing element. The devices were fabricated by lift-off metallization and near-room temperature, atmospheric pressure electrospray printing using a shadow mask. The sensors are sensitive to reactive gases at room temperature without requiring any post heat treatment, harsh chemical reduction, or doping with metal nanoparticles. The sensors’ response to humidity at atmospheric pressure tracks that of a commercial sensor, and is linear with changes in humidity in the 10%-60% relative humidity range while consuming recipes yielded nearly identical response characteristics, suggesting that intrinsic properties of the film control the sensing mechanism. The gas sensors successfully detected ammonia at concentrations down to 500 ppm (absolute partial pressure of ˜5 × 10-4 T) at ˜1 T pressure, room temperature conditions. The sensor technology can be used in a great variety of applications including air conditioning and sensing of reactive gas species in vacuum lines and abatement systems.

  16. Electrospray-printed nanostructured graphene oxide gas sensors

    International Nuclear Information System (INIS)

    Taylor, Anthony P; Velásquez-García, Luis F

    2015-01-01

    We report low-cost conductometric gas sensors that use an ultrathin film made of graphene oxide (GO) nanoflakes as transducing element. The devices were fabricated by lift-off metallization and near-room temperature, atmospheric pressure electrospray printing using a shadow mask. The sensors are sensitive to reactive gases at room temperature without requiring any post heat treatment, harsh chemical reduction, or doping with metal nanoparticles. The sensors’ response to humidity at atmospheric pressure tracks that of a commercial sensor, and is linear with changes in humidity in the 10%–60% relative humidity range while consuming <6 μW. Devices with GO layers printed by different deposition recipes yielded nearly identical response characteristics, suggesting that intrinsic properties of the film control the sensing mechanism. The gas sensors successfully detected ammonia at concentrations down to 500 ppm (absolute partial pressure of ∼5 × 10"−"4 T) at ∼1 T pressure, room temperature conditions. The sensor technology can be used in a great variety of applications including air conditioning and sensing of reactive gas species in vacuum lines and abatement systems. (paper)

  17. Progress in the development of semiconducting metal oxide gas sensors: a review

    International Nuclear Information System (INIS)

    Moseley, Patrick T

    2017-01-01

    Since the first suggestion, during the 1950s, that high-surface-area metal oxides could be used as conductometric gas sensors enormous efforts have been made to enhance both the selectivity and the sensitivity of such devices, and to reduce their operational power requirements. This development has involved the exploration of response mechanisms, the selection of the most appropriate oxide compositions, the fabrication of two-phase ‘hetero-structures’, the addition of metallic catalyst particles and the optimisation of the manner in which the materials are presented to the gas—the structure and the nanostructure of the sensing elements. Far more of the scientific literature has been devoted to seeking such improvements in metal oxide gas sensors than has been directed at all other solid-state gas sensors together. Recent progress in the research and development of metal oxide gas sensor technology is surveyed in this invited review. The advances that have been made are quite spectacular and the results of individual pieces of work are drawn together here so that trends can be seen. Emerging features include: the significance of n-type/p-type switching, the enhancement of sensing performance of materials through the incorporation of secondary components and the advantages of interrogating sensors with alternating current rather than direct current. (topical review)

  18. Synthesis and properties of ZnO nanorods as ethanol gas sensors

    International Nuclear Information System (INIS)

    Mirabbaszadeh, K; Mehrabian, M

    2012-01-01

    Uniform ZnO nanorods were synthesized via the sol-gel process under mild conditions in which different ZnO nanostructures have been prepared by changing the pH of growth solution. It was seen that the optimum nanorods were grown at pH 11.33. The prepared ZnO nanostructures and morphologies were characterized by x-ray diffraction and scanning electron microscopy measurements. The ZnO one-dimensional nanostructures were found to have a wurtzite hexagonal crystalline structure and grow along the [001] direction. The optimum nanorods were about 1 μm in length and less than 100 nm in diameter. The ZnO nanostructures have been tested for different concentrations and different operating temperatures for ethanol vapor in air and the surface resistance of the sensors has been evaluated as a function of different parameters. The gas sensor fabricated from ZnO nanorods grown in solution with a special pH exhibited good performance. The sensor response to 5000 ppm ethanol was up to about 2.5 at the operating temperature of 300 °C. The differences in gas-sensing performance between the sensors were analyzed based on the defects created in the nanorods during their fast growth. The correlations between material structures and the properties of the gas sensors are discussed.

  19. Fast response time alcohol gas sensor using nanocrystalline F

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 36; Issue 4. Fast response time alcohol gas sensor using nanocrystalline F-doped SnO2 films derived via sol–gel method. Sarbani Basu Yeong-Her Wang C Ghanshyam Pawan Kapur. Volume 36 Issue 4 August 2013 pp 521-533 ...

  20. Improved zinc oxide film for gas sensor applications

    Indian Academy of Sciences (India)

    Zinc oxide (ZnO) is a versatile material for different commercial applications such as transparent electrodes, piezoelectric devices, varistors, SAW devices etc because of its high piezoelectric coupling, greater stability of its hexagonal phase and its pyroelectric property. In fact, ZnO is a potential material for gas sensor ...

  1. Thin-film antifuses for pellistor type gas sensors

    NARCIS (Netherlands)

    Kovalgin, Alexeij Y.; Holleman, J.; van den Berg, Albert; Wallinga, Hans

    2001-01-01

    This work extends our previously reported idea of using the nano-scale conductive link (antifuse) as a combined heating /detecting element in a Pellistor-type gas sensor. Our new thin-film antifuse is designed in such a way that the oxide, for minimising the bulk influence on surface temperature,

  2. Development of nanostructured protective "sight glasses" for IR gas sensors

    DEFF Research Database (Denmark)

    Bergmann, René; Davis, Zachary James; Schmidt, Michael Stenbæk

    2011-01-01

    In this work protective "sight glasses" for infrared gas sensors showing a sub-wavelength nanostructure with random patterns have been fabricated by reactive ion etching (RIE) in an easy and comparable cheap single step mask-less process. By an organic coating, the intrinsic water repellent...

  3. Chemical discrimination in turbulent gas mixtures with MOX sensors validated by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramón

    2014-10-16

    Chemical detection systems based on chemo-resistive sensors usually include a gas chamber to control the sample air flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the gas concentration fluctuations observed in natural environments and destroys the spatio-temporal information contained in gas plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent gas sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive gas sensors are exposed to dynamic gas mixtures generated with several concentration levels at the sources. Moreover, the ground truth of gas concentrations at the sensor location was estimated by means of gas chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient gas concentration coverage is used. We show that in open sampling systems, training the classifiers only on high concentrations of gases produces less effective classification and that it is important to calibrate the classification method with data at low gas concentrations to achieve optimal performance.

  4. Optical Graphene Gas Sensors Based on Microfibers: A Review

    Directory of Open Access Journals (Sweden)

    Yu Wu

    2018-03-01

    Full Text Available Graphene has become a bridge across optoelectronics, mechanics, and bio-chemical sensing due to its unique photoelectric characteristics. Moreover, benefiting from its two-dimensional nature, this atomically thick film with full flexibility has been widely incorporated with optical waveguides such as fibers, realizing novel photonic devices including polarizers, lasers, and sensors. Among the graphene-based optical devices, sensor is one of the most important branch, especially for gas sensing, as rapid progress has been made in both sensing structures and devices in recent years. This article presents a comprehensive and systematic overview of graphene-based microfiber gas sensors regarding many aspects including sensing principles, properties, fabrication, interrogating and implementations.

  5. Wearable, wireless gas sensors using highly stretchable and transparent structures of nanowires and graphene

    Science.gov (United States)

    Park, Jihun; Kim, Joohee; Kim, Kukjoo; Kim, So-Yun; Cheong, Woon Hyung; Park, Kyeongmin; Song, Joo Hyeb; Namgoong, Gyeongho; Kim, Jae Joon; Heo, Jaeyeong; Bien, Franklin; Park, Jang-Ung

    2016-05-01

    Herein, we report the fabrication of a highly stretchable, transparent gas sensor based on silver nanowire-graphene hybrid nanostructures. Due to its superb mechanical and optical characteristics, the fabricated sensor demonstrates outstanding and stable performances even under extreme mechanical deformation (stable until 20% of strain). The integration of a Bluetooth system or an inductive antenna enables the wireless operation of the sensor. In addition, the mechanical robustness of the materials allows the device to be transferred onto various nonplanar substrates, including a watch, a bicycle light, and the leaves of live plants, thereby achieving next-generation sensing electronics for the `Internet of Things' area.Herein, we report the fabrication of a highly stretchable, transparent gas sensor based on silver nanowire-graphene hybrid nanostructures. Due to its superb mechanical and optical characteristics, the fabricated sensor demonstrates outstanding and stable performances even under extreme mechanical deformation (stable until 20% of strain). The integration of a Bluetooth system or an inductive antenna enables the wireless operation of the sensor. In addition, the mechanical robustness of the materials allows the device to be transferred onto various nonplanar substrates, including a watch, a bicycle light, and the leaves of live plants, thereby achieving next-generation sensing electronics for the `Internet of Things' area. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01468b

  6. Methanol sensor operated in a passive mode

    Science.gov (United States)

    Ren, Xiaoming; Gottesfeld, Shimshon

    2002-01-01

    A sensor outputs a signal related to a concentration of methanol in an aqueous solution adjacent the sensor. A membrane electrode assembly (MEA) is included with an anode side and a cathode side. An anode current collector supports the anode side of the MEA and has a flow channel therethrough for flowing a stream of the aqueous solution and forms a physical barrier to control access of the methanol to the anode side of the MEA. A cathode current collector supports the cathode side of the MEA and is configured for air access to the cathode side of the MEA. A current sensor is connected to measure the current in a short circuit across the sensor electrodes to provide an output signal functionally related to the concentration of methanol in the aqueous solution.

  7. Measuring the exhaust gas dew point of continuously operated combustion plants

    Energy Technology Data Exchange (ETDEWEB)

    Fehler, D.

    1985-07-16

    Low waste-gas temperatures represent one means of minimizing the energy consumption of combustion facilities. However, condensation should be prevented to occur in the waste gas since this could result in a destruction of parts. Measuring the waste-gas dew point allows to control combustion parameters in such a way as to be able to operate at low temperatures without danger of condensation. Dew point sensors will provide an important signal for optimizing combustion facilities.

  8. Functionalised zinc oxide nanowire gas sensors: Enhanced NO(2) gas sensor response by chemical modification of nanowire surfaces.

    Science.gov (United States)

    Waclawik, Eric R; Chang, Jin; Ponzoni, Andrea; Concina, Isabella; Zappa, Dario; Comini, Elisabetta; Motta, Nunzio; Faglia, Guido; Sberveglieri, Giorgio

    2012-01-01

    Surface coating with an organic self-assembled monolayer (SAM) can enhance surface reactions or the absorption of specific gases and hence improve the response of a metal oxide (MOx) sensor toward particular target gases in the environment. In this study the effect of an adsorbed organic layer on the dynamic response of zinc oxide nanowire gas sensors was investigated. The effect of ZnO surface functionalisation by two different organic molecules, tris(hydroxymethyl)aminomethane (THMA) and dodecanethiol (DT), was studied. The response towards ammonia, nitrous oxide and nitrogen dioxide was investigated for three sensor configurations, namely pure ZnO nanowires, organic-coated ZnO nanowires and ZnO nanowires covered with a sparse layer of organic-coated ZnO nanoparticles. Exposure of the nanowire sensors to the oxidising gas NO(2) produced a significant and reproducible response. ZnO and THMA-coated ZnO nanowire sensors both readily detected NO(2) down to a concentration in the very low ppm range. Notably, the THMA-coated nanowires consistently displayed a small, enhanced response to NO(2) compared to uncoated ZnO nanowire sensors. At the lower concentration levels tested, ZnO nanowire sensors that were coated with THMA-capped ZnO nanoparticles were found to exhibit the greatest enhanced response. ΔR/R was two times greater than that for the as-prepared ZnO nanowire sensors. It is proposed that the ΔR/R enhancement in this case originates from the changes induced in the depletion-layer width of the ZnO nanoparticles that bridge ZnO nanowires resulting from THMA ligand binding to the surface of the particle coating. The heightened response and selectivity to the NO(2) target are positive results arising from the coating of these ZnO nanowire sensors with organic-SAM-functionalised ZnO nanoparticles.

  9. A smart microelectromechanical sensor and switch triggered by gas

    KAUST Repository

    Bouchaala, Adam M.

    2016-07-05

    There is an increasing interest to realize smarter sensors and actuators that can deliver a multitude of sophisticated functionalities while being compact in size and of low cost. We report here combining both sensing and actuation on the same device based on a single microstructure. Specifically, we demonstrate a smart resonant gas (mass) sensor, which in addition to being capable of quantifying the amount of absorbed gas, can be autonomously triggered as an electrical switch upon exceeding a preset threshold of absorbed gas. Toward this, an electrostatically actuated polymer microbeam is fabricated and is then functionalized with a metal-organic framework, namely, HKUST-1. The microbeam is demonstrated to absorb vapors up to a certain threshold, after which is shown to collapse through the dynamic pull-in instability. Upon pull-in, the microstructure can be made to act as an electrical switch to achieve desirable actions, such as alarming.

  10. Nanostructured Gas Sensors for Health Care: An Overview

    Science.gov (United States)

    Kaushik, Ajeet; Kumar, Rajesh; Jayant, Rahul Dev; Nair, Madhavan

    2015-01-01

    Nanostructured platforms have been utilized for fabrication of small, sensitive and reliable gas sensing devices owing to high functionality, enhanced charge transport and electro-catalytic property. As a result of globalization, rapid, sensitive and selective detection of gases in environment is essential for health care and security. Nonmaterial such as metal, metal oxides, organic polymers, and organic-inorganic hybrid nanocomposites exhibit interesting optical, electrical, magnetic and molecular properties, and hence are found potential gas sensing materials. Morphological, electrical, and optical properties of such nanostructures can be tailored via controlling the precursor concentration and synthesis conditions resulting to achieve desired sensing. This review presents applications of nano-enabling gas sensors to detect gases for environment monitoring. The recent update, challenges, and future vision for commercial applications of such sensor are also described here. PMID:26491544

  11. A smart microelectromechanical sensor and switch triggered by gas

    Science.gov (United States)

    Bouchaala, Adam; Jaber, Nizar; Shekhah, Osama; Chernikova, Valeriya; Eddaoudi, Mohamed; Younis, Mohammad I.

    2016-07-01

    There is an increasing interest to realize smarter sensors and actuators that can deliver a multitude of sophisticated functionalities while being compact in size and of low cost. We report here combining both sensing and actuation on the same device based on a single microstructure. Specifically, we demonstrate a smart resonant gas (mass) sensor, which in addition to being capable of quantifying the amount of absorbed gas, can be autonomously triggered as an electrical switch upon exceeding a preset threshold of absorbed gas. Toward this, an electrostatically actuated polymer microbeam is fabricated and is then functionalized with a metal-organic framework, namely, HKUST-1. The microbeam is demonstrated to absorb vapors up to a certain threshold, after which is shown to collapse through the dynamic pull-in instability. Upon pull-in, the microstructure can be made to act as an electrical switch to achieve desirable actions, such as alarming.

  12. The oil and gas operator as fiduciary

    International Nuclear Information System (INIS)

    Evans, Edward.

    1992-01-01

    What, if any, fiduciary duties are owed by those who direct oil and gas operations to their co-venturers? The question is a complex one that has led to much controversy among industry participants, lawyers, academics and judges. The law dealing with fiduciary duties has been constantly evolving in Canada as in other countries and has yet to reach its definitive form. The principles which underlie when a fiduciary relationship will exist and the scope of the duties that will be imposed on the fiduciary in a given relationship are elusive. Yet, while the courts in Canada have raised what amounts to a presumption against the existence of a fiduciary relationship in arm's length commercial transactions, it is clear that the presumption is rebuttable and may be disregarded in light of the facts of a particular case. Certain observations may be made about the potential fiduciary obligations of an operator of oil and gas properties from the decided cases in the oil and gas area and the trends in other areas of the law as they relate to fiduciaries. Such operators have routinely had imposed on them a duty of good faith or have been classified as in a fiduciary relationship with the non-operators, at least with respect to the management, administration and marketing of the product and ultimately the distribution of the revenues. These observations may provide useful guidelines to those companies who are operators or joint operators in a complex industry in which the same organisations may find themselves simultaneously to be conventurers in relation to one piece of property and intense competitors with respect to another. (Author)

  13. Ad hoc Sensor Networks to Support Maritime Interdiction Operations

    OpenAIRE

    Osmundson, John; Bordetsky, Alex

    2014-01-01

    Networking sensors, decision centers, and boarding parties supports success in Maritime Interdiction Operations. Led by a team from Naval Post-graduate School (NPS), experiments were conducted in 2012 to test the use of ad-hoc, self-forming communication networks to link sensors, people, and decision centers. The experiments involved international participants and successfully shared valuable biometric and radiological sensor data between boarding parties and decis...

  14. Inductive sensors for blade tip-timing in gas turbines

    Directory of Open Access Journals (Sweden)

    Przysowa Radosław

    2015-12-01

    Full Text Available The paper reviews features and applications of the upgraded inductive sensor for BTT, which is able to operate in contact with exhaust gases of temperature even as high as 1200 K. The new design includes metal-ceramic housing ensuring proper heat transfer, magnetic circuit containing set of permanent magnets with various magnetic field values and Curie temperatures, completely redesigned windings and current/voltage converter used instead of an electromotive force amplifier. Its principle of operation is based on electro-dynamical interaction and therefore it may be referred as a passive eddy-current sensor. The sensor technique has been demonstrated on four stages of a surplus military turbofan including the high pressure turbine as part of the engine health monitoring system. We present signal samples and review methods used for online processing of time-of-arrival signals when only a limited number of sensors is available.

  15. Retrofitting bus fleet for natural gas operation

    International Nuclear Information System (INIS)

    Stella, E.; Foresti, P.

    1992-01-01

    Buses, operating within a Florence (Italy) municipal transportation system, and equipped with Otto cycle engines, were selected for retrofitting taking into account the suitability of each vehicle's specific routing and service requirements. Cost benefit analyses indicated that it wouldn't be economically feasible to retrofit buses equipped with diesel engines. A computerized refuelling system was set up at the fleet's central service station which was hooked up to the natural gas utility's supply line. This paper tables the cost benefit analysis data comparing gasoline and methane operation and reflecting the cost savings which are expected to be accrued through this methanization program over a span of 14 years

  16. Chemically synthesized PbS Nano particulate thin films for a rapid NO2 gas sensor

    Directory of Open Access Journals (Sweden)

    Burungale Vishal V.

    2016-03-01

    Full Text Available Rapid NO2 gas sensor has been developed based on PbS nanoparticulate thin films synthesized by Successive Ionic Layer Adsorption and Reaction (SILAR method at different precursor concentrations. The structural and morphological properties were investigated by means of X-ray diffraction and field emission scanning electron microscope. NO2 gas sensing properties of PbS thin films deposited at different concentrations were tested. PbS film with 0.25 M precursor concentration showed the highest sensitivity. In order to optimize the operating temperature, the sensitivity of the sensor to 50 ppm NO2 gas was measured at different operating temperatures, from 50 to 200 °C. The gas sensitivity increased with an increase in operating temperature and achieved the maximum value at 150 °C, followed by a decrease in sensitivity with further increase of the operating temperature. The sensitivity was about 35 % for 50 ppm NO2 at 150 °C with rapid response time of 6 s. T90 and T10 recovery time was 97 s at this gas concentration.

  17. DNA sensor cGAS-mediated immune recognition

    Directory of Open Access Journals (Sweden)

    Pengyan Xia

    2016-09-01

    Full Text Available Abstract The host takes use of pattern recognition receptors (PRRs to defend against pathogen invasion or cellular damage. Among microorganism-associated molecular patterns detected by host PRRs, nucleic acids derived from bacteria or viruses are tightly supervised, providing a fundamental mechanism of host defense. Pathogenic DNAs are supposed to be detected by DNA sensors that induce the activation of NFκB or TBK1-IRF3 pathway. DNA sensor cGAS is widely expressed in innate immune cells and is a key sensor of invading DNAs in several cell types. cGAS binds to DNA, followed by a conformational change that allows the synthesis of cyclic guanosine monophosphate–adenosine monophosphate (cGAMP from adenosine triphosphate and guanosine triphosphate. cGAMP is a strong activator of STING that can activate IRF3 and subsequent type I interferon production. Here we describe recent progresses in DNA sensors especially cGAS in the innate immune responses against pathogenic DNAs.

  18. Flexible Graphene-Based Wearable Gas and Chemical Sensors.

    Science.gov (United States)

    Singh, Eric; Meyyappan, M; Nalwa, Hari Singh

    2017-10-11

    Wearable electronics is expected to be one of the most active research areas in the next decade; therefore, nanomaterials possessing high carrier mobility, optical transparency, mechanical robustness and flexibility, lightweight, and environmental stability will be in immense demand. Graphene is one of the nanomaterials that fulfill all these requirements, along with other inherently unique properties and convenience to fabricate into different morphological nanostructures, from atomically thin single layers to nanoribbons. Graphene-based materials have also been investigated in sensor technologies, from chemical sensing to detection of cancer biomarkers. The progress of graphene-based flexible gas and chemical sensors in terms of material preparation, sensor fabrication, and their performance are reviewed here. The article provides a brief introduction to graphene-based materials and their potential applications in flexible and stretchable wearable electronic devices. The role of graphene in fabricating flexible gas sensors for the detection of various hazardous gases, including nitrogen dioxide (NO 2 ), ammonia (NH 3 ), hydrogen (H 2 ), hydrogen sulfide (H 2 S), carbon dioxide (CO 2 ), sulfur dioxide (SO 2 ), and humidity in wearable technology, is discussed. In addition, applications of graphene-based materials are also summarized in detecting toxic heavy metal ions (Cd, Hg, Pb, Cr, Fe, Ni, Co, Cu, Ag), and volatile organic compounds (VOCs) including nitrobenzene, toluene, acetone, formaldehyde, amines, phenols, bisphenol A (BPA), explosives, chemical warfare agents, and environmental pollutants. The sensitivity, selectivity and strategies for excluding interferents are also discussed for graphene-based gas and chemical sensors. The challenges for developing future generation of flexible and stretchable sensors for wearable technology that would be usable for the Internet of Things (IoT) are also highlighted.

  19. 21 CFR 870.4410 - Cardiopulmonary bypass in-line blood gas sensor.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass in-line blood gas sensor... Cardiopulmonary bypass in-line blood gas sensor. (a) Identification. A cardiopulmonary bypass in-line blood gas sensor is a transducer that measures the level of gases in the blood. (b) Classification. Class II...

  20. Preparation and characterization of Ag-doped In2O3 nanoparticles gas sensor

    Science.gov (United States)

    Anand, Kanica; Kaur, Jasmeet; Singh, Ravi Chand; Thangaraj, Rengasamy

    2017-08-01

    Pure and Ag-doped In2O3 nanoparticles are synthesized by the co-precipitation method and are characterized by X-ray diffraction, transmission electron microscopy and photoluminescence spectroscopy. Gas sensing properties of the sensors has been investigated towards methanol, ethanol, acetone and LPG at different operating temperatures. It is found that the sensor response magnitude of the 3% Ag-doped In2O3 nanoparticles sensors is higher to 50 ppm of ethanol at 300 °C, to acetone at 350 °C and to LPG at 400 °C. This is mainly attributed to the large number of oxygen vacancies and defects in doped sensors as corroborated by the photoluminescence studies.

  1. Robust Design of SAW Gas Sensors by Taguchi Dynamic Method

    Directory of Open Access Journals (Sweden)

    Hsun-Heng Tsai

    2009-02-01

    Full Text Available This paper adopts Taguchi’s signal-to-noise ratio analysis to optimize the dynamic characteristics of a SAW gas sensor system whose output response is linearly related to the input signal. The goal of the present dynamic characteristics study is to increase the sensitivity of the measurement system while simultaneously reducing its variability. A time- and cost-efficient finite element analysis method is utilized to investigate the effects of the deposited mass upon the resonant frequency output of the SAW biosensor. The results show that the proposed methodology not only reduces the design cost but also promotes the performance of the sensors.

  2. Bedside arterial blood gas monitoring system using fluorescent optical sensors

    Science.gov (United States)

    Bartnik, Daniel J.; Rymut, Russell A.

    1995-05-01

    We describe a bedside arterial blood gas (ABG) monitoring system which uses fluorescent optical sensors in the measurement of blood pH, PCO2 and PO2. The Point-of-Care Arterial Blood Gas Monitoring System consists of the SensiCathTM optical sensor unit manufactured by Optical Sensors Incorporated and the TramTM Critical Care Monitoring System with ABG Module manufactured by Marquette Electronics Incorporated. Current blood gas measurement techniques require a blood sample to be removed from the patient and transported to an electrochemical analyzer for analysis. The ABG system does not require removal of blood from the patient or transport of the sample. The sensor is added to the patient's existing arterial line. ABG measurements are made by drawing a small blood sample from the arterial line in sufficient quantity to ensure an undiluted sample at the sensor. Measurements of pH, PCO2 and PO2 are made within 60 seconds. The blood is then returned to the patient, the line flushed and results appear on the bedside monitor. The ABG system offers several advantages over traditional electrochemical analyzers. Since the arterial line remains closed during the blood sampling procedure the patient's risk of infection is reduced and the caregiver's exposure to blood is eliminated. The single-use, disposable sensor can be measure 100 blood samples over 72 hours after a single two-point calibration. Quality Assurance checks are also available and provide the caregiver the ability to assess system performance even after the sensor is patient attached. The ABG module integrates with an existing bedside monitoring system. This allows ABG results to appear on the same display as ECG, respiration, blood pressure, cardiac output, SpO2, and other clinical information. The small module takes up little space in the crowded intensive care unit. Performance studies compare the ABG system with an electrochemical blood gas analyzer. Study results demonstrated accurate and precise blood

  3. Liquefied petroleum gas sensor based on manganese (III) oxide and zinc manganese (III) oxide nanoparticles

    Science.gov (United States)

    Sharma, Shiva; Chauhan, Pratima; Husain, Shahid

    2018-01-01

    In this paper, {{{Mn}}}2{{{O}}}3 and {{{ZnMn}}}2{{{O}}}4 nanoparticles (NPs) are successfully synthesized using chemical co-precipitation method at room temperature and further annealed at 450 °C. The structure, crystallite size, morphology, specific surface area (SSA) and band gap energy have been determined by x-ray diffraction, transmission electron microscopy, Brunauer-Emmett-Teller surface area analysis, scanning electron microscopy (SEM-EDS) and UV-visible spectrophotometer. The sensor films of the {{{Mn}}}2{{{O}}}3 NPs and {{{ZnMn}}}2{{{O}}}4 NPs have been fabricated onto glass substrate using spin coater system separately. These sensor films are investigated for different concentrations (200-1200 ppm) of liquefied petroleum gas (LPG) at different operating temperatures ranging from 100 °C to 400 °C. A comparative study of gas sensing properties shows that spinel {{{ZnMn}}}2{{{O}}}4 sensor film exhibit excellent response (≈ 80 % ) towards 1000 ppm LPG at 300 °C in comparison to {{{Mn}}}2{{{O}}}3 sensor films. The enhancement in the gas sensing characteristics of {{{ZnMn}}}2{{{O}}}4 sensor film is attributed to the reduced crystallite size, greater SSA, and modification in structure as well as morphology.

  4. Detection of Hydrogen Sulphide Gas Sensor Based Nanostructured Ba2CrMoO6 Thick Films

    Directory of Open Access Journals (Sweden)

    A. V. Kadu

    2007-11-01

    Full Text Available Nanocrystalline pure and doped Ba2CrMoO6, having an average crystallite size of 40 nm were synthesized by the sol-gel citrate method. Structural and gas-sensing characteristics were performed by using X-ray diffraction (XRD and sensitivity measurements. The gas sensing properties to reducing gases like Hydrogen sulphide (H2S, liquefied petroleum gas (LPG, carbon monoxide (CO and hydrogen gas (H2 were also discussed. The maximum sensitivity was obtained for 5 wt % Ni doped Ba2CrMoO6 at an operating temperature 250oC for H2S gas. Pd incorporation over 5 wt% Ni doped Ba2CrMoO6 improved the sensitivity, selectivity, response time, and reduced the operating temperature from 250 to 200oC of the sensor for H2S gas. This sensor also shows good satiability.

  5. Noise characterization of oil and gas operations.

    Science.gov (United States)

    Radtke, Cameron; Autenrieth, Daniel A; Lipsey, Tiffany; Brazile, William J

    2017-08-01

    In cooperation with The Colorado Oil and Gas Conservation Commission, researchers at Colorado State University performed area noise monitoring at 23 oil and gas sites throughout Northern Colorado. The goals of this study were to: (1) measure and compare the noise levels for the different phases of oil and gas development sites; (2) evaluate the effectiveness of noise barriers; and (3) determine if noise levels exceeded the Colorado Oil and Gas Conservation Commission noise limits. The four phases of oil and gas development include drilling, hydraulic fracturing, completion and production. Noise measurements were collected using the A- and C-weighted sound scales. Octave band analysis was also performed to characterize the frequency spectra of the noise measurements.  Noise measurements were collected using noise dosimeters and a hand-held sound-level meter at specified distances from the development sites in each cardinal direction. At 350 ft (107 m), drilling, hydraulic fracturing, and completion sites without noise barriers exceeded the maximum permissible noise levels for residential and commercial zones (55 dBA and 60 dBA, respectively). In addition, drilling and hydraulic fracturing sites with noise barriers exceeded the maximum permissible noise level for residential zones (55 dBA). However, during drilling, hydraulic fracturing, and completion operations, oil producers are allowed an exception to the noise permissible limits in that they only must comply with the industrial noise limit (80 dBA). It is stated in Rule 604.c.(2)A. that: "Operations involving pipeline or gas facility installation or maintenance, the use of a drilling rig, completion rig, workover rig, or stimulation is subject to the maximum permissible noise levels for industrial zones (80dBA)." [8] Production sites were within the Colorado Oil and Gas Conservation Commission permissible noise level criteria for all zones. At 350 ft (107 m) from the noise source, all drilling

  6. Development of a novel gas sensor based on oxide thick films

    International Nuclear Information System (INIS)

    Arshak, K.; Gaidan, I.

    2005-01-01

    Zinc and iron oxide thick film gas sensors were fabricated using screen-printing technology on glass substrates that had silver interdigitated electrodes. The sensor was used to detect methanol, ethanol and propanol with a concentration range of 0-8000 ppm. Using the formula to calculate a change in resistance, ΔR = R gas - R air, resistance was seen to increase linearly alongside increasing concentrations of the gas vapours. The sensor showed the highest sensitivity to propanol followed by ethanol and methanol when the operating temperature was 25 deg. C. The sensitivities (slope of graphs) of methanol, ethanol and propanol changed from 0.07, 0.5, and 3.54 to 0.075, 0.115, and 0.5 Ω/ppm when the operating temperature was increased from 25 to 50 deg. C. The response/recovery times of the sensor for 4000 ppm at room temperature were, 10/10, 15/20 and 40/70 s for methanol, ethanol and propanol, respectively. X-ray diffraction (XRD) was used to examine the final composition of the film, while scanning electron microscopy (SEM) was used to examine the final composition of grain size. The final composition has two phases: ZnO and ZnFe 2 O 4

  7. Low-Power, Chip-Scale, Carbon Dioxide Gas Sensors for Spacesuit Monitoring

    Science.gov (United States)

    Rani, Asha; Shi, Chen; Thomson, Brian; Debnath, Ratan; Wen, Boamei; Motayed, Abhishek; Chullen, Cinda

    2018-01-01

    N5 Sensors, Inc. through a Small Business Technology Transfer (STTR) contract award has been developing ultra-small, low-power carbon dioxide (CO2) gas sensors, suited for monitoring CO2 levels inside NASA spacesuits. Due to the unique environmental conditions within the spacesuits, such as high humidity, large temperature swings, and operating pressure swings, measurement of key gases relevant to astronaut's safety and health such as(CO2), is quite challenging. Conventional non-dispersive infrared absorption based CO2 sensors present challenges inside the spacesuits due to size, weight, and power constraints, along with the ability to sense CO2 in a high humidity environment. Unique chip-scale, nanoengineered chemiresistive gas-sensing architecture has been developed for this application, which can be operated in a typical space-suite environmental conditions. Unique design combining the selective adsorption properties of the nanophotocatalytic clusters of metal-oxides and metals, provides selective detection of CO2 in high relative humidity conditions. All electronic design provides a compact and low-power solution, which can be implemented for multipoint detection of CO2 inside the spacesuits. This paper will describe the sensor architecture, development of new photocatalytic material for better sensor response, and advanced structure for better sensitivity and shorter response times.

  8. Self Powered Non-Dispersive Infra-Red CO{sub 2} Gas Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, D R; MacGregor, C, E-mail: des@gassensing.co.uk [Gas Sensing Solutions Ltd, 60 Grayshill Road, Westfield North Courtyard, Glasgow G68 9HQ (United Kingdom)

    2011-08-17

    This paper describes a non-dispersive infra-red CO{sub 2} gas sensor, incorporating a mid-infra-red solid state light source/ detector combination, tuned to match the spectral absorption characteristic of CO{sub 2} gas. Injection moulded optics provide low cost manufacture. Continuous operation power consumption is < 3.5mW and pulsed mode with energy per measurement < 6mJ. Self powered operation using a solar cell is demonstrated together with wireless capability. Performance of two path length variants (20mm and 70mm) is described. The sensor shows invariant temperature output characteristic from -25 to 50 deg. C. Accuracy level is typically {+-}3% of reading.

  9. Sustained operation of sensor nodes with energy harvesters and supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Renner, Bernd-Christian

    2013-06-01

    Sensor nodes powered by energy harvesters and supercapacitors open the door to unlimited and uninterrupted operation. This dissertation closes the persistent gap of system integration w.r.t. holistic online energy assessment, develops a new concept for harvest forecasting while assessing the behavior and quality of known approaches, and proposes a novel load adaptation scheme to achieve sustained and uniform sensor node operation with low complexity and computational overhead. For this purpose, a prototype of an energy harvester with a supercapacitor for off-the-shelf sensor nodes is developed and used for practical evaluation.

  10. Nozzle-less Ultrasonic Spray Deposition for Flexible Ammonia and Ozone Gas Sensors

    Directory of Open Access Journals (Sweden)

    Mónica ACUAUTLA

    2016-06-01

    Full Text Available In the last years printing and flexible electronic is transforming the way we used electronic devices. Among these, special interest is given to the development of gas sensors for industrial and environmental applications. Nozzle-less ultrasonic spray deposition is a simple and precise technique, which offers good homogeneity and high quality of the sensitive thin film. In addition, it represents a potential fabrication process for flexible electronic with low cost production and low waste of material. In this paper, nanoparticles of zinc oxide were deposited by nozzle-less ultrasonic spray deposition on flexible substrate. The sensing properties towards reducing and oxidizing gases in function of the operational temperature are reported. The flexible platform consists in titanium/platinum interdigitated electrodes and a micro-heater device, both fabricated by lift-off and photolithography. The operating temperature of the sensor is also challenging in term of power consumption. It is allowing the reaction with the exposure gases. Most of the semiconducting metal oxide materials used for gas sensing applications require high temperatures above 250 °C. Flexible gas sensors fabricated in this work present good responses towards ammonia and ozone at 300 °C and 200 °C respectively, with fast response and recovery time in a wide range of gas concentration.

  11. A flexible, transparent and high-performance gas sensor based on layer-materials for wearable technology

    Science.gov (United States)

    Zheng, Zhaoqiang; Yao, Jiandong; Wang, Bing; Yang, Guowei

    2017-10-01

    Gas sensors play a vital role among a wide range of practical applications. Recently, propelled by the development of layered materials, gas sensors have gained much progress. However, the high operation temperature has restricted their further application. Herein, via a facile pulsed laser deposition (PLD) method, we demonstrate a flexible, transparent and high-performance gas sensor made of highly-crystalline indium selenide (In2Se3) film. Under UV-vis-NIR light or even solar energy activation, the constructed gas sensors exhibit superior properties for detecting acetylene (C2H2) gas at room temperature. We attribute these properties to the photo-induced charger transfer mechanism upon C2H2 molecule adsorption. Moreover, no apparent degradation in the device properties is observed even after 100 bending cycles. In addition, we can also fabricate this device on rigid substrates, which is also capable to detect gas molecules at room temperature. These results unambiguously distinguish In2Se3 as a new candidate for future application in monitoring C2H2 gas at room temperature and open up new opportunities for developing next generation full-spectrum activated gas sensors.

  12. Laser deposition of sulfonated phthalocyanines for gas sensors

    Czech Academy of Sciences Publication Activity Database

    Fitl, Přemysl; Vrňata, M.; Kopecký, D.; Vlček, J.; Škodová, J.; Bulíř, Jiří; Novotný, Michal; Pokorný, Petr

    2014-01-01

    Roč. 302, MAY (2014), s. 37-41 ISSN 0169-4332. [European-Materials-Research-Society Symposium on Laser Material Interactions for Micro- and Nano- Applications /5./. Strasbourg, 27.05.2013-31.05.2013] R&D Projects: GA ČR(CZ) GAP108/11/1298 Institutional support: RVO:68378271 Keywords : Matrix Assisted Pulsed Laser Evaporation * substituted phthalocyanine s * gas sensors * impedance measurements Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.711, year: 2014

  13. Optical Breath Gas Sensor for Extravehicular Activity Application

    Science.gov (United States)

    Wood, William R.; Casias, Miguel E.; Vakhtin, Andrei B.; Pilgrim, Jeffrey S.; Chullen, Cinda; Falconi, Eric A.; McMillin, Summer

    2013-01-01

    The function of the infrared gas transducer used during extravehicular activity in the current space suit is to measure and report the concentration of carbon dioxide (CO2) in the ventilation loop. The next generation portable life support system (PLSS) requires next generation CO2 sensing technology with performance beyond that presently in use on the Space Shuttle/International Space Station extravehicular mobility unit (EMU). Accommodation within space suits demands that optical sensors meet stringent size, weight, and power requirements. A laser diode spectrometer based on wavelength modulation spectroscopy is being developed for this purpose by Vista Photonics, Inc. Two prototype devices were delivered to NASA Johnson Space Center (JSC) in September 2011. The sensors incorporate a laser diode-based CO2 channel that also includes an incidental water vapor (humidity) measurement and a separate oxygen channel using a vertical cavity surface emitting laser. Both prototypes are controlled digitally with a field-programmable gate array/microcontroller architecture. The present development extends and upgrades the earlier hardware to the Advanced PLSS 2.0 test article being constructed and tested at JSC. Various improvements to the electronics and gas sampling are being advanced by this project. The combination of low power electronics with the performance of a long wavelength laser spectrometer enables multi-gas sensors with significantly increased performance over that presently offered in the EMU.

  14. Metal-modified and vertically aligned carbon nanotube sensors array for landfill gas monitoring applications.

    Science.gov (United States)

    Penza, M; Rossi, R; Alvisi, M; Serra, E

    2010-03-12

    demonstrates high sensitivity by providing minimal sub-ppm level detection, e.g., download up to 100 ppb NO(2), at the sensor temperature of 150 degrees C. The gas sensitivity of the CNT sensor array depends on operating temperature, showing a lower optimal temperature of maximum sensitivity for the metal-decorated CNT sensors compared to unmodified CNT sensors. Results indicate that the recovery mechanisms in the CNT chemiresistors can be altered by a rapid heating pulse from room temperature to about 110 degrees C. A comparison of the NO(2) gas sensitivity for the chemiresistors based on disorderly networked CNTs and vertically aligned CNTs is also reported. Cross-sensitivity towards relative humidity of the CNT sensors array is investigated. Finally, the sensing properties of the metal-decorated and vertically aligned CNT sensor arrays are promising to monitor gas events in the LFG for practical applications with low power consumption and moderate sensor temperature.

  15. The generalized heavy free gas thermalization operator

    International Nuclear Information System (INIS)

    Pitcher, H.H.W.

    1963-05-01

    This paper gives an introduction to the generalized heavy free gas (Horowitz) thermalization operator, which is a device for simplifying thermalization calculations. Analytical, experimental,and numerical methods for determining the energy-dependent function f in the operator are discussed. The dependence of f on the nature of the moderator, its temperature, and the absorption of the system are investigated, using a program FOCS which derives f's from DSN (multigroup) thermal spectra; it is found that for most purposes the dependence on absorption is negligible except when Pu240 is present. The sensitivity of calculated spectra and reaction rate to changes in f is considered. f is given for graphite at 300 and 600 deg. K. (author)

  16. Operation of high rate microstrip gas chambers

    CERN Document Server

    Barr, A J; Bouclier, Roger; Capéans-Garrido, M; Dominik, Wojciech; Manzin, G; Million, Gilbert; Hoch, M; Ropelewski, Leszek; Sauli, Fabio; Sharma, A

    1996-01-01

    We describe recent measurements carried out in well controlled and reproducible conditions to help understanding the factors affecting the short and long term behaviour of Microstrip Gas Chambers. Special care has been taken concerning the gas purity and choice of materials used in the system and for the detectors construction. Detectors built on glasses with surface resistivity in the range $10^{13}-10^{15} \\Omega/\\Box$ have shown satisfactory performance as they do not show charging-up process at high rate and stand the large doses required for the future high luminosity experiments (~10 mC·cm-1·yr-1). Concerning the lifetime measurements, it has been observed that chambers manufactured on high-resistivity glass are far more susceptible of suffering ageing than detectors made on low resistivity, electron-conducting supports, independently of the metal used for the artwork (chromium or gold) at least in clean gas conditions. The successfully operation in the laboratory of detectors manufactured on diamond-...

  17. Pollution Monitoring System Using Gas Sensor based on Wireless Sensor Network

    Directory of Open Access Journals (Sweden)

    M. Udin Harun Al Rasyid

    2016-01-01

    Full Text Available Carbon monoxide (CO and carbon dioxide (CO2 gases are classified as colorless and odorless gas so we need special tools to monitor their concentration in the air. Concentration of air pollution of CO and CO2 that are high in the air will give serious effects for health status. CO is a poisonous gas that damages the circulation of oxygen in the blood when inhaled, while CO2 is one of the gases that causes global warming. In this paper, we developed an integrated pollution monitoring (IPOM system to monitor the concentration of air pollution. This research implemented three sensor nodes (end-device which each node contains CO and CO2 sensors on the gas sensors board to perform sensing from the environment. Furthermore, the data taken from the environment by the sensor will be sent to the meshlium gateway using IEEE 802.15.4 Zigbee communications and processed by the gateway in order to be sent to the computer server. The data is stored in meshlium gateway using MySQL database as a backup, and it will be synchronized to the MySQL database in the computer server. We provide services for public to access the information in database server through a desktop and website application.

  18. Nanocrystalline SnO2:F Thin Films for Liquid Petroleum Gas Sensors

    Directory of Open Access Journals (Sweden)

    Sutichai Chaisitsak

    2011-07-01

    Full Text Available This paper reports the improvement in the sensing performance of nanocrystalline SnO2-based liquid petroleum gas (LPG sensors by doping with fluorine (F. Un-doped and F-doped tin oxide films were prepared on glass substrates by the dip-coating technique using a layer-by-layer deposition cycle (alternating between dip-coating a thin layer followed by a drying in air after each new layer. The results showed that this technique is superior to the conventional technique for both improving the film thickness uniformity and film transparency. The effect of F concentration on the structural, surface morphological and LPG sensing properties of the SnO2 films was investigated. Atomic Force Microscopy (AFM and X-ray diffraction pattern measurements showed that the obtained thin films are nanocrystalline SnO2 with nanoscale-textured surfaces. Gas sensing characteristics (sensor response and response/recovery time of the SnO2:F sensors based on a planar interdigital structure were investigated at different operating temperatures and at different LPG concentrations. The addition of fluorine to SnO2 was found to be advantageous for efficient detection of LPG gases, e.g., F-doped sensors are more stable at a low operating temperature (300 °C with higher sensor response and faster response/recovery time, compared to un-doped sensor materials. The sensors based on SnO2:F films could detect LPG even at a low level of 25% LEL, showing the possibility of using this transparent material for LPG leak detection.

  19. Hydrogen Sensors Boost Hybrids; Today's Models Losing Gas?

    Science.gov (United States)

    2005-01-01

    Advanced chemical sensors are used in aeronautic and space applications to provide safety monitoring, emission monitoring, and fire detection. In order to fully do their jobs, these sensors must be able to operate in a range of environments. NASA has developed sensor technologies addressing these needs with the intent of improving safety, optimizing combustion efficiencies, and controlling emissions. On the ground, the chemical sensors were developed by NASA engineers to detect potential hydrogen leaks during Space Shuttle launch operations. The Space Shuttle uses a combination of hydrogen and oxygen as fuel for its main engines. Liquid hydrogen is pumped to the external tank from a storage tank located several hundred feet away. Any hydrogen leak could potentially result in a hydrogen fire, which is invisible to the naked eye. It is important to detect the presence of a hydrogen fire in order to prevent a major accident. In the air, the same hydrogen-leak dangers are present. Stress and temperature changes can cause tiny cracks or holes to form in the tubes that line the Space Shuttle s main engine nozzle. Such defects could allow the hydrogen that is pumped through the nozzle during firing to escape. Responding to the challenges associated with pinpointing hydrogen leaks, NASA endeavored to improve propellant leak-detection capabilities during assembly, pre-launch operations, and flight. The objective was to reduce the operational cost of assembling and maintaining hydrogen delivery systems with automated detection systems. In particular, efforts have been focused on developing an automated hydrogen leak-detection system using multiple, networked hydrogen sensors that are operable in harsh conditions.

  20. Terahertz gas sensor based on absorption-induced transparency

    Directory of Open Access Journals (Sweden)

    Rodrigo Sergio G.

    2016-01-01

    Full Text Available A system for the detection of spectral signatures of gases at the Terahertz regime is presented. The system consists in an initially opaque holey metal film whereby the introduction of a gas provokes the appearance of spectral features in transmission and reflection, due to the phenomenom of absorption-induced transparency (AIT. The peaks in transmission and dips in reflection observed in AIT occur close to the absorption energies of the molecules, hence its name. The presence of the gas would be thus revealed as a strong drop in reflectivity measurements at one (or several of the gas absorption resonances. As a proof of principle, we theoretically demonstrate how the AIT-based sensor would serve to detect tiny amounts of hydrocyanic acid.

  1. Conductometric gas sensors based on metal oxides modified with gold nanoparticles: a review

    International Nuclear Information System (INIS)

    Korotcenkov, Ghenadii; Cho, Beong K.; Brinzari, Vladimir

    2016-01-01

    This review (with 170 refs.) discusses approaches towards surface functionalizaton of metal oxides by gold nanoparticles, and the application of the resulting nanomaterials in resistive gas sensors. The articles is subdivided into sections on (a) methods for modification of metal oxides with gold nanoparticles; (b) the response of gold nanoparticle-modified metal oxide sensors to gaseous species, (c) a discussion of the limitations of such sensors, and (d) a discussion on future tasks and trends along with an outlook. It is shown that, in order to achieve significant improvements in sensor parameters, it is necessary to warrant a good control the size and density of gold nanoparticles on the surface of metal oxide crystallites, the state of gold in the cluster, and the properties of the metal oxide support. Current challenges include an improved reproducibility of sensor preparation, better long-term stabilities, and a better resistance to sintering and poisoning of gold clusters during operation. Additional research focused on better understanding the role of gold clusters and nanoparticles in gas-sensing effects is also required. (author)

  2. Metal oxide-based gas sensor and microwave broad-band measurements: an innovative approach to gas sensing

    International Nuclear Information System (INIS)

    Jouhannaud, J; Rossignol, J; Stuerga, D

    2007-01-01

    We outline the development of a gas sensor using microwave technology (0.3 MHz to 3 GHz). The sensor is a coaxial structure into which is introduced a sensitive material. An electromagnetic field (microwave), sent out through the sensor by a vectorial network analyzer, solicits the sensitive material exposed to a gas. The observed variation in the sensor response is due to the variation in the adsorption of this gas. SrTiO 3 , demonstrated to be the highly sensitive to water vapour, is exposed to different gases (saturated vapour of water, ethanol and toluene). The response of the sensor is quantitative and typical for each gas. This method of measurement leads to the development of an alternative to the current gas sensor

  3. Infrastructure-Based Sensors Augmenting Efficient Autonomous Vehicle Operations: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Jun, Myungsoo [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Markel, Anthony J [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-11-15

    Autonomous vehicle technology development relies on an on-board network of fused sensor inputs for safe and efficient operation. The fused sensors offer multiple perspectives of similar information aiding in system decision robustness. The high cost of full systems on individual vehicles is seen as a potential barrier to broad adoption and achieving system energy efficiency gains. Since traffic in autonomous vehicle technology development relies on an on-board network of fused sensor inputs for safe and efficient operation. The fused sensors offer multiple perspectives of similar information aiding in system decision robustness. The high cost of full systems on individual vehicles is seen as a potential barrier to broad adoption and achieving system energy efficiency gains.

  4. Mobile Sensor System AGaMon for Breath Control: Numerical Signal Analysis of Ternary Gas Mixtures and First Field Tests

    Directory of Open Access Journals (Sweden)

    Rolf Seifert

    2018-01-01

    Full Text Available An innovative mobile sensor system for breath control in the exhaled air is introduced. In this paper, the application of alcohol control in the exhaled air is considered. This sensor system operates semiconducting gas sensor elements with respect to the application in a thermo-cyclic operation mode. This operation mode leads to so-called conductance-over-time-profiles (CTPs, which are fingerprints of the gas mixture under consideration and can be used for substance identification and concentration determination. Especially for the alcohol control in the exhaled air, ethanol is the leading gas component to be investigated. But, there are also other interfering gas components in the exhaled air, like H2 and acetone, which may influence the measurement results. Therefore, a ternary ethanol-H2-acetone gas mixture was investigated. The establishing of the mathematical calibration model and the data analysis was performed with a newly developed innovative calibration and evaluation procedure called ProSens 3.0. The analysis of ternary ethanol-H2-acetone gas samples with ProSens 3.0 shows a very good substance identification performance and a very good concentration determination of the leading ethanol component. The relative analysis errors for the leading component ethanol were in all considered samples less than 9 %. First field test performed with the sensor system AGaMon shows very promising results.

  5. Structural Stability and Performance of Noble Metal-Free SnO2-Based Gas Sensors

    Directory of Open Access Journals (Sweden)

    Antonio Tricoli

    2012-05-01

    Full Text Available The structural stability of pure SnO2 nanoparticles and highly sensitive SnO2-SiO2 nanocomposites (0–15 SiO2 wt% has been investigated for conditions relevant to their utilization as chemoresistive gas sensors. Thermal stabilization by SiO2 co-synthesis has been investigated at up to 600 °C determining regimes of crystal size stability as a function of SiO2-content. For operation up to 400 °C, thermally stable crystal sizes of ca. 24 and 11 nm were identified for SnO2 nanoparticles and 1.4 wt% SnO2-SiO2 nanocomposites, respectively. The effect of crystal growth during operation (TO = 320 °C on the sensor response to ethanol has been reported, revealing possible long-term destabilization mechanisms. In particular, crystal growth and sintering-neck formation were discussed with respect to their potential to change the sensor response and calibration. Furthermore, the effect of SiO2 cosynthesis on the cross-sensitivity to humidity of these noble metal-free SnO2-based gas sensors was assessed.

  6. Effect of Indium Doping on the Sensitivity of SnO2 Gas Sensor

    International Nuclear Information System (INIS)

    Suharni; Sayono

    2009-01-01

    The dependence of sensitivity f SnO 2 gas sensors on indium concentration has been studied. Undoped and indium-doped SnO 2 gas sensors have been prepared by DC sputtering technique with following parameters i.e : electrode voltage of 3 kV, current 20 mA, vacuum pressure 1.8 × 10 -1 torr, deposition time 60 minutes and temperature of 200℃. The effect of weight variations of indium in order of 0.0370; 0.0485 and 0.0702 grams into SnO 2 thin film gas sensor for optimum result were investigated. The measurement of resistance, sensitivity and response time for various temperature for detecting of carbon monoxide (CO), Ammonia (NH 3 ) and acetone (CH 3 COCH 3 ) gas for indium doped has been done. From the analysis result shows that for indium doped 0.0702 g on the SnO 2 the resistance can be decreased from 832.0 kΩ to 3.9 kΩ and the operating temperature from 200℃ to 90℃ and improving the sensitivity from 15.92% to 40.09% and a response time from 30 seconds to 10 seconds for CO. (author)

  7. Sensors of the gas CO in thin film of SnO2:Cu

    International Nuclear Information System (INIS)

    Tirado G, S.; Sanchez Z, F. E.

    2011-10-01

    Thin films of SnO 2 :Cu with different thickness, were deposited on soda-lime glass substrates and prepared by the Sol-gel process and repeated immersion. The sensor properties of these films to the gas CO for the range of 0-200 ppm in the gas concentration and operating to temperatures of 23, 100, 200, and 300 C were studied. Prepared films of pure SnO 2 were modified superficially with 1, 3, 5 and 10 layers of the catalyst Cu (SnO 2 :Cu) with the purpose of studying the effect on the sensor capacity of the gas CO by part of the films SnO 2 :Cu. Using the changes in the electric properties of the films with the incorporation of the different copper layers and experimental conditions, the sensor modifications of the gas CO were evaluated. To complete this study, was realized a characterization of the superficial morphology of the films by scanning electron microscopy and atomic force microscopy, equally was studied their structure and their electric and optical properties. (Author)

  8. Novel Modified Optical Fibers for High Temperature In-Situ Miniaturized Gas Sensors in Advanced Fossil Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Pickrell, Gary [Virginia Polytechnic Institute & State University, Blacksburg, VA (United States); Scott, Brian [Virginia Polytechnic Institute & State University, Blacksburg, VA (United States)

    2014-06-30

    This report covers the technical progress on the program “Novel Modified Optical Fibers for High Temperature In-Situ Miniaturized Gas Sensors in Advanced Fossil Energy Systems”, funded by the National Energy Technology Laboratory of the U.S. Department of Energy, and performed by the Materials Science & Engineering and Electrical & Computer Engineering Departments at Virginia Tech, and summarizes technical progress from July 1st, 2005 –June 30th, 2014. The objective of this program was to develop novel fiber materials for high temperature gas sensors based on evanescent wave absorption in optical fibers. This project focused on two primary areas: the study of a sapphire photonic crystal fiber (SPCF) for operation at high temperature and long wavelengths, and a porous glass based fiber optic sensor for gas detection. The sapphire component of the project focused on the development of a sapphire photonic crystal fiber, modeling of the new structures, fabrication of the optimal structure, development of a long wavelength interrogation system, testing of the optical properties, and gas and temperature testing of the final sensor. The fabrication of the 6 rod SPCF gap bundle (diameter of 70μm) with a hollow core was successfully constructed with lead-in and lead-out 50μm diameter fiber along with transmission and gas detection testing. Testing of the sapphire photonic crystal fiber sensor capabilities with the developed long wavelength optical system showed the ability to detect CO2 at or below 1000ppm at temperatures up to 1000°C. Work on the porous glass sensor focused on the development of a porous clad solid core optical fiber, a hollow core waveguide, gas detection capabilities at room and high temperature, simultaneous gas species detection, suitable joining technologies for the lead-in and lead-out fibers and the porous sensor, sensor system sensitivity improvement, signal processing improvement, relationship between pore structure and fiber

  9. Safety in Liquefied Natural Gas (LNG) Operations

    Energy Technology Data Exchange (ETDEWEB)

    Buhrow, C. [Technische Univ. Bergakademie, Freiberg (Germany). Lehrstuhl Bergbau/Tiefbau; Niemann-Delius, C.; Okafor, E. [Technische Hochschule Aachen (Germany). Lehrstuhl und Inst. fuer Bergbaukunde 3

    2005-07-01

    Germany needs an LNG receiving terminal to import LNG and supplement expected future gas supply shortages. Enormous economic benefits also abound if Germany is to install an LNG receiving terminal. Jobs will be created for several hundred people. New tax revenues will be generated for state and local governments and this will further enhance the economic competitiveness of Germany. Additionally, it will provide Germany with a reliable source of clean-burning energy. Any proposed LNG receiving terminal should incorporate safety right from the start. These safety requirements will: ensure that certain public land uses, people, and structures outside the LNG facility boundaries are protected in the event of LNG fire, prevent vapour clouds associated with an LNG spill from reaching a property line that can be built upon, prevent severe burns resulting from thermal radiation, specify requirements for design, construction and use of LNG facilities and other equipments, and promote safe, secure and reliable LNG operations. The German future LNG business will not be complete without the evolution of both local and international standards that can apply to LNG operations. Currently existing European standards also appear inadequate. With an OHSAS 18001 management system integrated with other existing standards we can better control our LNG occupational health and safety risks, and improve performance in the process. Additionally, an OHSAS 18001 System will help future German LNG contractors and operators safeguard their most important assets - their employees. (orig.)

  10. Production optimization of remotely operated gas wells

    Energy Technology Data Exchange (ETDEWEB)

    Juell, Aleksander

    2012-07-01

    From the introduction: The Remote Operations in Oklahoma Intended for Education (ROOKIE) project is a remote field laboratory constructed as a part of this research project. ROOKIE was initiated to provide data in research on production optimization of low productivity gas wells. In addition to this, ROOKIE is used as a teaching tool. Much of the remote operations technology used in the ROOKIE project has been used by the industry for several decades. The first use of remote data acquisition in Oklahoma was in 1989, as described by Luppens [7]. Even though this, for the most part, is old technology, the ROOKIE project is the first remote operations project set up with research and teaching as the main focus. This chapter will discuss the process of establishing the remote field laboratory and the data storage facilities. Results from the project will also be discussed. All testing, instrumentation installation, and modifications to the wells discussed in this chapter was performed by the author. The communication system between the well and NTNU, and the storage database was installed and configured by the author.(Author)

  11. Nanocrystalline Pd:NiFe2O4 thin films: A selective ethanol gas sensor

    Science.gov (United States)

    Rao, Pratibha; Godbole, R. V.; Bhagwat, Sunita

    2016-10-01

    In this work, Pd:NiFe2O4 thin films were investigated for the detection of reducing gases. These films were fabricated using spray pyrolysis technique and characterized using X-ray diffraction (XRD) to confirm the crystal structure. The surface morphology was studied using scanning electron microscopy (SEM). Magnetization measurements were carried out using SQUID VSM, which shows ferrimagnetic behavior of the samples. These thin film sensors were tested against methanol, ethanol, hydrogen sulfide and liquid petroleum gas, where they were found to be more selective to ethanol. The fabricated thin film sensors exhibited linear response signal for all the gases with concentrations up to 5 w/o Pd. Reduction in optimum operating temperature and enhancement in response was also observed. Pd:NiFe2O4 thin films exhibited faster response and recovery characteristic. These sensors have potential for industrial applications because of their long-term stability, low power requirement and low production cost.

  12. Evaluation of semiconductor gas sensor system for ethanol determination during fermentation processes

    Energy Technology Data Exchange (ETDEWEB)

    Picque, D; Corrieu, G

    1988-10-01

    Using commercial gas sensitive semi-conductors, an ethanol sensor has been constructed which operates by direct immersion in fermentation media. The calibration range of 0.1 to 10 or 13 % depending on the component. However, they are very often subjected to considerable drift (in the same case up to 10 %/h of the measured value). The electrical resistance of component may vary by a factor of 1 to 5 for a well-defined ethanol concentration. The effects of temperature changes in fermentation media are easily compensated. Other volatile compounds (methanol, ammonia,...) substantially affect component responses. Thus, all work on sensors requires careful calibration. Wine fermentation processes can be monitored satisfactorily, providing the sensor is recalibrated about every six hours.

  13. Nanostructure Engineered Chemical Sensors for Hazardous Gas and Vapor Detection

    Science.gov (United States)

    Li, Jing; Lu, Yijiang

    2005-01-01

    A nanosensor technology has been developed using nanostructures, such as single walled carbon nanotubes (SWNTs) and metal oxides nanowires or nanobelts, on a pair of interdigitated electrodes (IDE) processed with a silicon based microfabrication and micromachining technique. The IDE fingers were fabricated using thin film metallization techniques. Both in-situ growth of nanostructure materials and casting of the nanostructure dispersions were used to make chemical sensing devices. These sensors have been exposed to hazardous gases and vapors, such as acetone, benzene, chlorine, and ammonia in the concentration range of ppm to ppb at room temperature. The electronic molecular sensing in our sensor platform can be understood by electron modulation between the nanostructure engineered device and gas molecules. As a result of the electron modulation, the conductance of nanodevice will change. Due to the large surface area, low surface energy barrier and high thermal and mechanical stability, nanostructured chemical sensors potentially can offer higher sensitivity, lower power consumption and better robustness than the state-of-the-art systems, which make them more attractive for defense and space applications. Combined with MEMS technology, light weight and compact size sensors can be made in wafer scale with low cost.

  14. Fabrication and characterization of nano-gas sensor arrays

    International Nuclear Information System (INIS)

    Hassan, H. S.; Kashyout, A. B.; Morsi, I.; Nasser, A. A. A.; Raafat, A.

    2015-01-01

    A novel structures of Nanomaterials gas sensors array constructed using ZnO, and ZnO doped with Al via sol-gel technique. Two structure arrays are developed; the first one is a double sensor array based on doping with percentages of 1% and 5%. The second is a quadrature sensor array based on several doping ratios concentrations (0%, 1%, 5% and 10%). The morphological structures of prepared ZnO were revealed using scanning electron microscope (SEM). X-ray diffraction (XRD) patterns reveal a highly crystallized wurtzite structure and used for identifying phase structure and chemical state of both ZnO and ZnO doped with Al under different preparation conditions and different doping ratios. Chemical composition of Al-doped ZnO nanopowders was performed using energy dispersive x-ray (EDS) analysis. The electrical characteristics of the sensor are determined by measuring the two terminal sensor’s output resistance for O 2 , H 2 and CO 2 gases as a function of temperature

  15. Fabrication and characterization of nano-gas sensor arrays

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, H. S., E-mail: hassan.shokry@gmail.com; Kashyout, A. B., E-mail: hady8@yahoo.com [Electronic Materials Researches Department, Advanced Technology and New Materials Research Institute, City of Scientific Researches and technological applications, New Borg El-Arab City, Alexandria (Egypt); Morsi, I., E-mail: drimanmorsi@yahoo.com; Nasser, A. A. A., E-mail: menem-1954@yahoo.com; Raafat, A., E-mail: abrs-218@yahoo.com [Arab Academy for Science and Technology, and Maritime Transport, Alexandria, 21936 (Egypt)

    2015-03-30

    A novel structures of Nanomaterials gas sensors array constructed using ZnO, and ZnO doped with Al via sol-gel technique. Two structure arrays are developed; the first one is a double sensor array based on doping with percentages of 1% and 5%. The second is a quadrature sensor array based on several doping ratios concentrations (0%, 1%, 5% and 10%). The morphological structures of prepared ZnO were revealed using scanning electron microscope (SEM). X-ray diffraction (XRD) patterns reveal a highly crystallized wurtzite structure and used for identifying phase structure and chemical state of both ZnO and ZnO doped with Al under different preparation conditions and different doping ratios. Chemical composition of Al-doped ZnO nanopowders was performed using energy dispersive x-ray (EDS) analysis. The electrical characteristics of the sensor are determined by measuring the two terminal sensor’s output resistance for O{sub 2}, H{sub 2} and CO{sub 2} gases as a function of temperature.

  16. 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.

  17. Field-effect gas sensors and their application in exhaust treatment systems; Feldeffekt-Gassensoren und ihre Anwendung in Abgasnachbehandlungssystemen

    Energy Technology Data Exchange (ETDEWEB)

    Schalwig, Jan

    2002-07-01

    Tightening environmental constraints on exhaust gas emissions of gasoline and Diesel engines led to a growing interest in new and highly sophisticated gas sensors. Such sensors will be required in future exhaust gas aftertreatment systems for the selective real time detection of pollutants such as nitric oxides, hydrocarbons and carbon monoxide. Restrictions on cost and device dimensions imposed by the automobile industry make semiconductor gas sensors promising candidates for the realization of cheap and small-size sensor devices. This work deals with semiconductor field effect devices with catalytically active platinum (Pt) electrodes and potential applications of such devices in automotive exhaust gas aftertreatment systems. To allow for continuous operation at high temperatures, silicon carbide (SiC) and group III-nitrides such as GaN and AlGaN were used as semiconductor materials. Different devices have been realized with such materials: SiC based MOS capacitors (MOSiC), GaN Schottky diodes and GaN/AlGaN high electron mobility transistors (HEMT). The principle feasibility of SiC and GaN based field effect gas sensors for automotive applications was tested under laboratory conditions using synthetic gas mixtures. Exhaust gas components such as carbon monoxide (CO), nitric oxides (NO and NO{sub 2}), various saturated and unsaturated hydro-carbons as well as water vapor, oxygen (O{sub 2}) and hydrogen (H{sub 2}) were used as test gases in appropriate concentrations with the sensor devices being operated in a range of temperatures extending from room temperature up to 600{sup o}C. (orig.)

  18. Military Operational Research: the Sensor Coverage Problem

    NARCIS (Netherlands)

    Barros, A.I.; Koopmans, J.

    1999-01-01

    Military Operations Research is a field that has been growing since the Second World War, and in particular in the last decades. Within this vast area, Air Defence, the protection of the air space against an airborne threat, has become a hot topic. ln order to successfully protect a given zone

  19. Operating systems and network protocols for wireless sensor networks.

    Science.gov (United States)

    Dutta, Prabal; Dunkels, Adam

    2012-01-13

    Sensor network protocols exist to satisfy the communication needs of diverse applications, including data collection, event detection, target tracking and control. Network protocols to enable these services are constrained by the extreme resource scarcity of sensor nodes-including energy, computing, communications and storage-which must be carefully managed and multiplexed by the operating system. These challenges have led to new protocols and operating systems that are efficient in their energy consumption, careful in their computational needs and miserly in their memory footprints, all while discovering neighbours, forming networks, delivering data and correcting failures.

  20. Novel bacterial gas sensor proteins with transition metal-containing prosthetic groups as active sites.

    Science.gov (United States)

    Aono, Shigetoshi

    2012-04-01

    Gas molecules function as signaling molecules in many biological regulatory systems responsible for transcription, chemotaxis, and other complex physiological processes. Gas sensor proteins play a crucial role in regulating such biological systems in response to gas molecules. New sensor proteins that sense oxygen or nitric oxide have recently been found, and they have been characterized by X-ray crystallographic and/or spectroscopic analysis. It has become clear that the interaction between a prosthetic group and gas molecules triggers dynamic structural changes in the protein backbone when a gas sensor protein senses gas molecules. Gas sensor proteins employ novel mechanisms to trigger conformational changes in the presence of a gas. In gas sensor proteins that have iron-sulfur clusters as active sites, the iron-sulfur clusters undergo structural changes, which trigger a conformational change. Heme-based gas sensor proteins reconstruct hydrogen-bonding networks around the heme and heme-bound ligand. Gas sensor proteins have two functional states, on and off, which are active and inactive, respectively, for subsequent signal transduction in response to their physiological effector molecules. To fully understand the structure-function relationships of gas sensor proteins, it is vital to perform X-ray crystal structure analyses of full-length proteins in both the on and off states.

  1. Karakterisasi Sensor Gas Lpg (Liquefied Petroleum Gas) Dari Bahan Komposit Semikonduktor Tio2(cuo)

    OpenAIRE

    Dewi, Ratna Sari; -, Elvaswer

    2015-01-01

    The Liquefied Petroleum Gas (LPG's) sensor in the form of composite has been characterized. The steps of manufacturing processes are the mixing of materials, calcinations at 500ºC for 4 hours, blended, compacted and sintered at 700ºC for 4 hours. The sensor was tested at room temperature through current (I)-voltage (V) characteristics, sensitivity, and conductivity. Based on measurement I-V characteristic it's known that sample with 10% addition of CuO have sensitivity of 10 at 10 volt vol...

  2. Analisis Pengaruh Konsentrasi Gas LPG Menggunakan Sensor TGS 2610 Berbasis Mikrokontroler AVR ATMega8535

    OpenAIRE

    Nurhalimah

    2011-01-01

    Telah dilakukan analisis kuantitatif gas dalam LPG. Penelitian ini dilakukan untuk mengukur konsentrasi gas LPG terhadap sensor. Metoda yang digunakan untuk mengukur konsentrasi gas LPG yaitu sensor gas semikonduktor jenis TGS 2610 keluaran Figaro yang digunakan untuk mendeteksi keberadaan gas. Sementara yang menjadi pusat pengendalian dari seluruh alat yang dirancang digunakan mikrokontroler AVR ATMega8535. Selain itu sistem yang dirancang dilengkapi LCD sebagai tampilan nilai konsentrasi ga...

  3. Fabrication of a P3HT-ZnO Nanowires Gas Sensor Detecting Ammonia Gas

    Directory of Open Access Journals (Sweden)

    Chin-Guo Kuo

    2017-12-01

    Full Text Available In this study, an organic-inorganic semiconductor gas sensor was fabricated to detect ammonia gas. An inorganic semiconductor was a zinc oxide (ZnO nanowire array produced by atomic layer deposition (ALD while an organic material was a p-type semiconductor, poly(3-hexylthiophene (P3HT. P3HT was suitable for the gas sensing application due to its high hole mobility, good stability, and good electrical conductivity. In this work, P3HT was coated on the zinc oxide nanowires by the spin coating to form an organic-inorganic heterogeneous interface of the gas sensor for detecting ammonia gas. The thicknesses of the P3HT were around 462 nm, 397 nm, and 277 nm when the speeds of the spin coating were 4000 rpm, 5000 rpm, and 6000 rpm, respectively. The electrical properties and sensing characteristics of the gas sensing device at room temperature were evaluated by Hall effect measurement and the sensitivity of detecting ammonia gas. The results of Hall effect measurement for the P3HT-ZnO nanowires semiconductor with 462 nm P3HT film showed that the carrier concentration and the mobility were 2.7 × 1019 cm−3 and 24.7 cm2∙V−1∙s−1 respectively. The gas sensing device prepared by the P3HT-ZnO nanowires semiconductor had better sensitivity than the device composed of the ZnO film and P3HT film. Additionally, this gas sensing device could reach a maximum sensitivity around 11.58 per ppm.

  4. Limitations of potentiometric oxygen sensors operating at low oxygen levels

    DEFF Research Database (Denmark)

    Lund, Anders; Jacobsen, Torben; Hansen, Karin Vels

    2011-01-01

    The electrochemical processes that limit the range of oxygen partial pressures in which potentiometric oxygen sensors can be used, were analysed using a theoretical and an experimental approach. Electrochemical impedance spectroscopy was performed on porous Pt/yttria stabilised zirconia (YSZ......) electrodes between 10−6 and 0.2 bar and at temperatures between 500 and 950 °C. The flow of oxide ions and electron holes through a sensor cell, with a YSZ electrolyte, were calculated under similar conditions. The oxygen permeation of the sensor cell was insignificant at an oxygen partial pressure of 10......−6 bar for an inlet flow rate higher than 2 L h−1 between 600 and 800 °C. The polarisation resistance measured between 10−6 and 10−4 bar was found to be inversely proportional to the oxygen partial pressure, nearly temperature independent and inversely proportional to the inlet gas flow rate, which shows...

  5. Nanowire field-effect transistors for gas sensor applications

    Science.gov (United States)

    Constantinou, Marios

    Sensing BTEX (Benzene, Ethylbenzene, Toluene, Xylene) pollutants is of utmost importance to reduce health risk and ensure public safety. The lack of sensitivity and selectivity of the current gas sensors and the limited number of available technologies in the field of BTEX-sensing raises the demand for the development of high-performance gas sensors for BTEX applications. The scope of this thesis is the fabrication and characterisation of high-quality field-effect transistors (FETs), with functionalised silicon nanowires (SiNWs), for the selective sensing of benzene vs. other BTEX gases. This research addresses three main challenges in SiNW FET-sensor device development: i) controllable and reproducible assembly of high-quality SiNWs for FET sensor devices using the method of dielectrophoresis (DEP), ii) almost complete elimination of harmful hysteresis effect in the SiNW FET current-voltage characteristics induced by surface states using DMF solvent, iii) selective sensing of benzene with up to ppb range of sensitivity using calix[4]arene-derivatives. It is experimentally demonstrated that frequency-controlled DEP is a powerful tool for the selection and collection of semiconducting SiNWs with advanced electrical and morphological properties, from a poly-disperse as-synthesised NWs. The DEP assembly method also leads to a controllable and reproducible fabrication of high-quality NW-based FETs. The results highlight the superiority of DEP, performed at high signal frequencies (5-20 MHz) to selectively assemble only high-quality NWs which can respond to such high DEP frequencies. The SiNW FETs, with NWs collected at high DEP frequencies, have high mobility (≈50 cm2 V-1 s-1), low sub-threshold-swing (≈1.26 V/decade), high on-current (up to 3 mA) and high on/off ratio (106-107). The DEP NW selection is also demonstrated using an industrially scalable method, to allow establishing of NW response characteristics to different DEP frequencies in a very short time

  6. Rapid and selective detection of acetone using hierarchical ZnO gas sensor for hazardous odor markers application.

    Science.gov (United States)

    Jia, Qianqian; Ji, Huiming; Zhang, Ying; Chen, Yalu; Sun, Xiaohong; Jin, Zhengguo

    2014-07-15

    Hierarchical nanostructured ZnO dandelion-like spheres were synthesized via solvothermal reaction at 200°C for 4h. The products were pure hexagonal ZnO with large exposure of (002) polar facet. Side-heating gas sensor based on hierarchical ZnO spheres was prepared to evaluate the acetone gas sensing properties. The detection limit to acetone for the ZnO sensor is 0.25ppm. The response (Ra/Rg) toward 100ppm acetone was 33 operated at 230°C and the response time was as short as 3s. The sensor exhibited remarkable acetone selectivity with negligible response toward other hazardous gases and water vapor. The high proportion of electron depletion region and oxygen vacancies contributed to high gas response sensitivity. The hollow and porous structure of dandelion-like ZnO spheres facilitated the diffusion of gas molecules, leading to a rapid response speed. The largely exposed (002) polar facets could adsorb acetone gas molecules easily and efficiently, resulting in a rapid response speed and good selectivity of hierarchical ZnO spheres gas sensor at low operating temperature. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Gas-leak localization using distributed ultrasonic sensors

    Science.gov (United States)

    Huseynov, Javid; Baliga, Shankar; Dillencourt, Michael; Bic, Lubomir; Bagherzadeh, Nader

    2009-03-01

    We propose an ultrasonic gas leak localization system based on a distributed network of sensors. The system deploys highly sensitive miniature Micro-Electro-Mechanical Systems (MEMS) microphones and uses a suite of energy-decay (ED) and time-delay of arrival (TDOA) algorithms for localizing a source of a gas leak. Statistical tools such as the maximum likelihood (ML) and the least squares (LS) estimators are used for approximating the source location when closed-form solutions fail in the presence of ambient background nuisance and inherent electronic noise. The proposed localization algorithms were implemented and tested using a Java-based simulation platform connected to four or more distributed MEMS microphones observing a broadband nitrogen leak from an orifice. The performance of centralized and decentralized algorithms under ED and TDOA schemes is analyzed and compared in terms of communication overhead and accuracy in presence of additive white Gaussian noise (AWGN).

  8. Rapid and selective detection of acetone using hierarchical ZnO gas sensor for hazardous odor markers application

    International Nuclear Information System (INIS)

    Jia, Qianqian; Ji, Huiming; Zhang, Ying; Chen, Yalu; Sun, Xiaohong; Jin, Zhengguo

    2014-01-01

    Highlights: • ZnO spheres fabricated via solvothermal method are with (0 0 2) polar facet exposed. • Response time of ZnO sensor for detecting 100 ppm acetone is as short as 3 s. • R a /R g toward 100 ppm acetone is 33 when operated at 230 °C. • ZnO sensor exhibits good selectivity against other toxic gases and water vapor. • Porous structure and exposure of polar facet contribute to good sensing properties. - Abstract: Hierarchical nanostructured ZnO dandelion-like spheres were synthesized via solvothermal reaction at 200 °C for 4 h. The products were pure hexagonal ZnO with large exposure of (0 0 2) polar facet. Side-heating gas sensor based on hierarchical ZnO spheres was prepared to evaluate the acetone gas sensing properties. The detection limit to acetone for the ZnO sensor is 0.25 ppm. The response (R a /R g ) toward 100 ppm acetone was 33 operated at 230 °C and the response time was as short as 3 s. The sensor exhibited remarkable acetone selectivity with negligible response toward other hazardous gases and water vapor. The high proportion of electron depletion region and oxygen vacancies contributed to high gas response sensitivity. The hollow and porous structure of dandelion-like ZnO spheres facilitated the diffusion of gas molecules, leading to a rapid response speed. The largely exposed (0 0 2) polar facets could adsorb acetone gas molecules easily and efficiently, resulting in a rapid response speed and good selectivity of hierarchical ZnO spheres gas sensor at low operating temperature

  9. Low power gas sensor array on flexible acetate substrate

    Science.gov (United States)

    Benedict, Samatha; Basu, Palash Kumar; Bhat, Navakanta

    2017-07-01

    In this paper, we present a novel approach of fabricating a low-cost and low power gas sensor array on flexible acetate sheets for sensing CO, SO2, H2 and NO2 gases. The array has four sensor elements with an integrated microheater which can be individually controlled enabling the monitoring of four gases. The thermal properties of the microheater characterized by IR imaging are presented. The microheater with an active area of 15 µm  ×  5 µm reaches a temperature of 300 °C, consuming 2 mW power, the lowest reported on flexible substrates. A sensing electrode is patterned on top of the microheater, and a nanogap (100 nm) is created by an electromigration process. This nanogap is bridged by four sensing materials doped with platinum, deposited using a solution dispensing technique. The sensing material characterization is completed using energy dispersive x-ray analysis. The sensing characteristics of ZnO for CO, V2O5 for SO2, SnO2 for H2 and WO3 for NO2 gases are studied at different microheater voltages. The sensing characteristics of ZnO at different bending angles is also studied, which shows that the microheater and the sensing material are intact without any breaking upto a bending angle of 20°. The ZnO CO sensor shows sensitivity of 146.2% at 1 ppm with good selectivity.

  10. Solutions to operate transmission and distribution gas networks

    Directory of Open Access Journals (Sweden)

    Neacsu Sorin

    2017-01-01

    Full Text Available In order to respect the actual and future regulations, besides SCADA, there is a need for further modern operating solutions for the transmission and distribution gas network. The paper presents the newest operating principles and modern software solutions that represent a considerable help to operate the transmission and distribution gas networks.

  11. Future electro-optical sensors and processing in urban operations

    NARCIS (Netherlands)

    Grönwall, C.; Schwering, P.B.; Rantakokko, J.; Benoist, K.W.; Kemp, R.A.W.; Steinvall, O.; Letalick, D.; Björkert, S.

    2013-01-01

    In the electro-optical sensors and processing in urban operations (ESUO) study we pave the way for the European Defence Agency (EDA) group of Electro-Optics experts (IAP03) for a common understanding of the optimal distribution of processing functions between the different platforms. Combinations of

  12. Operations and Maintenance Manual, Atmospheric Contaminant Sensor, Revision B.

    Science.gov (United States)

    National Aeronautics and Space Administration, Washington, DC.

    The sensor is a mass spectrometer system which continuously monitors the atmospheric constituents of hydrogen, water vapor, nitrogen, oxygen, and carbon dioxide, and monitors the Freons on a demand sampling basis. The manual provides a system description, operational procedures, and maintenance and troubleshooting instructions. Circuit diagrams…

  13. Analysis of nanowire transistor based nitrogen dioxide gas sensor – A simulation study

    Directory of Open Access Journals (Sweden)

    Gaurav Saxena

    2015-06-01

    Full Text Available Sensors sensitivity, selectivity and stability has always been a prime design concern for gas sensors designers. Modeling and simulation of gas sensors aids the designers in improving their performance. In this paper, different routes for the modeling and simulation of a semiconducting gas sensor is presented. Subsequently, by employing one of the route, the response of Zinc Oxide nanowire transistor towards nitrogen dioxide ambient is simulated. In addition to the sensing mechanism, simulation study of gas species desorption by applying a recovery voltage is also presented.

  14. Nanocrystalline Pd:NiFe{sub 2}O{sub 4} thin films: A selective ethanol gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Pratibha; Godbole, R.V.; Bhagwat, Sunita, E-mail: smb.agc@gmail.com

    2016-10-15

    In this work, Pd:NiFe{sub 2}O{sub 4} thin films were investigated for the detection of reducing gases. These films were fabricated using spray pyrolysis technique and characterized using X-ray diffraction (XRD) to confirm the crystal structure. The surface morphology was studied using scanning electron microscopy (SEM). Magnetization measurements were carried out using SQUID VSM, which shows ferrimagnetic behavior of the samples. These thin film sensors were tested against methanol, ethanol, hydrogen sulfide and liquid petroleum gas, where they were found to be more selective to ethanol. The fabricated thin film sensors exhibited linear response signal for all the gases with concentrations up to 5 w/o Pd. Reduction in optimum operating temperature and enhancement in response was also observed. Pd:NiFe{sub 2}O{sub 4} thin films exhibited faster response and recovery characteristic. These sensors have potential for industrial applications because of their long-term stability, low power requirement and low production cost. - Highlights: • Ethanol gas sensors based on Pd:NiFe{sub 2}O{sub 4} nanoparticle thin film were fabricated. • Pd incorporation in NiFe{sub 2}O{sub 4} matrix inhibits grain growth. • The sensors were more selective to ethanol gas. • Sensors exhibited fast response and recovery when doped with palladium. • Pd:NiFe{sub 2}O{sub 4} thin film sensor displays excellent long–term stability.

  15. Increasing the selectivity and sensitivity of gas sensors for the detection of explosives

    Science.gov (United States)

    Mallin, Daniel

    Over the past decade, the use of improvised explosive devices (IEDs) has increased, domestically and internationally, highlighting a growing need for a method to quickly and reliably detect explosive devices in both military and civilian environments before the explosive can cause damage. Conventional techniques have been successful in explosive detection, however they typically suffer from enormous costs in capital equipment and maintenance, costs in energy consumption, sampling, operational related expenses, and lack of continuous and real-time monitoring. The goal was thus to produce an inexpensive, portable sensor that continuously monitors the environment, quickly detects the presence of explosive compounds and alerts the user. In 2012, here at URI, a sensor design was proposed for the detection of triacetone triperoxide (TATP). The design entailed a thermodynamic gas sensor that measures the heat of decomposition between trace TATP vapor and a metal oxide catalyst film. The sensor was able to detect TATP vapor at the part per million level (ppm) and showed great promise for eventual commercial use, however, the sensor lacked selectivity. Thus, the specific objective of this work was to take the original sensor design proposed in 2012 and to make several key improvements to advance the sensor towards commercialization. It was demonstrated that a sensor can be engineered to detect TATP and ignore the effects of interferent H2O2 molecules by doping SnO2 films with varying amounts of Pd. Compared with a pure SnO2 catalyst, a SnO2, film doped with 8 wt. % Pd had the highest selectivity between TATP and H2O2. Also, at 12 wt. % Pd, the response to TATP and H2O2 was enhanced, indicating that sensitivity, not only selectivity, can be increased by modifying the composition of the catalyst. An orthogonal detection system was demonstrated. The platform consists of two independent sensing mechanisms, one thermodynamic and one conductometric, which take measurements from

  16. Claims of operators, non-operators and third parties arising from oil and gas operations

    International Nuclear Information System (INIS)

    Block, R.W.; Semadeni, T.

    1999-01-01

    There has come a resurgence in the number of companies involved in the oil and gas industry seeking protection from their creditors because of the recent weakness in commodity prices. Because most operations in this industry are conducted jointly, a single insolvency can lead to a toppling of other participants in the joint venture and beyond. The problem is to minimize one's losses if other members of the joint venture become insolvent. An examination is included of some remedies which may be available to operators, non-operators and third parties when faced with an insolvent oil and gas participant. The remedies which may be available to the non-operator that is owed moneys by its operator are discussed. The remedies that the operator has against its non-operators, with an emphasis on the nature of the operator's lien and the right of set-off, are described. A brief review is included of some of the remedies that might be available to a third party as against the operators and non-operators. Some s uggestions are included for directors, bankers, third parties, non-operators and operators

  17. Inhomogeneous Oxygen Vacancy Distribution in Semiconductor Gas Sensors: Formation, Migration and Determination on Gas Sensing Characteristics

    Directory of Open Access Journals (Sweden)

    Jianqiao Liu

    2017-08-01

    Full Text Available The density of oxygen vacancies in semiconductor gas sensors was often assumed to be identical throughout the grain in the numerical discussion of the gas-sensing mechanism of the devices. In contrast, the actual devices had grains with inhomogeneous distribution of oxygen vacancy under non-ideal conditions. This conflict between reality and discussion drove us to study the formation and migration of the oxygen defects in semiconductor grains. A model of the gradient-distributed oxygen vacancy was proposed based on the effects of cooling rate and re-annealing on semiconductive thin films. The model established the diffusion equations of oxygen vacancy according to the defect kinetics of diffusion and exclusion. We described that the steady-state and transient-state oxygen vacancy distributions, which were used to calculate the gas-sensing characteristics of the sensor resistance and response to reducing gases under two different conditions. The gradient-distributed oxygen vacancy model had the applications in simulating the sensor performances, such as the power law, the grain size effect and the effect of depletion layer width.

  18. Inhomogeneous Oxygen Vacancy Distribution in Semiconductor Gas Sensors: Formation, Migration and Determination on Gas Sensing Characteristics.

    Science.gov (United States)

    Liu, Jianqiao; Gao, Yinglin; Wu, Xu; Jin, Guohua; Zhai, Zhaoxia; Liu, Huan

    2017-08-10

    The density of oxygen vacancies in semiconductor gas sensors was often assumed to be identical throughout the grain in the numerical discussion of the gas-sensing mechanism of the devices. In contrast, the actual devices had grains with inhomogeneous distribution of oxygen vacancy under non-ideal conditions. This conflict between reality and discussion drove us to study the formation and migration of the oxygen defects in semiconductor grains. A model of the gradient-distributed oxygen vacancy was proposed based on the effects of cooling rate and re-annealing on semiconductive thin films. The model established the diffusion equations of oxygen vacancy according to the defect kinetics of diffusion and exclusion. We described that the steady-state and transient-state oxygen vacancy distributions, which were used to calculate the gas-sensing characteristics of the sensor resistance and response to reducing gases under two different conditions. The gradient-distributed oxygen vacancy model had the applications in simulating the sensor performances, such as the power law, the grain size effect and the effect of depletion layer width.

  19. A versatile sensor network for urban search and rescue operations

    Science.gov (United States)

    Känsälä, Klaus; Korkalainen, Marko; Mäyrä, Aki

    2011-11-01

    The presentation is based in the research work carried out in EU funded project SGL for USaR (Second Generation Locator for Urban Search and Rescue Operations). The aim of this project is to develop wireless standalone communication system with embedded sensor network which can be globally used in rescue operations after accidents or terrorist attacks. The system should be able to operate without external support for several days: it should have autonomy with power supply and communication. The devices must be lightweight so that rescue team can easily carry them and finally they must be easy to install and use. The range of the wireless communication must cover an area of several square kilometers. The embedded sensor system must be able to detect sings of life but also detect hazards threatening the rescue operators thus preventing more accidents. It should also support positioning and digital mapping as well as the management of the search and rescue operation. This sensor network for urban search and rescue operations has been tested on a field conditions and it has proven to be robust and reliable and provides an energy efficient way of communication and positioning on harsh conditions.

  20. Gas Identification Using Passive UHF RFID Sensor Platform

    Directory of Open Access Journals (Sweden)

    Muhammad Ali AKBAR

    2015-11-01

    Full Text Available The concept of passive Radio Frequency Identification (RFID sensor tag is introduced to remove the dependency of current RFID platforms on battery life. In this paper, a gas identification system is presented using passive RFID sensor tag along with the processing unit. The RFID system is compliant to Electronics Product Code Generation 2 (EPC-Gen2 protocol in 902-928 MHz ISM band. Whereas the processing unit is implemented and analyzed in software and hardware platforms. The software platform uses MATLAB, whereas a High Level Synthesis (HLS tool is used to implement the processing unit on a Zynq platform. Moreover, two sets of different gases are used along with Principal Component Analysis (PCA and Linear Discriminant Analysis (LDA based feature reduction approaches to analyze in detail the best feature reduction approach for efficient classification of gas data. It is found that for the first set of gases, 90 % gases are identified using first three principal components, which is 7 % more efficient than LDA. However in terms of hardware overhead, LDA requires 50 % less hardware resources than PCA. The classification results for the second set of gases reveal that 91 % of gas classification is obtained using LDA and first four PCA, while LDA requires 52 % less hardware resources than PCA. The RFID tag used for transmission is implemented in 0.13 µm CMOS process, with simulated average power consumption of 2.6 µW from 1.2 V supply. ThingMagic M6e embedded reader is used for RFID platform implementation. It shows an output power of 31.5 dBm which allows a read range up to 9 meters.

  1. Design and operation of gas-heated thermal pumping units

    Energy Technology Data Exchange (ETDEWEB)

    Rostek, H A [Ruhrgas A.G., Essen (Germany, F.R.)

    1979-03-01

    The first gas heat pump systems have been operated since spring 1977. These are applied in living houses, school, swimming pools, and sport places and administration buildings. The heating performance of these systems is 150-3800 kW. Two of these systems, one in a swimming pool and one in a house for several families are operating, each of them for one heating period. The operational experiences with these gas heat pumps are reported on, basing on measurement results. The experience gathered from the operation of gas heat pumps systems is applied to the planning of other plants. The development of a standardized gas heat pump-series is emphasized.

  2. The Development of a Gas-Liquid Two-Phase Flow Sensor Applicable to CBM Wellbore Annulus.

    Science.gov (United States)

    Wu, Chuan; Wen, Guojun; Han, Lei; Wu, Xiaoming

    2016-11-18

    The measurement of wellbore annulus gas-liquid two-phase flow in CBM (coalbed methane) wells is of great significance for reasonably developing gas drainage and extraction processes, estimating CBM output, judging the operating conditions of CBM wells and analyzing stratum conditions. Hence, a specially designed sensor is urgently needed for real-time measurement of gas-liquid two-phase flow in CBM wellbore annulus. Existing flow sensors fail to meet the requirements of the operating conditions of CBM wellbore annulus due to such factors as an inapplicable measurement principle, larger size, poor sealability, high installation accuracy, and higher requirements for fluid media. Therefore, based on the principle of a target flowmeter, this paper designs a new two-phase flow sensor that can identify and automatically calibrate different flow patterns of two-phase flows. Upon the successful development of the new flow sensor, lab and field tests were carried out, and the results show that the newly designed sensor, with a measurement accuracy of ±2.5%, can adapt to the operating conditions of CBM wells and is reliable for long-term work.

  3. SnO2/PPy Screen-Printed Multilayer CO2 Gas Sensor

    Directory of Open Access Journals (Sweden)

    S.A. WAGHULEY

    2007-05-01

    Full Text Available Tin dioxide (SnO2 plays a dominant role in solid state gas sensors and exhibit sensitivity towards oxidizing and reducing gases by a variation of its electrical properties. The electrical conducting polymer-polypyrrole (PPy has high anisotropy of electrical conduction and used as a gas sensor. SnO2/PPy multilayer, pure SnO2, pure PPy sensors were prepared by screen-printing method on Al2O3 layer followed by glass substrate. The sensors were used for different concentration (ppm of CO2 gas investigation at room temperature (303 K. The sensitivity of SnO2/PPy multilayer sensor was found to be higher, compared with pure SnO2 and pure PPy sensors. The multilayer sensor exhibited improved stability. The response and recovery time of multilayer sensor were found to be ~2 min and ~10 min respectively.

  4. Wireless sensors in heterogeneous networked systems configuration and operation middleware

    CERN Document Server

    Cecilio, José

    2014-01-01

    This book presents an examination of the middleware that can be used to configure and operate heterogeneous node platforms and sensor networks. The middleware requirements for a range of application scenarios are compared and analysed. The text then defines middleware architecture that has been integrated in an approach demonstrated live in a refinery. Features: presents a thorough introduction to the major concepts behind wireless sensor networks (WSNs); reviews the various application scenarios and existing middleware solutions for WSNs; discusses the middleware mechanisms necessary for hete

  5. Methane leakage in natural gas operations

    International Nuclear Information System (INIS)

    Jennervik, A.

    1992-01-01

    The world gas industry is efficient in conservation of natural gas within its systems. As the influence of methane as an infra-red absorbent gas has been more widely recognized, the considerations of methane's greenhouse effect has become vitally important to gas companies around the world. The industry is universally environmentally conscious. natural gas transmission and distribution companies want to maintain their image as suppliers of clean fuel. Further reductions in methane leakage --- particularly in older distribution systems --- can, should and will be pursued. Unfortunately, there has been little exchange of views on methane leakages between commentators on environmental matters and gas companies and organizations. There is absolutely no need for the industry to avoid the issue of greenhouse gases. Without industry involvement, the environmental debate concerning fossil fuels could lead to selective interpretation of scientific views and available evidence. Companies and authorities would be presented with confusing, contradictory evidence on which to base policy approaches and regulations

  6. Photocatalytical Decomposition of Contaminants on Thin Film Gas Sensors

    International Nuclear Information System (INIS)

    Radecka, M.; Lyson, B.; Lubecka, M.; Czapla, A.; Zakrzewska, K.

    2010-01-01

    Gas sensing materials have been prepared in a form of TiO 2 -SnO 2 thin films by rf reactive sputtering from Ti:SnO 2 and Sn:TiO 2 targets. Material studies have been performed by scanning electron microscopy, atomic force microscopy, X-ray diffraction at grazing incidence, Moessbauer spectroscopy, X-ray photoelectron spectroscopy and optical spectrophotometry. Dynamic gas sensing responses have been recorded as reproducible changes in the electrical resistance upon introduction of hydrogen at a partial pressure of 100-6000 ppm over a wide temperature range 473-873 K. Contamination experiments have been carried out with the motor oil (40 vol.% solution in CCl 4 ) in order to study the effect of UV light illumination on the gas sensor response. Optical spectroscopy has been applied to monitor the photodecomposition of the test compound, bromothymol blue. The Electronic Nose, ALPHA MOS FOX 4000 has been used in order to differentiate between different groups of motor oil vapors. (author)

  7. Power consumption analysis of operating systems for wireless sensor networks.

    Science.gov (United States)

    Lajara, Rafael; Pelegrí-Sebastiá, José; Perez Solano, Juan J

    2010-01-01

    In this paper four wireless sensor network operating systems are compared in terms of power consumption. The analysis takes into account the most common operating systems--TinyOS v1.0, TinyOS v2.0, Mantis and Contiki--running on Tmote Sky and MICAz devices. With the objective of ensuring a fair evaluation, a benchmark composed of four applications has been developed, covering the most typical tasks that a Wireless Sensor Network performs. The results show the instant and average current consumption of the devices during the execution of these applications. The experimental measurements provide a good insight into the power mode in which the device components are running at every moment, and they can be used to compare the performance of different operating systems executing the same tasks.

  8. Gas characterization system operation, maintenance, and calibration plan

    International Nuclear Information System (INIS)

    Tate, D.D.

    1996-01-01

    This document details the responsibilities and requirements for operation, maintenance, and calibration of the Gas Characterization Systems (GCS) analytical instrumentation. It further, defines the division of responsibility between the Characterization Monitoring Development organization and Tank Farms Operations

  9. Natural gas co-operation in the Baltic region

    International Nuclear Information System (INIS)

    Jensen, J.K.

    1996-01-01

    Co-operation between the gas companies in the Baltic Region has been in place for several years. The overview given in this paper shows that the co-operation has been developed in trade, investments, privatisation and participation in the restructuring process. Finally, through a broad technical co-operation, significant efforts are made to establish common operational practices, codes and standards and the integrity of gas transmission pipelines. The Baltic Region, from a resource and gas interconnection point of view, enjoys a strategic position in the future development of the gas industry in Europe. The Baltic gas sector represents an interesting and growing gas market with the significant gas storage capacity. The region is also located strategically for planned gas interconnections and could serve as a transit corridor for the future gas supplies from western Siberia or the North Sea. This co-operation in the region is being supported by international regulations and agreements such as the Energy Charter between the European Union and the central and east European countries. However, at present the gas industry in the Baltic Region seems to be ahead of these international agreements. It may well be seen that trade arrangements such as Third Party Access are implemented directly by market forces rather than through international agreements. The regional development may thus be a driving force for the implementation of the Internal Energy Market for the gas industry

  10. Operating Systems for Wireless Sensor Networks: A Survey

    Directory of Open Access Journals (Sweden)

    Muhammad Omer Farooq

    2011-05-01

    Full Text Available This paper presents a survey on the current state-of-the-art in Wireless Sensor Network (WSN Operating Systems (OSs. In recent years, WSNs have received tremendous attention in the research community, with applications in battlefields, industrial process monitoring, home automation, and environmental monitoring, to name but a few. A WSN is a highly dynamic network because nodes die due to severe environmental conditions and battery power depletion. Furthermore, a WSN is composed of miniaturized motes equipped with scarce resources e.g., limited memory and computational abilities. WSNs invariably operate in an unattended mode and in many scenarios it is impossible to replace sensor motes after deployment, therefore a fundamental objective is to optimize the sensor motes’ life time. These characteristics of WSNs impose additional challenges on OS design for WSN, and consequently, OS design for WSN deviates from traditional OS design. The purpose of this survey is to highlight major concerns pertaining to OS design in WSNs and to point out strengths and weaknesses of contemporary OSs for WSNs, keeping in mind the requirements of emerging WSN applications. The state-of-the-art in operating systems for WSNs has been examined in terms of the OS Architecture, Programming Model, Scheduling, Memory Management and Protection, Communication Protocols, Resource Sharing, Support for Real-Time Applications, and additional features. These features are surveyed for both real-time and non-real-time WSN operating systems.

  11. Operating Systems for Wireless Sensor Networks: A Survey

    Science.gov (United States)

    Farooq, Muhammad Omer; Kunz, Thomas

    2011-01-01

    This paper presents a survey on the current state-of-the-art in Wireless Sensor Network (WSN) Operating Systems (OSs). In recent years, WSNs have received tremendous attention in the research community, with applications in battlefields, industrial process monitoring, home automation, and environmental monitoring, to name but a few. A WSN is a highly dynamic network because nodes die due to severe environmental conditions and battery power depletion. Furthermore, a WSN is composed of miniaturized motes equipped with scarce resources e.g., limited memory and computational abilities. WSNs invariably operate in an unattended mode and in many scenarios it is impossible to replace sensor motes after deployment, therefore a fundamental objective is to optimize the sensor motes’ life time. These characteristics of WSNs impose additional challenges on OS design for WSN, and consequently, OS design for WSN deviates from traditional OS design. The purpose of this survey is to highlight major concerns pertaining to OS design in WSNs and to point out strengths and weaknesses of contemporary OSs for WSNs, keeping in mind the requirements of emerging WSN applications. The state-of-the-art in operating systems for WSNs has been examined in terms of the OS Architecture, Programming Model, Scheduling, Memory Management and Protection, Communication Protocols, Resource Sharing, Support for Real-Time Applications, and additional features. These features are surveyed for both real-time and non-real-time WSN operating systems. PMID:22163934

  12. Operating systems for wireless sensor networks: a survey.

    Science.gov (United States)

    Farooq, Muhammad Omer; Kunz, Thomas

    2011-01-01

    This paper presents a survey on the current state-of-the-art in Wireless Sensor Network (WSN) Operating Systems (OSs). In recent years, WSNs have received tremendous attention in the research community, with applications in battlefields, industrial process monitoring, home automation, and environmental monitoring, to name but a few. A WSN is a highly dynamic network because nodes die due to severe environmental conditions and battery power depletion. Furthermore, a WSN is composed of miniaturized motes equipped with scarce resources e.g., limited memory and computational abilities. WSNs invariably operate in an unattended mode and in many scenarios it is impossible to replace sensor motes after deployment, therefore a fundamental objective is to optimize the sensor motes' life time. These characteristics of WSNs impose additional challenges on OS design for WSN, and consequently, OS design for WSN deviates from traditional OS design. The purpose of this survey is to highlight major concerns pertaining to OS design in WSNs and to point out strengths and weaknesses of contemporary OSs for WSNs, keeping in mind the requirements of emerging WSN applications. The state-of-the-art in operating systems for WSNs has been examined in terms of the OS Architecture, Programming Model, Scheduling, Memory Management and Protection, Communication Protocols, Resource Sharing, Support for Real-Time Applications, and additional features. These features are surveyed for both real-time and non-real-time WSN operating systems.

  13. Temperature Gradient Effect on Gas Discrimination Power of a Metal-Oxide Thin-Film Sensor Microarray

    Directory of Open Access Journals (Sweden)

    Joachim Goschnick

    2004-05-01

    Full Text Available Abstract: The paper presents results concerning the effect of spatial inhomogeneous operating temperature on the gas discrimination power of a gas-sensor microarray, with the latter based on a thin SnO2 film employed in the KAMINA electronic nose. Three different temperature distributions over the substrate are discussed: a nearly homogeneous one and two temperature gradients, equal to approx. 3.3 oC/mm and 6.7 oC/mm, applied across the sensor elements (segments of the array. The gas discrimination power of the microarray is judged by using the Mahalanobis distance in the LDA (Linear Discrimination Analysis coordinate system between the data clusters obtained by the response of the microarray to four target vapors: ethanol, acetone, propanol and ammonia. It is shown that the application of a temperature gradient increases the gas discrimination power of the microarray by up to 35 %.

  14. Investigation of Continuous Gas Engine CHP Operation on Biomass Producer Gas

    DEFF Research Database (Denmark)

    Ahrenfeldt, Jesper; Henriksen, Ulrik Birk; Jensen, Torben Kvist

    2005-01-01

    More than 2000 hours of gas engine operation with producer gas from biomass as fuel has been conducted on the gasification CHP demonstration and research plant, named “Viking” at the Technical University of Denmark. The gas engine is an integrated part of the entire gasification plant. The excess...... operates with varying excess of air due to variation in gas composition and thus stoichiometry, and a second where the excess of air in the exhaust gas is fixed and the flow rate of produced gas from the gasifier is varying. The interaction between the gas engine and the gasification system has been...... investigated. The engine and the plant are equipped with continuously data acquisition that monitors the operation including the composition of the producer gas and the flow. Producer gas properties and contaminations have been investigated. No detectable tar or particle content was observed...

  15. Preparation of the spacer for narrow electrode gap configuration in ionization-based gas sensor

    International Nuclear Information System (INIS)

    Saheed, Mohamed Shuaib Mohamed; Mohamed, Norani Muti; Burhanudin, Zainal Arif

    2012-01-01

    Carbon nanotubes (CNTs) have started to be developed as the sensing element for ionization-based gas sensors due to the demand for improved sensitivity, selectivity, stability and other sensing properties beyond what can be offered by the conventional ones. Although these limitations have been overcome, the problems still remain with the conventional ionization-based gas sensors in that they are bulky and operating with large breakdown voltage and high temperature. Recent studies have shown that the breakdown voltage can be reduced by using nanostructured electrodes and narrow electrode gap. Nanostructured electrode in the form of aligned CNTs array with evenly distributed nanotips can enhance the linear electric field significantly. The later is attributed to the shorter conductivity path through narrow electrode gap. The paper presents the study on the design consideration in order to realize ionization based gas sensor using aligned carbon nanotubes array in an optimum sensor configuration with narrow electrode gap. Several deposition techniques were studied to deposit the spacer, the key component that can control the electrode gap. Plasma spray deposition, electron beam deposition and dry oxidation method were employed to obtain minimum film thickness around 32 μm. For plasma spray method, sand blasting process is required in order to produce rough surface for strong bonding of the deposited film onto the surface. Film thickness, typically about 39 μm can be obtained. For the electron beam deposition and dry oxidation, the film thickness is in the range of nanometers and thus unsuitable to produce the spacer. The deposited multilayer film consisting of copper, alumina and ferum on which CNTs array will be grown was found to be removed during the etching process. This is attributed to the high etching rate on the thin film which can be prevented by reducing the rate and having a thicker conductive copper film.

  16. Preparation of the spacer for narrow electrode gap configuration in ionization-based gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Saheed, Mohamed Shuaib Mohamed; Mohamed, Norani Muti; Burhanudin, Zainal Arif [Electrical and Electronic Engineering, Universiti Teknologi PETRONAS, Seri Iskandar, Tronoh, Perak. (Malaysia); Fundamental and Applied Science, Universiti Teknologi PETRONAS, Seri Iskandar, Tronoh, Perak. (Malaysia); Electrical and Electronic Engineering, Universiti Teknologi PETRONAS, Seri Iskandar, Tronoh, Perak. (Malaysia)

    2012-09-26

    Carbon nanotubes (CNTs) have started to be developed as the sensing element for ionization-based gas sensors due to the demand for improved sensitivity, selectivity, stability and other sensing properties beyond what can be offered by the conventional ones. Although these limitations have been overcome, the problems still remain with the conventional ionization-based gas sensors in that they are bulky and operating with large breakdown voltage and high temperature. Recent studies have shown that the breakdown voltage can be reduced by using nanostructured electrodes and narrow electrode gap. Nanostructured electrode in the form of aligned CNTs array with evenly distributed nanotips can enhance the linear electric field significantly. The later is attributed to the shorter conductivity path through narrow electrode gap. The paper presents the study on the design consideration in order to realize ionization based gas sensor using aligned carbon nanotubes array in an optimum sensor configuration with narrow electrode gap. Several deposition techniques were studied to deposit the spacer, the key component that can control the electrode gap. Plasma spray deposition, electron beam deposition and dry oxidation method were employed to obtain minimum film thickness around 32 {mu}m. For plasma spray method, sand blasting process is required in order to produce rough surface for strong bonding of the deposited film onto the surface. Film thickness, typically about 39 {mu}m can be obtained. For the electron beam deposition and dry oxidation, the film thickness is in the range of nanometers and thus unsuitable to produce the spacer. The deposited multilayer film consisting of copper, alumina and ferum on which CNTs array will be grown was found to be removed during the etching process. This is attributed to the high etching rate on the thin film which can be prevented by reducing the rate and having a thicker conductive copper film.

  17. Novel sensors to enable closed-loop active clearance control in gas turbine engines

    Science.gov (United States)

    Geisheimer, Jonathan; Holst, Tom

    2014-06-01

    Active clearance control within the turbine section of gas turbine engines presents and opportunity within aerospace and industrial applications to improve operating efficiencies and the life of downstream components. Open loop clearance control is currently employed during the development of all new large core aerospace engines; however, the ability to measure the gap between the blades and the case and close down the clearance further presents as opportunity to gain even greater efficiencies. The turbine area is one of the harshest environments for long term placement of a sensor in addition to the extreme accuracy requirements required to enable closed loop clearance control. This paper gives an overview of the challenges of clearance measurements within the turbine as well as discusses the latest developments of a microwave sensor designed for this application.

  18. Tunable Diode Laser Absorption Spectroscopy Sensor for Calibration Free Humidity Measurements in Pure Methane and Low CO2 Natural Gas.

    Science.gov (United States)

    Nwaboh, Javis Anyangwe; Pratzler, Sonja; Werhahn, Olav; Ebert, Volker

    2017-05-01

    We report a new direct tunable diode laser absorption spectroscopy (dTDLAS) sensor for absolute measurements of H 2 O in methane, ethane, propane, and low CO 2 natural gas. The sensor is operated with a 2.7 µm DFB laser, equipped with a high pressure single pass gas cell, and used to measure H 2 O amount of substance fractions in the range of 0.31-25 000 µmol/mol. Operating total gas pressures are up to 5000 hPa. The sensor has been characterized, addressing the traceability of the spectrometric results to the SI and the evaluation of the combined uncertainty, following the guide to the expression of uncertainty in measurement (GUM). The relative reproducibility of H 2 O amount of substance fraction measurements at 87 µmol/mol is 0.26% (0.23 µmol/mol). The maximum precision of the sensor was determined using a H 2 O in methane mixture, and found to be 40 nmol/mol for a time resolution of 100 s. This corresponds to a normalized detection limit of 330 nmol mol -1 ·m Hz -1/2 . The relative combined uncertainty of H 2 O amount fraction measurements delivered by the sensor is 1.2%.

  19. Ammonia gas sensing property of gadolinium oxide using fiber optic gas sensor

    Science.gov (United States)

    Kumar, J. Santhosh; Ranganathan, B.; Sastikumar, D.

    2017-05-01

    The design of fiber optic sensor is based on a cladding modification methodology. A fiber-optic chemical sensor is developed by replacing a certain portion of the original cladding with a chemically sensitive material, specifically, calcinated gadolinium oxide (Gd2O3).Both the light absorption co-efficient and refractive index change upon exposure to chemical vapours of volatile organic compounds (VOCs) such as ammonia (NH3), ethanol (CH3CH2OH), and methanol (CH3OH). The spectral characteristics of the sensor were studied for different concentrations ranging from 0-500 ppm. These changes induced the optical intensity modulation of the transmitted optical signal. During interaction between the sensing material and VOCs, the output intensity is taken into account to detect the toxic VOCs present in the environment. This was systematically investigated by X-ray diffractometer (XRD) and SEM. The XRD analysis indicated that the calcinated Gd2O3 was formed in cubic structure with the crystallite size of 13 nm. The Gd2O3 nanorods with thickness ranging from 80 to 120 nm were confirmed from SEM. The ammonia gas response of the Gd2O3 sensor is presented. A model is proposed for understanding the spectral intensity variations.

  20. 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)

  1. Operation of transition-edge sensors with excess thermal noise

    International Nuclear Information System (INIS)

    Maasilta, I J; Kinnunen, K M; Nuottajaervi, A K; Leppaeniemi, J; Luukanen, A

    2006-01-01

    The superconducting transition-edge sensor (TES) is currently one of the most attractive choices for ultra-high resolution calorimetry in the keV x-ray band, and is being considered for future ESA and NASA missions. We have performed a study on the noise characteristics of Au/Ti bilayer TESs, at operating temperatures around ∼100 mK, with the SQUID readout at 1.5 K. Experimental results indicate that without modifications the back-action noise from the SQUID chip degrades the noise characteristics significantly. We present a simple and effective solution to the problem: by installing an extra shunt resistor which absorbs the excess radiation from the SQUID input, we have reduced the excess thermal (photon) noise power down by approximately a factor of five, allowing high resolution operation of the sensors

  2. Study on the inside gas flow visualization of oxygen sensor cover; Kashika ni yoru O2 sensor cover nai no gas nagare hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Hocho, S; Mitsuishi, Y; Inagaki, M [Nippon Soken, Inc., Tokyo (Japan); Hamaguchi, S; Mizusawa, K [Toyota Motor Corp., Aichi (Japan)

    1997-10-01

    In order to make clear the difference of the response time between the oxygen sensors with different protection covers, we visualized gas flow inside of sensor covers by means of two experimental methods: One is `Smoke Suspension Method` using liquid paraffin vapor as the smoke. With smoke suspension method, we detected the streamlines inside of the covers. The other is `Color Reaction Method` using the reaction of phenolphthalein and NH3 gas. With color reaction method, we confirmed the streamline inside of the cover and furthermore detected the difference of the response time of each sensor. 3 refs., 7 figs., 1 tab.

  3. Gas dependent sensing mechanism in ZnO nanobelt sensor

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Manmeet, E-mail: manmeet@barc.gov.in [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai (India); Kailasaganapathi, S.; Ramgir, Niranjan; Datta, Niyanta [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai (India); Kumar, Sushil [Heavy Water Plant (Manuguru), Gautaminagar, Dist. Khammam, Telangana (India); Debnath, A.K.; Aswal, D.K.; Gupta, S.K. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai (India)

    2017-02-01

    Highlights: • ZnO nanobelts exhibit an appreciable response towards H{sub 2}S and NO. • At room temperature, sensor recovers completely after exposure to NO (1 to 60 ppm). • At room temperature, incomplete recovery observed on exposure to higher concentrations of H{sub 2}S (> 5 ppm). • Complete recovery on exposure to concentrations higher than 5 ppm H{sub 2}S is achieved by heating the sensor films at 250 °C. • Incomplete recovery after exposure to higher concentrations of H{sub 2}S is due to formation of ZnS. - Abstract: Gas sensing properties of ZnO nanobelts synthesized using carbothermal reduction method has been investigated. At room temperature (28 °C), the sensor films exhibit an appreciable response towards H{sub 2}S and NO and response of these two gases were studied as a function of concentration. For NO the sensor films exhibit a complete reversible curve for the concentration range between 1 and 60 ppm. However, for H{sub 2}S a complete recovery was obtained for concentration <5 ppm and for higher concentration a partial recovery of the baseline resistance was observed. The reason for the incomplete recovery was investigated using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) studies of the sample before and after the H{sub 2}S exposure. After exposure, appearance of an additional peak at 26.6° corresponding to the formation of ZnS was observed in XRD. Formation of additional phase was further corroborated using the results of XPS. H{sub 2}S exposure causes decrease in the intensity of O 1s peak and appearance of sulphide peaks at binding energies of 162.8 and 161.8 eV corresponding to S-2p peaks – 2p{sub 3/2} and 2p{sub 1/2}, confirms the formation of ZnS upon exposure.

  4. Synthesis of Nanocrystalline SnO2 Modified TiO2:a Material for Carbon Monoxide Gas Sensor

    Directory of Open Access Journals (Sweden)

    A. B. BODADE

    2008-11-01

    Full Text Available Nanocrystalline SnO2 doped TiO2 having average crystallite size of 45-50 nm were synthesized by the sol-gel method and studied for gas sensing behavior to reducing gases like CO, liquefied petroleum gas (LPG, NH3 and H2. The material characterization was done by using X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR and scanning electron microscope (SEM. The sensitivity measurements were carried out as a function of different operating temperature in SnO2 doped TiO2. The 15 wt.% SnO2 doped TiO2 based CO sensor shows better sensitivity at an operating temperature 240°C Incorporation of 0.5 wt% Pd improved the sensitivity, selectivity, response time and reduced the operating temperature from 240°C to 200°C for CO sensor.

  5. Synthesis, characterization and gas sensing properties of undoped and Zn-doped γ-Fe2O3-based gas sensors

    International Nuclear Information System (INIS)

    Jing Zhihong

    2006-01-01

    In this study, undoped and Zn-doped γ-Fe 2 O 3 nanopowders have been prepared using Fe(NO 3 ) 3 .9H 2 O and Zn(NO 3 ) 2 .6H 2 O as starting materials and lauryl alcohol as anhydrous medium. Thermo-gravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron micrograph (TEM) were employed to characterize the products. Sensitivity characteristics of the undoped and Zn-doped γ-Fe 2 O 3 semiconductor gas sensors have been investigated. The results show that both of the undoped and 15 mol% Zn-doped γ-Fe 2 O 3 -based gas sensors present good sensitivity and selectivity to acetone and ethanol in presence of CH 4 , H 2 and CO at the operating temperatures of 240 and 270 deg. C, respectively. After being doped with 15 mol% Zn addition, the γ-Fe 2 O 3 -based gas element displays higher sensitivity and selectivity as well as shorter response-recovery time compared with the undoped, suggesting that the promoting effect of ZnO is excellent. So, it seems that the γ-Fe 2 O 3 -based gas sensor doped with 15 mol% Zn is expected to be a promising sensor for detecting acetone and ethanol

  6. CO{sub 2} gas sensors based on rare earth oxycarbonates

    Energy Technology Data Exchange (ETDEWEB)

    Haensch, Alexander

    2016-07-01

    This title presents a new type of CO{sub 2} gas sensor, that allows the measurement of CO{sub 2} gas with very low effort. The measurement principle is based on two semiconducting materials. One the ''receptor'' and a ''transducer'' form a semiconductor junction. Electronic changes in the receptor change the electrical resistance in the transducer and therefor allow the easy electrical measurement. The reactivity and the reaction mechanism is thoroughly studied. In the first part the basics and resistance measurements are presented. A comparison between different mixtures is done. The main part studies the surface chemistry with operando DRIFT spectroscopy. The chemical reactivity of different target gases and background gases is studied thoroughly. The electronic properties of Oxycarbonates and the combination of oxycarbonate and tin oxide were studied using operando Kelvin probes measurements. The result is that CO{sub 2} alters the electron affinity of the material. Once moisture is present, an additional band bending is visible. The band bending dominated in a humid atmosphere, the work function changes. The electronic connection of oxycarbonate and tin oxide, the work function change of Oxycarbonates can be transferred to the tin oxide. Using the collected data, a basic idea of the operation will be presented by a two-semiconductor materials gas sensor.

  7. Sensors and OBIA synergy for operational monitoring of surface water

    Science.gov (United States)

    Masson, Eric; Thenard, Lucas

    2010-05-01

    This contribution will focus on combining Object Based Image Analysis (i.e. OBIA with e-Cognition 8) and recent sensors (i.e. Spot 5 XS, Pan and ALOS Prism, Avnir2, Palsar) to address the technical feasibility for an operational monitoring of surface water. Three cases of river meandering (India), flood mapping (Nepal) and dam's seasonal water level monitoring (Morocco) using recent sensors will present various application of surface water monitoring. The operational aspect will be demonstrated either by sensor properties (i.e. spatial resolution and bandwidth), data acquisition properties (i.e. multi sensor, return period and near real-time acquisition) but also with OBIA algorithms (i.e. fusion of multi sensors / multi resolution data and batch processes). In the first case of river meandering (India) we will address multi sensor and multi date satellite acquisition to monitor the river bed mobility within a floodplain using an ALOS dataset. It will demonstrate the possibility of an operational monitoring system that helps the geomorphologist in the analysis of fluvial dynamic and sediment budget for high energy rivers. In the second case of flood mapping (Nepal) we will address near real time Palsar data acquisition at high spatial resolution to monitor and to map a flood extension. This ALOS sensor takes benefit both from SAR and L band properties (i.e. atmospheric transparency, day/night acquisition, low sensibility to surface wind). It's a real achievement compared to optical imagery or even other high resolution SAR properties (i.e. acquisition swath, bandwidth and data price). These advantages meet the operational needs set by crisis management of hydrological disasters but also for the implementation of flood risk management plans. The last case of dam surface water monitoring (Morocco) will address an important issue of water resource management in countries affected by water scarcity. In such countries water users have to cope with over exploitation

  8. Gas-sensing properties of SnO2-TiO2-based sensor for volatile organic compound gas and its sensing mechanism

    International Nuclear Information System (INIS)

    Zeng Wen; Liu Tianmo

    2010-01-01

    We report the microstructure and gas-sensing properties of the SnO 2 -TiO 2 composite oxide dope with Ag ion prepared by the sol-gel method. Of all various volatile organic compounds (VOCs) such as ethanol, methanol, acetone and formaldehyde were examined, the sensor exhibits remarkable selectivity to each VOCs at different operating temperature. Further investigations based on quantum chemistry calculation show that difference orbital energy of VOCs molecule may be a qualitative factor to affect the selectivity of the sensor.

  9. Concept of Operations for Nuclear Warhead Embedded Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Rockett, P D; Koncher, T R

    2012-05-16

    Embedded arms-control-sensors provide a powerful new paradigm for managing compliance with future nuclear weapons treaties, where deployed warhead numbers will be reduced to 1000 or less. The CONOPS (Concept of Operations) for use with these sensors is a practical tool with which one may help define design parameters, including size, power, resolution, communications, and physical structure. How frequently must data be acquired and must a human be present? Will such data be acquired for only stored weapons or will it be required of deployed weapons as well? Will tactical weapons be subject to such monitoring or will only strategic weapons apply? Which data will be most crucial? Will OSI's be a component of embedded sensor data management or will these sensors stand alone in their data extraction processes? The problem space is massive, but can be constrained by extrapolating to a reasonable future treaty regime and examining the bounded options this scenario poses. Arms control verification sensors, embedded within the warhead case or aeroshell, must provide sufficient but not excessively detailed data, confirming that the item is a nuclear warhead and that it is a particular warhead without revealing sensitive information. Geolocation will be provided by an intermediate transceiver used to acquire the data and to forward the data to a central processing location. Past Chain-of-Custody projects have included such devices and will be primarily responsible for adding such indicators in the future. For the purposes of a treaty regime a TLI will be verified as a nuclear warhead by knowledge of (a) the presence and mass of SNM, (b) the presence of HE, and (c) the reporting of a unique tag ID. All of these parameters can be obtained via neutron correlation measurements, Raman spectroscopy, and fiber optic grating fabrication, respectively. Data from these sensors will be pushed out monthly and acquired nearly daily, providing one of several verification layers in

  10. Optical fiber tip interferometer gas pressure sensor based on anti-resonant reflecting guidance mechanism

    Science.gov (United States)

    Yang, Y. B.; Wang, D. N.; Xu, Ben; Wang, Z. K.

    2018-05-01

    We propose and demonstrate a gas pressure sensor based on an anti-resonant reflecting guidance (ARRG) mechanism in quartz capillary tube with an open cavity. The device is simple in fabrication by only fusion splicing a segment of capillary tube with single mode fiber. It has compact size, robust structure, convenient mode of operation, and high sensitivity of 4.278 nm/MPa. Moreover, as two Faby-Perot cavities exist in the device, which create the interference spectrum with several distinct resonance dips, a simultaneous gas pressure and temperature detection can be readily achieved by tracing two dip wavelengths. The error in the measurement due to the choice of different resonant dips can be effectively reduced by using the Fourier band pass filtering method.

  11. A Nose for Hydrogen Gas: Fast, Sensitive H2 Sensors Using Electrodeposited Nanomaterials.

    Science.gov (United States)

    Penner, Reginald M

    2017-08-15

    Hydrogen gas (H 2 ) is odorless and flammable at concentrations above 4% (v/v) in air. Sensors capable of detecting it rapidly at lower concentrations are needed to "sniff" for leaked H 2 wherever it is used. Electrical H 2 sensors are attractive because of their simplicity and low cost: Such sensors consist of a metal (usually palladium, Pd) resistor. Exposure to H 2 causes a resistance increase, as Pd metal is converted into more resistive palladium hydride (PdH x ). Sensors based upon Pd alloy films, developed in the early 1990s, were both too slow and too insensitive to meet the requirements of H 2 safety sensing. In this Account, we describe the development of H 2 sensors that are based upon electrodeposited nanomaterials. This story begins with the rise to prominence of nanowire-based sensors in 2001 and our demonstration that year of the first nanowire-based H 2 sensor. The Pd nanowires used in these experiments were prepared by electrodepositing Pd at linear step-edge defects on a graphite electrode surface. In 2005, lithographically patterned nanowire electrodeposition (LPNE) provided the capability to pattern single Pd nanowires on dielectrics using electrodeposition. LPNE also provided control over the nanowire thickness (±1 nm) and width (±10-15%). Using single Pd nanowires, it was demonstrated in 2010 that smaller nanowires responded more rapidly to H 2 exposure. Heating the nanowire using Joule self-heating (2010) also dramatically accelerated sensor response and recovery, leading to the conclusion that thermally activated H 2 chemisorption and desorption of H 2 were rate-limiting steps in sensor response to and recovery from H 2 exposure. Platinum (Pt) nanowires, studied in 2012, showed an inverted resistance response to H 2 exposure, that is, the resistance of Pt nanowires decreased instead of increased upon H 2 exposure. H 2 dissociatively chemisorbs at a Pt surface to form Pt-H, but in contrast to Pd, it stays on the Pt surface. Pt nanowires

  12. A Robust and Low-Complexity Gas Recognition Technique for On-Chip Tin-Oxide Gas Sensor Array

    Directory of Open Access Journals (Sweden)

    Farid Flitti

    2008-01-01

    Full Text Available Gas recognition is a new emerging research area with many civil, military, and industrial applications. The success of any gas recognition system depends on its computational complexity and its robustness. In this work, we propose a new low-complexity recognition method which is tested and successfully validated for tin-oxide gas sensor array chip. The recognition system is based on a vector angle similarity measure between the query gas and the representatives of the different gas classes. The latter are obtained using a clustering algorithm based on the same measure within the training data set. Experimented results on our in-house gas sensors array show more than 98% of correct recognition. The robustness of the proposed method is tested by recognizing gas measurements with simulated drift. Less than 1% of performance degradation is noted at the worst case scenario which represents a significant improvement when compared to the current state-of-the-art.

  13. The Precise Mechanisms of a High-Speed Ultrasound Gas Sensor and Detecting Human-Specific Lung Gas Exchange

    Directory of Open Access Journals (Sweden)

    Hideki Toda

    2012-12-01

    Full Text Available In this paper, we propose and develop a new real-time human respiration process analysis method using a high-time-sampling gas concentration sensor based on ultrasound. A unique point about our proposed gas concentration sensor is its 1 kHz gas concentration sampling speed. This figure could not have been attained by previously proposed gas concentration measurement methods such as InfraRed, semiconductor gas sensors, or GC-MS, because the gas analysis speeds were a maximum of a few hundred milliseconds. First, we describe the proposed new ultrasound sound speed measurement method and the signal processing, and present the measurement circuit diagram. Next, we analyse the human respiration gas variation patterns of five healthy subjects using a newly developed gas-mask-type respiration sensor. This reveals that the rapid gas exchange from H2O to CO2 contains air specific to the human being. In addition, we also measured medical symptoms in subjects suffering from asthma, hyperventilation and bronchial asthma. The millisecond level high-speed analysis of the human respiration process will be useful for the next generation of healthcare, rehabilitation and sports science technology.

  14. Development of metal oxide gas sensors for very low concentration (ppb) of BTEX vapors

    Science.gov (United States)

    Favard, A.; Aguir, K.; Contaret, T.; Caris, L.; Bendahan, M.

    2017-12-01

    The control and analysis of air quality have become a major preoccupation of the last twenty years. In 2008, the European Union has introduced a Directive (2008/50/EC) to impose measurement obligations and thresholds to not exceed for some pollutants, including BTEX gases, in view of their adverse effects on the health. In this paper, we show the ability to detect very low concentrations of BTEX using a gas microsensor based on metal oxide thin-film. A test bench able to generate very low vapors concentrations has been achieved and fully automated. Thin metal oxides layers have been realized by reactive magnetron sputtering. The sensitive layers are functionalized with gold nanoparticles by thermal evaporation technique. Our sensors have been tested on a wide range of concentrations of BTEX (5 - 500 ppb) and have been able to detect concentrations of a few ppb for operating temperatures below 593 K. These results are very promising for detection of very low BTEX concentration for indoor as well as outdoor application. We showed that the addition of gold nanoparticles on the sensitive layers decreases the sensors operating temperature and increases the response to BTEX gas. The best results are obtained with a sensitive layer based on ZnO.

  15. Nanocrystalline SnO2-Pt Thick Film Gas Sensor for Air Pollution Applications

    Directory of Open Access Journals (Sweden)

    M. H. Shahrokh Abadi

    2011-02-01

    Full Text Available A series of xSnO2(1-xPt nanopowder (x = 1, 0.995, 0.99, 0.985, 0.98 was calcinated at 950 °C, mixed with an organic vehicle, printed on premade silver electrodes, and fired at 650 °C. Microstructural, morphological, and elemental properties of the mixed powders and films were determined by using XRD, TEM, SEM, and EDX. Samples were exposed to ethyl alcohol, xylene, methanol, isopropanol, acetone, isobutane, and truck exhaust fumes, at wide range of operating temperature, and sensitivity as well as response time of the samples were measured and compared with Taguchi Gas Sensors of TGS2602 (air contaminants, TGS3870 (CO, and TGS4160 (CO2. It was discovered that crystallite sizes of SnO2 powder and response times of samples are decreased with increasing Pt contents, whilst sensitivity is increased. Measurements are shown that 1 wt.% Pt loaded sensor, operating at 300 °C, can detect exhaust gas with high differentiating between the applied gases.

  16. Characterization and calibration of gas sensor systems at ppb level—a versatile test gas generation system

    Science.gov (United States)

    Leidinger, Martin; Schultealbert, Caroline; Neu, Julian; Schütze, Andreas; Sauerwald, Tilman

    2018-01-01

    This article presents a test gas generation system designed to generate ppb level gas concentrations from gas cylinders. The focus is on permanent gases and volatile organic compounds (VOCs) for applications like indoor and outdoor air quality monitoring or breath analysis. In the design and the setup of the system, several issues regarding handling of trace gas concentrations have been considered, addressed and tested. This concerns not only the active fluidic components (flow controllers, valves), which have been chosen specifically for the task, but also the design of the fluidic tubing regarding dead volumes and delay times, which have been simulated for the chosen setup. Different tubing materials have been tested for their adsorption/desorption characteristics regarding naphthalene, a highly relevant gas for indoor air quality monitoring, which has generated high gas exchange times in a previous gas mixing system due to long time adsorption/desorption effects. Residual gas contaminations of the system and the selected carrier air supply have been detected and quantified using both an analytical method (GC-MS analysis according to ISO 16000-6) and a metal oxide semiconductor gas sensor, which detected a maximum contamination equivalent to 28 ppb of carbon monoxide. A measurement strategy for suppressing even this contamination has been devised, which allows the system to be used for gas sensor and gas sensor system characterization and calibration in the low ppb concentration range.

  17. Fabrication of Micromachined SnO2 Based MOS Gas Sensor with Inbuilt Microheater for Detection of Methanol

    Directory of Open Access Journals (Sweden)

    Priyanka Kakoty

    2016-09-01

    Full Text Available This paper presents a simple method to fabricate a vertical closed membrane structured gas sensor on silicon substrate using micromachining technology for methanol detection at lower concentration. An undoped tin dioxide thin film is deposited by DC magnetron sputtering technique on a pair of gold interdigitated microelectrodes of dimension 820 µm ´ 925 µm. A meander shaped platinum micro heater of dimension 1025 µm ´ 1000 µm is incorporated to provide optimum operating temperature (about 350 0C for sensing operation. Energy dispersive X-ray spectroscopy is done to confirm the chemical composition of the sensor. Temperature coefficient of resistance of the inbuilt micro heater is found to be 0.0941 /0C. The sensor resistance shows significant change when micro heater voltage is varied from 1.5 V-3 V. I-V analysis of the sensor is carried out at 25 0C, 50 0C and 75 0C, and shifts in current through the sensor at different temperatures are observed. I-V characterization is also carried out at different methanol concentration levels (50-110 ppm and it is found that at minimum 80 ppm, the sensor exhibits promising result. The response time and recovery time of the sensor is found to be 160 s and 167 s respectively.

  18. Titanium dioxide-based carbon monoxide gas sensors: Effects of crystallinity and chemistry on sensitivity

    Science.gov (United States)

    Seeley, Zachary Mark

    Among metal-oxide gas sensors which change electrical resistive properties upon exposure to target gasses, titanium dioxide (TiO2) has received attention for its sensitivity and stability during high temperature (>500°C) operation. However, due to the sensing mechanism sensitivity, selectivity, and stability remain as critical deficiencies to be resolved before these sensors reach commercial use. In this study, TiO2 thick films of approximately 30mum and thin films of approximately 1mum thick were fabricated to assess the influence of their material properties on gas sensing mechanism. Increased calcination temperature of TiO2 thick films led to grain growth, reduction in specific surface area, and particle-particle necking. These properties are known to degrade sensitivity; however the measured carbon monoxide (CO) gas response improved with increasing calcination temperature up to 800°C. It was concluded that the sensing improvement was due to increased crystallinity within the films. Sensing properties of TiO2 thin films of were also dependent on crystallization, however; due to the smaller volume of material, they reached optimized crystallization at lower temperatures of 650°C, compared to 800°C for thick films. Incorporation of tungsten (W) and nickel (Ni) ions into the films created donor and acceptor defect sites, respectively, within the electronic band gap of TiO2. The additional n-type defects in W-doped TiO 2 improved n-type CO response, while p-type defects in Ni-doped TiO 2 converted the gas response to p-type. Chemistry of thin films had a more significant impact on the electrical properties and gas response than did microstructure or crystallinity. Doped films could be calcined at higher temperatures and yet remain highly sensitive to CO. Thin films with p-n bi-layer structure were fabricated to determine the influence of a p-n junction on gas sensing properties. No effect of the junction was observed and the sensing response neared the average

  19. Estimation of the limit of detection in semiconductor gas sensors through linearized calibration models.

    Science.gov (United States)

    Burgués, Javier; Jiménez-Soto, Juan Manuel; Marco, Santiago

    2018-07-12

    The limit of detection (LOD) is a key figure of merit in chemical sensing. However, the estimation of this figure of merit is hindered by the non-linear calibration curve characteristic of semiconductor gas sensor technologies such as, metal oxide (MOX), gasFETs or thermoelectric sensors. Additionally, chemical sensors suffer from cross-sensitivities and temporal stability problems. The application of the International Union of Pure and Applied Chemistry (IUPAC) recommendations for univariate LOD estimation in non-linear semiconductor gas sensors is not straightforward due to the strong statistical requirements of the IUPAC methodology (linearity, homoscedasticity, normality). Here, we propose a methodological approach to LOD estimation through linearized calibration models. As an example, the methodology is applied to the detection of low concentrations of carbon monoxide using MOX gas sensors in a scenario where the main source of error is the presence of uncontrolled levels of humidity. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Solid State Gas Sensor Research in Germany – a Status Report

    Directory of Open Access Journals (Sweden)

    Udo Weimar

    2009-06-01

    Full Text Available This status report overviews activities of the German gas sensor research community. It highlights recent progress in the field of potentiometric, amperometric, conductometric, impedimetric, and field effect-based gas sensors. It is shown that besides step-by-step improvements of conventional principles, e.g. by the application of novel materials, novel principles turned out to enable new markets. In the field of mixed potential gas sensors, novel materials allow for selective detection of combustion exhaust components. The same goal can be reached by using zeolites for impedimetric gas sensors. Operando spectroscopy is a powerful tool to learn about the mechanisms in n-type and in p-type conductometric sensors and to design knowledge-based improved sensor devices. Novel deposition methods are applied to gain direct access to the material morphology as well as to obtain dense thick metal oxide films without high temperature steps. Since conductometric and impedimetric sensors have the disadvantage that a current has to pass the gas sensitive film, film morphology, electrode materials, and geometrical issues affect the sensor signal. Therefore, one tries to measure directly the Fermi level position either by measuring the gas-dependent Seebeck coefficient at high temperatures or at room temperature by applying a modified miniaturized Kelvin probe method, where surface adsorption-based work function changes drive the drain-source current of a field effect transistor.

  1. Construction of MoS2/Si nanowire array heterojunction for ultrahigh-sensitivity gas sensor

    Science.gov (United States)

    Wu, Di; Lou, Zhenhua; Wang, Yuange; Xu, Tingting; Shi, Zhifeng; Xu, Junmin; Tian, Yongtao; Li, Xinjian

    2017-10-01

    Few-layer MoS2 thin films were synthesized by a two-step thermal decomposition process. In addition, MoS2/Si nanowire array (SiNWA) heterojunctions exhibiting excellent gas sensing properties were constructed and investigated. Further analysis reveals that such MoS2/SiNWA heterojunction devices are highly sensitive to nitric oxide (NO) gas under reverse voltages at room temperature (RT). The gas sensor demonstrated a minimum detection limit of 10 ppb, which represents the lowest value obtained for MoS2-based sensors, as well as an ultrahigh response of 3518% (50 ppm NO, ˜50% RH), with good repeatability and selectivity of the MoS2/SiNWA heterojunction. The sensing mechanisms were also discussed. The performance of the MoS2/SiNWA heterojunction gas sensors is superior to previous results, revealing that they have great potential in applications relating to highly sensitive gas sensors.

  2. TFTR neutral beam D-T gas injection system operational experiences of the first two years

    International Nuclear Information System (INIS)

    Oldaker, M.E.; Lawson, J.E.; Stevenson, T.N.; Kamperschroer, J.H.

    1995-01-01

    The TFTR Neutral Beam Tritium Gas Injection System (TGIS) has successfully performed tritium operations since December 1993. TGIS operation has been reliable, with no leaks to the secondary containment to date. Notable operational problems include throughput leaks on fill, exit and piezoelectric valves. Repair of a TGIS requires replacement of the assembly, involving TFTR downtime and extensive purging, since the TGIS assembly is highly contaminated with residual tritium, and is located within secondary containment. Modifications to improve reliability and operating range include adjustable reverse bias voltage to the piezoelectric valves, timing and error calculation changes to tune the PLC and hardwired timing control, and exercising piezoelectric valves without actually pulsing gas prior to use after extended inactivity. A pressure sensor failure required the development of an open loop piezoelectric valve drive control scheme, using a simple voltage ramp to partially compensate for declining plenum pressure. Replacement of TGIS's have been performed, maintaining twelve system tritium capability as part of scheduled project maintenance activity

  3. Data-driven modeling of nano-nose gas sensor arrays

    DEFF Research Database (Denmark)

    Alstrøm, Tommy Sonne; Larsen, Jan; Nielsen, Claus Højgård

    2010-01-01

    We present a data-driven approach to classification of Quartz Crystal Microbalance (QCM) sensor data. The sensor is a nano-nose gas sensor that detects concentrations of analytes down to ppm levels using plasma polymorized coatings. Each sensor experiment takes approximately one hour hence...... the number of available training data is limited. We suggest a data-driven classification model which work from few examples. The paper compares a number of data-driven classification and quantification schemes able to detect the gas and the concentration level. The data-driven approaches are based on state...

  4. Data–driven modeling of nano-nose gas sensor arrays

    DEFF Research Database (Denmark)

    Alstrøm, Tommy Sonne; Larsen, Jan; Nielsen, Claus Højgård

    2010-01-01

    We present a data-driven approach to classification of Quartz Crystal Microbalance (QCM) sensor data. The sensor is a nano-nose gas sensor that detects concentrations of analytes down to ppm levels using plasma polymorized coatings. Each sensor experiment takes approximately one hour hence...... the number of available training data is limited. We suggest a data-driven classification model which work from few examples. The paper compares a number of data-driven classification and quantification schemes able to detect the gas and the concentration level. The data-driven approaches are based on state...

  5. 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.

  6. SnO2 Nanostructure as Pollutant Gas Sensors: Synthesis, Sensing Performances, and Mechanism

    Directory of Open Access Journals (Sweden)

    Brian Yuliarto

    2015-01-01

    Full Text Available A significant amount of pollutants is produced from factories and motor vehicles in the form of gas. Their negative impact on the environment is well known; therefore detection with effective gas sensors is important as part of pollution prevention efforts. Gas sensors use a metal oxide semiconductor, specifically SnO2 nanostructures. This semiconductor is interesting and worthy of further investigation because of its many uses, for example, as lithium battery electrode, energy storage, catalyst, and transistor, and has potential as a gas sensor. In addition, there has to be a discussion of the use of SnO2 as a pollutant gas sensor especially for waste products such as CO, CO2, SO2, and NOx. In this paper, the development of the fabrication of SnO2 nanostructures synthesis will be described as it relates to the performances as pollutant gas sensors. In addition, the functionalization of SnO2 as a gas sensor is extensively discussed with respect to the theory of gas adsorption, the surface features of SnO2, the band gap theory, and electron transfer.

  7. Analyzer for measurement of nitrogen oxide concentration by ozone content reduction in gas using solid state chemiluminescent sensor

    Science.gov (United States)

    Chelibanov, V. P.; Ishanin, G. G.; Isaev, L. N.

    2014-05-01

    Role of nitrogen oxide in ambient air is described and analyzed. New method of nitrogen oxide concentration measurement in gas phase is suggested based on ozone concentration measurement with titration by nitrogen oxide. Research of chemiluminescent sensor composition is carried out on experimental stand. The sensor produced on the base of solid state non-activated chemiluminescent composition is applied as ozone sensor. Composition is put on the surface of polymer matrix with developed surface. Sensor compositions includes gallic acid with addition of rodamine-6G. Model of interaction process between sensor composition and ozone has been developed, main products appeared during reaction are identified. The product determining the speed of luminescense appearance is found. This product belongs to quinone class. Then new structure of chemiluminescent composition was suggested, with absence of activation period and with high stability of operation. Experimental model of gas analyzer was constructed and operation algorithm was developed. It was demonstrated that developed NO measuring instrument would be applied for monitoring purposes of ambient air. This work was partially financially supported by Government of Russian Federation, Grant 074-U01

  8. Operation of flooded wells by the gas-lift method

    Energy Technology Data Exchange (ETDEWEB)

    Li, G S; Kabirov, M M; Nigay, Yu V

    1983-01-01

    A study is made of the factors which influence the effectiveness of operation of the gas-lift lifter during progressive flooding of a well. The law governing the change in its efficiency under the given conditions is also examined.

  9. 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...

  10. Advances in Hydrogen, Carbon Dioxide, and Hydrocarbon Gas Sensor Technology Using GaN and ZnO-Based Devices

    Directory of Open Access Journals (Sweden)

    Jenshan Lin

    2009-06-01

    Full Text Available In this paper, we review our recent results in developing gas sensors for hydrogen using various device structures, including ZnO nanowires and GaN High Electron Mobility Transistors (HEMTs. ZnO nanowires are particularly interesting because they have a large surface area to volume ratio, which will improve sensitivity, and because they operate at low current levels, will have low power requirements in a sensor module. GaN-based devices offer the advantage of the HEMT structure, high temperature operation, and simple integration with existing fabrication technology and sensing systems. Improvements in sensitivity, recoverability, and reliability are presented. Also reported are demonstrations of detection of other gases, including CO2 and C2H4 using functionalized GaN HEMTs. This is critical for the development of lab-on-a-chip type systems and can provide a significant advance towards a market-ready sensor application.

  11. Advances in Hydrogen, Carbon Dioxide, and Hydrocarbon Gas Sensor Technology Using GaN and ZnO-Based Devices.

    Science.gov (United States)

    Anderson, Travis; Ren, Fan; Pearton, Stephen; Kang, Byoung Sam; Wang, Hung-Ta; Chang, Chih-Yang; Lin, Jenshan

    2009-01-01

    In this paper, we review our recent results in developing gas sensors for hydrogen using various device structures, including ZnO nanowires and GaN High Electron Mobility Transistors (HEMTs). ZnO nanowires are particularly interesting because they have a large surface area to volume ratio, which will improve sensitivity, and because they operate at low current levels, will have low power requirements in a sensor module. GaN-based devices offer the advantage of the HEMT structure, high temperature operation, and simple integration with existing fabrication technology and sensing systems. Improvements in sensitivity, recoverability, and reliability are presented. Also reported are demonstrations of detection of other gases, including CO(2) and C(2)H(4) using functionalized GaN HEMTs. This is critical for the development of lab-on-a-chip type systems and can provide a significant advance towards a market-ready sensor application.

  12. Titanium Dioxide-Based 64∘ YX LiNbO3 Surface Acoustic Wave Hydrogen Gas Sensors

    Directory of Open Access Journals (Sweden)

    A. Z. Sadek

    2008-01-01

    Full Text Available Amorphous titanium dioxide (TiO2 and gold (Au doped TiO2-based surface acoustic wave (SAW sensors have been investigated as hydrogen gas detectors. The nanocrystal-doped TiO2 films were synthesized through a sol-gel route, mixing a Ti-butoxide-based solution with diluted colloidal gold nanoparticles. The films were deposited via spin coating onto 64∘ YX LiNbO3 SAW transducers in a helium atmosphere. The SAW gas sensors were operated at various temperatures between 150 and 310∘C. It was found that gold doping on TiO2 increased the device sensitivity and reduced the optimum operating temperature.

  13. Scalable Pressure Sensor Based on Electrothermally Operated Resonator

    KAUST Repository

    Hajjaj, Amal Z.; Hafiz, Md Abdullah Al; Alcheikh, Nouha; Younis, Mohammad I.

    2017-01-01

    We experimentally demonstrate a new pressure sensor that offers the flexibility of being scalable to small sizes up to the nano regime. Unlike conventional pressure sensors that rely on large diaphragms and big-surface structures, the principle of operation here relies on convective cooling of the air surrounding an electrothermally heated resonant structure, which can be a beam or a bridge. This concept is demonstrated using an electrothermally tuned and electrostatically driven MEMS resonator, which is designed to be deliberately curved. We show that the variation of pressure can be tracked accurately by monitoring the change in the resonance frequency of the resonator at a constant electrothermal voltage. We show that the range of the sensed pressure and the sensitivity of detection are controllable by the amount of the applied electrothermal voltage. Theoretically, we verify the device concept using a multi-physics nonlinear finite element model. The proposed pressure sensor is simple in principle and design and offers the possibility of further miniaturization to the nanoscale.

  14. Scalable Pressure Sensor Based on Electrothermally Operated Resonator

    KAUST Repository

    Hajjaj, Amal Z.

    2017-11-03

    We experimentally demonstrate a new pressure sensor that offers the flexibility of being scalable to small sizes up to the nano regime. Unlike conventional pressure sensors that rely on large diaphragms and big-surface structures, the principle of operation here relies on convective cooling of the air surrounding an electrothermally heated resonant structure, which can be a beam or a bridge. This concept is demonstrated using an electrothermally tuned and electrostatically driven MEMS resonator, which is designed to be deliberately curved. We show that the variation of pressure can be tracked accurately by monitoring the change in the resonance frequency of the resonator at a constant electrothermal voltage. We show that the range of the sensed pressure and the sensitivity of detection are controllable by the amount of the applied electrothermal voltage. Theoretically, we verify the device concept using a multi-physics nonlinear finite element model. The proposed pressure sensor is simple in principle and design and offers the possibility of further miniaturization to the nanoscale.

  15. The Optimal Operation Criteria for a Gas Turbine Cogeneration System

    Directory of Open Access Journals (Sweden)

    Atsushi Akisawa

    2009-04-01

    Full Text Available The study demonstrated the optimal operation criteria of a gas turbine cogeneration system based on the analytical solution of a linear programming model. The optimal operation criteria gave the combination of equipment to supply electricity and steam with the minimum energy cost using the energy prices and the performance of equipment. By the comparison with a detailed optimization result of an existing cogeneration plant, it was shown that the optimal operation criteria successfully provided a direction for the system operation under the condition where the electric power output of the gas turbine was less than the capacity

  16. PALLADIUM DOPED TIN OXIDE BASED HYDROGEN GAS SENSORS FOR SAFETY APPLICATIONS

    International Nuclear Information System (INIS)

    Kasthurirengan, S.; Behera, Upendra; Nadig, D. S.

    2010-01-01

    Hydrogen is considered to be a hazardous gas since it forms a flammable mixture between 4 to 75% by volume in air. Hence, the safety aspects of handling hydrogen are quite important. For this, ideally, highly selective, fast response, small size, hydrogen sensors are needed. Although sensors based on different technologies may be used, thin-film sensors based on palladium (Pd) are preferred due to their compactness and fast response. They detect hydrogen by monitoring the changes to the electrical, mechanical or optical properties of the films. We report the development of Pd-doped tin-oxide based gas sensors prepared on thin ceramic substrates with screen printed platinum (Pt) contacts and integrated nicrome wire heaters. The sensors are tested for their performances using hydrogen-nitrogen gas mixtures to a maximum of 4%H 2 in N 2 . The sensors detect hydrogen and their response times are less than a few seconds. Also, the sensor performance is not altered by the presence of helium in the test gas mixtures. By the above desired performance characteristics, field trials of these sensors have been undertaken. The paper presents the details of the sensor fabrication, electronic circuits, experimental setup for evaluation and the test results.

  17. Data-driven fault detection, isolation and estimation of aircraft gas turbine engine actuator and sensors

    Science.gov (United States)

    Naderi, E.; Khorasani, K.

    2018-02-01

    In this work, a data-driven fault detection, isolation, and estimation (FDI&E) methodology is proposed and developed specifically for monitoring the aircraft gas turbine engine actuator and sensors. The proposed FDI&E filters are directly constructed by using only the available system I/O data at each operating point of the engine. The healthy gas turbine engine is stimulated by a sinusoidal input containing a limited number of frequencies. First, the associated system Markov parameters are estimated by using the FFT of the input and output signals to obtain the frequency response of the gas turbine engine. These data are then used for direct design and realization of the fault detection, isolation and estimation filters. Our proposed scheme therefore does not require any a priori knowledge of the system linear model or its number of poles and zeros at each operating point. We have investigated the effects of the size of the frequency response data on the performance of our proposed schemes. We have shown through comprehensive case studies simulations that desirable fault detection, isolation and estimation performance metrics defined in terms of the confusion matrix criterion can be achieved by having access to only the frequency response of the system at only a limited number of frequencies.

  18. Selectivity enhancement of indium-doped SnO2 gas sensors

    International Nuclear Information System (INIS)

    Salehi, A.

    2002-01-01

    Indium doping was used to enhance the selectivity of SnO 2 gas sensor. Both indium-doped and undoped SnO 2 gas sensors fabricated with different deposition techniques were investigated. The changes in the sensitivity of the sensors caused by selective gases (hydrogen and wood smoke) ranging from 500 to 3000 ppm were measured at different temperatures from 50 to 300 deg. C. The sensitivity peaks of the samples exhibit different values for selective gases with a response time of approximately 0.5 s. Thermally evaporated indium-doped SnO 2 gas sensor shows a considerable increase in the sensitivity peak of 27% in response to wood smoke, whereas it shows a sensitivity peak of 7% to hydrogen. This is in contrast to the sputter deposited indium-doped SnO 2 gas sensor, which exhibits a much lower sensitivity peak of approximately 2% to hydrogen and wood smoke compared to undoped SnO 2 gas sensors fabricated by chemical vapor deposition and spray pyrolysis. Scanning electron microscopy shows that different deposition techniques result in different porosity of the films. It is observed that the thermally evaporated indium-doped SnO 2 gas sensor shows high porosity, while the sputtered sample exhibits almost no porosity

  19. On-chip growth of semiconductor metal oxide nanowires for gas sensors: A review

    Directory of Open Access Journals (Sweden)

    Chu Manh Hung

    2017-09-01

    Full Text Available Semiconductor metal oxide nanowires (SMO-NWs show great potential for novel gas sensor applications because of their distinct properties, such as a high surface area to volume aspect ratio, high crystallinity and perfect pathway for electron transfer (length of NW. SMO-NW sensors can be configured as resistors or field-effect transistors for gas detection and different configurations, such as a single NW, multiple NWs, and networked NW films, have been established. Surface-functionalizing NWs with catalyst elements and self-heating NWs provide additional advantages for highly selective and low-power consumption gas sensors. However, an appropriate design of SMO-NWs is of practical importance in enhancing the gas-sensing performance of SMO-NW sensors. The on-chip growth of SMO-NWs possesses many advantages which can thus be effectively used for the large-scale fabrication of SMO-NW sensors with improved gas response and stability. This review aims to provide up-to-date information on the on-chip fabrication of SnO2, ZnO, WO3, CuO, and other SMO-NW sensors. It also discusses a variety of promising approaches that help advance the on-chip fabrication of SMO-NW-based gas sensors and other NW-based devices.

  20. Advanced Gas Sensors Using SERS-Activated Waveguides

    Science.gov (United States)

    Lascola, Robert; McWhorter, Scott; Murph, Simona Hunyadi

    2010-08-01

    non-specific interactions between the surface coating and additional nanoparticles suspended in solution to which the analyte had been coupled. Clearly, for a gas sensor, such a scheme is not feasible, and in any event the reliance on the random configuration of the nanoparticles and the analyte is not expected to lead to efficient enhancement. Here, we report the creation of capillary coatings of self-assembled, aggregated high aspect ratio metallic nanoparticles (e.g. rod, wires) with a solution-phase technique. Self-assembly offers the possibility for a high density of SERS hot spots, which are often observed at the junction of adjacent particles. Shaped nanoparticles also enhance self-assembled deposition, and allow further control of the optical properties of the coating through manipulation of the morphology. SERS enhancements for gases are reported relative to mirrored capillaries and free-space measurements.

  1. Application of Notched Long-Period Fiber Grating Based Sensor for CO2 Gas Sensing

    Science.gov (United States)

    Wu, Chao-Wei; Chiang, Chia-Chin

    2016-01-01

    An inductively coupled plasma etching process to fabricate notched long-period fiber gratings for CO2 gas sensing is proposed in this article. In the gas sensing test, the 15% mixed CO2 gas was used for characterization of CO2 adsorption by the amine-modified nanoporous silica foams of the notched long-period fiber grating sensor. The results shows the spectra were changed with the CO2 gas flow within 13 min. During the absorption process, the transmission of the resonant dip was decreased by 2.884 dB. Therefore, the proposed notched long-period fiber grating gas sensor shows good performance and is suitable as a gas sensor for monitoring the CO2 adsorption process.

  2. Mobile robot multi-sensor unit for unsupervised gas discrimination in uncontrolled environments

    OpenAIRE

    Xing, Yuxin; Vincent, Timothy A.; Cole, Marina; Gardner, Julian W.; Fan, Han; Hernandez Bennetts, Victor; Schaffernicht, Erik; Lilienthal, Achim

    2017-01-01

    In this work we present a novel multi-sensor unit to detect and discriminate unknown gases in uncontrolled environments. The unit includes three metal oxide (MOX) sensors with CMOS micro heaters, a plasmonic enhanced non-dispersive infra-red (NDIR) sensor, a commercial temperature humidity sensor, and a flow sensor. The proposed sensing unit was evaluated with plumes of gases (propanol, ethanol and acetone) in both, a laboratory setup on a gas testing bench and on-board a mobile robot operati...

  3. Sensor Selection for Aircraft Engine Performance Estimation and Gas Path Fault Diagnostics

    Science.gov (United States)

    Simon, Donald L.; Rinehart, Aidan W.

    2016-01-01

    This paper presents analytical techniques for aiding system designers in making aircraft engine health management sensor selection decisions. The presented techniques, which are based on linear estimation and probability theory, are tailored for gas turbine engine performance estimation and gas path fault diagnostics applications. They enable quantification of the performance estimation and diagnostic accuracy offered by different candidate sensor suites. For performance estimation, sensor selection metrics are presented for two types of estimators including a Kalman filter and a maximum a posteriori estimator. For each type of performance estimator, sensor selection is based on minimizing the theoretical sum of squared estimation errors in health parameters representing performance deterioration in the major rotating modules of the engine. For gas path fault diagnostics, the sensor selection metric is set up to maximize correct classification rate for a diagnostic strategy that performs fault classification by identifying the fault type that most closely matches the observed measurement signature in a weighted least squares sense. Results from the application of the sensor selection metrics to a linear engine model are presented and discussed. Given a baseline sensor suite and a candidate list of optional sensors, an exhaustive search is performed to determine the optimal sensor suites for performance estimation and fault diagnostics. For any given sensor suite, Monte Carlo simulation results are found to exhibit good agreement with theoretical predictions of estimation and diagnostic accuracies.

  4. A Novel Solid State Non-Dispersive Infrared CO2 Gas Sensor Compatible with Wireless and Portable Deployment

    Directory of Open Access Journals (Sweden)

    Desmond Gibson

    2013-05-01

    Full Text Available This paper describes development of a novel mid-infrared light emitting diode (LED and photodiode (PD light source/detector combination and use within a non-dispersive infrared (NDIR carbon dioxide gas sensor. The LED/PD based NDIR sensor provides fast stabilisation time (time required to turn on the sensor from cold, warm up, take and report a measurement, and power down again ≈1 second, longevity (>15 years, low power consumption and low cost. Described performance is compatible with “fit and forget” wireless deployed sensors in applications such as indoor air quality monitoring/control & energy conservation in buildings, transport systems, horticultural greenhouses and portable deployment for safety, industrial and medical applications. Fast stabilisation time, low intrinsic power consumption and cycled operation offer typical energy consumption per measurement of mJ’s, providing extended operation using battery and/or energy harvesting strategies (measurement interval of ≈ 2 minutes provides >10 years operation from one AA battery. Specific performance data is provided in relation to measurement accuracy and noise, temperature performance, cross sensitivity, measurement range (two pathlength variants are described covering ambient through to 100% gas concentration, comparison with NDIR utilizing thermal source/pyroelectric light source/detector combination and compatibility with energy harvesting. Semiconductor based LED/PD processing together with injection moulded reflective optics and simple assembly provide a route to low cost high volume manufacturing.

  5. A novel solid state non-dispersive infrared CO2 gas sensor compatible with wireless and portable deployment.

    Science.gov (United States)

    Gibson, Desmond; MacGregor, Calum

    2013-05-29

    This paper describes development of a novel mid-infrared light emitting diode (LED) and photodiode (PD) light source/detector combination and use within a non-dispersive infrared (NDIR) carbon dioxide gas sensor. The LED/PD based NDIR sensor provides fast stabilisation time (time required to turn on the sensor from cold, warm up, take and report a measurement, and power down again ≈1 second), longevity (>15 years), low power consumption and low cost. Described performance is compatible with "fit and forget" wireless deployed sensors in applications such as indoor air quality monitoring/control & energy conservation in buildings, transport systems, horticultural greenhouses and portable deployment for safety, industrial and medical applications. Fast stabilisation time, low intrinsic power consumption and cycled operation offer typical energy consumption per measurement of mJ's, providing extended operation using battery and/or energy harvesting strategies (measurement interval of ≈ 2 minutes provides >10 years operation from one AA battery). Specific performance data is provided in relation to measurement accuracy and noise, temperature performance, cross sensitivity, measurement range (two pathlength variants are described covering ambient through to 100% gas concentration), comparison with NDIR utilizing thermal source/pyroelectric light source/detector combination and compatibility with energy harvesting. Semiconductor based LED/PD processing together with injection moulded reflective optics and simple assembly provide a route to low cost high volume manufacturing.

  6. A simple operational gas release and swelling model. Pt. 1

    International Nuclear Information System (INIS)

    Wood, M.H.; Matthews, J.R.

    1980-01-01

    A new and simple model of fission gas release and swelling has been developed for oxide nuclear fuel under operational conditions. The model, which is to be incorporated into a fuel element behaviour code, is physically based and applicable to fuel at both thermal and fast reactor ratings. In this paper we present that part of the model describing the behaviour of intragranular gas: a future paper will detail the treatment of the grain boundary gas. The results of model calculations are compared with recent experimental observations of intragranular bubble concentrations and sizes, and gas release from fuel irradiated under isothermal conditions. Good agreement is found between experiment and theory. (orig.)

  7. Characterization of gas sensors for measurement of unburned gases in small district heating furnaces; Karaktaerisering av gassensorer foer maetning av ofoerbraenda aemnen i naervaermecentraler

    Energy Technology Data Exchange (ETDEWEB)

    Eskilsson, David; Roennbaeck, Marie [Swedish National Testing and Research Inst., Boraas (Sweden)

    2004-11-01

    Small district heating boilers are often equipped with a simple O{sub 2}-gauge (lambda sensor) that controls the air supply. There is a great need in small furnaces of continuous measurements of several gas components such as CO, THC and NO{sub x} by simple and cheap technique. Recently, new types of cheap gas sensors have been developed which can be suitable. These gas sensors measure the amount of unburned species (sum of carbon monoxide, hydrocarbons and hydrogen). The objective with this project has been to characterise several gas sensors for unburnt in order to evaluate if they are suitable for combustion control and surveillance of small district heating furnaces. In this work three different gas sensors have been characterised. The sensors were characterised in the laboratory where they were exposed for mixtures of pure gases. The sensors were mounted inside the flue gas channel from a small district heating furnace during 3 months in order to estimate the sensors robustness and the character of the signal in flue gas. The tests with pure gases show that all sensors also reacts for other components besides CO and THC. It is mainly the oxygen concentrations that affect the sensors characteristics but also an altered humidity is important. Measurements in the small district heating furnace showed that none of the sensors was able to measure correctly when mounted directly in the flue gas channel (in situ). The in situ sensors are covered with fly ash and the fly ash also slowly destroys the sensors. Sensors mounted after a filter (exposed for a particle free flue gas) work satisfactory. All of the tested sensors, mounted after a filter, follow the changes in CO concentration well. Some of the sensors are capable of detecting CO as low as 15 ppm. But the accuracy of how well the sensors are able to detect CO varies from sensor to sensor. The measurements also show that even if the sensor is able to follow the changes in CO concentration, the ground signal of

  8. European standards applied by Gas Transmission System Operator

    International Nuclear Information System (INIS)

    Witek, M.; Kuchta, K.; Oleszkiewicz, J.; Teperek, T.

    2005-01-01

    The lecture described actual state of implementation of European standards concerning transmission of natural gas and underlined their importance for proper performance of Transmission System Operator (TSO). European standards implemented to Polish Standards as PN-EN, necessary for TSO, related to design, construction and operation of high pressure gas network were also described. The lecture underlined as well the impact of standards application on preparation process of national regulations. They obligate TSO to create the technical conditions that ensure safety of gas transmission network functioning as well as environmental and surroundings safety. (authors)

  9. Enhancement of methane gas sensing characteristics of graphene oxide sensor by heat treatment and laser irradiation.

    Science.gov (United States)

    Assar, Mohammadreza; Karimzadeh, Rouhollah

    2016-12-01

    The present study uses a rapid, easy and practical method for cost-effective fabrication of a methane gas sensor. The sensor was made by drop-casting a graphene oxide suspension onto an interdigital circuit surface. The electrical conductivity and gas-sensing characteristics of the sensor were determined and then heat treatment and in situ laser irradiation were applied to improve the device conductivity and gas sensitivity. Real-time monitoring of the evolution of the device current as a function of heat treatment time revealed significant changes in the conductance of the graphene oxide sensor. The use of low power laser irradiation enhanced both the electrical conductivity and sensing response of the graphene oxide sensor. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Kaunas gas, Lithuania. Operation and maintenance report. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    The main objective of this project was to transfer knowledge accumulated in Denmark about modern techniques of natural gas distribution to employees of the Lithuanian gas sector by informing them about modern measuring equipment and evaluating the results. The main objectives were: To improve the efficiency of maintenance and repair works of the distribution network in Kaunas; To decrease the number of leakages and to improve the operation of the cathodic protection system; To ensure protection of the pipelines and to avoid damages on other constructions and installations. The project consisted of four components which will all exert an influence on the future rehabilitation of steel pipe networks in the gas sector of Lithuania. The components were the following: Preparation of Operation and Maintenance Manual for Kaunas Gas Company; Cathodic measuring and pilot investigation; Analysis and improvement of the organisation of the Kaunas Gas Company; Training material for cathodic protection in Lithaunia. (au)

  11. Oxygen sensor using proton-conductor thick-film operative at room temperature. Puroton dodentai atsumaku wo mochiita joon sadogata sanso sensor

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Norio; Yoshida, Nobuaki; Matayoshi, Naoko; Shimizu, Yoichi; Yamazoe, Noboru; Kuwata, Shigeki [Kyushu Univ., Fukuoka, (Japan) Niihama National College of Tech., Ehime, (Japan)

    1989-10-01

    An amperometric solid-state oxygen sensor using a proton-conductor thick-film was examined as a miniaturized and intelligent oxygen sensor operative at room temperature. The good-conditioned proton-conductor film of about 10{mu}m in thickness without holes was formed on a porous alumina substrate by spin-coating the paste containing antimonic acid and a polyvinyl alcohol binder. Using this material, the thick-film oxygen sensor was made. A limiting current, controlled by oxygen permeation through the gas-diffusion layer, was observed when an external voltage was over 1.4V. The limiting current increased linearly with an increase in oxygen partial pressure up to 1.0 atm at an external voltage of 1.6V. The 90% response time for increasing oxygen partial pressure was about 40 seconds at 30 centigrade. Moreover, it was found that the sensor could also respond to dissolved oxygen in water at room temperature. With a sensor using a hydrophobic gas-diffusion layer containing a polystyrene binder, the limiting current was linear to the dissolved oxygen concentration up to 20ppm. 15 refs., 5 figs.

  12. Micro-Structured Sapphire Fiber Sensors for Simultaneous Measurements of High-T and Dynamic Gas Pressure in Harsh Environments

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Hai [Clemson Univ., SC (United States); Tsai, Hai-Lung [Missouri Univ. of Science and Technology, Rolla, MO (United States); Dong, Junhang [Univ. of Cincinnati, OH (United States)

    2014-09-30

    This is the final report for the program “Micro-Structured Sapphire Fiber Sensors for Simultaneous Measurements of High Temperature and Dynamic Gas Pressure in Harsh Environments”, funded by NETL, and performed by Missouri University of Science and Technology, Clemson University and University of Cincinnati from October 1, 2009 to September 30, 2014. Securing a sustainable energy economy by developing affordable and clean energy from coal and other fossil fuels is a central element to the mission of The U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL). To further this mission, NETL funds research and development of novel sensor technologies that can function under the extreme operating conditions often found in advanced power systems. The main objective of this research program is to conduct fundamental and applied research that will lead to successful development and demonstration of robust, multiplexed, microstructured silica and single-crystal sapphire fiber sensors to be deployed into the hot zones of advanced power and fuel systems for simultaneous measurements of high temperature and gas pressure. The specific objectives of this research program include: 1) Design, fabrication and demonstration of multiplexed, robust silica and sapphire fiber temperature and dynamic gas pressure sensors that can survive and maintain fully operational in high-temperature harsh environments. 2) Development and demonstration of a novel method to demodulate the multiplexed interferograms for simultaneous measurements of temperature and gas pressure in harsh environments. 3) Development and demonstration of novel sapphire fiber cladding and low numerical aperture (NA) excitation techniques to assure high signal integrity and sensor robustness.

  13. Integrating Metal-Oxide-Decorated CNT Networks with a CMOS Readout in a Gas Sensor

    Directory of Open Access Journals (Sweden)

    Suhwan Kim

    2012-02-01

    Full Text Available We have implemented a tin-oxide-decorated carbon nanotube (CNT network gas sensor system on a single die. We have also demonstrated the deposition of metallic tin on the CNT network, its subsequent oxidation in air, and the improvement of the lifetime of the sensors. The fabricated array of CNT sensors contains 128 sensor cells for added redundancy and increased accuracy. The read-out integrated circuit (ROIC was combined with coarse and fine time-to-digital converters to extend its resolution in a power-efficient way. The ROIC is fabricated using a 0.35 µm CMOS process, and the whole sensor system consumes 30 mA at 5 V. The sensor system was successfully tested in the detection of ammonia gas at elevated temperatures.

  14. Harsh Environment Gas Sensor Array for Venus Atmospheric Measurements, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Makel Engineering and the Ohio State University propose to develop a harsh environment tolerant gas sensor array for atmospheric analysis in future Venus missions....

  15. A physicochemical mechanism of chemical gas sensors using an AC analysis.

    Science.gov (United States)

    Moon, Jaehyun; Park, Jin-Ah; Lee, Su-Jae; Lee, Jeong-Ik; Zyung, Taehyong; Shin, Eui-Chol; Lee, Jong-Sook

    2013-06-21

    Electrical modeling of the chemical gas sensors was successfully applied to TiO2 nanofiber gas sensors by developing an equivalent circuit model where the junction capacitance as well as the resistance can be separated from the comparable stray capacitance. The Schottky junction impedance exhibited a characteristic skewed arc described by a Cole-Davidson function, and the variation of the fit and derived parameters with temperature, bias, and NO2 gas concentration indicated definitely a physicochemical sensing mechanism based on the Pt|TiO2 Schottky junctions against the conventional supposition of the enhanced sensitivity in nanostructured gas sensors with high grain boundary/surface area. Analysis on a model Pt|TiO2|Pt structure also confirmed the characteristic impedance response of TiO2 nanofiber sensors.

  16. Diode Laser-Based Sensor for Fast Measurement of Binary Gas Mixtures

    National Research Council Canada - National Science Library

    McNesby, Kevin

    1999-01-01

    The development and characterization of a gas sensor to measure binary mixtures of oxygen and the vapor from a series of volatile organic compounds, with a time resolution of 10 milliseconds, is described...

  17. High-Temperature, High-Bandwidth Fiber Optic Pressure and Temperature Sensors for Gas Turbine Applications

    National Research Council Canada - National Science Library

    Fielder, Robert S; Palmer, Matthew E

    2003-01-01

    ..., and redesign compressor and turbine stages based on actual measurements. There currently exists no sensor technology capable of making pressure measurements in the critical hot regions of gas turbine engines...

  18. Toward high value sensing: monolayer-protected metal nanoparticles in multivariable gas and vapor sensors.

    Science.gov (United States)

    Potyrailo, Radislav A

    2017-08-29

    For detection of gases and vapors in complex backgrounds, "classic" analytical instruments are an unavoidable alternative to existing sensors. Recently a new generation of sensors, known as multivariable sensors, emerged with a fundamentally different perspective for sensing to eliminate limitations of existing sensors. In multivariable sensors, a sensing material is designed to have diverse responses to different gases and vapors and is coupled to a multivariable transducer that provides independent outputs to recognize these diverse responses. Data analytics tools provide rejection of interferences and multi-analyte quantitation. This review critically analyses advances of multivariable sensors based on ligand-functionalized metal nanoparticles also known as monolayer-protected nanoparticles (MPNs). These MPN sensing materials distinctively stand out from other sensing materials for multivariable sensors due to their diversity of gas- and vapor-response mechanisms as provided by organic and biological ligands, applicability of these sensing materials for broad classes of gas-phase compounds such as condensable vapors and non-condensable gases, and for several principles of signal transduction in multivariable sensors that result in non-resonant and resonant electrical sensors as well as material- and structure-based photonic sensors. Such features should allow MPN multivariable sensors to be an attractive high value addition to existing analytical instrumentation.

  19. Acoustic sensor for in-pile fuel rod fission gas release measurement

    International Nuclear Information System (INIS)

    Fourmentel, D.; Villard, J. F.; Ferrandis, J. Y.; Augereau, F.; Rosenkrantz, E.; Dierckx, M.

    2009-01-01

    We have developed a specific acoustic sensor to improve the knowledge of fission gas release in Pressurized Water Reactor (PWR) fuel rods when irradiated in materials testing reactors. In order to perform experimental programs related to the study of the fission gas release kinetics, the CEA (French Nuclear Energy Commission) acquired the ability to equip a pre-irradiated PWR fuel rod with three sensors, allowing the simultaneous on-line measurements of the following parameters: - fuel temperature with a centre-line thermocouple type C, - internal pressure with a specific counter-pressure sensor, - fraction of fission gas released in the fuel rod with an innovative acoustic sensor. The third detector is the subject of this paper. This original acoustic sensor has been designed to measure the molar mass and pressure of the gas contained in the fuel rod plenum. For in-pile instrumentation, the fraction of fission gas, such as Krypton and Xenon, in Helium, can be deduced online from this measurement. The principle of this acoustical sensor is the following: a piezoelectric transducer generates acoustic waves in a cavity connected to the fuel rod plenum. The acoustic waves are propagated and reflected in this cavity and then detected by the transducer. The data processing of the signal gives the velocity of the acoustic waves and their amplitude, which can be related respectively to the molar mass and to the pressure of the gas. The piezoelectric material of this sensor has been qualified in nuclear conditions (gamma and neutron radiations). The complete sensor has also been specifically designed to be implemented in materials testing reactors conditions. For this purpose some technical points have been studied in details: - fixing of the piezoelectric sample in a reliable way with a suitable signal transmission, - size of the gas cavity to avoid any perturbation of the acoustic waves, - miniaturization of the sensor because of narrow in-pile experimental devices

  20. The Effects of Two Thick Film Deposition Methods on Tin Dioxide Gas Sensor Performance

    OpenAIRE

    Bakrania, Smitesh D.; Wooldridge, Margaret S.

    2009-01-01

    This work demonstrates the variability in performance between SnO2 thick film gas sensors prepared using two types of film deposition methods. SnO2 powders were deposited on sensor platforms with and without the use of binders. Three commonly utilized binder recipes were investigated, and a new binder-less deposition procedure was developed and characterized. The binder recipes yielded sensors with poor film uniformity and poor structural integrity, compared to the binder-less deposition meth...

  1. Palladium Gate All Around - Hetero Dielectric -Tunnel FET based highly sensitive Hydrogen Gas Sensor

    Science.gov (United States)

    Madan, Jaya; Chaujar, Rishu

    2016-12-01

    The paper presents a novel highly sensitive Hetero-Dielectric-Gate All Around Tunneling FET (HD-GAA-TFET) based Hydrogen Gas Sensor, incorporating the advantages of band to band tunneling (BTBT) mechanism. Here, the Palladium supported silicon dioxide is used as a sensing media and sensing relies on the interaction of hydrogen with Palladium-SiO2-Si. The high surface to volume ratio in the case of cylindrical GAA structure enhances the fortuities for surface reactions between H2 gas and Pd, and thus improves the sensitivity and stability of the sensor. Behaviour of the sensor in presence of hydrogen and at elevated temperatures is discussed. The conduction path of the sensor which is dependent on sensors radius has also been varied for the optimized sensitivity and static performance analysis of the sensor where the proposed design exhibits a superior performance in terms of threshold voltage, subthreshold swing, and band to band tunneling rate. Stability of the sensor with respect to temperature affectability has also been studied, and it is found that the device is reasonably stable and highly sensitive over the bearable temperature range. The successful utilization of HD-GAA-TFET in gas sensors may open a new door for the development of novel nanostructure gas sensing devices.

  2. Selective mixed potential based ammonia exhaust gas sensor; Selektiver Ammoniakabgassensor auf Mischpotentialbasis

    Energy Technology Data Exchange (ETDEWEB)

    Schoenauer, D.; Moos, R. [Bayreuth Univ. (Germany). Lehrstuhl fuer Funktionsmaterialien; Wiesner, K.; Fleischer, M. [Siemens AG, CT PS 6, Muenchen (Germany)

    2007-07-01

    Mixed potential sensors with additional catalytic deposits on one of two electrodes show a high potential for NH{sub 3} detection. With defined reactions at the covered electrode it is possible to derive a temperature dependent correlation between the gas concentration/composition and the sensor signal which is characteristic for the used electrode material and the catalyst.

  3. Exploitation of Unique Properties of Zeolites in the Development of Gas Sensors

    Directory of Open Access Journals (Sweden)

    Prabir K. Dutta

    2012-04-01

    Full Text Available The unique properties of microporous zeolites, including ion-exchange properties, adsorption, molecular sieving, catalysis, conductivity have been exploited in improving the performance of gas sensors. Zeolites have been employed as physical and chemical filters to improve the sensitivity and selectivity of gas sensors. In addition, direct interaction of gas molecules with the extraframework cations in the nanoconfined space of zeolites has been explored as a basis for developing new impedance-type gas/vapor sensors. In this review, we summarize how these properties of zeolites have been used to develop new sensing paradigms. There is a considerable breadth of transduction processes that have been used for zeolite incorporated sensors, including frequency measurements, optical and the entire gamut of electrochemical measurements. It is clear from the published literature that zeolites provide a route to enhance sensor performance, and it is expected that commercial manifestation of some of the approaches discussed here will take place. The future of zeolite-based sensors will continue to exploit its unique properties and use of other microporous frameworks, including metal organic frameworks. Zeolite composites with electronic materials, including metals will lead to new paradigms in sensing. Use of nano-sized zeolite crystals and zeolite membranes will enhance sensor properties and make possible new routes of miniaturized sensors.

  4. Sensors of the gas CO in thin film of SnO{sub 2}:Cu; Sensores del gas CO en pelicula delgada de SnO{sub 2}:Cu

    Energy Technology Data Exchange (ETDEWEB)

    Tirado G, S.; Sanchez Z, F. E., E-mail: tirado@esfm.ipn.mx [IPN, Escuela Superior de Fisica y Matematicas, Unidad Profesional Adolfo Lopez Mateos, San Pedro Zacatenco, 07738 Mexico D. F. (Mexico)

    2011-10-15

    Thin films of SnO{sub 2}:Cu with different thickness, were deposited on soda-lime glass substrates and prepared by the Sol-gel process and repeated immersion. The sensor properties of these films to the gas CO for the range of 0-200 ppm in the gas concentration and operating to temperatures of 23, 100, 200, and 300 C were studied. Prepared films of pure SnO{sub 2} were modified superficially with 1, 3, 5 and 10 layers of the catalyst Cu (SnO{sub 2}:Cu) with the purpose of studying the effect on the sensor capacity of the gas CO by part of the films SnO{sub 2}:Cu. Using the changes in the electric properties of the films with the incorporation of the different copper layers and experimental conditions, the sensor modifications of the gas CO were evaluated. To complete this study, was realized a characterization of the superficial morphology of the films by scanning electron microscopy and atomic force microscopy, equally was studied their structure and their electric and optical properties. (Author)

  5. Mapping reactor operating regimes for heavy gas oil hydrotreating

    Energy Technology Data Exchange (ETDEWEB)

    Munteanu, Mugurel Catalin; Chen, Jinwen [CanmetENERGY, Natural Resources Canada (Canada)

    2011-07-01

    Hydrotreating (HDT) is used in oil refineries at temperatures of 350-400 degree C and pressure of 50-100 bars in a fixed bed to improve the quality of distillate fraction. HDT operates as a gas-liquid-solid process, trickle bed. Efforts have been made to model it but volatilization of liquid oil is often ignored. The aim of this paper is to predict vapor-liquid equilibrium (VLE) for a typical heavy distillate feed in pilot plant hydrotreaters. The study was conducted under various operating conditions and a flash calculation program calibrated in-house was used to predict VLE. VLE values were found and results showed that higher pressure, lower gas/oil ratio and temperature should be used to maintain the desired operating regimes when hydrotreating heavy distillate feed. This study determined the operating conditions for maintaining the desired operating regimes and these findings could be useful for operators.

  6. A novel methanol sensor based on gas-penetration through a porous polypyrrole-coated polyacrylonitrile nanofiber mat.

    Science.gov (United States)

    Jun, Tae-Sun; Ho, Thi Anh; Rashid, Muhammad; Kim, Yong Shin

    2013-09-01

    In this work, we propose a novel chemoresistive gas sensor operated under a vertical analyte flow passing through a permeable sensing membrane. Such a configuration is different from the use of a planar sensor implemented under a conventional horizontal flow. A highly porous core-shell polyacrylonitrile-polypyrrole (PAN@PPy) nanofiber mat was prepared as the sensing element via electrospinning and two-step vapor-phase polymerization (VPP). Various analysis methods such as SEM, TEM, FT-IR and XPS measurements were employed in order to characterize structural features of the porous sensing mat. These analyses confirmed that very thin (ca. 10 nm) conductive PPy sheath layers were deposited by VPP on electrospun PAN nanofibers with an average diameter of 258 nm. Preliminary results revealed that the gas penetration-type PAN@PPy sensor had a higher sensor response and shorter detection and recovery times upon exposure to methanol analyte when compared with a conventional horizontal flow sensor due to efficient and fast analyte transfer into the sensing layer.

  7. Sulfophenyl-Functionalized Reduced Graphene Oxide Networks on Electrospun 3D Scaffold for Ultrasensitive NO2 Gas Sensor

    Directory of Open Access Journals (Sweden)

    Bin Zou

    2017-12-01

    Full Text Available Ultrasensitive room temperature real-time NO2 sensors are highly desirable due to potential threats on environmental security and personal respiratory. Traditional NO2 gas sensors with highly operated temperatures (200–600 °C and limited reversibility are mainly constructed from semiconducting oxide-deposited ceramic tubes or inter-finger probes. Herein, we report the functionalized graphene network film sensors assembled on an electrospun three-dimensional (3D nanonetwork skeleton for ultrasensitive NO2 sensing. The functional 3D scaffold was prepared by electrospinning interconnected polyacrylonitrile (PAN nanofibers onto a nylon window screen to provide a 3D nanonetwork skeleton. Then, the sulfophenyl-functionalized reduced graphene oxide (SFRGO was assembled on the electrospun 3D nanonetwork skeleton to form SFRGO network films. The assembled functionalized graphene network film sensors exhibit excellent NO2 sensing performance (10 ppb to 20 ppm at room temperature, reliable reversibility, good selectivity, and better sensing cycle stability. These improvements can be ascribed to the functionalization of graphene with electron-withdrawing sulfophenyl groups, the high surface-to-volume ratio, and the effective sensing channels from SFRGO wrapping onto the interconnected 3D scaffold. The SFRGO network-sensing film has the advantages of simple preparation, low cost, good processability, and ultrasensitive NO2 sensing, all advantages that can be utilized for potential integration into smart windows and wearable electronic devices for real-time household gas sensors.

  8. Sulfophenyl-Functionalized Reduced Graphene Oxide Networks on Electrospun 3D Scaffold for Ultrasensitive NO₂ Gas Sensor.

    Science.gov (United States)

    Zou, Bin; Guo, Yunlong; Shen, Nannan; Xiao, Anshan; Li, Mingjun; Zhu, Liang; Wan, Pengbo; Sun, Xiaoming

    2017-12-19

    Ultrasensitive room temperature real-time NO₂ sensors are highly desirable due to potential threats on environmental security and personal respiratory. Traditional NO₂ gas sensors with highly operated temperatures (200-600 °C) and limited reversibility are mainly constructed from semiconducting oxide-deposited ceramic tubes or inter-finger probes. Herein, we report the functionalized graphene network film sensors assembled on an electrospun three-dimensional (3D) nanonetwork skeleton for ultrasensitive NO₂ sensing. The functional 3D scaffold was prepared by electrospinning interconnected polyacrylonitrile (PAN) nanofibers onto a nylon window screen to provide a 3D nanonetwork skeleton. Then, the sulfophenyl-functionalized reduced graphene oxide (SFRGO) was assembled on the electrospun 3D nanonetwork skeleton to form SFRGO network films. The assembled functionalized graphene network film sensors exhibit excellent NO₂ sensing performance (10 ppb to 20 ppm) at room temperature, reliable reversibility, good selectivity, and better sensing cycle stability. These improvements can be ascribed to the functionalization of graphene with electron-withdrawing sulfophenyl groups, the high surface-to-volume ratio, and the effective sensing channels from SFRGO wrapping onto the interconnected 3D scaffold. The SFRGO network-sensing film has the advantages of simple preparation, low cost, good processability, and ultrasensitive NO₂ sensing, all advantages that can be utilized for potential integration into smart windows and wearable electronic devices for real-time household gas sensors.

  9. New European context for gas producers/operators

    International Nuclear Information System (INIS)

    Deyirmendjian, J.

    2008-01-01

    The development of the European Union towards more integration would enter a new phase if the draft Third Directive regarding the natural gas industry and the deregulation of gas markets would be validated as it stands. The stakes for gas producing/operating companies are very high: they must position themselves either as networks and installations companies or as production and trading companies - meaning regulation and recurring revenues or the opportunities and risks of production and trade. Changes such these, added to the globalisation of gas flows linked to the development of liquefied natural gas (LNG), require more investments than in the past. These additional investments and this technological progress nevertheless give hope that this transformation will not noticeably weaken the security of gas supplies within the European Union (EU) despite the greater volatility of the markets, which are increasingly dominated by the strategies of financial operators. The author reviews the history of the development of the gas distribution networks in Europe and discusses details of the new draft directive aiming at more competition on a market that has been dominated so far by vertical structures. Similarities and differences to the deregulation of the European electricity market are discussed. The divergent attitudes of the EU Member States and the negotiation strategy of the European Commission are discussed. Merges of gas and electricity utilities are on the agenda. The author then reviews the current situation of natural gas consumption and supplies and the transportation and distribution facilities. Political factors influencing the security of supply are discussed. Underground gas storage facilities are crucial in this context. Several projects for new main gas pipelines are discussed. Diversification of supply sources is considered as of strategic relevance. The article is richly illustrated and includes several maps and diagrams.

  10. Hydrogen Detection With a Gas Sensor Array – Processing and Recognition of Dynamic Responses Using Neural Networks

    Directory of Open Access Journals (Sweden)

    Gwiżdż Patryk

    2015-03-01

    Full Text Available An array consisting of four commercial gas sensors with target specifications for hydrocarbons, ammonia, alcohol, explosive gases has been constructed and tested. The sensors in the array operate in the dynamic mode upon the temperature modulation from 350°C to 500°C. Changes in the sensor operating temperature lead to distinct resistance responses affected by the gas type, its concentration and the humidity level. The measurements are performed upon various hydrogen (17-3000 ppm, methane (167-3000 ppm and propane (167-3000 ppm concentrations at relative humidity levels of 0-75%RH. The measured dynamic response signals are further processed with the Discrete Fourier Transform. Absolute values of the dc component and the first five harmonics of each sensor are analysed by a feed-forward back-propagation neural network. The ultimate aim of this research is to achieve a reliable hydrogen detection despite an interference of the humidity and residual gases.

  11. On electrochemical sensor for determining elemental iodine in gas media

    International Nuclear Information System (INIS)

    Goffman, V.G.; Shajmerdinov, B.U.; Kotelkin, I.M.; Mikhajlova, A.M.; Dobrovol'skij, Yu.A.

    1993-01-01

    The possibility to use solid electrolyte cells of Ag, AgI/AgI/Au as sensors for determining concentration of element iodine in gaseous media was studied. Independent character of sensor parameters on oxygen content and radiation burden at different humidity was ascertained

  12. Influence of Fabricating Process on Gas Sensing Properties of ZnO Nanofiber-Based Sensors

    International Nuclear Information System (INIS)

    Xu Lei; Wang Rui; Liu Yong; Dong Liang

    2011-01-01

    ZnO nanofibers are synthesized by an electrospinning method and characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). Two types of gas sensors are fabricated by loading these nanofibers as the sensing materials and their performances are investigated in detail. Compared with the sensors based on traditional ceramic tubes with Au electrodes (traditional sensors), the sensors fabricated by spinning ZnO nanofibers on ceramic planes with Ag-Pd electrodes (plane sensors) exhibit much higher sensing properties. The sensitivity for the plane sensors is about 30 to 100 ppm ethanol at 300°C, while the value is only 13 for the traditional sensors. The response and recovery times are about 2 and 3s for the plane sensors and are 3 and 6s for the traditional sensors, respectively. Lower minimum-detection-limit is also found for the plane sensors. These improvements are explained by considering the morphological damage in the fabricating process for traditional sensors. The results suggest that the plane sensors are more suitable to sensing investigation for higher veracity. (general)

  13. Kinetic response study in chemiresistive gas sensor based on carbon nanotube surface functionalized with substituted phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Anshul Kumar; Saini, Rajan; Bedi, R. K.; Mahajan, Aman, E-mail: dramanmahajan@yahoo.co.in, E-mail: anshulsharma.phy@gmail.com [Material Science Laboratory, Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Kumar, Pankaj [Department of Applied Sciences, I.K. Gujral Punjab Technical University, Kapurthala 144601 (India)

    2016-05-06

    A kind of hybrid material is prepared by functionalizing multi-wall carbon nanotubes (MWCNTs-COOH) with substituted copper phthalocyanine and the formation of CuPcOC{sub 8}/MWCNTs-COOH hybrid is confirmed by scanning electron microscopy and transmission electron microscopy. The results indicated that on the surface of nanotubes substituted CuPcOC{sub 8} derivatives has been successfully anchored through π-π stacking interaction. The gas sensing application of the fabricated hybrid material is tested upon exposure to different hazardous species, specifically NO{sub 2}, NO, Cl{sub 2} and NH{sub 3} at operating temperature of 150°C. It has been demonstrated that for Cl{sub 2} minimum detection limit of CuPcOC{sub 8}/MWCNTs-COOH hybrid is 100 ppb. The response of hybrid sensor is found to be increased with increase in the concentration of Cl{sub 2}.

  14. Using Wireless Sensor Networks to Achieve Intelligent Monitoring for High-Temperature Gas-Cooled Reactor

    Directory of Open Access Journals (Sweden)

    Jianghai Li

    2017-01-01

    Full Text Available High-temperature gas-cooled reactors (HTGR can incorporate wireless sensor network (WSN technology to improve safety and economic competitiveness. WSN has great potential in monitoring the equipment and processes within nuclear power plants (NPPs. This technology not only reduces the cost of regular monitoring but also enables intelligent monitoring. In intelligent monitoring, large sets of heterogeneous data collected by the WSN can be used to optimize the operation and maintenance of the HTGR. In this paper, WSN-based intelligent monitoring schemes that are specific for applications of HTGR are proposed. Three major concerns regarding wireless technology in HTGR are addressed: wireless devices interference, cybersecurity of wireless networks, and wireless standards selected for wireless platform. To process nonlinear and non-Gaussian data obtained by WSN for fault diagnosis, novel algorithms combining Kernel Entropy Component Analysis (KECA and support vector machine (SVM are developed.

  15. Design and simulation of resistive SOI CMOS micro-heaters for high temperature gas sensors

    International Nuclear Information System (INIS)

    Iwaki, T; Covington, J A; Udrea, F; Ali, S Z; Guha, P K; Gardner, J W

    2005-01-01

    This paper describes the design of doped single crystal silicon (SCS) microhotplates for gas sensors. Resistive heaters are formed by an n+/p+ implantation into a Silicon-On-Insulator (SOI) wafer with a post-CMOS deep reactive ion etch to remove the silicon substrate. Hence they are fully compatible with CMOS technologies and allows for the integration of associated drive/detection circuitry. 2D electro-thermal models have been constructed and the results of numerical simulations using FEMLAB[reg] are given. Simulations show these micro-hotplates can operate at temperatures of 500 deg. C with a drive voltage of only 5 V and a power consumption of less than 100 mW

  16. Kinetic response study in chemiresistive gas sensor based on carbon nanotube surface functionalized with substituted phthalocyanines

    Science.gov (United States)

    Sharma, Anshul Kumar; Kumar, Pankaj; Saini, Rajan; Bedi, R. K.; Mahajan, Aman

    2016-05-01

    A kind of hybrid material is prepared by functionalizing multi-wall carbon nanotubes (MWCNTs-COOH) with substituted copper phthalocyanine and the formation of CuPcOC8/MWCNTs-COOH hybrid is confirmed by scanning electron microscopy and transmission electron microscopy. The results indicated that on the surface of nanotubes substituted CuPcOC8 derivatives has been successfully anchored through π-π stacking interaction. The gas sensing application of the fabricated hybrid material is tested upon exposure to different hazardous species, specifically NO2, NO, Cl2 and NH3 at operating temperature of 150˚C. It has been demonstrated that for Cl2 minimum detection limit of CuPcOC8/MWCNTs-COOH hybrid is 100 ppb. The response of hybrid sensor is found to be increased with increase in the concentration of Cl2.

  17. Pyrometer model based on sensor physical structure and thermal operation

    International Nuclear Information System (INIS)

    Sebastian, Eduardo; Armiens, Carlos; Gomez-Elvira, Javier

    2010-01-01

    This paper proposes a new simplified thermal model for pyrometers, which takes into account both their internal and external physical structure and operation. The model is experimentally tested on the REMS GTS, an instrument for measuring ground temperature, which is part of the payload of the NASA MSL mission to Mars. The proposed model is based on an energy balance equation that represents the heat fluxes exchanged between sensor elements through radiation, conduction and convection. Despite being mathematically more complex than the more commonly used model, the proposed model makes it possible to design a methodology to compensate the effects of sensor spatial thermal gradients. The paper includes a practical methodology for identifying model constants, which is part of the GTS instrument calibration plan and uses a differential approach to avoid setup errors. Experimental results of the model identification methodology and a target temperature measurement performance after identification has been made are reported. Results demonstrate the good behaviour of the model, with errors below 0.15 deg. C in target temperature estimates.

  18. Optimising gas pipeline operation - factors to consider in selecting flow measurement technology; Gas flow measurement

    Energy Technology Data Exchange (ETDEWEB)

    Fromm, Frank

    2010-07-01

    Multipath ultrasonic transit-time flow meters (UFM) have been employed in the gas industries for many years. Since their inception in the early seventies, advancements in the technology have been made with regard to available configurations, electronics offered and sensor design. Today, UFMs have proven to be reliable, versatile and capable of meeting the demands of the gas markets. It is clear that various UFM technologies have different advantages with regards to design and application use, which ultimately makes one more appropriate than the other. (Author)

  19. Breakdown voltage reduction by field emission in multi-walled carbon nanotubes based ionization gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Saheed, M. Shuaib M.; Muti Mohamed, Norani; Arif Burhanudin, Zainal, E-mail: zainabh@petronas.com.my [Centre of Innovative Nanostructures and Nanodevices, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2014-03-24

    Ionization gas sensors using vertically aligned multi-wall carbon nanotubes (MWCNT) are demonstrated. The sharp tips of the nanotubes generate large non-uniform electric fields at relatively low applied voltage. The enhancement of the electric field results in field emission of electrons that dominates the breakdown mechanism in gas sensor with gap spacing below 14 μm. More than 90% reduction in breakdown voltage is observed for sensors with MWCNT and 7 μm gap spacing. Transition of breakdown mechanism, dominated by avalanche electrons to field emission electrons, as decreasing gap spacing is also observed and discussed.

  20. PDMS membranes as sensing element in optical sensors for gas detection in water

    Directory of Open Access Journals (Sweden)

    Stefania Torino

    2017-11-01

    Full Text Available Polydimethylsiloxane (PDMS has been introduced the first time about 20years ago. This polymer is worldwide used for the rapid prototyping of microfluidic device through a replica molding process. However, the great popularity of PDMS is not only related to its easy processability, but also to its chemical and physical properties. For its interesting properties, the polymer has been implied for several applications, including sensing. In this work, we investigated how to use functionalized PDMS membranes as sensing elements in optical sensors for gas detection in water samples. Keywords: Polydimethylsiloxane (PDMS, Surface Plasmon Resonance (SPR sensors, Gas sensor

  1. Development of Microfabricated Chemical Gas Sensors and Sensor Arrays for Aerospace Applications

    Science.gov (United States)

    Hunter, G. W.; Neudeck, P. G.; Fralick, G.; Thomas, V.; Liu, C. C.; Wu, W. H.; Ward, B.; Makel, D.

    2002-01-01

    Aerospace applications require the development of chemical sensors with capabilities beyond those of commercially available sensors. In particular, factors such as minimal sensor size, weight, and power consumption are particularly important. Development areas which have potential aerospace applications include launch vehicle leak detection, engine health monitoring, fire detection, and environmental monitoring. Sensor development for these applications is based on progress in three types of technology: 1) Micromachining and microfabrication (Microsystem) technology to fabricate miniaturized sensors. 2) The use of nanocrystalline materials to develop sensors with improved stability combined with higher sensitivity. 3) The development of high temperature semiconductors, especially silicon carbide. However, due to issues of selectivity and cross-sensitivity, individual sensors are limited in the amount of information that they can provide in environments that contain multiple chemical species. Thus, sensor arrays are being developed to address detection needs in such multi-species environments. This paper discusses the needs of space applications as well as the point-contact sensor technology and sensor arrays being developed to address these needs. Sensors to measure hydrogen, hydrocarbons, hydrazine, nitrogen oxides (NO,), carbon monoxide, oxygen, and carbon dioxide are being developed as well as arrays for leak, fire, and emissions detection. Demonstrations of the technology will also be discussed. It is concluded that microfabricated sensor technology has significant potential for use in a range of aerospace applications.

  2. Swift heavy ion irradiated SnO_2 thin film sensor for efficient detection of SO_2 gas

    International Nuclear Information System (INIS)

    Tyagi, Punit; Sharma, Savita; Tomar, Monika; Singh, Fouran; Gupta, Vinay

    2016-01-01

    Highlights: • Response of Ni"7"+ ion irradiated (100 MeV) SnO_2 film have been performed. • Effect of irradiation on the structural and optical properties of SnO_2 film is studied. • A decrease in operating temperature and increased response is seen after irradiation. - Abstract: Gas sensing response studies of the Ni"7"+ ion irradiated (100 MeV) and non-irradiated SnO_2 thin film sensor prepared under same conditions have been performed towards SO_2 gas (500 ppm). The effect of irradiation on the structural, surface morphological, optical and gas sensing properties of SnO_2 thin film based sensor have been studied. A significant decrease in operating temperature (from 220 °C to 60 °C) and increased sensing response (from 1.3 to 5.0) is observed for the sample after irradiation. The enhanced sensing response obtained for the irradiated SnO_2 thin film based sensor is attributed to the desired modification in the surface morphology and material properties of SnO_2 thin film by Ni"7"+ ions.

  3. THIN FILM-BASED SENSOR FOR MOTOR VEHICLE EXHAUST GAS, NH3, AND CO DETECTION

    Directory of Open Access Journals (Sweden)

    S. Sujarwata

    2016-10-01

    Full Text Available A copper phthalocyanine (CuPc thin film based gas sensor with FET structure and channel length 100 μm has been prepared by VE method and lithography technique to detect NH3, motor cycle exhaust gases and CO. CuPc material layer was deposited on SiO2 by the vacuum evaporator (VE method at room temperature and pressure of 8 x10-4 Pa. The stages of manufacturing gas sensor were Si/SiO2 substrate blenching with ethanol in an ultrasonic cleaner, source, and drain electrodes deposition on the substrate by using a vacuum evaporator, thin film deposition between the source/drain and gate deposition. The sensor response times to NH3, motorcycle exhaust gases and CO were 75 s, 135 s, and 150, respectively. The recovery times were 90 s, 150 s and 225, respectively. It is concluded that the CuPc thin film-based gas sensor with FET structure is the best sensor to detect the NH3 gas.Sensor gas berbasis film tipis copper phthalocyanine (CuPc berstruktur FET dengan panjang channel 100 μm telah dibuatdengan metode VE dan teknik lithography untuk mendeteksi NH3 gas buang kendaraan bermotor dan CO. Lapisan bahan CuPc dideposisikan pada permukaan silikon dioksida (SiO2 dengan metode vacuum evaporator (VE pada temperatur ruang dengan tekanan 8 x10-4 Pa. Tahapan pembuatan sensor gas adalah pencucian substrat Si/SiO2 dengan etanol dalam ultrasonic cleaner, deposisi elektroda source dan drain di atas substrat dengan metode vacuum evaporator, deposisi film tipis diantara source/drain dan deposisi gate. Waktu tanggap sensor terhadap NH3, gas buang kendaraan bermotor dan CO berturut-turut adalah 75 s, 135 s,dan 150 s. Waktu pemulihan berturut-turut adalah 90 s, 150 s,dan 225 s. Disimpulkan bahwa sensor gas berstruktur FET berbasis film tipis CuPc merupakan sensor paling baik untuk mendeteksi adanya gas NH3.

  4. Investigation of the Performance of HEMT-Based NO, NO₂ and NH₃ Exhaust Gas Sensors for Automotive Antipollution Systems.

    Science.gov (United States)

    Halfaya, Yacine; Bishop, Chris; Soltani, Ali; Sundaram, Suresh; Aubry, Vincent; Voss, Paul L; Salvestrini, Jean-Paul; Ougazzaden, Abdallah

    2016-02-23

    We report improved sensitivity to NO, NO₂ and NH₃ gas with specially-designed AlGaN/GaN high electron mobility transistors (HEMT) that are suitable for operation in the harsh environment of diesel exhaust systems. The gate of the HEMT device is functionalized using a Pt catalyst for gas detection. We found that the performance of the sensors is enhanced at a temperature of 600 °C, and the measured sensitivity to 900 ppm-NO, 900 ppm-NO₂ and 15 ppm-NH₃ is 24%, 38.5% and 33%, respectively, at 600 °C. We also report dynamic response times as fast as 1 s for these three gases. Together, these results indicate that HEMT sensors could be used in a harsh environment with the ability to control an anti-pollution system in real time.

  5. Cr2O3 nanoparticle-functionalized WO3 nanorods for ethanol gas sensors

    Science.gov (United States)

    Choi, Seungbok; Bonyani, Maryam; Sun, Gun-Joo; Lee, Jae Kyung; Hyun, Soong Keun; Lee, Chongmu

    2018-02-01

    Pristine WO3 nanorods and Cr2O3-functionalized WO3 nanorods were synthesized by the thermal evaporation of WO3 powder in an oxidizing atmosphere, followed by spin-coating of the nanowires with Cr2O3 nanoparticles and thermal annealing in an oxidizing atmosphere. Scanning electron microscopy was used to examine the morphological features and X-ray diffraction was used to study the crystallinity and phase formation of the synthesized nanorods. Gas sensing tests were performed at different temperatures in the presence of test gases (ethanol, acetone, CO, benzene and toluene). The Cr2O3-functionalized WO3 nanorods sensor showed a stronger response to these gases relative to the pristine WO3 nanorod sensor. In particular, the response of the Cr2O3-functionalized WO3 nanorods sensor to 200 ppm ethanol gas was 5.58, which is approximately 4.4 times higher that of the pristine WO3 nanorods sensor. Furthermore, the Cr2O3-functionalized WO3 nanorods sensor had a shorter response and recovery time. The pristine WO3 nanorods had no selectivity toward ethanol gas, whereas the Cr2O3-functionalized WO3 nanorods sensor showed good selectivity toward ethanol. The gas sensing mechanism of the Cr2O3-functionalized WO3 nanorods sensor toward ethanol is discussed in detail.

  6. Tin dioxide opals and inverted opals: near-ideal microstructures for gas sensors

    Energy Technology Data Exchange (ETDEWEB)

    Scott, R.W.J.; Yang, S.M.; Coombs, N.; Ozin, G.A. [Toronto Univ., ON (Canada). Materials Chemistry Research Group; Chabanis, G.; Williams, D.E. [University Coll., London (United Kingdom). Dept. of Chemistry

    2001-10-02

    Periodic macroporous forms of nc-SnO{sub 2} have been synthesized by two methods, giving opals and inverse opals that can be used as structurally well-defined gas sensors, as demonstrated for CO gas, as well as for toluene and ethanol vapors. The inverse opals, in particular, seem to approximate ''ideal'' behavior. (orig.)

  7. Distinguishing feature of metal oxide films' structural engineering for gas sensor applications

    International Nuclear Information System (INIS)

    Korotcenkov, G; Golovanov, V; Brinzari, V; Cornet, A; Morante, J; Ivanov, M

    2005-01-01

    The different methods of structural engineering, used for improvement of solid state gas sensors parameters are reviewed in this paper. The wide possibilities of structural engineering in optimization of gas sensing properties were demonstrated on the example of thin tin dioxide films deposited by spray pyrolysis

  8. Optimal sensor locations for the backward Lagrangian stochastic technique in measuring lagoon gas emission

    Science.gov (United States)

    This study evaluated the impact of gas concentration and wind sensor locations on the accuracy of the backward Lagrangian stochastic inverse-dispersion technique (bLS) for measuring gas emission rates from a typical lagoon environment. Path-integrated concentrations (PICs) and 3-dimensional (3D) wi...

  9. Ether gas-sensor based on Au nanoparticles-decorated ZnO microstructures

    Directory of Open Access Journals (Sweden)

    Roberto López

    Full Text Available An ether gas-sensor was fabricated based on gold nanoparticles (Au-NPs decorated zinc oxide microstructures (ZnO-MS. Scanning electron microscope (SEM and high-resolution transmission electron microscope (HRTEM measurements were performed to study morphological and structural properties, respectively, of the ZnO-MS. The gas sensing response was evaluated in a relatively low temperature regime, which ranged between 150 and 250 °C. Compared with a sensor fabricated from pure ZnO-MS, the sensor based on Au-NPs decorated ZnO-MS showed much better ether gas response at the highest working temperature. In fact, pure ZnO-MS based sensor only showed a weak sensitivity of about 25%. The improvement of the ether gas response for sensor fabricated with Au-NPs decorated ZnO-MS was attributed to the catalytic activity of the Au-NPs. Keywords: ZnO microstructures, Au nanoparticles, Ether, Gas sensor

  10. Development of fabric-based chemical gas sensors for use as wearable electronic noses.

    Science.gov (United States)

    Seesaard, Thara; Lorwongtragool, Panida; Kerdcharoen, Teerakiat

    2015-01-16

    Novel gas sensors embroidered into fabric substrates based on polymers/ SWNT-COOH nanocomposites were proposed in this paper, aiming for their use as a wearable electronic nose (e-nose). The fabric-based chemical gas sensors were fabricated by two main processes: drop coating and embroidery. Four potential polymers (PVC, cumene-PSMA, PSE and PVP)/functionalized-SWCNT sensing materials were deposited onto interdigitated electrodes previously prepared by embroidering conductive thread on a fabric substrate to make an optimal set of sensors. After preliminary trials of the obtained sensors, it was found that the sensors yielded a electrical resistance in the region of a few kilo-Ohms. The sensors were tested with various volatile compounds such as ammonium hydroxide, ethanol, pyridine, triethylamine, methanol and acetone, which are commonly found in the wastes released from the human body. These sensors were used to detect and discriminate between the body odors of different regions and exist in various forms such as the urine, armpit and exhaled breath odor. Based on a simple pattern recognition technique, we have shown that the proposed fabric-based chemical gas sensors can discriminate the human body odor from two persons.

  11. Development of Fabric-Based Chemical Gas Sensors for Use as Wearable Electronic Noses

    Directory of Open Access Journals (Sweden)

    Thara Seesaard

    2015-01-01

    Full Text Available Novel gas sensors embroidered into fabric substrates based on polymers/ SWNT-COOH nanocomposites were proposed in this paper, aiming for their use as a wearable electronic nose (e-nose. The fabric-based chemical gas sensors were fabricated by two main processes: drop coating and embroidery. Four potential polymers (PVC, cumene-PSMA, PSE and PVP/functionalized-SWCNT sensing materials were deposited onto interdigitated electrodes previously prepared by embroidering conductive thread on a fabric substrate to make an optimal set of sensors. After preliminary trials of the obtained sensors, it was found that the sensors yielded a electrical resistance in the region of a few kilo-Ohms. The sensors were tested with various volatile compounds such as ammonium hydroxide, ethanol, pyridine, triethylamine, methanol and acetone, which are commonly found in the wastes released from the human body. These sensors were used to detect and discriminate between the body odors of different regions and exist in various forms such as the urine, armpit and exhaled breath odor. Based on a simple pattern recognition technique, we have shown that the proposed fabric-based chemical gas sensors can discriminate the human body odor from two persons.

  12. Sensor Nanny, data management services for marine observation operators

    Science.gov (United States)

    Loubrieu, Thomas; Détoc, Jérôme; Thorel, Arnaud; Azelmat, Hamza

    2016-04-01

    In marine sciences, the diversity of observed properties (from water physic to contaminants in observed in biological individuals or sediment) and observation methodologies (from manned sampling and analysis in labs to large automated networks of homogeneous platforms) requires different expertises and thus dedicated scientific program (ARGO, EMSO, GLOSS, GOSHIP, OceanSites, GOSUD, Geotrace, SOCAT, member state environment monitoring networks, experimental research…). However, all of them requires similar IT services to support the maintenance of their network (calibrations, deployment strategy, spare part management...) and their data management. In Europe, the National Oceanographic Data Centres coordinated by the IOC/IODE and SeaDataNet provide reliable reference services (e.g. vocabularies, contact directories), standards and long term data preservation. Besides the regional operational oceanographic centres (ROOSes) coordinated by EuroGOOS and Copernicus In-Situ Thematic Assembly Centre provide efficient data management for near real time or delayed mode services focused on physics and bio-geo-chemistry in the water column. Other e-infrastructures, such as euroBIS for biodiversity, are focused on specific disciplines. Beyond the current scope of these well established infrastructures, Sensor Nanny is a web application providing services for operators of observatories to manage their observations on the "cloud". The application stands against the reference services (vocabularies, organization directory) and standard profiles (OGC/Sensor Web Enablement) provided by SeaDataNet. The application provides an on-line editor to graphically describe, literally draw, their observatory (acquisition and processing systems). The observatory description is composed by the user from a palette of hundreds of pre-defined sensors or hardware linked together. In addition, the data providers can upload their data in CSV and netCDF formats on a dropbox-like system. The latest

  13. A Review on Graphene-Based Gas/Vapor Sensors with Unique Properties and Potential Applications

    Institute of Scientific and Technical Information of China (English)

    Tao Wang; Da Huang; Zhi Yang; Shusheng Xu; Guili He; Xiaolin Li; Nantao Hu; Guilin Yin; Dannong He; Liying Zhang

    2016-01-01

    Graphene-based gas/vapor sensors have attracted much attention in recent years due to their variety of structures, unique sensing performances, room-temperature working conditions, and tremendous application prospects, etc.Herein, we summarize recent advantages in graphene preparation, sensor construction, and sensing properties of various graphene-based gas/vapor sensors, such as NH3, NO2, H2, CO, SO2, H2S, as well as vapor of volatile organic compounds.The detection mechanisms pertaining to various gases are also discussed. In conclusion part, some existing problems which may hinder the sensor applications are presented. Several possible methods to solve these problems are proposed, for example, conceived solutions, hybrid nanostructures, multiple sensor arrays, and new recognition algorithm.

  14. Fast wire-mesh sensors for gas-liquid flows - Visualisation with up to 10 000 frames per second

    International Nuclear Information System (INIS)

    Prasser, H.M.; Zschau, J.; Peters, D.; Pietzsch, G.; Taubert, W.; Trepte, M.

    2002-01-01

    A wire-mesh sensor developed by the Forschungszentrum Rossendorf produces sequences of instantaneous gas fraction distributions in a cross section at a rate of up to 10 000 frames per second and a spatial resolution of about 2-3 mm. This sensor was applied to an upwards air-liquid flow in a vertical pipe of 51.2 mm diameter. After a brief introduction of the functioning of the sensor, the paper presents results obtained in a at vertical pipe operated with an air-water mixture. Two wire-mesh sensors with a measuring matrix of 24 x 24 points (resolution 2 mm) were placed in a small axial distance behind each other. They were used to study the flow structure in the transition region from bubble to slug flow at an imaging frequency of 2 500 Hz. The two available measuring planes allowed to obtain velocity profiles of the gaseous phase. A sensor with 16 x 16 points (resolution 3 mm) was applied to visualize the transition from bubbly via churn turbulent to annular flow with 10 000 frames per second. In the churn flow region, periodic plug-like structures were found. In the annular flow the sensor is able to resolve wispy structures. (authors)

  15. Investigation of thiol derivatized gold nanoparticle sensors for gas analysis

    Science.gov (United States)

    Stephens, Jared S.

    Analysis of volatile organic compounds (VOCs) in air and exhaled breath by sensor array is a very useful testing technique. It can provide non-invasive, fast, inexpensive testing for many diseases. Breath analysis has been very successful in identifying cancer and other diseases by using a chemiresistor sensor or array with gold nanoparticles to detect biomarkers. Acetone is a biomarker for diabetes and having a portable testing device could help to monitor diabetic and therapeutic progress. An advantage to this testing method is it is conducted at room temperature instead of 200 degrees Celsius. 3. The objective of this research is to determine the effect of thiol derivatized gold nanoparticles based on sensor(s) detection of VOCs. The VOCs to be tested are acetone, ethanol, and a mixture of acetone and ethanol. Each chip is tested under all three VOCs and three concentration levels (0.1, 1, and 5.0 ppm). VOC samples are used to test the sensors' ability to detect and differentiate VOCs. Sensors (also referred to as a chip) are prepared using several types of thiol derivatized gold nanoparticles. The factors are: thiol compound and molar volume loading of the thiol in synthesis. The average resistance results are used to determine the VOC selectivity of the sensors tested. The results show a trend of increasing resistance as VOC concentration is increased relative to dry air; which is used as baseline for VOCs. Several sensors show a high selectivity to one or more VOCs. Overall the 57 micromoles of 4-methoxy-toluenethiol sensor shows the strongest selectivity for VOCs tested. 3. Gerfen, Kurt. 2012. Detection of Acetone in Air Using Silver Ion Exchanged ZSM-5 and Zinc Oxide Sensing Films. Master of Science thesis, University of Louisville.

  16. Gas turbine control for islanding operation of distribution systems

    DEFF Research Database (Denmark)

    Mahat, Pukar; Chen, Zhe; Bak-Jensen, Birgitte

    2009-01-01

    Danish distribution systems are characterized by a significant penetration of small gas turbine generators (GTGs) and fixed speed wind turbine generators (WTGs). Island operation of these distribution systems are becoming a viable option for economical and technical reasons. However, stabilizing...... frequency in an islanded system is one of the major challenges. This paper presents three different gas turbine governors for possible operation of distribution systems in an islanding mode. Simulation results are presented to show the performance of these governors in grid connected and islanding mode....

  17. Silicon Carbide-Based Hydrogen Gas Sensors for High-Temperature Applications

    Directory of Open Access Journals (Sweden)

    Sangchoel Kim

    2013-10-01

    Full Text Available We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5 layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures.

  18. Response mechanism for surface acoustic wave gas sensors based on surface-adsorption.

    Science.gov (United States)

    Liu, Jiansheng; Lu, Yanyan

    2014-04-16

    A theoretical model is established to describe the response mechanism of surface acoustic wave (SAW) gas sensors based on physical adsorption on the detector surface. Wohljent's method is utilized to describe the relationship of sensor output (frequency shift of SAW oscillator) and the mass loaded on the detector surface. The Brunauer-Emmett-Teller (BET) formula and its improved form are introduced to depict the adsorption behavior of gas on the detector surface. By combining the two methods, we obtain a theoretical model for the response mechanism of SAW gas sensors. By using a commercial SAW gas chromatography (GC) analyzer, an experiment is performed to measure the frequency shifts caused by different concentration of dimethyl methylphosphonate (DMMP). The parameters in the model are given by fitting the experimental results and the theoretical curve agrees well with the experimental data.

  19. Peptide modified ZnO nanoparticles as gas sensors array for volatile organic compounds (VOCs)

    Science.gov (United States)

    Mascini, Marcello; Gaggiotti, Sara; Della Pelle, Flavio; Di Natale, Corrado; Qakala, Sinazo; Iwuoha, Emmanuel; Pittia, Paola; Compagnone, Dario

    2018-04-01

    In this work a peptide based gas sensor array based of ZnO nanoparticles (ZnONPs) has been realized. Four different pentapeptides molecularly modelled for alcohols and esters having cysteine as a common spacer have been immobilized onto ZnONPs. ZnONPs have been morphologically and spectroscopically characterized. Modified nanoparticles have been then deposited onto quartz crystal microbalances (QCMs) and used as gas sensors with nitrogen as carrier gas. Analysis of the pure compounds modelled demonstrated a nice fitting of modelling with real data. The peptide based ZnONPs had very low sensitivity to water, compared to previously studied AuNPs peptide based gas sensors allowing the use of the array on samples with high water content. Real samples of fruit juices have been assayed; stability of the signal, good repeatability and discrimination ability of the array was achieved.

  20. Peptide Modified ZnO Nanoparticles as Gas Sensors Array for Volatile Organic Compounds (VOCs

    Directory of Open Access Journals (Sweden)

    Marcello Mascini

    2018-04-01

    Full Text Available In this work a peptide based gas sensor array based of ZnO nanoparticles (ZnONPs has been realized. Four different pentapeptides molecularly modeled for alcohols and esters having cysteine as a common spacer have been immobilized onto ZnONPs. ZnONPs have been morphologically and spectroscopically characterized. Modified nanoparticles have been then deposited onto quartz crystal microbalances (QCMs and used as gas sensors with nitrogen as carrier gas. Analysis of the pure compounds modeled demonstrated a nice fitting of modeling with real data. The peptide based ZnONPs had very low sensitivity to water, compared to previously studied AuNPs peptide based gas sensors allowing the use of the array on samples with high water content. Real samples of fruit juices have been assayed; stability of the signal, good repeatability, and discrimination ability of the array was achieved.

  1. Effect of zero discharge permits on oil and gas operations

    International Nuclear Information System (INIS)

    Higdon, G.D.

    1994-01-01

    This paper examines one of the more prominent effects of the Clean Water Act (CWA) upon oil and gas operations. To that end, the paper begins with a general discussion of the regulatory background and permitting framework which serves as the foundation for water pollution control. From this discussion, the paper will then move into a discussion of particular permit provisions which govern the discharge of wastes generated from oil and gas operations. Upon discussing these provisions, the paper will then discuss potential enforcement options available to the Environmental Protection Agency (EPA) to address violations of the regulations and permits it has issued to implement the CWA. In that regard, the paper will also discuss some recent enforcement theories advocated by the EPA which may have significant impacts upon oil and gas operators and the way in which they conduct their operations. In light of some of these recent enforcement activities, the paper will close with a discussion of the implications of the theories of liability espoused by EPA and steps which oil and gas operators may taking in response to the positions assumed by EPA

  2. Experience with managing, operating and maintaining gas turbine powerplants

    International Nuclear Information System (INIS)

    Wadman, B.

    1994-01-01

    Stewart ampersand Stevenson, a major supplier of gas turbine powered cogeneration systems to worldwide markets, established plant management, operations and maintenance capabilities in 1985 in order to provide complete service capability to the customer. As of the fall of 1993, twenty-two individual cogeneration facilities are now being operated and maintained by this company with a total capacity of 1100+ MW. More than 300 plant management and operating personnel are employed in this operation. To date, activities have been concentrated in North and South America. Negotiations are in process in a number of other areas including the Pacific Rim, China, and several Middle East countries. 7 figs

  3. Lightweight Fiber Optic Gas Sensor for Monitoring Regenerative Food Production

    Science.gov (United States)

    Schmidlin, Edward; Goswami, Kisholoy

    1995-01-01

    In this final report, Physical Optics Corporation (POC) describes its development of sensors for oxygen, carbon dioxide, and relative humidity. POC has constructed a phase fluorometer that can detect oxygen over the full concentration range from 0 percent to 100 percent. Phase-based measurements offer distinct advantages, such as immunity to source fluctuation, photobleaching, and leaching. All optics, optoelectronics, power supply, and the printed circuit board are included in a single box; the only external connections to the fluorometer are the optical fiber sensor and a power cord. The indicator-based carbon dioxide sensor is also suitable for short-term and discrete measurements over the concentration range from 0 percent to 100 percent. The optical fiber-based humidity sensor contains a porous core for direct interaction of the light beam with water vapor within fiber pores; the detection range for the humidity sensor is 10 percent to 100 percent, and response time is under five minutes. POC is currently pursuing the commercialization of these oxygen and carbon dioxide sensors for environmental applications.

  4. Towards an operational sensor-fusion system for anti-personnel landmine detection

    NARCIS (Netherlands)

    Cremer, F.; Schutte, K.; Schavemaker, J.G.M.; Breejen, E. den

    2000-01-01

    To acquire detection performance required for an operational system for the detection of anti-personnel landmines, it is necessary to use multiple sensors and sensor-fusion techniques. This paper describes five decision-level sensor-fusion techniques and their common optimisation method. The

  5. Operation and planning of coordinated natural gas and electricity infrastructures

    Science.gov (United States)

    Zhang, Xiaping

    Natural gas is becoming rapidly the optimal choice for fueling new generating units in electric power system driven by abundant natural gas supplies and environmental regulations that are expected to cause coal-fired generation retirements. The growing reliance on natural gas as a dominant fuel for electricity generation throughout North America has brought the interaction between the natural gas and power grids into sharp focus. The primary concern and motivation of this research is to address the emerging interdependency issues faced by the electric power and natural gas industry. This thesis provides a comprehensive analysis of the interactions between the two systems regarding the short-term operation and long-term infrastructure planning. Natural gas and renewable energy appear complementary in many respects regarding fuel price and availability, environmental impact, resource distribution and dispatchability. In addition, demand response has also held the promise of making a significant contribution to enhance system operations by providing incentives to customers for a more flat load profile. We investigated the coordination between natural gas-fired generation and prevailing nontraditional resources including renewable energy, demand response so as to provide economical options for optimizing the short-term scheduling with the intense natural gas delivery constraints. As the amount and dispatch of gas-fired generation increases, the long-term interdependency issue is whether there is adequate pipeline capacity to provide sufficient gas to natural gas-fired generation during the entire planning horizon while it is widely used outside the power sector. This thesis developed a co-optimization planning model by incorporating the natural gas transportation system into the multi-year resource and transmission system planning problem. This consideration would provide a more comprehensive decision for the investment and accurate assessment for system adequacy and

  6. Analysis of Simulated Output Characteristics of Gas Sensor Based on Graphene Nanoribbon

    Directory of Open Access Journals (Sweden)

    A. Mahmoudi

    2016-01-01

    Full Text Available This work presents simulated output characteristics of gas sensor transistors based on graphene nanoribbon (GNRFET. The device studied in this work is a new generation of gas sensing devices, which are easy to use, ultracompact, ultrasensitive, and highly selective. We will explain how the exposure to the gas changes the conductivity of graphene nanoribbon. The equations of the GNRFET gas sensor model include the Poisson equation in the weak nonlocality approximation with proposed sensing parameters. As we have developed this model as a platform for a gas detection sensor, we will analyze the current-voltage characteristics after exposure of the GNRFET nanosensor device to NH3 gas. A sensitivity of nearly 2.7% was indicated in our sensor device after exposure of 1 ppm of NH3. The given results make GNRFET the right candidate for use in gas sensing/measuring appliances. Thus, we will investigate the effect of the channel length on the ON- and OFF-current.

  7. Chemical Vapor Identification by Plasma Treated Thick Film Tin Oxide Gas Sensor Array and Pattern Recognition

    Directory of Open Access Journals (Sweden)

    J. K. Srivastava

    2011-02-01

    Full Text Available Present study deals the class recognition potential of a four element plasma treated thick film tin oxide gas sensor array exposed with volatile organic compounds (VOCs. Methanol, Ethanol and Acetone are selected as target VOCs and exposed on sensor array at different concentration in range from 100-1000 ppm. Sensor array consist of four tin oxide sensors doped with 1-4 % PbO concentrations were fabricated by thick film technology and then treated with oxygen plasma for 5-10 minute durations. Sensor signal is analyzed by principal component analysis (PCA for visual classification of VOCs. Further output of PCA is used as input for classification of VOCs by four pattern classification techniques as: linear discriminant analysis (LDA, k-nearest neighbor (KNN, back propagation neural network (BPNN and support vector machine (SVM. All the four classifier results 100 % correct classification rate of VOCs by response analysis of sensor array treated with plasma for 5 minute.

  8. In situ high-temperature gas sensors: continuous monitoring of the combustion quality of different wood combustion systems and optimization of combustion process

    Directory of Open Access Journals (Sweden)

    H. Kohler

    2018-03-01

    Full Text Available The sensing characteristics and long-term stability of different kinds of CO ∕ HC gas sensors (non-Nernstian mixed potential type during in situ operation in flue gas from different types of low-power combustion systems (wood-log- and wood-chip-fuelled were investigated. The sensors showed representative but individual sensing behaviour with respect to characteristically varying flue gas composition over the combustion process. The long-term sensor signal stability evaluated by repeated exposure to CO ∕ H2 ∕ N2 ∕ synthetic air mixtures showed no sensitivity loss after operation in the flue gas. Particularly for one of the sensors (Heraeus GmbH, this high signal stability was observed in a field test experiment even during continuous operation in the flue gas of the wood-chip firing system over 4 months. Furthermore, it was experimentally shown that the signals of these CO ∕ HC sensing elements yield important additional information about the wood combustion process. This was demonstrated by the adaptation of an advanced combustion airstream control algorithm on a wood-log-fed fireplace and by the development of a combustion quality monitoring system for wood-chip-fed central heaters.

  9. On-line component ratio measurement of oil/gas/water mixtures using an admittance sensor

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, J A

    1984-01-01

    The operator of a production platform is primarily interested in which types of fluids a well is producing and how quickly these different components are being produced. The component ratio and production rate of a well vary during the life of a field. To optimize production, measurement of each well's output is thus desirable. Current designs for subsea production systems lack means of continuously measuring three-component flows. A new method of component ratio measurement is described. The fraction of oil, gas and water flowing between two insulated electrode plates is determined by measuring both the electrical conductance and suseptance across the sensor. A preliminary evaluation of the new measurement system has been performed using a process oil/ water/air mixture. The method is not limited to small pipe diameters. The only possible limitation is that for low velocities in very large pipe diameters an in-line mixer may be required. Advantages of this new system are that real-time measurement of void fraction and water content is possible if a non-intrusive rugged sensor is used, and there are no range limitations, as each component may be measured for any given concentration. 4 references.

  10. Optical Breath Gas Extravehicular Activity Sensor for the Advanced Portable Life Support System

    Science.gov (United States)

    Wood, William R.; Casias, Miguel E.; Pilgrim, Jeffrey S.; Chullen, Cinda; Campbell, Colin

    2016-01-01

    The infrared gas transducer used during extravehicular activity (EVA) in the extravehicular mobility unit (EMU) measures and reports the concentration of carbon dioxide (CO2) in the ventilation loop. It is nearing its end of life and there are a limited number remaining. Meanwhile, the next generation advanced portable life support system (PLSS) now being developed requires CO2 sensing technology with performance beyond that presently in use. A laser diode (LD) spectrometer based on wavelength modulation spectroscopy (WMS) is being developed to address both applications by Vista Photonics, Inc. Accommodation within space suits demands that optical sensors meet stringent size, weight, and power requirements. Version 1.0 devices were delivered to NASA Johnson Space Center (JSC) in 2011. The sensors incorporate a laser diode based CO2 channel that also includes an incidental water vapor (humidity) measurement. The prototypes are controlled digitally with a field-programmable gate array (FPGA)/microcontroller architecture. Version 2.0 devices with improved electronics and significantly reduced wetted volumes were delivered to JSC in 2012. A version 2.5 upgrade recently implemented wavelength stabilized operation, better humidity measurement, and much faster data analysis/reporting. A wholly reconfigured version 3.0 will maintain the demonstrated performance of earlier versions while being backwards compatible with the EMU and offering a radiation tolerant architecture.

  11. Design and fabrication of a CMOS-compatible MHP gas sensor

    Directory of Open Access Journals (Sweden)

    Ying Li

    2014-03-01

    Full Text Available A novel micro-hotplate (MHP gas sensor is designed and fabricated with a standard CMOS technology followed by post-CMOS processes. The tungsten plugging between the first and the second metal layer in the CMOS processes is designed as zigzag resistor heaters embedded in the membrane. In the post-CMOS processes, the membrane is released by front-side bulk silicon etching, and excellent adiabatic performance of the sensor is obtained. Pt/Ti electrode films are prepared on the MHP before the coating of the SnO2 film, which are promising to present better contact stability compared with Al electrodes. Measurements show that at room temperature in atmosphere, the device has a low power consumption of ∼19 mW and a rapid thermal response of 8 ms for heating up to 300 °C. The tungsten heater exhibits good high temperature stability with a slight fluctuation (<0.3% in the resistance at an operation temperature of 300 °C under constant heating mode for 336 h, and a satisfactory temperature coefficient of resistance of about 1.9‰/°C.

  12. Au@NiO core-shell nanoparticles as a p-type gas sensor: Novel synthesis, characterization, and their gas sensing properties with sensing mechanism

    KAUST Repository

    Majhi, Sanjit Manohar

    2018-04-25

    In this work, Au@NiO core-shell nanoparticles (C-S NPs) as a p-type gas sensing material was synthesized by a facile wet-chemical method, and evaluated their gas sensing properties as compared to the pristine NiO NPs gas sensors. Transmission electron microscope (TEM) results exhibited the well-dispersed formation of Au@NiO C-S NPs having the total size of 70–120 nm and NiO shells having 30–50 nm thickness. The C-S morphology as well as the overall particle sizes are unchanged even at 500 °C. The gas sensing result reveals that the response of Au@NiO C-S NPs gas sensor is higher than pristine NiO NPs gas sensor for 100 ppm of ethanol at 200 °C operating temperature. The baseline resistance in the air for Au@NiO C-S NPs sensor is lowered as compared to pristine NiO NPs, which is due to the increased number of holes as charge carriers in Au@NiO C-S NPs. The high response of Au@NiO core-shell NPs as compared to pristine NiO NPs is attributed to electronic and chemical sensitization effects of Au. In Au@NiO C-S structure, the contact between metal (Au) and semiconductor (NiO) formed a Schottky junction since Au metal acted as electron acceptor, a withdrawal of electrons from NiO by Au metal core leaved behind number of holes as charge carriers in Au@NiO C-S NPs. Therefore, the baseline resistance of Au@NiO C-S NPs greatly decreased than pristine NiO NPs, as a result the Au@NiO C-S NPs showed higher response. On the other hand, in chemical sensitization effect, Au NPs catalyzed to dissociate O2 molecules into ionic species. This work will give some clue to the researchers for the further development of p-type based C-S NPs sensors.

  13. A pathway to eliminate the gas flow dependency of a hydrocarbon sensor for automotive exhaust applications

    Directory of Open Access Journals (Sweden)

    G. Hagen

    2018-02-01

    Full Text Available Gas sensors will play an essential role in future combustion-based mobility to effectively reduce emissions and monitor the exhausts reliably. In particular, an application in automotive exhausts is challenging due to the high gas temperatures that come along with highly dynamic flow rates. Recently, a thermoelectric hydrocarbon sensor was developed by using materials which are well known in the exhausts and therefore provide the required stability. As a sensing mechanism, the temperature difference that is generated between a catalytically activated area during the exothermic oxidation of said hydrocarbons and an inert area of the sensor is measured by a special screen-printed thermopile structure. As a matter of principle, this thermovoltage significantly depends on the mass flow rate of the exhausts under certain conditions. The present contribution helps to understand this cross effect and proposes a possible setup for its avoidance. By installing the sensor in the correct position of a bypass solution, the gas flow around the sensor is almost free of turbulence. Now, the signal depends only on the hydrocarbon concentration and not on the gas flow. Such a setup may open up new possibilities of applying novel sensors in automotive exhausts for on-board-measurement (OBM purposes.

  14. Considerations in modeling fission gas release during normal operation

    International Nuclear Information System (INIS)

    Rumble, E.T.; Lim, E.Y.; Stuart, R.G.

    1977-01-01

    The EPRI LWR fuel rod modeling code evaluation program analyzed seven fuel rods with experimental fission gas release data. In these cases, rod-averged burnups are less than 20,000 MWD/MTM, while the fission gas release fractions range roughly from 2 to 27%. Code results demonstrate the complexities in calculating fission gas release in certain operating regimes. Beyond this work, the behavior of a pre-pressurized PWR rod is simulated to average burnups of 40,000 MWD/MTM using GAPCON-THERMAL-2. Analysis of the sensitivity of fission gas release to power histories and release correlations indicate the strong impact that LMFBR type release correlations induce at high burnup. 15 refs

  15. Hysteresis phenomenon during operation of gas condensate fields

    Energy Technology Data Exchange (ETDEWEB)

    Sadykh-Zade, E S; Karakashev, V K; Ismailov, D Kh

    1966-01-01

    Hysteresis behavior of gas-condensate mixtures was studied with a PVT apparatus. The study was conducted at 26 and 80/sup 0/C, with recombined samples having gas factors of 3,000, 6,500, and 10,000 cu meters per ton. Pressure on samples was decreased or increased at rates of 0.2; 0.1; 0.05; and 0.025 atm per sec. Composition of gas- condensate is given. It is reported that different amounts of liquid were produced by condensation and evaporation processes, i.e., results depended on whether pressure was being increased or decreased. It is suggested that the effect of hysteresis should be considered in operation of gas-condensate fields.

  16. Design requirements, operation and maintenance of gas-cooled reactors

    International Nuclear Information System (INIS)

    1989-06-01

    At the invitation of the Government of the USA the Technical Committee Meeting on Design Requirements, Operation and Maintenance of Gas-Cooled Reactors, was held in San Diego on September 21-23, 1988, in tandem with the GCRA Conference. Both meetings attracted a large contingent of foreign participants. Approximately 100 delegates from 18 different countries participated in the Technical Committee meeting. The meeting was divided into three sessions: Gas-cooled reactor user requirement (8 papers); Gas-cooled reactor improvements to facilitate operation and maintenance (10 papers) and Safety, environmental impacts and waste disposal (5 papers). A separate abstract was prepared for each of these 23 papers. Refs, figs and tabs

  17. Synthesis of ZnO nanorods by spray pyrolysis for H2S gas sensor

    International Nuclear Information System (INIS)

    Shinde, S.D.; Patil, G.E.; Kajale, D.D.; Gaikwad, V.B.; Jain, G.H.

    2012-01-01

    Highlights: ► Hexagonal pillar shaped ZnO nanorods with different sizes have been successfully synthesized by spray pyrolysis technique. ► ZnO nanorods thin films showed much better sensitivity and stability than the conventional materials to H 2 S gas (100 ppm) at 50 °C. ► This ZnO thin film has potential in application of room temperature H 2 S gas sensing. - Abstract: Hexagonal pillar shaped ZnO nanorods with different sizes have been successfully synthesized by spray pyrolysis technique (SPT). The equal amount of methanol and water is used as a solvent to dissolve the AR grade Zinc acetate for precursor solution. This solution is sprayed on to the glass substrate heated at 350 °C. The films were characterized by ultra-violet spectroscopy (UV), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The deposition of thin films results in a layer comprising well-shaped hexagonal ZnO nanorods with diameter of 90–120 nm and length of up to 200 nm. The gas sensing properties of these films have been investigated for various interfering gases such as CO 2 , CO, ethanol, NH 3 and H 2 S, etc. at operating temperature from 30° (room temperature) to 450 °C. The results indicate that the ZnO nanorods thin films showed much better sensitivity and stability than the conventional materials to H 2 S gas (100 ppm) at 50 °C. The hexagonal pillar shaped ZnO nanorods can improve the sensitivity and selectivity of the sensors.

  18. Effects of Operating Conditions on Gas Release Thermal ...

    African Journals Online (AJOL)

    The gas release rates and the flame length of the potential jet fires were initially estimated using Simplex Source Term Models which pay limited attention to operating conditions. Finally a more detailed follow-up study, accounting for a range of practical factors was conducted. A number of useful risk management metrics ...

  19. Soft Sensors: Chemoinformatic Model for Efficient Control and Operation in Chemical Plants.

    Science.gov (United States)

    Funatsu, Kimito

    2016-12-01

    Soft sensor is statistical model as an essential tool for controlling pharmaceutical, chemical and industrial plants. I introduce soft sensor, the roles, the applications, the problems and the research examples such as adaptive soft sensor, database monitoring and efficient process control. The use of soft sensor enables chemical industrial plants to be operated more effectively and stably. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Plasmonic nanocomposite thin film enabled fiber optic sensors for simultaneous gas and temperature sensing at extreme temperatures.

    Science.gov (United States)

    Ohodnicki, Paul R; Buric, Michael P; Brown, Thomas D; Matranga, Christopher; Wang, Congjun; Baltrus, John; Andio, Mark

    2013-10-07

    Embedded sensors capable of operation in extreme environments including high temperatures, high pressures, and highly reducing, oxidizing and/or corrosive environments can make a significant impact on enhanced efficiencies and reduced greenhouse gas emissions of current and future fossil-based power generation systems. Relevant technologies can also be leveraged in a wide range of other applications with similar needs including nuclear power generation, industrial process monitoring and control, and aviation/aerospace. Here we describe a novel approach to embedded sensing under extreme temperature conditions by integration of Au-nanoparticle based plasmonic nanocomposite thin films with optical fibers in an evanescent wave absorption spectroscopy configuration. Such sensors can potentially enable simultaneous temperature and gas sensing at temperatures approaching 900-1000 °C in a manner compatible with embedded and distributed sensing approaches. The approach is demonstrated using the Au/SiO2 system deposited on silica-based optical fibers. Stability of optical fibers under relevant high temperature conditions and interactions with changing ambient gas atmospheres is an area requiring additional investigation and development but the simplicity of the sensor design makes it potentially cost-effective and may offer a potential for widespread deployment.

  1. Application of Conductive Carbon Nanotube Fibers and Composites: Gas Sensor

    Science.gov (United States)

    2013-05-01

    changes in Raman spectroscopy data when single wall carbon nanotubes (SWNT) are immersed in various liquids, including common organics (12). In...Resistance -- (82) 2007 Su H2O MWNT PMMA, KOH Gas Impedance -- (83) 2011 Tang H2O MWNT PI Gas Resistance -- (84) 2003 Wang H2O2, NADH SWNT

  2. Global Environmental Micro Sensors Test Operations in the Natural Environment

    Science.gov (United States)

    Adams, Mark L.; Buza, Matthew; Manobianco, John; Merceret, Francis J.

    2007-01-01

    ENSCO, Inc. is developing an innovative atmospheric observing system known as Global Environmental Micro Sensors (GEMS). The GEMS concept features an integrated system of miniaturized in situ, airborne probes measuring temperature, relative humidity, pressure, and vector wind velocity. In order for the probes to remain airborne for long periods of time, their design is based on a helium-filled super-pressure balloon. The GEMS probes are neutrally buoyant and carried passively by the wind at predetermined levels. Each probe contains onboard satellite communication, power generation, processing, and geolocation capabilities. ENSCO has partnered with the National Aeronautics and Space Administration's Kennedy Space Center (KSC) for a project called GEMS Test Operations in the Natural Environment (GEMSTONE) that will culminate with limited prototype flights of the system in spring 2007. By leveraging current advances in micro and nanotechnology, the probe mass, size, cost, and complexity can be reduced substantially so that large numbers of probes could be deployed routinely to support ground, launch, and landing operations at KSC and other locations. A full-scale system will improve the data density for the local initialization of high-resolution numerical weather prediction systems by at least an order of magnitude and provide a significantly expanded in situ data base to evaluate launch commit criteria and flight rules. When applied to launch or landing sites, this capability will reduce both weather hazards and weather-related scrubs, thus enhancing both safety and cost-avoidance for vehicles processed by the Shuttle, Launch Services Program, and Constellation Directorates. The GEMSTONE project will conclude with a field experiment in which 10 to 15 probes are released over KSC in east central Florida. The probes will be neutrally buoyant at different altitudes from 500 to 3000 meters and will report their position, speed, heading, temperature, humidity, and

  3. Current and emerging laser sensors for greenhouse gas sensing and leak detection

    Science.gov (United States)

    Frish, Michael B.

    2014-05-01

    To reduce atmospheric accumulation of the greenhouse gases methane and carbon dioxide, networks of continuously operating sensors that monitor and map their sources are desirable. In this paper, we discuss advances in laser-based open-path leak detectors, as well as technical and economic challenges inhibiting widespread sensor deployment for "ubiquitous monitoring". We describe permanently-installed, wireless, solar-powered sensors that overcome previous installation and maintenance difficulties while providing autonomous real-time leak reporting without false alarms.

  4. Facile Quantification and Identification Techniques for Reducing Gases over a Wide Concentration Range Using a MOS Sensor in Temperature-Cycled Operation

    OpenAIRE

    Caroline Schultealbert; Tobias Baur; Andreas Schütze; Tilman Sauerwald

    2018-01-01

    Dedicated methods for quantification and identification of reducing gases based on model-based temperature-cycled operation (TCO) using a single commercial MOS gas sensor are presented. During high temperature phases the sensor surface is highly oxidized, yielding a significant sensitivity increase after switching to lower temperatures (differential surface reduction, DSR). For low concentrations, the slope of the logarithmic conductance during this low-temperature phase is evaluated and can ...

  5. Simulations of Propane and Butane Gas Sensor Based on Pristine Armchair Graphene Nanoribbon

    Science.gov (United States)

    Rashid, Haroon; Koel, Ants; Rang, Toomas

    2018-05-01

    Over the last decade graphene and its derivatives have gained a remarkable place in research field. As silicon technology is approaching to its geometrical limits so there is a need of alternate that can replace it. Graphene has emerged as a potential candidate for future nano-electronics applications due to its exceptional and extraordinary chemical, optical, electrical and mechanical properties. Graphene based sensors have gained significance for a wide range of sensing applications like detection of biomolecules, chemicals and gas molecules. It can be easily used to make electrical contacts and manipulate them according to the requirements as compared to the other nanomaterials. The intention of the work presented in this article is to contribute in this field by simulating a novel and cheap graphene nanoribbon sensor for the household gas leakage detection. QuantumWise Atomistix (ATK) software is used for the simulations of propane and butane gas sensor. Projected device density of the states (PDDOS) and the transmission spectrum of the device in the proximity of gas molecules are calculated and discussed. The change in the electric current through the device in the presence of the gas molecules is used as a gas detection mechanism for the simulated sensor.

  6. Preparation and characterization of polyaniline-cadmium sulfide nanocomposite for gas sensor application

    Science.gov (United States)

    Al-Jawad, Selma M. H.; Rafic, Sewench N.; Muhsen, Mustafa M.

    2017-09-01

    Polyaniline (PANI) was prepared by chemical oxidative polymerization of aniline monomers as emeraldine salt form. By the same method, polyaniline-cadmium sulfide nanocomposites were synthesized in the presence of different percentages (10-50 wt.%) of cadmium sulfide (CdS) which was prepared by using sol-gel method. The optical band gap was decrease with increasing of CdS concentration, that is obtained from UV-VIS measurements. From SEM and AFM, there is uniform distribution for cadmium sulfide nanoparticles in the PANI matrix. The electrical measurements of nanocomposites exhibit the effect of crystallite size and the high resistivity of CdS on the resistivity of nanocomposites. Emeraldine salt PANI, CdS and PANI-CdS nanocomposites were investigated as gas sensors. From this investigation, the sensitivity of PANI-CdS for NO2 gas increase with the increasing of operation temperature and the optimum sensitivity was obtained at 200∘C. The sensitivity of nanocomposites at best temperature (200∘C) was increased and faster response time with the increasing of CdS contents.

  7. Operation of Ferroelectric Plasma Sources in a Gas Discharge Mode

    International Nuclear Information System (INIS)

    Dunaevsky, A.; Fisch, N.J.

    2004-01-01

    Ferroelectric plasma sources in vacuum are known as sources of ablative plasma, formed due to surface discharge. In this paper, observations of a gas discharge mode of operation of the ferroelectric plasma sources (FPS) are reported. The gas discharge appears at pressures between approximately 20 and approximately 80 Torr. At pressures of 1-20 Torr, there is a transition from vacuum surface discharge to the gas discharge, when both modes coexist and the surface discharges sustain the gas discharge. At pressures between 20 and 80 Torr, the surface discharges are suppressed, and FPS operate in pure gas discharge mode, with the formation of almost uniform plasma along the entire surface of the ceramics between strips. The density of the expanding plasma is estimated to be about 1013 cm-3 at a distance of 5.5 mm from the surface. The power consumption of the discharge is comparatively low, making it useful for various applications. This paper also presents direct measurements of the yield of secondary electron emission from ferroelectric ceramics, which, at low energies of primary electrons, is high and dependent on the polarization of the ferroelectric material

  8. Three-Dimensional Sensor Common Operating Picture (3-D Sensor COP)

    Science.gov (United States)

    2017-01-01

    DEMs that have been computed from the point clouds . Additionally, Fusion3D can also display 3-D data created using photogrammetry software...Picture (3-D Sensor COP). To test the 3-D Sensor COP, we took advantage of a sensor network that had been deployed for the Enterprise Challenge 2016 at...took advantage of a sensor network that had been deployed for the Enterprise Challenge 2016 (EC16) at Fort Huachuca in Sierra Vista, Arizona. The

  9. Barriers Keep Drops Of Water Out Of Infrared Gas Sensors

    Science.gov (United States)

    Murray, Sean K.

    1996-01-01

    Infrared-sensor cells used for measuring partial pressures of CO(2) and other breathable gases modified to prevent entry of liquid water into sensory optical paths of cells. Hydrophobic membrane prevents drops of water entrained in flow from entering optical path from lamp to infrared detectors.

  10. Operation and management of aging gas distribution systems

    Energy Technology Data Exchange (ETDEWEB)

    McNorgan, J.D. (Southern California Gas Co., Los Angeles, CA (United States))

    1993-05-01

    Southern California Gas Company, transports billions of cubic feet of natural gas through large-diameter, high-pressure transmission lines, across hundreds of miles of varying terrain, to satisfy the needs of over four and a half million customers. Operating an aging gas system can be truly expensive. Repair costs are very high. Recent figures experienced by our company show that it cost over $800 to repair a main leak, $400 to replace a service, and over $40 a foot to replace even small sized mains. A hidden cost is the effect of the physical limitations imposed by an aging system. It could be under-sized, or limited to a low pressure, thus restricting the volume of gas that can be delivered. Additionally there is the potential loss of valuable gas through leaks or blow downs when making repairs or replacements, and the damage it could do to the environment. For some years Southern California Gas Company has had on-going special and routine pipe replacement programs. The special pipe replacement program is driven primarily to increase the safety of the system, while at the same time improving reliability of service to the customers and reducing their total costs.

  11. Reducing greenhouse gas emissions through operations and supply chain management

    International Nuclear Information System (INIS)

    Plambeck, Erica L.

    2012-01-01

    The experiences of the largest corporation in the world and those of a start-up company show how companies can profitably reduce greenhouse gas emissions in their supply chains. The operations management literature suggests additional opportunities to profitably reduce emissions in existing supply chains, and provides guidance for expanding the capacity of new “zero emission” supply chains. The potential for companies to profitably reduce emissions is substantial but (without effective climate policy) likely insufficient to avert dangerous climate change. - Highlights: ► Describes how firms are profitably reducing greenhouse gas emissions in their supply chains ► Highlights academic literature relevant to supply chain emission reduction

  12. Highly sensitive room temperature ammonia gas sensor based on Ir-doped Pt porous ceramic electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wenlong [College of pharmacy and biological engineering, Chengdu University, Chengdu, 610106 (China); Department of chemical and materials engineering, National Chin-Yi University of Technology, Taichung 411, Taiwan (China); Liu, Yen-Yu [Department of chemical and materials engineering, Tunghai University, Taichung 407, Taiwan (China); Do, Jing-Shan, E-mail: jsdo@ncut.edu.tw [Department of chemical and materials engineering, National Chin-Yi University of Technology, Taichung 411, Taiwan (China); Li, Jing, E-mail: lijing@cdu.edu.cn [College of pharmacy and biological engineering, Chengdu University, Chengdu, 610106 (China)

    2016-12-30

    Highlights: • Water vapors seem to hugely improve the electrochemical activity of the Pt and Pt-Ir porous ceramic electrodes. • The gas sensors based on the Pt and Pt-Ir alloy electrodes possess good sensing performances. • The reaction path of the ammonia on platinum has been discussed. - Abstract: Room temperature NH{sub 3} gas sensors based on Pt and Pt-Ir (Ir doping Pt) porous ceramic electrodes have been fabricated by both electroplating and sputtering methods. The properties of the gaseous ammonia sensors have been examined by polarization and chronoamperometry techniques. The influence of humidity on the features of the resulting sensors in the system has also been discussed, and the working potential was optimized. Water vapors seem to hugely improve the electrochemical activity of the electrode. With increasing the relative humidity, the response of the Pt-Ir(E)/Pt(S)/PCP sensor to NH{sub 3} gas could be enhanced remarkably, and the sensitivity increases from 1.14 to 12.06 μA ppm{sup −1} cm{sup −2} .Then we have also discussed the sensing mechanism of the Pt-Ir sensor and the result has been confirmed by X-ray photoelectron spectroscopy of the electrode surface before and after reaction in the end.

  13. 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.

  14. Aplikasi Sistem Peringatan Dini Pada Kebocoran Gas Dan Asap Menggunakan Sensor Gas MQ-7 Dengan Program C

    Directory of Open Access Journals (Sweden)

    Aan Burhanudin

    2016-06-01

    Full Text Available Abstract - Health Safety and Environment (HSE in the development will be more accentuate on the prevention of occupational accidents and occupational diseases by identifying the potential to cause accidents and occupational diseases as well as anticipatory measures in case of accidents and occupational diseases. The working environment is directly in contact with toxic materials would be very harmful to the human body when exposed continuously. An environment or factory containing toxic gases as an example of CO, SO or LPG gas in certain concentrations can cause eye irritation or shortness of breath. Therefore we need an early warning system that can measure the concentration of these gases and may give a warning to workers associated with the concentration of the gas to the workers. The early warning system was made using three gas sensors, three heat sensors, LEDs and buzzer. Recitation and processing of the sensor is processed by a 16 bit microcontroller which will condition the room. In making such a system is used programmable fuzzy algorithms previously simulated with MATLAB, C Programming used as logic programming refers to the simulation results, miniature rooms created with three main space for workers in a hallway and an emergency exit. The results of such a system is in a room when the detected gas concentration exceeds the threshold, the system will activate the buzzer and will activated LED as the safest evacuation route directions. Keyword -- C Proframming, Fuzzy Logic, Matlab

  15. Novel polymer derived ceramic-high temperature heat flux sensor for gas turbine environment

    International Nuclear Information System (INIS)

    Nagaiah, N R; Kapat, J S; An, L; Chow, L

    2006-01-01

    This paper attempts to prove the feasibility of a novel High Temperature Heat Flux (HTHF) sensor for gas turbine environment. Based on the latest improvement in a new type of Polymer-Derived Ceramic (PDC) material, the authors present the design and development of a HTHF sensor based on PDC material, and show that such a sensor is indeed feasible. The PDC-HTHF sensor is fabricated using newly developed polymer derived SiCN, whose conductivity is controlled by proper composition and treatment condition. Direct measurements and characterization of the relevant material properties are presented. Electrical conductivity can be varied from 0 (insulator) to 100 (ohm.cm) -1 ; in addition a value of 4000 ppm/ 0 C (at 600 K) is obtained for temperature coefficient of resistance. This novel sensor is found to perform quite satisfactorily at about 1400 0 C for long term as compared to conventional heat flux sensors available commercially. This type of PDC-HTHF sensor can be used in harsh environments due to its high temperature resistance and resistance to oxidation. This paper also discusses lithography as a microfabrication technique to manufacture the proposed PDC-HTHF sensor. In our current design, the sensor dimensions are 2.5mm in diameter and 250 μm thickness

  16. Steady-state modelling of the universal exhaust gas oxygen (UEGO) sensor

    International Nuclear Information System (INIS)

    Collings, N; Hegarty, K; Ramsander, T

    2012-01-01

    The universal exhaust gas oxygen (UEGO) sensor is a well-established device which was developed for the measurement of relative air fuel ratio in internal combustion engines. There is, however, little information available which allows for the prediction of the UEGO's behaviour when exposed to arbitrary gas mixtures, pressures and temperatures. Here we present a steady-state model for the sensor, based on a solution of the Stefan–Maxwell equation, and which includes a momentum balance. The response of the sensor is dominated by a diffusion barrier, which controls the rate of diffusion of gas species between the exhaust and a cavity. Determination of the diffusion barrier characteristics, especially the mean pore size, porosity and tortuosity, is essential for the purposes of modelling, and a measurement technique based on identification of the sensor pressure giving zero temperature sensitivity is shown to be a convenient method of achieving this. The model, suitably calibrated, is shown to make good predictions of sensor behaviour for large variations of pressure, temperature and gas composition. (paper)

  17. Calibration of low-cost gas sensors for an urban air quality monitoring network

    Science.gov (United States)

    Scott, A.; Kelley, C.; He, C.; Ghugare, P.; Lehman, A.; Benish, S.; Stratton, P.; Dickerson, R. R.; Zuidema, C.; Azdoud, Y.; Ren, X.

    2017-12-01

    In a warming world, environmental pollution may be exacerbated by anthropogenic activities, such as climate change and the urban heat island effect, as well as natural phenomena such as heat waves. However, monitoring air pollution at federal reference standards (approximately 1 part per billion or ppb for ambient ozone) is cost-prohibitive in heterogeneous urban areas as many expensive devices are required to fully capture a region's geo-spatial variability. Innovation in low-cost sensors provide a potential solution, yet technical challenges remain to overcome possible imprecision in the data. We present the calibrations of ozone and nitrous dioxide from a low-cost air quality monitoring device designed for the Baltimore Open Air Project. The sensors used in this study are commercially available thin film electrochemical sensors from SPEC Sensor, which are amperometric, meaning they generate current proportional to volumetric fraction of gas. The results of sensor calibrations in the laboratory and field are presented.

  18. Enhancement of NH3 gas sensitivity at room temperature by carbon nanotube-based sensor coated with Co nanoparticles.

    Science.gov (United States)

    Nguyen, Lich Quang; Phan, Pho Quoc; Duong, Huyen Ngoc; Nguyen, Chien Duc; Nguyen, Lam Huu

    2013-01-30

    Multi-walled carbon nanotube (MWCNT) film has been fabricated onto Pt-patterned alumina substrates using the chemical vapor deposition method for NH(3) gas sensing applications. The MWCNT-based sensor is sensitive to NH(3) gas at room temperature. Nanoclusters of Co catalysts have been sputtered on the surface of the MWCNT film to enhance gas sensitivity with respect to unfunctionalized CNT films. The gas sensitivity of Co-functionalized MWCNT-based gas sensors is thus significantly improved. The sensor exhibits good repeatability and high selectivity towards NH(3), compared with alcohol and LPG.

  19. Enhancement of NH3 Gas Sensitivity at Room Temperature by Carbon Nanotube-Based Sensor Coated with Co Nanoparticles

    Directory of Open Access Journals (Sweden)

    Lich Quang Nguyen

    2013-01-01

    Full Text Available Multi-walled carbon nanotube (MWCNT film has been fabricated onto Pt-patterned alumina substrates using the chemical vapor deposition method for NH3 gas sensing applications. The MWCNT-based sensor is sensitive to NH3 gas at room temperature. Nanoclusters of Co catalysts have been sputtered on the surface of the MWCNT film to enhance gas sensitivity with respect to unfunctionalized CNT films. The gas sensitivity of Co-functionalized MWCNT-based gas sensors is thus significantly improved. The sensor exhibits good repeatability and high selectivity towards NH3, compared with alcohol and LPG.

  20. Characterization and Modeling of Electrical Response of Electrode Catalyzed Reactions in AIGaN/GaN-Based Gas Sensors

    Science.gov (United States)

    Melby, Jacob H.

    AlGaN/GaN high electron mobility transistors (HEMT) and AlGaN/GaN diodes have promise for use as hydrogen and hydrocarbon sensors for a variety of industrial, military, and commercial applications. These semiconductor-based sensors have a number of advantages over other sensor technologies, such as the ability to operate at high temperatures, in corrosive environments, or under ionizing radiation. The high sensitivity of these devices to hydrogen-containing gases is associated with polarization differences within the AlGaN/GaN heterostructure that give rise to the formation of a two-dimensional electron gas (2DEG); exposure of the device to hydrogen changes the density of the 2DEG, which can be detected in a HEMT or diode structure. Although sensitivity to a range of gases has been reported, the factors that influence the behavior of the sensors are not well studied. The overarching goals of the research that follows were to determine how gas exposure conditions affect sensor behavior, to characterize and model the relationship between the electrical response of the sensors and the external gaseous environment, and to investigate the effects of using different metal catalysts on sensor behavior. The heterostructures used in this work were grown via metalorganic vapor phase epitaxy (MOVPE). Schottky diode and transistor devices employing platinum-group (Pd, Pt, Rh, Ir, Ru, and Os) catalysts were fabricated to allow electrical sensitivity in the presence of hydrogen and hydrogen containing gases. The generation of atomic hydrogen on the catalyst surface results in the rapid formation of hydrogen dipoles at the metal-semiconductor interface, which produces a measurable electronic response. The electrical response of Pt-gated HEMT-based sensors were measured in a flowing gaseous stream consisting of hydrogen in a pure nitrogen diluent at ambient and elevated temperatures. The transistors exhibited excellent transfer characteristics for temperatures ranging from 25

  1. Preparation and characterization of indium tin oxide thin films for their application as gas sensors

    International Nuclear Information System (INIS)

    Vaishnav, V.S.; Patel, P.D.; Patel, N.G.

    2005-01-01

    The structural and electrical properties of indium tin oxide (In 2 O 3 /SnO 2 ) thin films grown using direct evaporation technique on various substrates at different temperatures were studied. The effect of annealing, of films with different weight percent concentration of SnO 2 in In 2 O 3 and of different thickness on the structural and electrical properties were studied and optimized for use as gas sensor. The stability of the films against time and temperature variations was studied. The effect of the catalytic layers on the sensor microstructure and its performance towards the gas sensing application was observed

  2. Zinc-oxide nanorod / copper-oxide thin-film heterojunction for a nitrogen-monoxide gas sensor

    International Nuclear Information System (INIS)

    Yoo, Hwansu; Kim, Hyojin; Kim, Dojin

    2014-01-01

    A novel p - n oxide heterojunction structure was fabricated by employing n-type zinc-oxide (ZnO) nanorods grown on an indium-tin-oxide-coated glass substrate by using the hydrothermal method and a p-type copper-oxide (CuO) thin film deposited onto the ZnO nanorod array by using the sputtering method. The crystallinities and microstructures of the heterojunction materials were examined by using X-ray diffraction and scanning electron microscopy. The observed current - voltage characteristics of the p - n oxide heterojunction showed a nonlinear diode-like rectifying behavior. The effects of an oxidizing or electron acceptor gas, such as nitrogen monoxide (NO), on the ZnO nanorod/CuO thin-film heterojunction were investigated to determine the potential applications of the fabricated material for use in gas sensors. The forward current of the p - n heterojunction was remarkably reduced when NO gas was introduced into dry air at temperatures from 100 to 250 .deg. C. The NO gas response of the oxide heterojunction reached a maximum value at an operating temperature of 180 .deg. C and linearly increased as the NO gas concentration was increased from 5 to 30 ppm. The sensitivity value was observed to be as high as 170% at 180 .deg. C when biased at 2 V in the presence of 20-ppm NO. The ZnO nanorod/CuO thin-film heterojunction also exhibited a stable and repeatable response to NO gas. The experimental results suggest that the ZnO nanorod/CuO thin-film heterojunction structure may be a novel candidate for gas sensors.

  3. Zinc-oxide nanorod / copper-oxide thin-film heterojunction for a nitrogen-monoxide gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Hwansu; Kim, Hyojin; Kim, Dojin [Chungnam National University, Daejeon (Korea, Republic of)

    2014-11-15

    A novel p - n oxide heterojunction structure was fabricated by employing n-type zinc-oxide (ZnO) nanorods grown on an indium-tin-oxide-coated glass substrate by using the hydrothermal method and a p-type copper-oxide (CuO) thin film deposited onto the ZnO nanorod array by using the sputtering method. The crystallinities and microstructures of the heterojunction materials were examined by using X-ray diffraction and scanning electron microscopy. The observed current - voltage characteristics of the p - n oxide heterojunction showed a nonlinear diode-like rectifying behavior. The effects of an oxidizing or electron acceptor gas, such as nitrogen monoxide (NO), on the ZnO nanorod/CuO thin-film heterojunction were investigated to determine the potential applications of the fabricated material for use in gas sensors. The forward current of the p - n heterojunction was remarkably reduced when NO gas was introduced into dry air at temperatures from 100 to 250 .deg. C. The NO gas response of the oxide heterojunction reached a maximum value at an operating temperature of 180 .deg. C and linearly increased as the NO gas concentration was increased from 5 to 30 ppm. The sensitivity value was observed to be as high as 170% at 180 .deg. C when biased at 2 V in the presence of 20-ppm NO. The ZnO nanorod/CuO thin-film heterojunction also exhibited a stable and repeatable response to NO gas. The experimental results suggest that the ZnO nanorod/CuO thin-film heterojunction structure may be a novel candidate for gas sensors.

  4. A gas sensor comprising two back-to-back connected Au/TiO2 Schottky diodes

    Science.gov (United States)

    Dehghani, Niloofar; Yousefiazari, Ehsan

    2018-04-01

    A miniature, but sturdy, gas sensor capable of operation at temperatures as high as 600 °C is presented. The device comprises two back-to-back connected gold/rutile Schottky diodes, which are fabricated on the opposite bases of a self-standing 100 μm-thick pellet of polycrystalline rutile. The rutile layer is formed by the direct oxidation of titanium metal in air at 900 °C, and the Au/rutile diodes are formed by the diffusion bonding of the gold wire segments to the pellet bases. The current versus voltage diagrams and gas sensing properties of the Au/rutile/Au structured device are recorded at different voltage sweeping frequencies and operating temperatures. The interesting features of these diagrams are explained based on an equivalent circuit of the device, which considers Schottky-type contacts at both bases and memristive conduction for the rutile in between. The device current is controlled by the leakage current of the reverse biased diode, which depends on the concentration of the oxygen vacancy at the Au/rutile interface and, hence, on the composition of the surrounding atmosphere. The device current increases 15 times in response to the presence of 1000 ppm of ethanol vapor in air. Consisting only of bulk gold and bulk rutile, the device is resilient to harsh environments and elevated temperatures; a suitable gas sensor for in-exhaust installation.

  5. Simulation of gas turbines operating in off-design condition

    Energy Technology Data Exchange (ETDEWEB)

    Walter, Arnaldo [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Energia]. E-mail: walter@fem.unicamp.br

    2000-07-01

    In many countries thermal power plants based on gas turbines have been the main option for new investment into the electric system due to their relatively high efficiency and low capital cost. Cogeneration systems based on gas turbines have also been an important option for the electric industry. Feasibility studies of power plants based on gas turbine should consider the effect of atmospheric conditions and part-load operation on the machine performance. Doing this, an off-design procedure is required. A G T off-design simulation procedure is described in this paper. Ruston R M was used to validate the simulation procedure that, general sense, presents deviations lower than 2.5% in comparison to manufacturer's data. (author)

  6. QCM gas sensor characterization of ALD-grown very thin TiO2 films

    Science.gov (United States)

    Boyadjiev, S.; Georgieva, V.; Vergov, L.; Szilágyi, I. M.

    2018-03-01

    The paper presents a technology for preparation and characterization of titanium dioxide (TiO2) thin films suitable for gas sensor applications. Applying atomic layer deposition (ALD), very thin TiO2 films were deposited on quartz resonators, and their gas sensing properties were studied using the quartz crystal microbalance (QCM) method. The TiO2 thin films were grown using Ti(iOPr)4 and water as precursors. The surface of the films was observed by scanning electron microscopy (SEM), coupled with energy dispersive X-ray analysis (EDX) used for a composition study. The research was focused on the gas-sensing properties of the films. Films of 10-nm thickness were deposited on quartz resonators with Au electrodes and the QCMs were used to build highly sensitive gas sensors, which were tested for detecting NO2. Although very thin, these ALD-grown TiO2 films were sensitive to NO2 already at room temperature and could register as low concentrations as 50 ppm, while the sorption was fully reversible, and the sensors could be fully recovered. With the technology presented, the manufacturing of gas sensors is simple, fast and cost-effective, and suitable for energy-effective portable equipment for real-time environmental monitoring of NO2.

  7. Carbon materials-functionalized tin dioxide nanoparticles toward robust, high-performance nitrogen dioxide gas sensor.

    Science.gov (United States)

    Zhang, Rui; Liu, Xiupeng; Zhou, Tingting; Wang, Lili; Zhang, Tong

    2018-08-15

    Carbon (C) materials, which process excellent electrical conductivity and high carrier mobility, are promising sensing materials as active units for gas sensors. However, structural agglomeration caused by chemical processes results in a small resistance change and low sensing response. To address the above issues, structure-derived carbon-coated tin dioxide (SnO 2 ) nanoparticles having distinct core-shell morphology with a 3D net-like structure and highly uniform size are prepared by careful synthesis and fine structural design. The optimum carbon-coated SnO 2 nanoparticles (SnO 2 /C)-based gas sensor exhibits a low working temperature, excellent selectivity and fast response-recovery properties. In addition, the SnO 2 /C-based gas sensor can maintain a sensitivity to nitrogen dioxide (NO 2 ) of 3 after being cycled 4 times at 140 °C for, suggesting its good long-term stability. The structural integrity, good synergistic properties, and high gas-sensing performance of SnO 2 /C render it a promising sensing material for advanced gas sensors. Copyright © 2018 Elsevier Inc. All rights reserved.

  8. Gas turbines and operation of gas turbines 2011; Gasturbinen und Gasturbinenbetrieb 2011

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    Within the VGB Conference at 11th and 12th May, 2011 in Offenbach/Main (Federal Republic of Germany), the following lectures were held: (1) The future of high temperature gas turbines in power plants (Konrad Vogeler); (2) Development of reliable thermal barrier coatings for high-loaded turbine and combustor parts (Hans-Peter Bossmann); (3) CCPP Irsching 4 with gas turbine SGT5-8000H, on the way to 60 % CC efficiency (Willibald Fischer); (4) First test results of MAN's new 6 MW gas turbine (Markus Beukenberg); (5) Design characteristics and key thermodynamic parameters of the recuperated 4 MW solar turbines Mercury 50 gas turbines: - Economics and environmental feasibility, - operating experience in combined cycle applications with recuperation (Ulrich Stang); (6) Medium size gas turbines - OEM concept for continued reduction of life cycle costs (Vladimir Navrotsky); (7) Fracture mechanical analysis on fatigue failures of gas turbine components: - Root cause analysis - fracture mechanics - stress corrosion cracking - examples of failure analysis (Peter Verstraete); (8) The effectiveness of blade superalloy reheat treatment (Michael Wood); (9) An innovative combustion technology for high efficient gas turbines (Christian Oliver Paschereit); (10) Damping of thermo-acoustic vibrations in gas turbine combustion chambers (Sermed Sadig); (11) Alstom GT13E2 combustor upgrade for Vattenfalls Berlin Mitte combined heat and power plant (Klaus Doebbeling); (12) Optimisation of air inlet filtration for dust, rain and humidity (Heiko Manstein); (13) Life cycle cost reduction through high efficiency membrane based air intake filters (Helmut Krah); (14) Status and impact of national, European and international standardization on GT plants; GT standardizing status quo? (Gerd Weber); (15) Technical and thermodynamic aspects of compresssed air energy storage (Peter Radgen); (16) Requirements on the gas turbine in the course of time - intelligent OEM-concepts to ensure reliable

  9. Intelligent Design of Metal Oxide Gas Sensor Arrays Using Reciprocal Kernel Support Vector Regression

    Science.gov (United States)

    Dougherty, Andrew W.

    Metal oxides are a staple of the sensor industry. The combination of their sensitivity to a number of gases, and the electrical nature of their sensing mechanism, make the particularly attractive in solid state devices. The high temperature stability of the ceramic material also make them ideal for detecting combustion byproducts where exhaust temperatures can be high. However, problems do exist with metal oxide sensors. They are not very selective as they all tend to be sensitive to a number of reduction and oxidation reactions on the oxide's surface. This makes sensors with large numbers of sensors interesting to study as a method for introducing orthogonality to the system. Also, the sensors tend to suffer from long term drift for a number of reasons. In this thesis I will develop a system for intelligently modeling metal oxide sensors and determining their suitability for use in large arrays designed to analyze exhaust gas streams. It will introduce prior knowledge of the metal oxide sensors' response mechanisms in order to produce a response function for each sensor from sparse training data. The system will use the same technique to model and remove any long term drift from the sensor response. It will also provide an efficient means for determining the orthogonality of the sensor to determine whether they are useful in gas sensing arrays. The system is based on least squares support vector regression using the reciprocal kernel. The reciprocal kernel is introduced along with a method of optimizing the free parameters of the reciprocal kernel support vector machine. The reciprocal kernel is shown to be simpler and to perform better than an earlier kernel, the modified reciprocal kernel. Least squares support vector regression is chosen as it uses all of the training points and an emphasis was placed throughout this research for extracting the maximum information from very sparse data. The reciprocal kernel is shown to be effective in modeling the sensor

  10. Application of ZnO Nanoparticle as Sulphide Gas Sensor Using UV/VIS/NIR-Spectrophotometer

    International Nuclear Information System (INIS)

    Juliasih, N; Buchari; Noviandri, I

    2017-01-01

    The nanoparticle of metal oxides has great unique characteristics that applicable to the wide industrial as sensors and catalysts for reducing environmental pollution. Sulphide gas monitors and detectors are required for assessing safety aspects, due to its toxicity level. A thin film of ZnO as the sulphide gas sensor was synthesised by the simple method of chemical liquid deposition with variation of annealing temperature from 200 ºC to 500 ºC, and characterised by Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), and UV/VIS/NIR-Spectrophotometer. Characterization studies showed nanoparticle size from the range 62 – 92 nm of diameters. The application this ZnO thin film to sulfide gas, detected by UV/VIS/NIR Spectrophotometer with diffuse reflectance, showed specific chemical reaction by the shifting of maximum % Reflectance peak. The gas sensing using this method is applicable at room. (paper)

  11. Map of gas facilities and operators in Northeast British Columbia

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2005-06-01

    This map represents 57 gas facilities and operators and references location on the map to the facility and operator. The Northern Rockies Regional district is indicated, as is the Peace River Regional district. Roads, truck trails, railroads, pipeline and airstrips are indicated as well as oil and gas fields. Various protected areas and First Nations settlement areas and regions are also indicated. The following companies placed advertisements on the map, detailing the services they provide: Wellco Energy Services; C.E. Franklin Ltd.; the City of Fort St. John, Region of Chetwynd; Smith Bits; the City of Dawson Creek, Economic Development and Tourism; Fort Nelson and Northern Rockies Regional District; Pipetech Corp.; Kenwood; Hughes Christensen; Spartan Controls; FI Canada Oil Services Ltd.; Northstar Drillstem Testers Inc.; Rainbow Transport Ltd.1 fig.

  12. Response speed of SnO2-based H2S gas sensors with CuO nanoparticles

    International Nuclear Information System (INIS)

    Chowdhuri, Arijit; Gupta, Vinay; Sreenivas, K.; Kumar, Rajeev; Mozumdar, Subho; Patanjali, P. K.

    2004-01-01

    CuO nanoparticles on sputtered SnO 2 thin-film surface exhibit a fast response speed (14 s) and recovery time (61 s) for trace level (20 ppm) H 2 S gas detection. The sensitivity of the sensor (S∼2.06x10 3 ) is noted to be high at a low operating temperature of 130 deg. C. CuO nanoparticles on SnO 2 allow effective removal of excess adsorbed oxygen from the uncovered SnO 2 surface due to spillover of hydrogen dissociated from the H 2 S-CuO interaction

  13. Development of mobile sensor for volcanic observation "HOMURA": Test campaigns for a long-term operation

    Science.gov (United States)

    Kaneko, K.; Iwahori, K.; Ito, K.; Sagi, H.

    2016-12-01

    Unmanned robots are useful to observe volcanic phenomena near active volcanic vents, to learn symptoms and transitions of eruptions, and to mitigate volcanic disasters. We have been trying to develop a practical UGV robot for flexible observation of active volcanic vents. We named this system "Homura". In this presentation, we report results of test campaigns of Homura for observation in a volcanic field. We have developed a prototype of Homura, which is a small robot vehicle with six wheels (75 x 43 x 31 cm and a weight of about 12 kg). It is remotely controlled with mobile phone radio waves; it can move in volcanic fields and send real time data of sensors (camera and gas sensors) equipped in the vehicle to the base station. Homura has a small solar panel (4 W). Power consumption of Homura is about 4 W in operation of sensors and less than 0.1 W in idle state, so that Homura can work outdoors for a long time by intermittent operation.We carried out two test campaigns of Homura at Iwo-yama to examine if Homura can work for a few month in natural volcanic fields (however, it had no solar panel in these campaigns). Iwo-yama is one of craters in the Kirishima volcanic field, SW Japan; the area within 1 km from the crater was an off-limit area from Oct., 2014 to May, 2015 and from Feb. to Mar., 2016 because of strong volcanic seismicity. On Feb. 19th, 2015 and Mar. 7th, 2016, we carried and put Homura at the rim of the crater. Unfortunately, mobile phone connectivity was not entirely stable around Iwo-yama. Then, we did not move Homura and only obtain real time data of the sensors. In the two campaigns, we operated Homura at our office for a few hours every day for 49 and 37 days, respectively. Although the weather was often bad (rain, fog, or cold temperature) during the campaigns, Homura perfectly worked. The results of these campaigns indicate that Homura is useful as s simple monitoring station in volcanic fields where mobile phone connection is available.

  14. Methane emissions from U.S. natural gas operations

    International Nuclear Information System (INIS)

    Lott, R.A.

    1992-01-01

    The Gas Research Institute and the U.S. Environmental Protection Agency are cofunding and comanaging a program to evaluate methane emissions from U.S. natural gas operations. The purpose of the program is to provide an emissions inventory accurate enough for global climate modeling and for addressing the policy question of ''whether encouraging the increased use of natural gas is a viable strategy for reducing the U.S. contribution to global warming''. The program is comprised of three phases: Scoping, Methods Development, and Implementation. The purpose of Phase I was to define the problem. Phase II of the program concentrated on developing techniques for measuring steady state or fugitive emissions and for calculating the highly variable unsteady emissions from the variety of sources that comprise the gas industry. Because of the large number of sources within each source type, techniques were also developed for extrapolating emissions data to similar sources within the industry. Phase III of the program was started in early 1992 and should be completed in early 1994. The purpose of the current phase of the program is to collect sufficient data to achieve the accuracy goal of determining emissions to within ± 0.5 percent of production. Based on the limited amount of data collected to date, methane emissions from the U.S. gas industry appear to be in the range of 1 percent of production. (au) (19 refs.)

  15. Worchester Solenoid Actuated Gas Operated MCO Isolation Valves

    International Nuclear Information System (INIS)

    VAN KATWIJK, C.

    2000-01-01

    These valves are 1 inch gas-operated full-port ball valves incorporating a solenoid and limit switches as integral parts of the actuator that are used in process streams within the CVDF hood. The valves fail closed (on loss of pressure or electrical) to prevent MCO vent drain to either reduce air in-leakage or loss of He. The valves have couplings for transverse actuator mounting

  16. Pilot plant for flue gas treatment - continuous operation tests

    International Nuclear Information System (INIS)

    Chmielewski, A.G.; Tyminski, B.; Iller, E.; Zimek, Z.; Licki, J.; Radzio, B.

    1995-01-01

    Tests of continuous operation have been performed on pilot plant at EPS Kaweczyn in the wide range of SO 2 concentration (500-3000 ppm). The bag filter has been applied for aerosol separation. The high efficiencies of SO 2 and NO x removal, approximately 90% were obtained and influenced by such process parameters as: dose, gas temperature and ammonia stoichiometry. The main apparatus of the pilot plant (e.g. both accelerators) have proved their reliability in hard industrial conditions. (Author)

  17. The characteristics of operation of the Shatlyk gas condensate deposit

    Energy Technology Data Exchange (ETDEWEB)

    Zatov, G.A.; Friman, Yu.M.; Frumson, Yu.V.; Koshayev, T.K.; Stepanov, N.G.; Tverkovkin, S.M.

    1983-01-01

    Results are correlated of the operation of the Shatlyksk deposit for a 10 year period from the start of its development through 1982. The rates of gas withdrawal from the deposits are analyzed, along with the conditions for manifestation of elastic, water thrust modes, the characteristics of the studied wells and other issues. The results of modeling the advancement of stratum waters are cited. The modeling was performed on a computer (EVM) using a system of two dimensional, two phase filtration.

  18. Worcester Solenoid-Actuated Gas Operated MCO Isolation Valves

    International Nuclear Information System (INIS)

    VAN KATWIJK, C.

    2000-01-01

    These valves are 1 inch gas-operated full-port ball valves incorporating a solenoid and limit switches as Integral parts of the actuator that are used in different process streams within the CVDF hood. The valves fail closed (on loss of pressure or electrical) for MCO isolation to either reduce air in leakage or loss of He. All valves have coupling for transverse actuator mounting

  19. Study of Influencing Factors of Dynamic Measurements Based on SnO2 Gas Sensor

    Directory of Open Access Journals (Sweden)

    Jinhuai Liu

    2004-08-01

    Full Text Available Abstract: The gas-sensing behaviour based on a dynamic measurement method of a single SnO2 gas sensor was investigated by comparison with the static measurement. The influencing factors of nonlinear response such as modulation temperature, duty ratio, heating waveform (rectangular, sinusoidal, saw-tooth, pulse, etc. were also studied. Experimental data showed that temperature was the most essential factor because the changes of frequency and heating waveform could result in the changes of temperature essentially.

  20. Environmental requirements for oil and gas operations in Saskatchewan

    International Nuclear Information System (INIS)

    Nystuen, L.J.

    1997-01-01

    The administration and regulation of environmental issues regarding the oil and gas industry in Saskatchewan were discussed. The political and cultural differences in Saskatchewan that make environmental processes distinct from its neighbouring jurisdictions were described. The following Saskatchewan legislation deals with environmental requirements: Environmental Management and Protection Act, Environmental Assessment Act, Oil and Gas Conservation Act, Wildlife Habitat Protection Act, Clean Air Act, Planning and Development Act, Forest Act, Water Corporation Act, Heritage Property Act, and Parks Act. The Saskatchewan Department of Energy and Mines (SEM) is the primary regulator of the upstream oil and gas industry. It regulates the construction, operation, reporting and abandonment requirements for oilfield operations. SEM also manages crude oil prior to refining and manages the wastes contaminated with crude oil. Provisions of the relevant Acts regarding drilling in environmentally sensitive areas, flaring requirements, transporting and disposing of oilfield wastes, road-building, operating restrictions, emergency response plans, spill clean-up responsibilities, well abandonment and site reclamation responsibilities were discussed. 8 refs., 2 tabs

  1. Orthorhombic MoO{sub 3} nanobelts based NO{sub 2} gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Mane, A.A. [Thin Film Nanomaterials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India); General Science and Humanities Department, Sant Gajanan Maharaj College of Engineering, Mahagaon, 416 503 (India); Moholkar, A.V., E-mail: avmoholkar@gmail.com [Thin Film Nanomaterials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India)

    2017-05-31

    Highlights: • The effect of thickness on physicochemical and NO{sub 2} gas sensing properties of sprayed MoO{sub 3} nanobelts has been reported. • The sprayed MoO{sub 3} nanobelts show the NO{sub 2} gas response of 68% for 100 ppm concentration at an operating temperature of 200 °C. • The lower detection limit of MoO{sub 3} nanobelts based NO{sub 2} sensor is found to be half of the IDLH value (20 ppm). - Abstract: Molybdenum trioxide (MoO{sub 3}) nanobelts have been deposited onto the glass substrates using chemical spray pyrolysis (CSP) deposition method. The XRD patterns reveal that films are polycrystalline having an orthorhombic crystal structure. Raman spectra confirm that the films are orthorhombic in phase. The XPS study shows the presence of two well resolved spectral lines of Mo-3d core levels appearing at the binding energy values of 232.82 eV and 235.95 eV corresponding to Mo-3d{sub 5/2} and Mo-3d{sub 3/2}, respectively. These binding energy values are assigned to Mo{sup 6+} oxidation state of fully oxidized MoO{sub 3}. The FE-SEM micrographs show the formation of nanobelts-like morphology. The AFM micrographs reveal that the RMS surface roughness increases from 16.5 nm to 17.5 nm with increase in film thickness from 470 nm to 612 nm and then decreases to 16 nm for 633 nm film thickness. The band gap energy is found to be decreased from 3.40 eV to 3.38 eV. To understand the electronic transport phenomenon in MoO{sub 3} thin films, dielectric properties are studied. For 612 nm film thickness, the highest NO{sub 2} gas response of 68% is obtained at an operating temperature of 200 °C for 100 ppm concentration with response and recovery times of 15 s and 150 s, respectively. The lower detection limit is found to be 10 ppm which is half of the immediately dangerous to life or health (IDLH) value of 20 ppm. Finally, NO{sub 2} gas sensing mechanism in an orthorhombic MoO{sub 3} crystal structure is discussed in detail.

  2. Recent Developments in 2D Nanomaterials for Chemiresistive-Type Gas Sensors

    Science.gov (United States)

    Choi, Seon-Jin; Kim, Il-Doo

    2018-03-01

    Two-dimensional (2D) nanostructures are gaining tremendous interests due to the fascinating physical, chemical, electrical, and optical properties. Recent advances in 2D nanomaterials synthesis have contributed to optimization of various parameters such as physical dimension and chemical structure for specific applications. In particular, development of high performance gas sensors is gaining vast importance for real-time and on-site environmental monitoring by detection of hazardous chemical species. In this review, we comprehensively report recent achievements of 2D nanostructured materials for chemiresistive-type gas sensors. Firstly, the basic sensing mechanism is described based on charge transfer behavior between gas species and 2D nanomaterials. Secondly, diverse synthesis strategies and characteristic gas sensing properties of 2D nanostructures such as graphene, metal oxides, transition metal dichalcogenides (TMDs), metal organic frameworks (MOFs), phosphorus, and MXenes are presented. In addition, recent trends in synthesis of 2D heterostructures by integrating two different types of 2D nanomaterials and their gas sensing properties are discussed. Finally, this review provides perspectives and future research directions for gas sensor technology using various 2D nanomaterials.

  3. Recent Developments in 2D Nanomaterials for Chemiresistive-Type Gas Sensors

    Science.gov (United States)

    Choi, Seon-Jin; Kim, Il-Doo

    2018-05-01

    Two-dimensional (2D) nanostructures are gaining tremendous interests due to the fascinating physical, chemical, electrical, and optical properties. Recent advances in 2D nanomaterials synthesis have contributed to optimization of various parameters such as physical dimension and chemical structure for specific applications. In particular, development of high performance gas sensors is gaining vast importance for real-time and on-site environmental monitoring by detection of hazardous chemical species. In this review, we comprehensively report recent achievements of 2D nanostructured materials for chemiresistive-type gas sensors. Firstly, the basic sensing mechanism is described based on charge transfer behavior between gas species and 2D nanomaterials. Secondly, diverse synthesis strategies and characteristic gas sensing properties of 2D nanostructures such as graphene, metal oxides, transition metal dichalcogenides (TMDs), metal organic frameworks (MOFs), phosphorus, and MXenes are presented. In addition, recent trends in synthesis of 2D heterostructures by integrating two different types of 2D nanomaterials and their gas sensing properties are discussed. Finally, this review provides perspectives and future research directions for gas sensor technology using various 2D nanomaterials.

  4. Paradigms of underground gas storage operation; Paradigmas del funcionamiento de un almacenamiento subterraneo de gas

    Energy Technology Data Exchange (ETDEWEB)

    Bonoris, Patricia; Vizcarra, Rodolfo; Buciak, Jorge [Companias Asociadas Petroleras S.A. (Argentina)

    2004-07-01

    The main objective of the study was to determine, for the underground storage of gas, the Current Useful Volume and Maximum Useful Current of operation, as well as have an acceptable interpretation that allows calculating the investment needed to reach this Maximum Usable Volume.

  5. Development of gas sensors using ZnO nanostructures

    Indian Academy of Sciences (India)

    Administrator

    effect of oxidizing gases is opposite to that of reduc- ing gases. ... 600 and 900°C under argon atmosphere (flow rate. 500 cc/min) and on ... argon gas at temperatures between 800 and 1050°C. Nature of ... strates by thermal evaporation.

  6. High temperature ultrasonic sensor for fission gas characterization in MTR harsh environment

    Science.gov (United States)

    Gatsa, O.; Combette, P.; Rozenkrantz, E.; Fourmentel, D.; Destouches, C.; Ferrandis, J. Y. AD(; )

    2018-01-01

    In the contemporary world, the measurements in hostile environment is one of the predominant necessity for automotive, aerospace, metallurgy and nuclear plant. The measurement of different parameters in experimental reactors is an important point in nuclear power strategy. In the near past, IES (Institut d'Électronique et des Systèmes) on collaboration with CEA (Commissariat à l'Energie Atomique et aux Energies Alternatives) have developed the first ultrasonic sensor for the application of gas quantity determination that has been tested in a Materials Testing Reactor (MTR). Modern requirements state to labor with the materials that possess stability on its parameters around 350°C in operation temperature. Previous work on PZT components elaboration by screen printing method established the new basis in thick film fabrication and characterization in our laboratory. Our trials on Bismuth Titanate ceramics showed the difficulties related to high electrical conductivity of fabricated samples that postponed further research on this material. Among piezoceramics, the requirements on finding an alternative solution on ceramics that might be easily polarized and fabricated by screen printing approach were resolved by the fabrication of thick film from Sodium Bismuth Titanate (NBT) piezoelectric powder. This material exhibits high Curie temperature, relatively good piezoelectric and coupling coefficients, and it stands to be a good solution for the anticipated application. In this paper, we present NBT thick film fabrication by screen printing, characterization of piezoelectric, dielectric properties and material parameters studies in dependence of temperature. Relatively high resistivity in the range of 1.1013 Ohm.cm for fabricated thick film is explained by Aurivillius structure in which a-and b-layers form perovskite structure between oxides of c-layer. Main results of this study are presented and discussed in terms of feasibility for an application to a new sensor

  7. Design of Highly Selective Gas Sensors via Physicochemical Modification of Oxide Nanowires: Overview

    Directory of Open Access Journals (Sweden)

    Hyung-Sik Woo

    2016-09-01

    Full Text Available Strategies for the enhancement of gas sensing properties, and specifically the improvement of gas selectivity of metal oxide semiconductor nanowire (NW networks grown by chemical vapor deposition and thermal evaporation, are reviewed. Highly crystalline NWs grown by vapor-phase routes have various advantages, and thus have been applied in the field of gas sensors over the years. In particular, n-type NWs such as SnO2, ZnO, and In2O3 are widely studied because of their simple synthetic preparation and high gas response. However, due to their usually high responses to C2H5OH and NO2, the selective detection of other harmful and toxic gases using oxide NWs remains a challenging issue. Various strategies—such as doping/loading of noble metals, decorating/doping of catalytic metal oxides, and the formation of core–shell structures—have been explored to enhance gas selectivity and sensitivity, and are discussed herein. Additional methods such as the transformation of n-type into p-type NWs and the formation of catalyst-doped hierarchical structures by branch growth have also proven to be promising for the enhancement of gas selectivity. Accordingly, the physicochemical modification of oxide NWs via various methods provides new strategies to achieve the selective detection of a specific gas, and after further investigations, this approach could pave a new way in the field of NW-based semiconductor-type gas sensors.

  8. Highly selective gas sensor arrays based on thermally reduced graphene oxide.

    Science.gov (United States)

    Lipatov, Alexey; Varezhnikov, Alexey; Wilson, Peter; Sysoev, Victor; Kolmakov, Andrei; Sinitskii, Alexander

    2013-06-21

    The electrical properties of reduced graphene oxide (rGO) have been previously shown to be very sensitive to surface adsorbates, thus making rGO a very promising platform for highly sensitive gas sensors. However, poor selectivity of rGO-based gas sensors remains a major problem for their practical use. In this paper, we address the selectivity problem by employing an array of rGO-based integrated sensors instead of focusing on the performance of a single sensing element. Each rGO-based device in such an array has a unique sensor response due to the irregular structure of rGO films at different levels of organization, ranging from nanoscale to macroscale. The resulting rGO-based gas sensing system could reliably recognize analytes of nearly the same chemical nature. In our experiments rGO-based sensor arrays demonstrated a high selectivity that was sufficient to discriminate between different alcohols, such as methanol, ethanol and isopropanol, at a 100% success rate. We also discuss a possible sensing mechanism that provides the basis for analyte differentiation.

  9. Advances in SAW gas sensors based on the condensate-adsorption effect.

    Science.gov (United States)

    Liu, Jiuling; Wang, Wen; Li, Shunzhou; Liu, Minghua; He, Shitang

    2011-01-01

    A surface-acoustic-wave (SAW) gas sensor with a low detection limit and fast response for volatile organic compounds (VOCs) based on the condensate-adsorption effect detection is developed. In this sensor a gas chromatography (GC) column acts as the separator element and a dual-resonator oscillator acts as the detector element. Regarding the surface effective permittivity method, the response mechanism analysis, which relates the condensate-adsorption effect, is performed, leading to the sensor performance prediction prior to fabrication. New designs of SAW resonators, which act as feedback of the oscillator, are devised in order to decrease the insertion loss and to achieve single-mode control, resulting in superior frequency stability of the oscillator. Based on the new phase modulation approach, excellent short-term frequency stability (±3 Hz/s) is achieved with the SAW oscillator by using the 500 MHz dual-port resonator as feedback element. In a sensor experiment investigating formaldehyde detection, the implemented SAW gas sensor exhibits an excellent threshold detection limit as low as 0.38 pg.

  10. Realization of rapid debugging for detection circuit of optical fiber gas sensor: Using an analog signal source

    Science.gov (United States)

    Tian, Changbin; Chang, Jun; Wang, Qiang; Wei, Wei; Zhu, Cunguang

    2015-03-01

    An optical fiber gas sensor mainly consists of two parts: optical part and detection circuit. In the debugging for the detection circuit, the optical part usually serves as a signal source. However, in the debugging condition, the optical part can be easily influenced by many factors, such as the fluctuation of ambient temperature or driving current resulting in instability of the wavelength and intensity for the laser; for dual-beam sensor, the different bends and stresses of the optical fiber will lead to the fluctuation of the intensity and phase; the intensity noise from the collimator, coupler, and other optical devices in the system will also result in the impurity of the optical part based signal source. In order to dramatically improve the debugging efficiency of the detection circuit and shorten the period of research and development, this paper describes an analog signal source, consisting of a single chip microcomputer (SCM), an amplifier circuit, and a voltage-to-current conversion circuit. It can be used to realize the rapid debugging detection circuit of the optical fiber gas sensor instead of optical part based signal source. This analog signal source performs well with many other advantages, such as the simple operation, small size, and light weight.

  11. Gas Sensing Properties of Metal Doped WO3 Thin Film Sensors Prepared by Pulsed Laser Deposition and DC Sputtering Process

    Science.gov (United States)

    Bhuiyan, Md. Mosharraf Hossain; Ueda, Tsuyoshi; Ikegami, Tomoaki; Ebihara, Kenji

    2006-10-01

    Tungsten trioxide (WO3) thin films gas sensors were prepared by the KrF excimer pulsed laser deposition (PLD) method. The films were prepared on the quartz glass, silicon and also on the Al2O3 sensor substrates with platinum interdigitated electrodes. The effect of doping of the platinum (Pt), palladium (Pd) or gold (Au) on the WO3 thin film was also investigated. These metals were doped to the WO3 thin film by the DC sputtering process during the PLD. The substrate temperature and the oxygen pressure were 400 °C and 100 mTorr, respectively, during the deposition. The films were characterized by atomic force microscopy (AFM) and X-ray diffraction (XRD). The sensitivity of the prepared sensors to 60 ppm NO gas was examined using the two terminal resistance method in a chamber at atmospheric pressure and operating temperatures of 25-350 °C. The sensitivity of the WO3 thin films doped with Pt, Pd, or Au was found to be higher than that of the undoped WO3 thin film.

  12. Effect of Humid Aging on the Oxygen Adsorption in SnO₂ Gas Sensors.

    Science.gov (United States)

    Suematsu, Koichi; Ma, Nan; Watanabe, Ken; Yuasa, Masayoshi; Kida, Tetsuya; Shimanoe, Kengo

    2018-01-16

    To investigate the effect of aging at 580 °C in wet air (humid aging) on the oxygen adsorption on the surface of SnO₂ particles, the electric properties and the sensor response to hydrogen in dry and humid atmospheres for SnO₂ resistive-type gas sensors were evaluated. The electric resistance in dry and wet atmospheres at 350 °C was strongly increased by humid aging. From the results of oxygen partial pressure dependence of the electric resistance, the oxygen adsorption equilibrium constants ( K ₁; for O - adsorption, K ₂; for O 2- adsorption) were estimated on the basis of the theoretical model of oxygen adsorption. The K ₁ and K ₂ in dry and wet atmospheres at 350 °C were increased by humid aging at 580 °C, indicating an increase in the adsorption amount of both O - and O 2- . These results suggest that hydroxyl poisoning on the oxygen adsorption is suppressed by humid aging. The sensor response to hydrogen in dry and wet atmosphere at 350 °C was clearly improved by humid aging. Such an improvement of the sensor response seems to be caused by increasing the oxygen adsorption amount. Thus, the humid aging offers an effective way to improve the sensor response of SnO₂ resistive-type gas sensors in dry and wet atmospheres.

  13. Effect of Humid Aging on the Oxygen Adsorption in SnO2 Gas Sensors

    Directory of Open Access Journals (Sweden)

    Koichi Suematsu

    2018-01-01

    Full Text Available To investigate the effect of aging at 580 °C in wet air (humid aging on the oxygen adsorption on the surface of SnO2 particles, the electric properties and the sensor response to hydrogen in dry and humid atmospheres for SnO2 resistive-type gas sensors were evaluated. The electric resistance in dry and wet atmospheres at 350 °C was strongly increased by humid aging. From the results of oxygen partial pressure dependence of the electric resistance, the oxygen adsorption equilibrium constants (K1; for O− adsorption, K2; for O2− adsorption were estimated on the basis of the theoretical model of oxygen adsorption. The K1 and K2 in dry and wet atmospheres at 350 °C were increased by humid aging at 580 °C, indicating an increase in the adsorption amount of both O− and O2−. These results suggest that hydroxyl poisoning on the oxygen adsorption is suppressed by humid aging. The sensor response to hydrogen in dry and wet atmosphere at 350 °C was clearly improved by humid aging. Such an improvement of the sensor response seems to be caused by increasing the oxygen adsorption amount. Thus, the humid aging offers an effective way to improve the sensor response of SnO2 resistive-type gas sensors in dry and wet atmospheres.

  14. A Preliminary Test for Skin Gas Assessment Using a Porphyrin Based Evanescent Wave Optical Fiber Sensor

    Directory of Open Access Journals (Sweden)

    Roman SELYANCHYN

    2011-02-01

    Full Text Available An evanescent-wave optical fibre sensor modified with tetrakis-(4-sulfophenyl porphine (TSPP and poly(allylamine hydrochloride (PAH bilayers using layer-by-layer (LbL electrostatic self-assembly was tested to measure the gas emitted from human skin. Optical intensity changes at different wavelengths in the transmission spectrum of the porphyrin-based film were induced by the human skin gas and measured as sensor response. Influence of relative humidity, which can be a major interference to sensor response, was thoroughly studied and shown to be significantly different when compared to the influence of skin emanations. Responses of the current optical sensor system could be considered as composite sensor array, where different optical wavelengths act as channels that have selective response to specific volatile compounds. Data obtained from the sensor system was analyzed using principal component analysis (PCA. This approach enabled to distinguish skin odors of different people and their altered physiological conditions after alcohol consumption.

  15. Low Temperature CVD Grown Graphene for Highly Selective Gas Sensors Working under Ambient Conditions

    NARCIS (Netherlands)

    Ricciardella, F.; Vollebregt, S.; Polichetti, T.; Alfano, B.; Massera, E.; Sarro, P.M.

    2017-01-01

    In this paper we report on gas sensors based on graphene grown by Chemical Vapor Deposition at 850 °C. Mo was used as catalyst for graphene nucleation. Resistors were directly designed on pre-patterned Mo using the transfer-free process we recently developed, thus avoiding films damage during the

  16. Highly versatile fiber-based optical Fabry-Pérot gas sensor.

    Science.gov (United States)

    Liu, Jing; Sun, Yuze; Fan, Xudong

    2009-02-16

    We develop a versatile, compact, and sensitive fiber-based optical Fabry-Pérot (FP) gas sensor. The sensor probe is composed of a silver layer and a vapor-sensitive polymer layer that are sequentially deposited on the cleaved fiber endface, thus forming an FP cavity. The interference spectrum resulting from the reflected light at the silver-polymer and polymer-air interfaces changes when the polymer is exposed to gas analytes. This structure enables using any polymer regardless of the polymer refractive index (RI), which significantly enhances the sensor versatility. In experiments, we use polyethylene glycol (PEG) 400 (RI=1.465-1.469) and Norland Optical Adhesive (NOA) 81 (RI=1.53-1.56) as the gas sensing polymer and show drastically different sensor response to hexanol, methanol, and acetone. The estimated sensitivity for methanol vapor is 3.5 pm/ppm and 0.1 pm/ppm for PEG 400 and NOA 81, respectively, with a detection limit on the order of 1-10 ppm. Gas sensing for the analytes delivered in both continuous flow mode and pulsed mode is demonstrated.

  17. Application of Gas Sensor Arrays in Assessment of Wastewater Purification Effects

    Directory of Open Access Journals (Sweden)

    Łukasz Guz

    2014-12-01

    Full Text Available A gas sensor array consisting of eight metal oxide semiconductor (MOS type gas sensors was evaluated for its ability for assessment of the selected wastewater parameters. Municipal wastewater was collected in a wastewater treatment plant (WWTP in a primary sedimentation tank and was treated in a laboratory-scale sequential batch reactor (SBR. A comparison of the gas sensor array (electronic nose response to the standard physical-chemical parameters of treated wastewater was performed. To analyze the measurement results, artificial neural networks were used. E-nose—gas sensors array and artificial neural networks proved to be a suitable method for the monitoring of treated wastewater quality. Neural networks used for data validation showed high correlation between the electronic nose readouts and: (I chemical oxygen demand (COD (r = 0.988; (II total suspended solids (TSS (r = 0.938; (III turbidity (r = 0.940; (IV pH (r = 0.554; (V nitrogen compounds: N-NO3 (r = 0.958, N-NO2 (r = 0.869 and N-NH3 (r = 0.978; (VI and volatile organic compounds (VOC (r = 0.987. Good correlation of the abovementioned parameters are observed under stable treatment conditions in a laboratory batch reactor.

  18. Improved capacitance sensor with variable operating frequency for scanning capacitance microscopy

    International Nuclear Information System (INIS)

    Kwon, Joonhyung; Kim, Joonhui; Jeong, Jong-Hwa; Lee, Euy-Kyu; Seok Kim, Yong; Kang, Chi Jung; Park, Sang-il

    2005-01-01

    Scanning capacitance microscopy (SCM) has been gaining attention for its capability to measure local electrical properties in doping profile, oxide thickness, trapped charges and charge dynamics. In many cases, stray capacitance produced by different samples and measurement conditions affects the resonance frequency of a capacitance sensor. The applications of conventional SCM are critically limited by the fixed operating frequency and lack of tunability in its SCM sensor. In order to widen SCM application to various samples, we have developed a novel SCM sensor with variable operating frequency. By performing variable frequency sweep over the band of 160 MHz, the SCM sensor is tuned to select the best and optimized resonance frequency and quality factor for each sample measurement. The fundamental advantage of the new variable frequency SCM sensor was demonstrated in the SCM imaging of silicon oxide nano-crystals. Typical sensitivity of the variable frequency SCM sensor was found to be 10 -19 F/V

  19. Highly Sensitive and Selective Gas Sensor Using Hydrophilic and Hydrophobic Graphenes

    Science.gov (United States)

    Some, Surajit; Xu, Yang; Kim, Youngmin; Yoon, Yeoheung; Qin, Hongyi; Kulkarni, Atul; Kim, Taesung; Lee, Hyoyoung

    2013-01-01

    New hydrophilic 2D graphene oxide (GO) nanosheets with various oxygen functional groups were employed to maintain high sensitivity in highly unfavorable environments (extremely high humidity, strong acidic or basic). Novel one-headed polymer optical fiber sensor arrays using hydrophilic GO and hydrophobic reduced graphene oxide (rGO) were carefully designed, leading to the selective sensing of volatile organic gases for the first time. The two physically different surfaces of GO and rGO could provide the sensing ability to distinguish between tetrahydrofuran (THF) and dichloromethane (MC), respectively, which is the most challenging issue in the area of gas sensors. The eco-friendly physical properties of GO allowed for faster sensing and higher sensitivity when compared to previous results for rGO even under extreme environments of over 90% humidity, making it the best choice for an environmentally friendly gas sensor. PMID:23736838

  20. Automatic Carbon Dioxide-Methane Gas Sensor Based on the Solubility of Gases in Water

    Directory of Open Access Journals (Sweden)

    Raúl O. Cadena-Pereda

    2012-08-01

    Full Text Available Biogas methane content is a relevant variable in anaerobic digestion processing where knowledge of process kinetics or an early indicator of digester failure is needed. The contribution of this work is the development of a novel, simple and low cost automatic carbon dioxide-methane gas sensor based on the solubility of gases in water as the precursor of a sensor for biogas quality monitoring. The device described in this work was used for determining the composition of binary mixtures, such as carbon dioxide-methane, in the range of 0–100%. The design and implementation of a digital signal processor and control system into a low-cost Field Programmable Gate Array (FPGA platform has permitted the successful application of data acquisition, data distribution and digital data processing, making the construction of a standalone carbon dioxide-methane gas sensor possible.

  1. Automatic carbon dioxide-methane gas sensor based on the solubility of gases in water.

    Science.gov (United States)

    Cadena-Pereda, Raúl O; Rivera-Muñoz, Eric M; Herrera-Ruiz, Gilberto; Gomez-Melendez, Domingo J; Anaya-Rivera, Ely K

    2012-01-01

    Biogas methane content is a relevant variable in anaerobic digestion processing where knowledge of process kinetics or an early indicator of digester failure is needed. The contribution of this work is the development of a novel, simple and low cost automatic carbon dioxide-methane gas sensor based on the solubility of gases in water as the precursor of a sensor for biogas quality monitoring. The device described in this work was used for determining the composition of binary mixtures, such as carbon dioxide-methane, in the range of 0-100%. The design and implementation of a digital signal processor and control system into a low-cost Field Programmable Gate Array (FPGA) platform has permitted the successful application of data acquisition, data distribution and digital data processing, making the construction of a standalone carbon dioxide-methane gas sensor possible.

  2. Membrane-Coated Electrochemical Sensor for Corrosion Monitoring in Natural Gas Pipelines

    Directory of Open Access Journals (Sweden)

    J. Beck

    2017-07-01

    Full Text Available Electrochemical sensors can be used for a wide range of online in- situ process monitoring applications. However, the lack of a consistent electrolyte layer has previously limited electrochemical monitoring in gas and supercritical fluid streams. A solid state sensor is being designed that uses an ion conducting membrane to perform conductivity and corrosion measurements in natural gas pipelines up to 1000 psi. Initial results show that membrane conductivity measurements can be correlated directly to water content down to dew points of 1°C with good linearity. Corrosion monitoring can also be performed using methods such as linear polarization resistance and electrochemical impedance spectroscopy (EIS, though care must be taken in the electrode design to minimize deviation between sensors.

  3. [INVITED] Porphyrin-nanoassembled fiber-optic gas sensor fabrication: Optimization of parameters for sensitive ammonia gas detection

    Science.gov (United States)

    Korposh, Sergiy; Kodaira, Suguru; Selyanchyn, Roman; Ledezma, Francisco H.; James, Stephen W.; Lee, Seung-Woo

    2018-05-01

    Highly sensitive fiber-optic ammonia gas sensors were fabricated via layer-by-layer deposition of poly(diallyldimethylammonium chloride) (PDDA) and tetrakis(4-sulfophenyl)porphine (TSPP) onto the surface of the core of a hard-clad multimode fiber that was stripped of its polymer cladding. The effects of film thickness, length of sensing area, and depth of evanescent wave penetration were investigated to clearly understand the sensor performance. The sensitivity of the fiber-optic sensor to ammonia was linear in the concentration range of 0.5-50 ppm and the response and recovery times were less than 3 min, with a limit of detection of 0.5 ppm, when a ten-cycle PDDA/TSPP film was assembled on the surface of the core along a 1 cm-long stripped section of the fiber. The sensor's response towards ammonia was also checked under different relative humidity conditions and a simple statistical data treatment approach, principal component analysis, demonstrated the feasibility of ammonia sensing in environmental relative humidity ranging from dry 7% to highly saturated 80%. Penetration depths of the evanescent wave for the optimal sensor configuration were estimated to be 30 and 33 nm at wavelengths of 420 and 706 nm, which are in a good agreement with the thickness of the 10-cycle deposited film (ca. 30 nm).

  4. Dynamic gas flow during plasma operation in TMX-U

    International Nuclear Information System (INIS)

    Pickles, W.L.; Carter, M.R.; Clower, C.A.; Drake, R.P.; Hunt, A.L.; Simonen, T.C.; Turner, W.C.

    1982-01-01

    Control of the neutral density outside of the plasma radius is essential for proper operation of the various plasma configurations in TMX-U. TMX-U excess-beam, stream-gun, gas-box, and beam-reflux gases are pumped internally in regions defined by 73 0 Ti-gettered liners and warm Ti-gettered plasma liners. The array of fast and slow ion gauges - a large TMX-U diagnostic - has been used to measure the dynamic pressure in many of the liner-defined regions on three time scales. The natural divertor action, or plasma pump effect, of mirror plasmas has been measured using the ion gauge diagnostics on a fast time scale during operation of TMX-U with ECRH start-up. Routine operation of TMX-U is enhanced by the ability to verify the effectiveness of gettering and to locate leaks using pressure data collected on the two slow time scales. A computer code, DYNAVAC 6, which treats TMX-U as a set of conductance-coupled regions with pumping and sources in each region, has been used to successfully model the overall gas dynamics during all phases of TMX-U operation

  5. Combined raman and IR fiber-based sensor for gas detection

    Science.gov (United States)

    Carter, Jerry C; Chan, James W; Trebes, James E; Angel, Stanley M; Mizaikoff, Boris

    2014-06-24

    A double-pass fiber-optic based spectroscopic gas sensor delivers Raman excitation light and infrared light to a hollow structure, such as a hollow fiber waveguide, that contains a gas sample of interest. A retro-reflector is placed at the end of this hollow structure to send the light back through the waveguide where the light is detected at the same end as the light source. This double pass retro reflector design increases the interaction path length of the light and the gas sample, and also reduces the form factor of the hollow structure.

  6. Test results for fuel cell operation on anaerobic digester gas

    Science.gov (United States)

    Spiegel, R. J.; Preston, J. L.

    EPA, in conjunction with ONSI, embarked on a project to define, design, test, and assess a fuel cell energy recovery system for application at anaerobic digester waste water (sewage) treatment plants. Anaerobic digester gas (ADG) is produced at these plants during the process of treating sewage anaerobically to reduce solids. ADG is primarily comprised of methane (57-66%), carbon dioxide (33-39%), nitrogen (1-10%), and a small amount of oxygen (sulfur-bearing compounds (principally hydrogen sulfide) and halogen compounds (chlorides). The project has addressed two major issues: development of a cleanup system to remove fuel cell contaminants from the gas and testing/assessing of a modified ONSI PC25 C fuel cell power plant operating on the cleaned, but dilute, ADG. Results to date demonstrate that the ADG fuel cell power plant can, depending on the energy content of the gas, produce electrical output levels close to full power (200 kW) with measured air emissions comparable to those obtained by a natural gas fuel cell. The cleanup system results show that the hydrogen sulfide levels are reduced to below 10 ppbv and halides to approximately 30 ppbv.

  7. Operation of sealed microstrip gas chambers at the ILL

    CERN Document Server

    Clergeau, J F; Feltin, D; Fischer, H E; Guérard, B; Hansen, T; Manzin, G; Oed, A; Palleau, P

    2001-01-01

    Microstrip Gas Counters (MSGCs) were introduced at the ILL as a response to the problem of fabricating the large area neutron detector of the D20 neutron powder diffractometer. This banana-like detector consists of 48 MSGCs, each comprising 32 counting cells. It was in operation during 18 months before being stopped due to the progressive deterioration of the anode strips. In order to increase its lifetime, significant modifications were introduced in the recently assembled new version. Another instrument, D4C, was recently equipped with a modular detector made of nine MSGCs, each of them in an individual gas vessel. Besides the unidimensional individual readout MSGC of D20 and D4C, the ILL has developed bidimensional MSGCs with a charge division readout. All these detectors employ sealed vessels containing a gas mixture at a pressure which can be as high as 15 bar, necessitating very clean conditions. This paper describes the experience acquired at the ILL in the fabrication and operation of these detectors.

  8. Stabilizing operation point technique based on the tunable distributed feedback laser for interferometric sensors

    Science.gov (United States)

    Mao, Xuefeng; Zhou, Xinlei; Yu, Qingxu

    2016-02-01

    We describe a stabilizing operation point technique based on the tunable Distributed Feedback (DFB) laser for quadrature demodulation of interferometric sensors. By introducing automatic lock quadrature point and wavelength periodically tuning compensation into an interferometric system, the operation point of interferometric system is stabilized when the system suffers various environmental perturbations. To demonstrate the feasibility of this stabilizing operation point technique, experiments have been performed using a tunable-DFB-laser as light source to interrogate an extrinsic Fabry-Perot interferometric vibration sensor and a diaphragm-based acoustic sensor. Experimental results show that good tracing of Q-point was effectively realized.

  9. Fabrication of gas sensor based on field ionization from SWCNTs with tripolar microelectrode

    Science.gov (United States)

    Cai, Shengbing; Zhang, Yong; Duan, Zhemin

    2012-12-01

    We report the nanofabrication of a sulfur dioxide (SO2) sensor with a tripolar on-chip microelectrode utilizing a film of single-walled carbon nanotubes (SWCNTs) as the field ionization cathode, where the ion flow current and the partial discharge current generated by the field ionization process of gaseous molecules can be gauged to gas species and concentration. The variation of the sensitivity is less than 4% for all of the tested devices, and the sensor has selectivity against gases such as He, NO2, CO, H2, SO2 and O2. Further, the sensor response presents well-defined and reproducible linear behavior with regard to concentration in the range investigated and a detection limitation of tripolar on-chip microelectrode with SWCNTs as a cathode exhibits an impressive performance with respect to stability and anti-oxidation behavior, which are significantly better than had been possible before in the traditional bipolar sensor under explicit circumstances at room temperature.

  10. Tailored Algorithm for Sensitivity Enhancement of Gas Concentration Sensors Based on Tunable Laser Absorption Spectroscopy.

    Science.gov (United States)

    Vargas-Rodriguez, Everardo; Guzman-Chavez, Ana Dinora; Baeza-Serrato, Roberto

    2018-06-04

    In this work, a novel tailored algorithm to enhance the overall sensitivity of gas concentration sensors based on the Direct Absorption Tunable Laser Absorption Spectroscopy (DA-ATLAS) method is presented. By using this algorithm, the sensor sensitivity can be custom-designed to be quasi constant over a much larger dynamic range compared with that obtained by typical methods based on a single statistics feature of the sensor signal output (peak amplitude, area under the curve, mean or RMS). Additionally, it is shown that with our algorithm, an optimal function can be tailored to get a quasi linear relationship between the concentration and some specific statistics features over a wider dynamic range. In order to test the viability of our algorithm, a basic C 2 H 2 sensor based on DA-ATLAS was implemented, and its experimental measurements support the simulated results provided by our algorithm.

  11. MEGAS multi-electrode gas sensor system. Final report; MEGAS - Multi-Elektroden-Gassensorsystem. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Kelleter, J.

    2003-07-01

    In the context of the MEGAS project, GTE developed and and constructed an electronic system for controlling and data acquisition of sensors for laboratory and test applications. The system is based on microcontrollers and has a data bus connection. Measurements made in order to find out whether the concentrations of a binary gas mixture and combustion gases are detected separately were successful. A demonstration system was constructed. The MEGAS project showed that it is possible to separate two gases by a sensitive layer at constant sensor temperature. The sensor element is a promising technology. Further research is required on suppressing sensor poisoning by siloxanes, and on reduced sensitivity to interfering gases (e.g. ethanol in the case of combustion gases). (orig.)

  12. Dióxido de estanho nanoestruturado como sensor de NOx Nanostructured tin dioxide as a NOx gas sensor

    Directory of Open Access Journals (Sweden)

    A. P. Maciel

    2003-09-01

    Full Text Available Neste trabalho, nanopartículas de SnO2 foram obtidas pelo método do precursor polimérico e caracterizadas por difração de raios X, isotermas de adsorção-dessorção, microscopia eletrônica de varredura e microscopia eletrônica de transmissão. Apenas a fase cassiterita (tetragonal foi observada. O material obtido apresenta com alta área superficial e porosidade. Estas características são pré-requisitos para um bom sensor de gás. A sensibilidade ao NOx para o SnO2 foi estudado na faixa de temperatura compreendida entre 200 e 500 ºC. Observou-se uma baixa sensibilidade entre 200 e 350 ºC, porém, a partir de 400 ºC ocorreu um aumento de três vezes na sensibilidade do sensor. A máxima sensibilidade ocorreu em 400 ºC, com um tempo de resposta de 730 s.In this work SnO2 nanoparticles were obtained by the polimeric precursor method and characterized by X-ray diffraction, gas adsorption and desorption isotherms, scanning electron microscopy and transmission electron microscopy. Only the cassiterite (tetragonal phase was observed. The obtained material presents a high surface area and high porosity. These characteristics are prerequisites for a good gas sensor. The NOx sensibility was studied in the temperature range between 200 and 500 °C. A low sensibility between 200 to 350 °C is also observed; however, starting from 400 °C, an increase of three times in the sensor sensibility occurs. The maximum sensibility was measured at 400 °C with a response time of 730 s.

  13. Real-Time Gas Identification by Analyzing the Transient Response of Capillary-Attached Conductive Gas Sensor

    Directory of Open Access Journals (Sweden)

    Behzad Bahraminejad

    2010-05-01

    Full Text Available In this study, the ability of the Capillary-attached conductive gas sensor (CGS in real-time gas identification was investigated. The structure of the prototype fabricated CGS is presented. Portions were selected from the beginning of the CGS transient response including the first 11 samples to the first 100 samples. Different feature extraction and classification methods were applied on the selected portions. Validation of methods was evaluated to study the ability of an early portion of the CGS transient response in target gas (TG identification. Experimental results proved that applying extracted features from an early part of the CGS transient response along with a classifier can distinguish short-chain alcohols from each other perfectly. Decreasing time of exposition in the interaction between target gas and sensing element improved the reliability of the sensor. Classification rate was also improved and time of identification was decreased. Moreover, the results indicated the optimum interval of the early transient response of the CGS for selecting portions to achieve the best classification rates.

  14. Electrochemical cell with integrated hydrocarbon gas sensor for automobile exhaust gas; Elektrochemische Zelle mit integriertem Kohlenwasserstoff-Gassensor fuer das Automobilabgas

    Energy Technology Data Exchange (ETDEWEB)

    Biskupski, D.; Moos, R. [Univ. Bayreuth (Germany). Bayreuth Engine Research Center, Lehrstuhl fuer Funktionsmaterialien; Wiesner, K.; Fleischer, M. [Siemens AG, Corporate Technology, CT PS 6, Muenchen (Germany)

    2007-07-01

    In the future sensors will be necessary to control the compliance with hydrocarbon limiting values, allowing a direct detection of the hydrocarbons. Appropriate sensor-active functional materials are metal oxides, which have a hydrocarbon sensitivity but are also dependent on the oxygen partial pressure. It is proposed that the gas-sensing layer should be integrated into an electrochemical cell. The authors show that the integration of a resistive oxygen sensor into a pump cell allows a defined oxygen concentration level at the sensor layer in any exhaust gas.

  15. Large-scale syntheses of uniform ZnO nanorods and ethanol gas sensors application

    International Nuclear Information System (INIS)

    Chen Jin; Li Jin; Li Jiahui; Xiao Guoqing; Yang Xiaofeng

    2011-01-01

    Research highlights: → The uniform ZnO nanorods could be synthesized by a low temperature, solution-based method. → The results showed that the sample had uniform rod-like morphology with a narrow size distribution and highly crystallinity. → Room-temperature photoluminescence spectra of these nanorods show an exciton emission around 382 nm and a weak deep level emission, indicating the nanorods have high quality. → The sensor exhibited high sensitivity and fast response to ethanol gas at a work temperature of 400 deg. C. - Abstract: Uniform ZnO nanorods with a gram scale were prepared by a low temperature and solution-based method. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL). The results showed that the sample had uniform rod-like morphology with a narrow size distribution and highly crystallinity. Room-temperature PL spectra of these nanorods show an exciton emission around 382 nm and a negligible deep level emission, indicating the nanorods have high quality. The gas-sensing properties of the materials have been investigated. The results indicate that the as-prepared nanorods show much better sensitivity and stability. The n-type semiconductor gas sensor exhibited high sensitivity and fast response to ethanol gas at a work temperature of 400 deg. C. ZnO nanorods are excellent potential candidates for highly sensitive gas sensors and ultraviolet laser.

  16. Gas Sensor Based on 3-D WO3 Inverse Opal: Design and Applications

    Directory of Open Access Journals (Sweden)

    Ruiqing Xing

    2017-03-01

    Full Text Available A three-dimensional inverse opal (3DIO WO3 architecture has been synthesized via a simple sacrificial template method. Morphology features of the 3DIO were characterized by scanning electron microscope (SEM and its structure was characterized by X-ray diffraction (XRD. The shrinking ratio of the PMMA spheres was ~28.2% through measuring the distribution of the PMMA spheres and 3DIO WO3 center-to-center distance between the spheres and macropores, respectively. Beyond that, the 3DIO gas sensing properties were investigated systematically and the sensing mechanism of 3DIO WO3 was proposed. The results indicated that the response of the 3DIO sensor possessed excellent sensitivity to acetone gas, especially at trace levels. The 3DIO gas sensor response was ~7 to 5 ppm of acetone and could detect acetone low to 0.2 ppm effectively, which was in close proximity to the theoretical low detection limit of 0.14 ppm when Ra/Rg ≥ 1.2 was used as the criterion for reliable gas sensing. All in all, the obvious satisfaction of the gas-sensing properties was ascribed to the structure of the 3DIO, and the sensor could be a promising novel device in the future.

  17. Gas Sensor Based on 3-D WO₃ Inverse Opal: Design and Applications.

    Science.gov (United States)

    Xing, Ruiqing; Du, Yang; Zhao, Xiaonan; Zhang, Xiu

    2017-03-29

    A three-dimensional inverse opal (3DIO) WO₃ architecture has been synthesized via a simple sacrificial template method. Morphology features of the 3DIO were characterized by scanning electron microscope (SEM) and its structure was characterized by X-ray diffraction (XRD). The shrinking ratio of the PMMA spheres was ~28.2% through measuring the distribution of the PMMA spheres and 3DIO WO₃ center-to-center distance between the spheres and macropores, respectively. Beyond that, the 3DIO gas sensing properties were investigated systematically and the sensing mechanism of 3DIO WO₃ was proposed. The results indicated that the response of the 3DIO sensor possessed excellent sensitivity to acetone gas, especially at trace levels. The 3DIO gas sensor response was ~7 to 5 ppm of acetone and could detect acetone low to 0.2 ppm effectively, which was in close proximity to the theoretical low detection limit of 0.14 ppm when R a /R g ≥ 1.2 was used as the criterion for reliable gas sensing. All in all, the obvious satisfaction of the gas-sensing properties was ascribed to the structure of the 3DIO, and the sensor could be a promising novel device in the future.

  18. Porous Silicon Sensors- Elusive and Erudite

    OpenAIRE

    H. Saha, Prof.

    2017-01-01

    Porous Silicon Sensors have been fabricated and tested successfully over the last few years as humidity sensors, vapour sensors, gas sensors, piezoresistive pressure sensors and bio- sensors. In each case it has displayed remarkably sensitivity, relatively low temperature operation and ease of fabrication. Brief description of fabrication and properties of all these types of different sensors is reported in this paper. The barriers of porous silicon like contact, non- uniformity, instability ...

  19. ALAT PENDETEKSI KEBOCORAN GAS BERACUN CO PADA MOBIL DENGAN ARRAY SENSOR MENGGUNAKAN FUZZY CONTROLLER

    Directory of Open Access Journals (Sweden)

    Slamet Widodo

    2016-03-01

    Full Text Available Perkembangan teknologi otomotif sekarang ini semakin pesat yaitu dengan fasilitas accessories mobil yang semakin lengkap. Namun berbagai fasilitas yang terdapat dalam mobil tanpa disadari menyimpan ancaman bahaya bagi pengguna mobil salah satunya ketika system pada AC (Air Conditioner terjadi kebocoran maka gas CO (karbon monoksida akan memenuhi ruang mobil yang tertutup. Gas CO ini sangat berbahaya karena gas ini tidak berwarna, tidak berbau, dan tidak berasa sehingga sulit untuk dideteksi yang dapat menyebabkan orang yang ada didalam mobil menjadi mati lemas tanpa disadari karena menghirup gas CO yang bocor. Dengan fenomena tersebut dibutuhkan sebuah alat yang dapat mendeteksi dan mengontrol kebocoran gas CO untuk memberikan rasa aman kepada pengguna mobil. Alat ini menggunakan kendali logika fuzzy sebagai proses pengambilan keputusan sebagai hasil nilai dari inferensi kerja array sensor. Pengendali utama pada sistem menggunakan mikrokontroller ATmega32. Ketika array sensor yaitu TGS2442 dan TGS2600 mendeteksi kadar gas CO >29,0 ppm berarti dalam status bahaya sehingga buzzer akan aktif diikuti motor DC yang menggerakkan kaca mobil agar terbuka. Berdasarkan lima kali pengujian yang dilakukan didapatkanlah rata-rata selisih error output gas sebesar 0.29 ppm disaat kondisi aman dan 3.87 ppm disaat kondisi bahaya.

  20. Al2O3- BSST Based Chemical Sensors for Ammonia Gas Sensing

    Directory of Open Access Journals (Sweden)

    L. A. Patil

    2009-10-01

    Full Text Available Gas sensing behaviour of pure and modified (Ba0.9Sr0.1(Sn0.5Ti0.5O3 (BSST thick films is reported in this article. The surface of the BSST thick film was modified by dipping it into aqueous solution of AlCl3, for different intervals of time. These films were then dried at 500 0C for 24 hours in air ambient for transformation of AlCl3 into Al2O3, for the evaporation of organic binders and also to improve the texture of the film. The gas response, selectivity, response and recovery time of the sensors were measured and presented. The role played by the aluminium species to improve the gas sensing performance of the sensors is discussed.

  1. Global Coverage Measurement Planning Strategies for Mobile Robots Equipped with a Remote Gas Sensor

    Directory of Open Access Journals (Sweden)

    Muhammad Asif Arain

    2015-03-01

    Full Text Available The problem of gas detection is relevant to many real-world applications, such as leak detection in industrial settings and landfill monitoring. In this paper, we address the problem of gas detection in large areas with a mobile robotic platform equipped with a remote gas sensor. We propose an algorithm that leverages a novel method based on convex relaxation for quickly solving sensor placement problems, and for generating an efficient exploration plan for the robot. To demonstrate the applicability of our method to real-world environments, we performed a large number of experimental trials, both on randomly generated maps and on the map of a real environment. Our approach proves to be highly efficient in terms of computational requirements and to provide nearly-optimal solutions.

  2. Gas Sensors Characterization and Multilayer Perceptron (MLP) Hardware Implementation for Gas Identification Using a Field Programmable Gate Array (FPGA)

    Science.gov (United States)

    Benrekia, Fayçal; Attari, Mokhtar; Bouhedda, Mounir

    2013-01-01

    This paper develops a primitive gas recognition system for discriminating between industrial gas species. The system under investigation consists of an array of eight micro-hotplate-based SnO2 thin film gas sensors with different selectivity patterns. The output signals are processed through a signal conditioning and analyzing system. These signals feed a decision-making classifier, which is obtained via a Field Programmable Gate Array (FPGA) with Very High-Speed Integrated Circuit Hardware Description Language. The classifier relies on a multilayer neural network based on a back propagation algorithm with one hidden layer of four neurons and eight neurons at the input and five neurons at the output. The neural network designed after implementation consists of twenty thousand gates. The achieved experimental results seem to show the effectiveness of the proposed classifier, which can discriminate between five industrial gases. PMID:23529119

  3. Chemical sensors for breath gas analysis: the latest developments at the Breath Analysis Summit 2013.

    Science.gov (United States)

    Tisch, Ulrike; Haick, Hossam

    2014-06-01

    Profiling the body chemistry by means of volatile organic compounds (VOCs) in the breath opens exciting new avenues in medical diagnostics. Gas sensors could provide ideal platforms for realizing portable, hand-held breath testing devices in the near future. This review summarizes the latest developments and applications in the field of chemical sensors for diagnostic breath testing that were presented at the Breath Analysis Summit 2013 in Wallerfangen, Germany. Considerable progress has been made towards clinically applicable breath testing devices, especially by utilizing chemo-sensitive nanomaterials. Examples of several specialized breath testing applications are presented that are either based on stand-alone nanomaterial-based sensors being highly sensitive and specific to individual breath compounds over others, or on combinations of several highly specific sensors, or on experimental nanomaterial-based sensors arrays. Other interesting approaches include the adaption of a commercially available MOx-based sensor array to indirect breath testing applications, using a sample pre-concentration method, and the development of compact integrated GC-sensor systems. The recent trend towards device integration has led to the development of fully integrated prototypes of point-of-care devices. We describe and compare the performance of several prototypes that are based on different sensing technologies and evaluate their potential as low-cost and readily available next-generation medical devices.

  4. Gas Selectivity Control in Co3O4 Sensor via Concurrent Tuning of Gas Reforming and Gas Filtering using Nanoscale Hetero-Overlayer of Catalytic Oxides.

    Science.gov (United States)

    Jeong, Hyun-Mook; Jeong, Seong-Yong; Kim, Jae-Hyeok; Kim, Bo-Young; Kim, Jun-Sik; Abdel-Hady, Faissal; Wazzan, Abdulaziz A; Al-Turaif, Hamad Ali; Jang, Ho Won; Lee, Jong-Heun

    2017-11-29

    Co 3 O 4 sensors with a nanoscale TiO 2 or SnO 2 catalytic overlayer were prepared by screen-printing of Co 3 O 4 yolk-shell spheres and subsequent e-beam evaporation of TiO 2 and SnO 2 . The Co 3 O 4 sensors with 5 nm thick TiO 2 and SnO 2 overlayers showed high responses (resistance ratios) to 5 ppm xylene (14.5 and 28.8) and toluene (11.7 and 16.2) at 250 °C with negligible responses to interference gases such as ethanol, HCHO, CO, and benzene. In contrast, the pure Co 3 O 4 sensor did not show remarkable selectivity toward any specific gas. The response and selectivity to methylbenzenes and ethanol could be systematically controlled by selecting the catalytic overlayer material, varying the overlayer thickness, and tuning the sensing temperature. The significant enhancement of the selectivity for xylene and toluene was attributed to the reforming of less reactive methylbenzenes into more reactive and smaller species and oxidative filtering of other interference gases, including ubiquitous ethanol. The concurrent control of the gas reforming and oxidative filtering processes using a nanoscale overlayer of catalytic oxides provides a new, general, and powerful tool for designing highly selective and sensitive oxide semiconductor gas sensors.

  5. An Object Model for Integrating Diverse Remote Sensing Satellite Sensors: A Case Study of Union Operation

    Directory of Open Access Journals (Sweden)

    Chuli Hu

    2014-01-01

    Full Text Available In the Earth Observation sensor web environment, the rapid, accurate, and unified discovery of diverse remote sensing satellite sensors, and their association to yield an integrated solution for a comprehensive response to specific emergency tasks pose considerable challenges. In this study, we propose a remote sensing satellite sensor object model, based on the object-oriented paradigm and the Open Geospatial Consortium Sensor Model Language. The proposed model comprises a set of sensor resource objects. Each object consists of identification, state of resource attribute, and resource method. We implement the proposed attribute state description by applying it to different remote sensors. A real application, involving the observation of floods at the Yangtze River in China, is undertaken. Results indicate that the sensor inquirer can accurately discover qualified satellite sensors in an accurate and unified manner. By implementing the proposed union operation among the retrieved sensors, the inquirer can further determine how the selected sensors can collaboratively complete a specific observation requirement. Therefore, the proposed model provides a reliable foundation for sharing and integrating multiple remote sensing satellite sensors and their observations.

  6. Preparation and characterization of ALD deposited ZnO thin films studied for gas sensors

    Energy Technology Data Exchange (ETDEWEB)

    Boyadjiev, S.I., E-mail: boiajiev@gmail.com [MTA-BME Technical Analytical Chemistry Research Group, Szent Gellért tér 4, Budapest, H-1111 (Hungary); Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Georgieva, V. [Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Yordanov, R. [Department of Microelectronics, Technical University of Sofia, 8 Kliment Ohridski Blvd., 1756 Sofia (Bulgaria); Raicheva, Z. [Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Szilágyi, I.M. [MTA-BME Technical Analytical Chemistry Research Group, Szent Gellért tér 4, Budapest, H-1111 (Hungary); Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry, Szent Gellért tér 4, Budapest, H-1111 (Hungary)

    2016-11-30

    Highlights: • For the first time the gas sensing towards NO{sub 2} of very thin ALD ZnO films is studied. • The very thin ALD ZnO films showed excellent sensitivity to NO{sub 2} at room temperature. • These very thin film ZnO-based QCM sensors very well register even low concentrations. • The sensors have fully reversible sorption and are able to be recovered in short time. • Described fast and cost-effective ALD deposition of ZnO thin films for QCM gas sensor. - Abstract: Applying atomic layer deposition (ALD), very thin zinc oxide (ZnO) films were deposited on quartz resonators, and their gas sensing properties were studied using the quartz crystal microbalance (QCM) method. The gas sensing of the ZnO films to NO{sub 2} was tested in the concentration interval between 10 and 5000 ppm. On the basis of registered frequency change of the QCM, for each concentration the sorbed mass was calculated. Further characterization of the films was carried out by various techniques, i.e. by SEM-EDS, XRD, ellipsometry, and FTIR spectroscopy. Although being very thin, the films were gas sensitive to NO{sub 2} already at room temperature and could register very well as low concentrations as 100 ppm, while the sorption was fully reversible. Our results for very thin ALD ZnO films show that the described fast, simple and cost-effective technology could be implemented for producing gas sensors working at room temperature and being capable to detect in real time low concentrations of NO{sub 2}.

  7. Possibility of gas sensor based on C{sub 20} molecular devices

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Wenkai [School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025 (China); Yang, Chuanlu, E-mail: yangchuanlu@126.com [School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025 (China); Zou, Dongqing [School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Sun, Zhaopeng [School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025 (China); Ji, Guomin [Electrical and Computer Engineering, The University of Oklahoma, Norman, Tulsa, OK 74078 (United States)

    2017-06-09

    We theoretically investigate the possibility of diatomic gas detection (NO, CO, O{sub 2}) by making use of the transport properties of the C{sub 20} molecular junctions. The calculations are performed by using nonequilibrium Green's function (NEGF) formalism in combination with density functional theory (DFT). In this work, we systematically study the most stable adsorption structural configurations, adsorption energy, and the transport properties on C{sub 20} molecular junctions with these diatomic gas molecules. It is found that NO and O{sub 2} gas molecule can be detected selectively. We suggest its possibility of nanosensors for highly sensitive and selective based on C{sub 20} molecular junction systems. - Highlights: • The most favorable adsorption site is investigated. • The mechanism of gas sensors is revealed. • NO and O{sub 2} gas molecules can be detected by C{sub 20} selectively.

  8. Extraction of diagnostic parameters from the transient response of a porous electro ceramic gas sensor

    International Nuclear Information System (INIS)

    Hossein-Babaei, F.; Orvatinia, M.

    2004-01-01

    A novel concept for the diagnosis of a pure target gas in air is presented. The method employs a resistive gas sensor with a mm-thick highly porous electro ceramic gas sensitive body. The diagnosis is based on the fact that the diffusion time of the target gas through the porous body would depend on its molecular properties. The transient response of the device was analyzed based on a diffusion reaction equation. The solutions of the equation were shown to be of diagnostic merits. Such a device was fabricated by partial sintering of a Zn O body formed by low pressure pressing. The transient responses of the device to methanol, ethanol, poropanol and butanol were recorded. The analytical data, and the diagnostic parameters were resulted as the fitting parameters. Comparison of the parameters obtained with those available from the calibration experiments afforded target gas identification

  9. Possibility of gas sensor based on C_2_0 molecular devices

    International Nuclear Information System (INIS)

    Zhao, Wenkai; Yang, Chuanlu; Zou, Dongqing; Sun, Zhaopeng; Ji, Guomin

    2017-01-01

    We theoretically investigate the possibility of diatomic gas detection (NO, CO, O_2) by making use of the transport properties of the C_2_0 molecular junctions. The calculations are performed by using nonequilibrium Green's function (NEGF) formalism in combination with density functional theory (DFT). In this work, we systematically study the most stable adsorption structural configurations, adsorption energy, and the transport properties on C_2_0 molecular junctions with these diatomic gas molecules. It is found that NO and O_2 gas molecule can be detected selectively. We suggest its possibility of nanosensors for highly sensitive and selective based on C_2_0 molecular junction systems. - Highlights: • The most favorable adsorption site is investigated. • The mechanism of gas sensors is revealed. • NO and O_2 gas molecules can be detected by C_2_0 selectively.

  10. Signal specific electric potential sensors for operation in noisy environments

    International Nuclear Information System (INIS)

    Beardsmore-Rust, S T; Prance, R J; Aydin, A; Prance, H; Harl, C J; Stiffell, P B

    2009-01-01

    Limitations on the performance of electric potential sensors are due to saturation caused by environmental electromagnetic noise. The work described involves tailoring the response of the sensors to reject the main components of the noise, thereby enhancing both the effective dynamic range and signal to noise. We show that by using real-time analogue signal processing it is possible to detect a human heartbeat at a distance of 40 cm from the front of a subject in an unshielded laboratory. This result has significant implications both for security sensing and biometric measurements in addition to the more obvious safety related applications.

  11. Signal specific electric potential sensors for operation in noisy environments

    Energy Technology Data Exchange (ETDEWEB)

    Beardsmore-Rust, S T; Prance, R J; Aydin, A; Prance, H; Harl, C J; Stiffell, P B, E-mail: r.j.prance@sussex.ac.u [Centre for Physical Electronics and Quantum Technology, Department of Engineering and Design, University of Sussex, Falmer, Brighton, BN1 9QT (United Kingdom)

    2009-07-01

    Limitations on the performance of electric potential sensors are due to saturation caused by environmental electromagnetic noise. The work described involves tailoring the response of the sensors to reject the main components of the noise, thereby enhancing both the effective dynamic range and signal to noise. We show that by using real-time analogue signal processing it is possible to detect a human heartbeat at a distance of 40 cm from the front of a subject in an unshielded laboratory. This result has significant implications both for security sensing and biometric measurements in addition to the more obvious safety related applications.

  12. Gas Sensors Based on Tin Oxide Nanoparticles Synthesized from a Mini-Arc Plasma Source

    Directory of Open Access Journals (Sweden)

    Ganhua Lu

    2006-01-01

    Full Text Available Miniaturized gas sensors or electronic noses to rapidly detect and differentiate trace amount of chemical agents are extremely attractive. In this paper, we report on the fabrication and characterization of a functional tin oxide nanoparticle gas sensor. Tin oxide nanoparticles are first synthesized using a convenient and low-cost mini-arc plasma source. The nanoparticle size distribution is measured online using a scanning electrical mobility spectrometer (SEMS. The product nanoparticles are analyzed ex-situ by high resolution transmission electron microscopy (HRTEM for morphology and defects, energy dispersive X-ray (EDX spectroscopy for elemental composition, electron diffraction for crystal structure, and X-ray photoelectron spectroscopy (XPS for surface composition. Nonagglomerated rutile tin oxide (SnO2 nanoparticles as small as a few nm have been produced. Larger particles bear a core-shell structure with a metallic core and an oxide shell. The nanoparticles are then assembled onto an e-beam lithographically patterned interdigitated electrode using electrostatic force to fabricate the gas sensor. The nanoparticle sensor exhibits a fast response and a good sensitivity when exposed to 100 ppm ethanol vapor in air.

  13. Landsat 8 Operational Land Imager (OLI)_Thermal Infared Sensor (TIRS) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract:The Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) are instruments onboard the Landsat 8 satellite, which was launched in February of...

  14. Ship Sensor Observations for Operation Deep Scope 2007 - Office of Ocean Exploration

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Hourly measurements made by selected ship sensors on the R/V Seward Johnson during the "Operation Deep Scope 2007" expedition sponsored by the National Oceanic and...

  15. Gas Sensors Based on Locally Heated Multiwall Carbon Nanotubes Decorated with Metal Nanoparticles

    Directory of Open Access Journals (Sweden)

    R. Savu

    2015-01-01

    Full Text Available We report the design and fabrication of microreactors and sensors based on metal nanoparticle-decorated carbon nanotubes. Titanium adhesion layers and gold films were sputtered onto Si/SiO2 substrates for obtaining the electrical contacts. The gold layers were electrochemically thickened until 1 μm and the electrodes were patterned using photolithography and wet chemical etching. Before the dielectrophoretic deposition of the nanotubes, a gap 1 μm wide and 5 μm deep was milled in the middle of the metallic line by focused ion beam, allowing the fabrication of sensors based on suspended nanotubes bridging the electrodes. Subsequently, the sputtering technique was used for decorating the nanotubes with metallic nanoparticles. In order to test the as-obtained sensors, microreactors (100 μL volume were machined from a single Kovar piece, being equipped with electrical connections and 1/4′′ Swagelok-compatible gas inlet and outlets for controlling the atmosphere in the testing chamber. The sensors, electrically connected to the contact pins by wire-bonding, were tested in the 10−5 to 10−2 W working power interval using oxygen as target gas. The small chamber volume allowed the measurement of fast characteristic times (response/recovery, with the sensors showing good sensitivity.

  16. Gas Sensors Built with Nanomaterials and Provided with a Heating Double Purpose Hot-plate

    Directory of Open Access Journals (Sweden)

    Cristian L. ARRIETA

    2017-01-01

    Full Text Available Pure or doped SnO2, has been used to build resistive type gas sensors from several decades. This subject has been retaken using pure or doped nanocrystalline SnO2 to build the sensors, finding considerable advantages in devices performance. The sensors working temperature (Tw decreases from (350-450 0C to (180-200 0C in comparison with that of devices built with microcrystalline conventional material. Sensitivity of sensors built with nanocrystalline material in comparison with that of devices built with conventional microcrystalline material, increases from 30 % to 37 %. In this work, SnO2 is synthesized using two different modified techniques based on gel-combustion and reactive oxidation and results of both syntheses are compared. Nanomaterials are characterised with X-ray diffraction (XRD, High Resolution Transmission Electron Microscopy (HRTEM and Field Emission Electron Scanning Microscopy (FESEM and absorption techniques (BET. An electronic system, already patented by the authors, enables to alternatively measure the sensor resistivity (which is proportional to the adsorbed gas concentration and set a constant working temperature, thus contributing to considerably save energy.

  17. 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.

  18. Modeling and Experimental Study on Characterization of Micromachined Thermal Gas Inertial Sensors

    Directory of Open Access Journals (Sweden)

    Yan Su

    2010-09-01

    Full Text Available Micromachined thermal gas inertial sensors based on heat convection are novel devices that compared with conventional micromachined inertial sensors offer the advantages of simple structures, easy fabrication, high shock resistance and good reliability by virtue of using a gaseous medium instead of a mechanical proof mass as key moving and sensing elements. This paper presents an analytical modeling for a micromachined thermal gas gyroscope integrated with signal conditioning. A simplified spring-damping model is utilized to characterize the behavior of the sensor. The model relies on the use of the fluid mechanics and heat transfer fundamentals and is validated using experimental data obtained from a test-device and simulation. Furthermore, the nonideal issues of the sensor are addressed from both the theoretical and experimental points of view. The nonlinear behavior demonstrated in experimental measurements is analyzed based on the model. It is concluded that the sources of nonlinearity are mainly attributable to the variable stiffness of the sensor system and the structural asymmetry due to nonideal fabrication.

  19. Laser-Based and Ultra-Portable Gas Sensor for Indoor and Outdoor Formaldehyde (HCHO) Monitoring

    Science.gov (United States)

    Shutter, J. D.; Allen, N.; Paul, J.; Thiebaud, J.; So, S.; Scherer, J. J.; Keutsch, F. N.

    2017-12-01

    While used as a key tracer of oxidative chemistry in the atmosphere, formaldehyde (HCHO) is also a known human carcinogen and is listed and regulated by the United States EPA as a hazardous air pollutant. Combustion processes and photochemical oxidation of volatile organic compounds (VOCs) are the major outdoor sources of HCHO, and building materials and household products are ubiquitous sources of indoor HCHO. Due to the ease with which humans can be exposed to HCHO, it is imperative to monitor levels of both indoor and outdoor HCHO exposure in both short and long-term studies.High-quality direct and indirect methods of quantifying HCHO mixing ratios exist, but instrument size and user-friendliness can make them cumbersome or impractical for certain types of indoor and long-term outdoor measurements. In this study, we present urban HCHO measurements by using a new, commercially-available, ppbv-level accurate HCHO gas sensor (Aeris Technologies' MIRA Pico VOC Laser-Based Gas Analyzer) that is highly portable (29 cm x 20 cm x 10 cm), lightweight (3 kg), easy-to-use, and has low power (15 W) consumption. Using an ultra-compact multipass cell, an absorption path length of 13 m is achieved, resulting in a sensor capable of achieving ppbv/s sensitivity levels with no significant spectral interferences.To demonstrate the utility of the gas sensor for emissions measurements, a GPS was attached to the sensor's housing in order to map mobile HCHO measurements in real-time around the Boston, Massachusetts, metro area. Furthermore, the sensor was placed in residential and industrial environments to show its usefulness for indoor and outdoor pollution measurements. Lastly, we show the feasibility of using the HCHO sensor (or a network of them) in long-term monitoring stations for hazardous air pollutants.

  20. ZnO nanoparticles based fiber optic gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Narasimman, S.; Sivacoumar, R.; Alex, Z. C. [MEMS and Sensor Division, School of Electronics Engineering, VIT University, Vellore 632 014 (India); Balakrishnan, L., E-mail: bslv85@gmail.com; Meher, S. R. [Materials Physics Division, School of Advanced Sciences, VIT University, Vellore 632 014 (India)

    2016-05-23

    In this work, ZnO nanoparticles were synthesized by simple aqueous chemical route method. The synthesized ZnO nanoparticles were characterized by X-ray diffraction and scanning electron microscope. The sensitivity of the nanoparticles was studied for different gases like acetone, ammonia and ethanol in terms of variation in spectral light intensity. The XRD and SEM analysis confirms the formation of hexagonal wurtzite structure with the grain size of 11.2 nm. The small cladding region of the optical fiber was replaced with the synthesized nanoparticles. The light spectrum was recorded for different gas concentrations. The synthesized nanoparticles showed high sensitivity towards ammonia in low ppm level and acetone in high ppm level.

  1. Deployment Algorithms of Wireless Sensor Networks for Near-surface Underground Oil and Gas Pipeline Monitoring

    Directory of Open Access Journals (Sweden)

    Hua-Ping YU

    2014-07-01

    Full Text Available Oil and gas pipelines are the infrastructure of national economic development. Deployment problem of wireless underground sensor networks (WUSN for oil and gas pipeline systems is a fundamental problem. This paper firstly analyzed the wireless channel characteristics and energy consumption model in near-surface underground soil, and then studied the spatial structure of oil and gas pipelines and introduced the three-layer system structure of WUSN for oil and gas pipelines monitoring. Secondly, the optimal deployment strategy in XY plane and XZ plane which were projected from three-dimensional oil and gas pipeline structure was analyzed. Thirdly, the technical framework of using kinetic energy of the fluid in pipelines to recharge sensor nodes and partition strategy for energy consumption balance based on the wireless communication technology of magnetic induction waveguide were proposed, which can effectively improve the energy performance and connectivity of the network, and provide theoretical guidance and practical basis for the monitoring of long oil and gas pipeline network, the city tap water pipe network and sewage pipe network.

  2. Precise measurements of neutral gas temperature using Fiber Bragg Grating sensor in Argon capacitively coupled plasmas

    Science.gov (United States)

    Han, Daoman; Liu, Zigeng; Liu, Yongxin; Peng, Wei; Wang, Younian

    2016-09-01

    Neutral gas temperature was measured using Fiber Bragg Grating sensor (FBGs) in capacitively coupled argon plasmas. Thermometry is based on the thermal equilibrium between the sensor and neutral gases, which is found to become faster with increasing pressure. It is also observed that the neutral gas temperature is higher than the room temperature by 10 120 °depending on the experiental conditions, and gas temperature shows significant non-uniformity in space. In addition, radial profiles of neutral temperature at different pressures, resemble these of ion density, obtained by a floating double probe. Specifically, at low pressure, neutral gas temperature and ion density peak at the center of the reactor, while the peak appears at the edge of the electrode at higher pressure. The neutral gas heating is mainly caused by the elastic collisions of Ar + with neutral gas atoms in the sheath region after Ar + gaining a certain energy. This work was supported by the National Natural Science Foundation of China (NSFC) (Grants No. 11335004, 11405018, and 61137005).

  3. A high sensitivity process variation sensor utilizing sub-threshold operation

    OpenAIRE

    Meterelliyoz, Mesut; Song, Peilin; Stellari, Franco; Kulkarni, Jaydeep P.; Roy, Kaushik

    2008-01-01

    In this paper, we propose a novel low-power, bias-free, high-sensitivity process variation sensor for monitoring random variations in the threshold voltage. The proposed sensor design utilizes the exponential current-voltage relationship of sub-threshold operation thereby improving the sensitivity by 2.3X compared to the above-threshold operation. A test-chip containing 128 PMOS and 128 NMOS devices has been fabri...

  4. Laboratory Connections--Gas Monitoring Transducers Part III: Combustible Gas Sensors.

    Science.gov (United States)

    Powers, Michael H.; Dahman, Doug

    1989-01-01

    Describes an interface that uses semiconductor metal oxides to detect low gas concentrations. Notes the detector has long life, high stability, good reproducibility, low cost, and is able to convert the gas concentration to an electrical signal with a simple circuit. Theory, schematic, and applications are provided. (MVL)

  5. A sensor management architecture concept for monitoring emissions from open-air demil operations.

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Michael M.; Robinson, Jerry D.; Stoddard, Mary Clare; Horn, Brent A.; Lipkin, Joel; Foltz, Greg W.

    2005-09-01

    Sandia National Laboratories, CA proposed a sensor concept to detect emissions from open-burning/open-detonation (OB/OD) events. The system would serve two purposes: (1) Provide data to demilitarization operations about process efficiency, allowing process optimization for cleaner emissions and higher efficiency. (2) Provide data to regulators and neighboring communities about materials dispersing into the environment by OB/OD operations. The proposed sensor system uses instrument control hardware and data visualization software developed at Sandia National Laboratories to link together an array of sensors to monitor emissions from OB/OD events. The suite of sensors would consist of various physical and chemical detectors mounted on stationary or mobile platforms. The individual sensors would be wirelessly linked to one another and controlled through a central command center. Real-time data collection from the sensors, combined with integrated visualization of the data at the command center, would allow for feedback to the sensors to alter operational conditions to adjust for changing needs (i.e., moving plume position, increased spatial resolution, increased sensitivity). This report presents a systems study of the problem of implementing a sensor system for monitoring OB/OD emissions. The goal of this study was to gain a fuller understanding of the political, economic, and technical issues for developing and fielding this technology.

  6. Integrated Analysis of Environment-driven Operational Effects in Sensor Networks

    Energy Technology Data Exchange (ETDEWEB)

    Park, Alfred J [ORNL; Perumalla, Kalyan S [ORNL

    2007-07-01

    There is a rapidly growing need to evaluate sensor network functionality and performance in the context of the larger environment of infrastructure and applications in which the sensor network is organically embedded. This need, which is motivated by complex applications related to national security operations, leads to a paradigm fundamentally different from that of traditional data networks. In the sensor networks of interest to us, the network dynamics depend strongly on sensor activity, which in turn is triggered by events in the environment. Because the behavior of sensor networks is sensitive to these driving phenomena, the integrity of the sensed observations, measurements and resource usage by the network can widely vary. It is therefore imperative to accurately capture the environmental phenomena, and drive the simulation of the sensor network operation by accounting fully for the environment effects. In this paper, we illustrate the strong, intimate coupling between the sensor network operation and the driving phenomena in their applications with an example sensor network designed to detect and track gaseous plumes.

  7. Enhanced gas sensing performance of TiO2 functionalized magneto-optical SPR sensors

    OpenAIRE

    Manera, Maria Grazia; Montagna, G.; Ferreiro-Vila, Elías; González-García, Lola; Sánchez-Valencia, J.R.; González-Elipe, Agustín R.; Cebollada, Alfonso; García-Martín, José Miguel; García-Martín, Antonio; Armelles Reig, Gaspar; Rella, Roberto

    2011-01-01

    Porous TiO2 thin films deposited by glancing angle deposition are used as sensing layers to monitor their sensing capabilities towards Volatile Organic Compounds both in a standard Surface Plasmon Resonance (SPR) sensor and in Magneto-Optical Surface Plasmon Resonance (MO-SPR) configuration in order to compare their sensing performances. Here our results on the enhanced sensing capability of these TiO2 functionalized MO-SPR sensors with Au/Co/Au transducers with respect to traditional SPR gas...

  8. Analysis and Optimization of Thermodiffusion of an FBG Sensor in the Gas Nitriding Process

    Directory of Open Access Journals (Sweden)

    Tso-Sheng Hsieh

    2016-12-01

    Full Text Available In this paper, we report the numerical calculations for a thermo-optical model and the temperature sensitivity of a fiber Bragg grating (FBG sensor. The thermally-induced behaviors of a FBG sensor in the gas nitriding process were analyzed for temperatures ranging from 100–650 °C. The FBG consisted of properly chosen photosensitive fiber materials with an optimized thermo-optic coefficient. The experimental and optimized thermo-optic coefficient results were consistent in terms of temperature sensitivity. In these experiments, the temperature sensitivity of the FBG was found to be 11.9 pm/°C.

  9. Electrospun ZnO Nanowires as Gas Sensors for Ethanol Detection

    Directory of Open Access Journals (Sweden)

    Huang Po-Jung

    2009-01-01

    Full Text Available Abstract ZnO nanowires were produced using an electrospinning method and used in gas sensors for the detection of ethanol at 220 °C. This electrospinning technique allows the direct placement of ZnO nanowires during their synthesis to bridge the sensor electrodes. An excellent sensitivity of nearly 90% was obtained at a low ethanol concentration of 10 ppm, and the rest obtained at higher ethanol concentrations, up to 600 ppm, all equal to or greater than 90%.

  10. Design and Experimentation with Sandwich Microstructure for Catalytic Combustion-Type Gas Sensors

    Directory of Open Access Journals (Sweden)

    Jun-Tao Gu

    2014-03-01

    Full Text Available The traditional handmade catalytic combustion gas sensor has some problems such as a pairing difficulty, poor consistency, high power consumption, and not being interchangeable. To address these issues, integrated double catalytic combustion of alcohol gas sensor was designed and manufactured using silicon micro-electro-mechanical systems (MEMS technology. The temperature field of the sensor is analyzed using the ANSYS finite element analysis method. In this work, the silicon oxide-PECVD-oxidation technique is used to manufacture a SiO2-Si3N2-SiO2 microstructure carrier with a sandwich structure, while wet etching silicon is used to form a beam structure to reduce the heat consumption. Thin-film technology is adopted to manufacture the platinum-film sensitive resistance. Nano Al2O3-ZrO-ThO is coated to format the sensor carrier, and the sensitive unit is dipped in a Pt-Pd catalyst solution to form the catalytic sensitive bridge arm. Meanwhile the uncoated catalyst carrier is considered as the reference unit, realizing an integrated chip based on a micro double bridge and forming sensors. The lines of the Pt thin-film resistance have been observed with an electronic microscope. The compensation of the sensitive material carriers and compensation materials have been analyzed using an energy spectrum. The results show that the alcohol sensor can detect a volume fraction between 0 and 4,500 × 10−6 and has good linear output characteristic. The temperature ranges from −20 to +40 °C. The humidity ranges from 30% to 85% RH. The zero output of the sensor is less than ±2.0% FS. The power consumption is ≤0.2 W, and both the response and recovery time are approximately 20 s.

  11. Laboratory-based validation of the baseline sensors of the ITER diagnostic residual gas analyzer

    International Nuclear Information System (INIS)

    Klepper, C.C.; Biewer, T.M.; Marcus, C.; Graves, V.B.; Andrew, P.; Hughes, S.; Gardner, W.L.

    2017-01-01

    The divertor-specific ITER Diagnostic Residual Gas Analyzer (DRGA) will provide essential information relating to DT fusion plasma performance. This includes pulse-resolving measurements of the fuel isotopic mix reaching the pumping ducts, as well as the concentration of the helium generated as the ash of the fusion reaction. In the present baseline design, the cluster of sensors attached to this diagnostic's differentially pumped analysis chamber assembly includes a radiation compatible version of a commercial quadrupole mass spectrometer, as well as an optical gas analyzer using a plasma-based light excitation source. This paper reports on a laboratory study intended to validate the performance of this sensor cluster, with emphasis on the detection limit of the isotopic measurement. This validation study was carried out in a laboratory set-up that closely prototyped the analysis chamber assembly configuration of the baseline design. This includes an ITER-specific placement of the optical gas measurement downstream from the first turbine of the chamber's turbo-molecular pump to provide sufficient light emission while preserving the gas dynamics conditions that allow for /textasciitilde 1 s response time from the sensor cluster [1].

  12. Laboratory-based validation of the baseline sensors of the ITER diagnostic residual gas analyzer

    Science.gov (United States)

    Klepper, C. C.; Biewer, T. M.; Marcus, C.; Andrew, P.; Gardner, W. L.; Graves, V. B.; Hughes, S.

    2017-10-01

    The divertor-specific ITER Diagnostic Residual Gas Analyzer (DRGA) will provide essential information relating to DT fusion plasma performance. This includes pulse-resolving measurements of the fuel isotopic mix reaching the pumping ducts, as well as the concentration of the helium generated as the ash of the fusion reaction. In the present baseline design, the cluster of sensors attached to this diagnostic's differentially pumped analysis chamber assembly includes a radiation compatible version of a commercial quadrupole mass spectrometer, as well as an optical gas analyzer using a plasma-based light excitation source. This paper reports on a laboratory study intended to validate the performance of this sensor cluster, with emphasis on the detection limit of the isotopic measurement. This validation study was carried out in a laboratory set-up that closely prototyped the analysis chamber assembly configuration of the baseline design. This includes an ITER-specific placement of the optical gas measurement downstream from the first turbine of the chamber's turbo-molecular pump to provide sufficient light emission while preserving the gas dynamics conditions that allow for \\textasciitilde 1 s response time from the sensor cluster [1].

  13. Laboratory-based validation of the baseline sensors of the ITER diagnostic residual gas analyzer

    Energy Technology Data Exchange (ETDEWEB)

    Biewer, Theodore M. [ORNL; Marcus, Chris [ORNL; Klepper, C Christopher [ORNL; Andrew, Philip [ITER Organization, Cadarache, France; Gardner, W. L. [United States ITER Project Office; Graves, Van B. [ORNL; Hughes, Shaun [ITER Organization, Saint Paul Lez Durance, France

    2017-10-01

    The divertor-specific ITER Diagnostic Residual Gas Analyzer (DRGA) will provide essential information relating to DT fusion plasma performance. This includes pulse-resolving measurements of the fuel isotopic mix reaching the pumping ducts, as well as the concentration of the helium generated as the ash of the fusion reaction. In the present baseline design, the cluster of sensors attached to this diagnostic's differentially pumped analysis chamber assembly includes a radiation compatible version of a commercial quadrupole mass spectrometer, as well as an optical gas analyzer using a plasma-based light excitation source. This paper reports on a laboratory study intended to validate the performance of this sensor cluster, with emphasis on the detection limit of the isotopic measurement. This validation study was carried out in a laboratory set-up that closely prototyped the analysis chamber assembly configuration of the baseline design. This includes an ITER-specific placement of the optical gas measurement downstream from the first turbine of the chamber's turbo-molecular pump to provide sufficient light emission while preserving the gas dynamics conditions that allow for \\textasciitilde 1 s response time from the sensor cluster [1].

  14. MIS gas sensors based on porous silicon with Pd and WO{sub 3}/Pd electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Solntsev, V.S. [Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028, Kiev (Ukraine); Gorbanyuk, T.I., E-mail: tatyanagor@mail.r [Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028, Kiev (Ukraine); Litovchenko, V.G.; Evtukh, A.A. [Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028, Kiev (Ukraine)

    2009-09-30

    Pd and WO{sub 3}/Pd gate metal-oxide-semiconductor (MIS) gas sensitive structures based on porous silicon layers are studied by the high frequency C(V) method. The chemical compositions of composite WO{sub 3}/Pd electrodes are characterized by secondary-ion mass spectrometry (SIMS). The atomic force microscopy (AFM) was used for morphologic studies of WO{sub 3}/Pd films. As shown in the experiments, WO{sub 3}/Pd structures are more sensitive and selective to the adsorption of hydrogen sulphide compared to Pd gate. The analyses of kinetic characteristics allow us to determine the response and characteristic times for these structures. The response time of MIS-structures with thin composite WO{sub 3}/Pd electrodes (the thickness of Pd is about 50 nm with WO{sub 3} clusters on its surface) is slower compared to the structures with Pd electrodes. Slower sensor responses of WO{sub 3}-based gas sensors may be associated with different mechanism of gas sensitivity of given structures. The enhanced sensitivity and selectivity to H{sub 2}S action of WO{sub 3}/Pd MIS-structures can also be explained by the chemical reaction that occurs at the catalytic active surface of gate electrodes. The possible mechanisms of enhanced sensitivity and selectivity to H{sub 2}S adsorption of MIS gas sensors with WO{sub 3}/Pd composite gate electrodes compared to pure Pd have been analyzed.

  15. Highly sensitive and selective room-temperature NO_2 gas sensor based on bilayer transferred chemical vapor deposited graphene

    International Nuclear Information System (INIS)

    Seekaew, Yotsarayuth; Phokharatkul, Ditsayut; Wisitsoraat, Anurat; Wongchoosuk, Chatchawal

    2017-01-01

    Highlights: • Simple and low-cost fabrication of bilayer graphene gas sensor was presented. • Layer effects of graphene on NO_2 gas-sensing properties were investigated. • Bilayer graphene sensor exhibited a high linear NO_2 sensitivity of 1.409 ppm"−"1. • The NO_2-sensing mechanisms based on band diagram were highlighted. - Abstract: This work presents a highly sensitive room-temperature gas sensor based on bilayer graphene fabricated by an interfacial transfer of chemical vapor deposited graphene onto nickel interdigitated electrodes. Scanning electron microscopic and Raman spectroscopic characterizations confirm the presence of graphene on interdigitated nickel electrodes with varying numbers of graphene layers. The NO_2 detection performances of bilayer graphene gas sensor have been investigated in comparison with those of monolayer and multilayer graphene gas sensors at room temperature. From results, the bilayer graphene gas sensor exhibits higher response, sensitivity and selectivity to NO_2 than monolayer and multilayer graphene. The sensitivity of bilayer graphene gas sensor is 1.409 ppm"−"1 towards NO_2 over a concentration range of 1–25 ppm, which is more than twice higher than that of monolayer graphene. The NO_2-sensing mechanism of graphene sensing film has been explained based on the direct charge transfer process due to the adsorption of NO_2 molecules.

  16. Micro controller based system for characterizing gas detector operating parameters

    International Nuclear Information System (INIS)

    Thakur, Vaishali M.; Verma, Amit K.; Anilkumar, S.; Babu, D.A.R.; Sharma, D.N.; Harikumar, M.

    2011-01-01

    The estimation and analysis of radioactivity levels in samples from environment and from various stages of nuclear fuel cycle operations has become a matter of concern for the implementation of radiological safety procedures. Gas filled/ flow detectors play crucial role in achieving this objective. Since these detectors need high voltage for their operation, the operating characteristics of each detector for optimum performance has to be determined before incorporating into the systems. The operating voltages of these detectors are ranging from few hundred volts to few kilo volts. Present paper describes the design of microcontroller based system to control two HV modules (Electron tubes make: PS2001/12P) independently and acquire data from different gas filled radiation detectors simultaneously. The system uses Philips 80C552 microcontroller based Single Board Computer (SBC). The inbuilt DAC and ADC of microcontroller were used to control HV from 0-2000 with less than ± 1 %, error 1000V. The starting HV, HV step size, decision making intelligence to terminate HV increment (for preset plateau slope) and data acquisition (for preset time), data acquisition time etc., can be programmed. Nearly 200 detectors data (20 data points per detector) can be stored and transferred to PC on request. Data collected by the system for LND 719 GM detectors with starting voltage from 500 V, HV step size of 24 V and 100 seconds counting time to find out the plateau length. The plateau slope and length obtained with this system for LND 719 GM detectors are 3-5%/100V and ∼ 150V respectively. (author)

  17. A Molecularly Imprinted Electrochemical Gas Sensor to Sense Butylated Hydroxytoluene in Air

    Directory of Open Access Journals (Sweden)

    Shadi Emam

    2018-01-01

    Full Text Available Alzheimer’s disease (AD is a neurodegenerative disease, which affects millions of people worldwide. Curing this disease has not gained much success so far. Exhaled breath gas analysis offers an inexpensive, noninvasive, and immediate method for detecting a large number of diseases, including AD. In this paper, a new method is proposed to detect butylated hydroxytoluene (BHT in the air, which is one of the chemicals found in the breath print of AD patients. A three-layer sensor was formed through deposition of a thin layer of graphene onto a glassy carbon substrate. Selective binding of the analyte was facilitated by electrochemically initiated polymerization of a solution containing the desired target molecule. Subsequent polymerization and removal of the analyte yielded a layer of polypyrrole, a conductive polymer, on top of the sensor containing molecularly imprinted cavities selective for the target molecule. Two sets of sensors have been developed. First, the graphene sensor has been fabricated with a layer of reduced graphene oxide (RGO and tested over 5–100 part per million (ppm. For the second batch, Prussian blue was added to graphene before polymerization, mainly for enhancing the electrochemical properties. The sensor was tested over 0.02-1 parts per billion (ppb level of concentration while the sensor resistance has been monitored.

  18. Sensor gas analyzer for acetone determination in expired air

    Science.gov (United States)

    Baranov, Vitaly V.

    2001-05-01

    Diseases and changes in the way of life change the concentration and composition of the expired air. Our adaptable gas analyzer is intended for the selective analysis of expired air and can be adapted for the solution of current diagnostic and analytical tasks by the user (a physician or a patient). Having analyzed the existing trends in the development of noninvasive diagnostics we have chosen the method of noninvasive acetone detection in expired air, where the acetone concentration correlates with blood and urine glucose concentrations. The appearance of acetone in expired air is indicative of disorders that may be caused not only by diabetes but also be wrong diet, incorrect sportsmen training etc. To control the disorders one should know the acetone concentration in the human body. This knowledge allows one to judge upon the state of the patient, choose a correct diet that will not cause damage to the patient's health, determine sportsmen training efficiency and results and solve the artificial pancreas problem. Our device provide highly accurate analysis, rapid diagnostics and authentic acetone quantification in the patient's body at any time aimed at prediction of the patient's state and assessing the efficiency of the therapy used. Clinical implementation of the device will improve the health and save lives of many thousands of diabetes sufferers.

  19. Miniaturized multi channel infrared optical gas sensor system

    Science.gov (United States)

    Wöllenstein, Jürgen; Eberhardt, Andre; Rademacher, Sven; Schmitt, Katrin

    2011-06-01

    Infrared spectroscopy uses the characteristic absorption of the molecules in the mid infrared and allows the determination of the gases and their concentration. Especially by the absorption at longer wavelengths between 8 μm and 12 μm, the so called "fingerprint" region, the molecules can be measured with highest selectivity. We present an infrared optical filter photometer for the analytical determination of trace gases in the air. The challenge in developing the filter photometer was the construction of a multi-channel system using a novel filter wheel concept - which acts as a chopper too- in order to measure simultaneously four gases: carbon monoxide, carbon dioxide, methane and ammonia. The system consists of a broadband infrared emitter, a long path cell with 1.7m optical path length, a filter wheel and analogue and digital signal processing. Multi channel filter photometers normally need one filter and one detector per target gas. There are small detection units with one, two or more detectors with integrated filters available on the market. One filter is normally used as reference at a wavelength without any cross-sensitivities to possible interfering gases (e.g. at 3.95 μm is an "atmospheric window" - a small spectral band without absorbing gases in the atmosphere). The advantage of a filter-wheel set-up is that a single IR-detector can be used, which reduces the signal drift enormously. Pyroelectric and thermopile detectors are often integrated in these kinds of spectrometers. For both detector types a modulation of the light is required and can be done - without an additional chopper - with the filter wheel.

  20. New Love wave liquid sensor operating at 2 GHz using an integrated micro-flow channel

    International Nuclear Information System (INIS)

    Assouar, M B; Kirsch, P; Alnot, P

    2009-01-01

    Surface acoustic wave (SAW) devices based on waveguide modes with shear-horizontal polarization (Love modes) are very promising for sensor applications, especially in liquid media. We present here the realization of a 2 GHz operating frequency sensor based on the SiO 2 /36YX LiTaO 3 structure with an integrated PDMS micro-flow channel and using electron beam lithography to realize the submicronic interdigital transducers. Using our developed sensor operating at 2 GHz, we carried out alternate cycles of nitrogen and water circulating in the PDMS micro-flow channel. We measured an absolute sensitivity of −19 001 Hz mm 2  ng −1 due to the interaction of the sensor with water. This sensitivity is higher than that of other devices operating at lower frequencies. The detection mechanism, including gravimetric and permittivity effects at high frequency, will be discussed