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Sample records for capacitive sensing interface

  1. Highly Sensitive Capacitive Gas Sensing at Ionic Liquid-Electrode Interfaces.

    Science.gov (United States)

    Wang, Zhe; Guo, Min; Mu, Xiaoyi; Sen, Soumyo; Insley, Thomas; Mason, Andrew J; Král, Petr; Zeng, Xiangqun

    2016-02-01

    We have developed an ultrasensitive gas-detection method based on the measurement of a differential capacitance of electrified ionic liquid (IL) electrode interfaces in the presence and absence of adsorbed gas molecules. The observed change of differential capacitance has a local maximum at a certain potential that is unique for each type of gas, and its amplitude is related to the concentration of the gas molecules. We establish and validate this gas-sensing method by characterizing SO2 detection at ppb levels with less than 1.8% signal from other interfering species (i.e., CO2, O2, NO2, NO, SO2, H2O, H2, and cyclohexane, tested at the same concentration as SO2). This study opens a new avenue of utilizing tunable electrified IL-electrode interfaces for selective sensing of molecules with a kinetic size resolution of 0.1 Å.

  2. Energy-Efficient Capacitive-Sensor Interfaces

    NARCIS (Netherlands)

    Tan, Z.

    2013-01-01

    This thesis describes the theory, design and realization of energy-efficient capacitive-sensor interfaces that are dedicated to energy-constrained applications. The goal of this work is to explore energy-efficient capacitive-sensor interface design techniques both at the system and the circuit level

  3. A novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances

    Institute of Scientific and Technical Information of China (English)

    Dong Linxi; Chen Jindan; Yan Haixia; Huo Weihong; Li Yongjie; Sun Lingling

    2009-01-01

    The comb capacitances fabricated by deep reactive ion etching (RIE) process have high aspect ratio which is usually smaller than 30 : 1 for the complicated process factors, and the combs are usually not parallel due to the well-known micro-loading effect and other process factors, which restricts the increase of the seismic mass by increasing the thickness of comb to reduce the thermal mechanical noise and the decrease of the gap of the comb capacitances for increasing the sensitive capacitance to reduce the electrical noise. Aiming at the disadvantage of the deep RIE, a novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances is developed. One part of sensing of inertial signal of the micro-accelerometer is by the grid strip capacitances whose overlapping area is variable and which do not have the non-parallel plate's effect caused by the deep RIE process. Another part is by the sensing gap alterable capacitances whose gap between combs can be reduced by the actuators. The designed initial gap of the alterable comb capacitances is relatively large to depress the effect of the maximum aspect ratio (30 : 1) of deep RIE process. The initial gap of the capacitance of the actuator is smaller than the one of the comb capacitances. The difference between the two gaps is the initial gap of the sensitive capacitor. The designed structure depresses greatly the requirement of deep RIE process. The effects of non-parallel combs on the accelerometer are also analyzed. The characteristics of the micro-accelerometer are discussed by field emission microscopy (FEM) tool ANSYS. The tested devices based on slide-film damping effect are fabricated, and the tested quality factor is 514, which shows that grid strip capacitance design can partly improve the resolution and also prove the feasibility of the designed silicon-glass anodically bonding process.

  4. Capacitive Structures for Gas and Biological Sensing

    KAUST Repository

    Sapsanis, Christos

    2015-04-01

    The semiconductor industry was benefited by the advances in technology in the last decades. This fact has an impact on the sensors field, where the simple transducer was evolved into smart miniaturized multi-functional microsystems. However, commercially available gas and biological sensors are mostly bulky, expensive, and power-hungry, which act as obstacles to mass use. The aim of this work is gas and biological sensing using capacitive structures. Capacitive sensors were selected due to its design simplicity, low fabrication cost, and no DC power consumption. In the first part, the dominant structure among interdigitated electrodes (IDEs), fractal curves (Peano and Hilbert) and Archimedean spiral was investigated from capacitance density perspective. The investigation consists of geometrical formula calculations, COMSOL Multiphysics simulations and cleanroom fabrication of the capacitors on a silicon substrate. Moreover, low-cost fabrication on flexible plastic PET substrate was conducted outside cleanroom with rapid prototyping using a maskless laser etching. The second part contains the humidity, Volatile Organic compounds (VOCs) and Ammonia sensing of polymers, Polyimide and Nafion, and metal-organic framework (MOF), Cu(bdc)2.xH2O using IDEs and tested in an automated gas setup for experiment control and data extraction. The last part includes the biological sensing of C - reactive protein (CRP) quantification, which is considered as a biomarker of being prone to cardiac diseases and Bovine serum albumin (BSA) protein quantification, which is used as a reference for quantifying unknown proteins.

  5. Capacitive Touch User Interface and Implementation with Virtual Refrigerator

    Directory of Open Access Journals (Sweden)

    MIT Academy of Engineering Global Technology and Engineering centre, Whirlpool of India

    2014-05-01

    Full Text Available The proposed User Interface incorporates 14 Touch keys, including slider and wheeler functionality using self capacitance technology, 24 side throw LED with intensity controlled Fade-IN, Fade-OUT effects, Buzzer chime, Voltage regulator circuit, and communication circuitry for the control board. The major advantage that this User Interface is that the entire assembly is less than 10mm thick including PCB, components, light guide and graphics sticker. In this project the mentioned capacitive touch user Interface is interfaced with a Lab view system simulating a virtual refrigerator capable of responding to the commands from the User Interface.

  6. Low Power/Low Voltage Interface Circuitry for Capacitive Sensors

    DEFF Research Database (Denmark)

    Furst, Claus Efdmann

    This thesis focuses mainly on low power/low voltage interface circuits, implemented in CMOS, for capacitive sensors. A brief discussion of demands and possibilities for analog signal processing in the future is presented. Techniques for low power design is presented. This is done by analyzing power...... consumption of different amplifier topologies. Next, low power features of different amplifier types are analyzed on transistor level. A brief comparison of SI circuits for low power applications vs. SC circuits is presented. Methodologies for low voltage design is presented. This is followed by a collection...... power consumption. It is shown that the Sigma-Delta modulator is advantageous when embedded in a feedback loop with a mechanical sensor. Here a micro mechanical capacitive microphone. Feedback and detection circuitry for a capacitive microphone is presented. Practical implementations of low power...

  7. An integrated energy-efficient capacitive sensor digital interface circuit

    KAUST Repository

    Omran, Hesham

    2014-06-19

    In this paper, we propose an energy-efficient 13-bit capacitive sensor interface circuit. The proposed design fully relies on successive approximation algorithm, which eliminates the need for oversampling and digital decimation filtering, and thus low-power consumption is achieved. The proposed architecture employs a charge amplifier stage to acheive parasitic insensitive operation and fine absolute resolution. Moreover, the output code is not affected by offset voltages or charge injection. The successive approximation algorithm is implemented in the capacitance-domain using a coarse-fine programmable capacitor array, which allows digitizing wide capacitance range in compact area. Analysis for the maximum achievable resolution due to mismatch is provided. The proposed design is insensitive to any reference voltage or current which translates to low temperature sensitivity. The operation of a prototype fabricated in a standard CMOS technology is experimentally verified using both on-chip and off-chip capacitive sensors. Compared to similar prior work, the fabricated prototype achieves and excellent energy efficiency of 34 pJ/step.

  8. Capacitance Sensing and Software-Realized Lock-in Amplifier for the Electromagnetically Levitated Micro Gyroscope

    Institute of Scientific and Technical Information of China (English)

    HUANG Xiao-gang; CHEN Wen-yuan; LIU Wu; ZHANG Wei-ping; WU Xiao-sheng

    2007-01-01

    In the novel prototype of micro-gyroscope structure, the new configured capacitance sensing scheme for the micro gyroscope was analyzed and the virtual instrument based detection scheme was implemented. The digital lock-in amplifier was employed in the capacitance detection to restrain the noise interference. The capacitance analysis shows that 1 fF capacitance variation corresponds to 0.1 degree of the turn angle. The differential capacitance bridge and the charge integral amplifier were used as the front signal input interface. In the implementation of digital lock-in amplifier, a new routine which warranted the exactly matching of the reference phase to signal phase was proposed. The result of the experiment shows that digital lock-in amplifier can greatly eliminate the noise in the output signal. The non linearity of the turn angle output is 2.3 % and the minimum resolution of turn angle is 0.04 degrees. The application of the software demodulation in the signal detection of micro-electro-mechanical-system (MEMS) device is a new attempt, and it shows the prospective for a high-performance application.

  9. An Enhanced Sensing Application Based on a Flexible Projected Capacitive-Sensing Mattress

    Directory of Open Access Journals (Sweden)

    Wen-Ying Chang

    2014-04-01

    Full Text Available This paper presents a cost-effective sensor system for mattresses that can classify the sleeping posture of an individual and prevent pressure ulcers. This system applies projected capacitive sensing to the field of health care. The charge time (CT method was used to sensitively and accurately measure the capacitance of the projected electrodes. The required characteristics of the projected capacitor were identified to develop large-area applications for sensory mattresses. The area of the electrodes, the use of shielding, and the increased length of the transmission line were calibrated to more accurately measure the capacitance of the electrodes in large-size applications. To offer the users comfort in the prone position, a flexible substrate was selected and covered with 16 × 20 electrodes. Compared with the static charge sensitive bed (SCSB, our proposed system-flexible projected capacitive-sensing mattress (FPCSM comes with more electrodes to increase the resolution of posture identification. As for the body pressure system (BPS, the FPCSM has advantages such as lower cost, higher aging-resistance capability, and the ability to sense the capacitance of the covered regions without physical contact. The proposed guard ring design effectively absorbs the noise and interrupts leakage paths. The projected capacitive electrode is suitable for proximity-sensing applications and succeeds at quickly recognizing the sleeping pattern of the user.

  10. A Tagless Indoor Localization System Based on Capacitive Sensing Technology

    Directory of Open Access Journals (Sweden)

    Alireza Ramezani Akhmareh

    2016-09-01

    Full Text Available Accurate indoor person localization is essential for several services, such as assisted living. We introduce a tagless indoor person localization system based on capacitive sensing and localization algorithms that can determine the location with less than 0.2 m average error in a 3 m × 3 m room and has recall and precision better than 70%. We also discuss the effects of various noise types on the measurements and ways to reduce them using filters suitable for on-sensor implementation to lower communication energy consumption. We also compare the performance of several standard localization algorithms in terms of localization error, recall, precision, and accuracy of detection of the movement trajectory.

  11. Insights on Capacitive Interdigitated Electrodes Coated with MOF Thin Films: Humidity and VOCs Sensing as a Case Study.

    Science.gov (United States)

    Sapsanis, Christos; Omran, Hesham; Chernikova, Valeriya; Shekhah, Osama; Belmabkhout, Youssef; Buttner, Ulrich; Eddaoudi, Mohamed; Salama, Khaled N

    2015-07-24

    A prototypical metal-organic framework (MOF), a 2D periodic porous structure based on the assembly of copper ions and benzene dicarboxylate (bdc) ligands (Cu(bdc)·xH2O), was grown successfully as a thin film on interdigitated electrodes (IDEs). IDEs have been used for achieving planar CMOS-compatible low-cost capacitive sensing structures for the detection of humidity and volatile organic compounds (VOCs). Accordingly, the resultant IDEs coated with the Cu(bdc)·xH2O thin film was evaluated, for the first time, as a capacitive sensor for gas sensing applications. A fully automated setup, using LabVIEW interfaces to experiment conduction and data acquisition, was developed in order to measure the associated gas sensing performance.

  12. Insights on Capacitive Interdigitated Electrodes Coated with MOF Thin Films: Humidity and VOCs Sensing as a Case Study

    KAUST Repository

    Sapsanis, Christos

    2015-07-24

    A prototypical metal-organic framework (MOF), a 2D periodic porous structure based on the assembly of copper ions and benzene dicarboxylate (bdc) ligands (Cu(bdc)·xH2O), was grown successfully as a thin film on interdigitated electrodes (IDEs). IDEs have been used for achieving planar CMOS-compatible low-cost capacitive sensing structures for the detection of humidity and volatile organic compounds (VOCs). Accordingly, the resultant IDEs coated with the Cu(bdc)·xH2O thin film was evaluated, for the first time, as a capacitive sensor for gas sensing applications. A fully automated setup, using LabVIEW interfaces to experiment conduction and data acquisition, was developed in order to measure the associated gas sensing performance.

  13. Insights on Capacitive Interdigitated Electrodes Coated with MOF Thin Films: Humidity and VOCs Sensing as a Case Study

    Directory of Open Access Journals (Sweden)

    Christos Sapsanis

    2015-07-01

    Full Text Available A prototypical metal-organic framework (MOF, a 2D periodic porous structure based on the assembly of copper ions and benzene dicarboxylate (bdc ligands (Cu(bdc·xH2O, was grown successfully as a thin film on interdigitated electrodes (IDEs. IDEs have been used for achieving planar CMOS-compatible low-cost capacitive sensing structures for the detection of humidity and volatile organic compounds (VOCs. Accordingly, the resultant IDEs coated with the Cu(bdc·xH2O thin film was evaluated, for the first time, as a capacitive sensor for gas sensing applications. A fully automated setup, using LabVIEW interfaces to experiment conduction and data acquisition, was developed in order to measure the associated gas sensing performance.

  14. Quantum Capacitance of a Topological Insulator-Ferromagnet Interface.

    Science.gov (United States)

    Siu, Zhuo Bin; Chowdhury, Debashree; Jalil, Mansoor B A; Basu, Banasri

    2017-03-24

    We study the quantum capacitance in a topological insulator thin film system magnetized in the in-plane direction in the presence of an out-of-plane magnetic field and hexagonal warping. To first order, the modification in quantum capacitance due to hexagonal warping compared to the clean case, where both the in-plane magnetization and hexagonal warping are absent, is always negative, and increases in magnitude monotonically with the energy difference from the charge neutrality point. In contrast, the change in the quantum capacitance due to in-plane magnetization oscillates with the energy in general, except when a certain relation between the inter-surface coupling, out of plane Zeeman energy splitting and magnetic field strength is satisfied. In this special case, the quantum capacitance remains unchanged by the in-plane magnetization for all energies.

  15. Mutual capacitance of liquid conductors in deformable tactile sensing arrays

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bin [Electrical and Computer Engineering Department, Drexel University, Philadelphia, Pennsylvania 19104 (United States); Fontecchio, Adam K. [Electrical and Computer Engineering and Materials Science and Engineering Departments, Drexel University, Philadelphia, Pennsylvania 19104 (United States); Visell, Yon [Electrical and Computer Engineering Department, Media Arts and Technology, California NanoSystems Institute, University of California, Santa Barbara, California 93106 (United States)

    2016-01-04

    Advances in highly deformable electronics are needed in order to enable emerging categories of soft computing devices ranging from wearable electronics, to medical devices, and soft robotic components. The combination of highly elastic substrates with intrinsically stretchable conductors holds the promise of enabling electronic sensors that can conform to curved objects, reconfigurable displays, or soft biological tissues, including the skin. Here, we contribute sensing principles for tactile (mechanical image) sensors based on very low modulus polymer substrates with embedded liquid metal microfluidic arrays. The sensors are fabricated using a single-step casting method that utilizes fine nylon filaments to produce arrays of cylindrical channels on two layers. The liquid metal (gallium indium alloy) conductors that fill these channels readily adopt the shape of the embedding membrane, yielding levels of deformability greater than 400%, due to the use of soft polymer substrates. We modeled the sensor performance using electrostatic theory and continuum mechanics, yielding excellent agreement with experiments. Using a matrix-addressed capacitance measurement technique, we are able to resolve strain distributions with millimeter resolution over areas of several square centimeters.

  16. Slow and fast capacitive process taking place at the ionic liquid/electrode interface.

    Science.gov (United States)

    Roling, Bernhard; Drüschler, Marcel; Huber, Benediki

    2012-01-01

    Electrochemical impedance spectroscopy was used to characterise the interface between the ultrapure room temperature ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate and a Au(111) working electrode at electrode potentials more positive than the open circuit potential (-0.14 V vs. Pt pseudo-reference). Plots of the potential-dependent data in the complex capacitance plane reveal the existence of a fast and a slow capacitive process. In order to derive the contribution of both processes to the overall capacitance, the complex capacitance data were fitted using an empirical Cole-Cole equation. The differential capacitance of the fast process is almost constant between -0.14 V and +0.2 V (vs. Pt pseudo-reference) and decreases at more positive potentials, while the differential capacitance of the slower process exhibits a maximum at +0.2 V. This maximum leads to a maximum in the overall differential capacitance. We attribute the slow process to charge redistributions in the innermost ion layer, which require an activation energy in excess of that for ion transport in the room temperature ionic liquid. The differential capacitance maximum of the slow process at +0.2 V is most likely caused by reorientations of the 1-butyl-1l-methylpyrrolidinium cations in the innermost layer with the positively charged ring moving away from the Au(111) surface and leaving behind voids which are then occupied by anions. In a recent Monte Carlo simulation by Federov, Georgi and Kornyshev (Electrochem. Commun. 2010, 12, 296), such a process was identified as the origin of a differential capacitance maximum in the anodic regime. Our results suggest that the time scales of capacitive processes at the ionic liquid/metal interface are an important piece of information and should be considered in more detail in future experimental and theoretical studies.

  17. A Polymer-Based Capacitive Sensing Array for Normal and Shear Force Measurement

    Directory of Open Access Journals (Sweden)

    Ming-Yuan Cheng

    2010-11-01

    Full Text Available In this work, we present the development of a polymer-based capacitive sensing array. The proposed device is capable of measuring normal and shear forces, and can be easily realized by using micromachining techniques and flexible printed circuit board (FPCB technologies. The sensing array consists of a polydimethlysiloxane (PDMS structure and a FPCB. Each shear sensing element comprises four capacitive sensing cells arranged in a 2 × 2 array, and each capacitive sensing cell has two sensing electrodes and a common floating electrode. The sensing electrodes as well as the metal interconnect for signal scanning are implemented on the FPCB, while the floating electrodes are patterned on the PDMS structure. This design can effectively reduce the complexity of the capacitive structures, and thus makes the device highly manufacturable. The characteristics of the devices with different dimensions were measured and discussed. A scanning circuit was also designed and implemented. The measured maximum sensitivity is 1.67%/mN. The minimum resolvable force is 26 mN measured by the scanning circuit. The capacitance distributions induced by normal and shear forces were also successfully captured by the sensing array.

  18. Negative Feedback for Small Capacitive Touchscreen Interfaces: A Usability Study for Data Entry Tasks.

    Science.gov (United States)

    Parikh, S P; Esposito, J M

    2012-01-01

    Touchscreen technology has become pervasive in the consumer product arena over the last decade, offering some distinct advantages such as software reconfigurable interfaces and the removal of space consuming mice and keyboards. However, there are significant drawbacks to these devices that have limited their adoption by some users. Most notably, standard touchscreens demand the user's visual attention and require them to look at the input device to avoid pressing the wrong button. This issue is particularly important for mobile, capacitive sensing, nonstylus devices, such as the iPhone where small button sizes can generate high error rates. While previous work has shown the benefits of augmenting such interfaces with audio or vibrotactile feedback, only positive feedback (confirmation of button presses) has been considered. In this paper, we present a simple prototype interface that provides negative vibrotactile feedback. By negative, we mean feedback is generated when an inactive or ambiguous part of the screen, such as the area between two buttons, is touched. First, we present a usability study comparing positive and negative vibrotactile feedback for a benchmark numerical data entry task. The difference in performance is not statistically significant, implying negative feedback provides comparable benefits. Next, based on the experimenter's observations and the users comments, we introduce a multimodal feedback strategy-combining complementary positive audio and negative vibrotactile signals. User tests on a text entry experiment show that, with multimodal feedback, users exhibit a (statistically significant) 24 percent reduction in corrective key presses, as compared to positive audio feedback alone. Exit survey comments indicate that users favor multimodal feedback.

  19. SALT segmented primary mirror: commissioning capacitive edge sensing system and performance comparison with inductive sensor

    Science.gov (United States)

    Buous, Sebastien; Menzies, John; Gajjar, Hitesh

    2008-07-01

    The SAMS (Segment Alignment Measurement System) is a capacitance-based edge sensing solution for the active alignment of the 10m SALT segmented primary mirror. Commissioning and calibrating the system has been an ongoing task in an attempt to counteract the unfavourable response of the sensors to high humidity conditions and high dust levels. Several solutions were implemented and tested including real-time feedback systems and the application of corrective functions. In parallel with the continuing efforts to improve the performance of the capacitive sensors, we have also been testing a prototype inductive sensor developed by Fogale Nanotech that is of a very similar flexible plate construction. In this paper we present the results obtained and performance gains achieved thus far with the capacitive edge-sensing system as well as a performance comparison of the Fogale inductive sensor to the capacitive edge sensor.

  20. A High Resolution Capacitive Sensing System for the Measurement of Water Content in Crude Oil

    Directory of Open Access Journals (Sweden)

    Muhammad Zubair Aslam

    2014-06-01

    Full Text Available This paper presents the design of a non-intrusive system to measure ultra-low water content in crude oil. The system is based on a capacitance to phase angle conversion method. Water content is measured with a capacitance sensor comprising two semi-cylindrical electrodes mounted on the outer side of a glass tube. The presence of water induces a capacitance change that in turn converts into a phase angle, with respect to a main oscillator. A differential sensing technique is adopted not only to ensure high immunity against temperature variation and background noise, but also to eliminate phase jitter and amplitude variation of the main oscillator that could destabilize the output. The complete capacitive sensing system was implemented in hardware and experiment results using crude oil samples demonstrated that a resolution of ±50 ppm of water content in crude oil was achieved by the proposed design.

  1. Sugar Cube Purity: Capacitive Sensing and Image Processing Approach

    Science.gov (United States)

    Madhumitha, S.; Rajath, R.; Venkatanathan, N.; Raajan, N. R.; Sridharan, M.

    2016-12-01

    Several methods have been implemented to find out if impurity is present in sugar cubes or powders so far. Several high end imaging techniques with X-ray scanners have been used to check the quality of the sugar. In this present study, without disturbing the physical nature of sugar, we have simply used the dielectric property analysis to check the purity of the sugar. This method can detect even infinitesimal amounts of impurity present in sugar with good accuracy. The positional accuracy is derived using artificial neural networks, which is been trained with various capacitance values when the impurity is present and gives the details on the change in capacitance value as the impurity position changes.

  2. A dielectric model of self-assembled monolayer interfaces by capacitive spectroscopy.

    Science.gov (United States)

    Góes, Márcio S; Rahman, Habibur; Ryall, Joshua; Davis, Jason J; Bueno, Paulo R

    2012-06-26

    The presence of self-assembled monolayers at an electrode introduces capacitance and resistance contributions that can profoundly affect subsequently observed electronic characteristics. Despite the impact of this on any voltammetry, these contributions are not directly resolvable with any clarity by standard electrochemical means. A capacitive analysis of such interfaces (by capacitance spectroscopy), introduced here, enables a clean mapping of these features and additionally presents a means of studying layer polarizability and Cole-Cole relaxation effects. The resolved resistive term contributes directly to an intrinsic monolayer uncompensated resistance that has a linear dependence on the layer thickness. The dielectric model proposed is fully aligned with the classic Helmholtz plate capacitor model and additionally explains the inherently associated resistive features of molecular films.

  3. Electron Density and Capacitance at the interface of Au-ZnO Based Schottky Diode

    Science.gov (United States)

    Wu, Chin-Sheng

    ZnO with wide direct band gap (3.37 eV) is a well-known and an interesting compound semiconducting material, which have been used for the fabrication of optical, electrical, and piezoelectric devices such as light emitting diodes, solar cells. Schottky diodes are associated with quicker switching and lower turn on voltages compared to p-n junction diodes. J-V characteristics exhibit nonlinear rectifying behavior with threshold voltage of 2.1 V. The barrier heights were found to be 0.61 eV. The measured capacitance for the Schottky junction depends on the reverse bias potential and frequency. At the lower frequencies the capacitance has the higher values due to the trapping occurred at the interface through the surface roughness and lattice mismatch. We perform model potential calculation with quantum well around the interface. Model potentials allow some degree of freedom in the design of the emitted wavelength through adjustment of the energy levels. We apply the various well width w and barrier height V in order to match the device information made by Willander. Solving the Schrödinger equation with exchange- correlation energy and effective mass of electrons will produce values of the energy levels and states. The variational barrier heights result in the change of the electron density This accounts for the excessive capacitance at the interface of Schottky diode.

  4. A dual-mode proximity sensor with integrated capacitive and temperature sensing units

    Science.gov (United States)

    Qiu, Shihua; Huang, Ying; He, Xiaoyue; Sun, Zhiguang; Liu, Ping; Liu, Caixia

    2015-10-01

    The proximity sensor is one of the most important devices in the field of robot application. It can accurately provide the proximity information to assistant robots to interact with human beings and the external environment safely. In this paper, we have proposed and demonstrated a dual-mode proximity sensor composed of capacitive and resistive sensing units. We defined the capacitive type proximity sensor perceiving the proximity information as C-mode and the resistive type proximity sensor detecting as R-mode. Graphene nanoplatelets (GNPs) were chosen as the R-mode sensing material because of its high performance. The dual-mode proximity sensor presents the following features: (1) the sensing distance of the dual-mode proximity sensor has been enlarged compared with the single capacitive proximity sensor in the same geometrical pattern; (2) experiments have verified that the proposed sensor can sense the proximity information of different materials; (3) the proximity sensing capability of the sensor has been improved by two modes perceive collaboratively, for a plastic block at a temperature of 60 °C: the R-mode will perceive the proximity information when the distance d between the sensor and object is 6.0-17.0 mm and the C-mode will do that when their interval is 0-2.0 mm additionally two modes will work together when the distance is 2.0-6.0 mm. These features indicate our transducer is very valuable in skin-like sensing applications.

  5. Capacitive charge storage at an electrified interface investigated via direct first-principles simulations

    Science.gov (United States)

    Radin, Maxwell D.; Ogitsu, Tadashi; Biener, Juergen; Otani, Minoru; Wood, Brandon C.

    2015-03-01

    Understanding the impact of interfacial electric fields on electronic structure is crucial to improving the performance of materials in applications based on charged interfaces. Supercapacitors store energy directly in the strong interfacial field between a solid electrode and a liquid electrolyte; however, the complex interplay between the two is often poorly understood, particularly for emerging low-dimensional electrode materials that possess unconventional electronic structure. Typical descriptions tend to neglect the specific electrode-electrolyte interaction, approximating the intrinsic "quantum capacitance" of the electrode in terms of a fixed electronic density of states. Instead, we introduce a more accurate first-principles approach for directly simulating charge storage in model capacitors using the effective screening medium method, which implicitly accounts for the presence of the interfacial electric field. Applying this approach to graphene supercapacitor electrodes, we find that results differ significantly from the predictions of fixed-band models, leading to improved consistency with experimentally reported capacitive behavior. The differences are traced to two key factors: the inhomogeneous distribution of stored charge due to poor electronic screening and interfacial contributions from the specific interaction with the electrolyte. Our results are used to revise the conventional definition of quantum capacitance and to provide general strategies for improving electrochemical charge storage, particularly in graphene and similar low-dimensional materials.

  6. Lower Limb Wearable Capacitive Sensing and Its Applications to Recognizing Human Gaits

    Directory of Open Access Journals (Sweden)

    Qining Wang

    2013-10-01

    Full Text Available In this paper, we present an approach to sense human body capacitance and apply it to recognize lower limb locomotion modes. The proposed wearable sensing system includes sensing bands, a signal processing circuit and a gait event detection module. Experiments on long-term working stability, adaptability to disturbance and locomotion mode recognition are carried out to validate the effectiveness of the proposed approach. Twelve able-bodied subjects are recruited, and eleven normal gait modes are investigated. With an event-dependent linear discriminant analysis classifier and feature selection procedure, four time-domain features are used for pattern recognition and satisfactory recognition accuracies (97:3% ± 0:5%, 97:0% ± 0:4%, 95:6% ± 0:9% and 97:0% ± 0:4% for four phases of one gait cycle respectively are obtained. The accuracies are comparable with that from electromyography-based systems and inertial-based systems. The results validate the effectiveness of the proposed lower limb capacitive sensing approach in recognizing human normal gaits.

  7. Capacitive sensing of N-formylamphetamine based on immobilized molecular imprinted polymers.

    Science.gov (United States)

    Graniczkowska, Kinga; Pütz, Michael; Hauser, Frank M; De Saeger, Sarah; Beloglazova, Natalia V

    2017-06-15

    A highly sensitive, capacitive biosensor was developed to monitor trace amounts of an amphetamine precursor in aqueous samples. The sensing element is a gold electrode with molecular imprinted polymers (MIPs) immobilized on its surface. A continuous-flow system with timed injections was used to simulate flowing waterways, such as sewers, springs, rivers, etc., ensuring wide applicability of the developed product. MIPs, implemented as a recognition element due to their stability under harsh environmental conditions, were synthesized using thermo- and UV-initiated polymerization techniques. The obtained particles were compared against commercially available MIPs according to specificity and selectivity metrics; commercial MIPs were characterized by quite broad cross-reactivity to other structurally related amphetamine-type stimulants. After the best batch of MIPs was chosen, different strategies for immobilizing them on the gold electrode's surface were evaluated, and their stability was also verified. The complete, developed system was validated through analysis of spiked samples. The limit of detection (LOD) for N-formyl amphetamine was determined to be 10μM in this capacitive biosensor system. The obtained results indicate future possible applications of this MIPs-based capacitive biosensor for environmental and forensic analysis. To the best of our knowledge there are no existing MIPs-based sensors toward amphetamine-type stimulants (ATS).

  8. Wireless Sensing Based on RFID and Capacitive Technologies for Safety in Marble Industry Process Control

    Directory of Open Access Journals (Sweden)

    Fabrizio Iacopetti

    2013-01-01

    Full Text Available This paper presents wireless sensing systems to increase safety and robustness in industrial process control, particularly in industrial machines for marble slab working. The process is performed by abrasive or cutting heads activated independently by the machine controller when the slab, transported on a conveyer belt, is under them. Current slab detection systems are based on electromechanical or optical devices at the machine entrance stage, suffering from deterioration and from the harsh environment. Slab displacement or break inside the machine due to the working stress may result in safety issues and damages to the conveyer belt due to incorrect driving of the working tools. The experimented contactless sensing techniques are based on four RFID and two capacitive sensing technologies and on customized hardware/software. The proposed solutions aim at overcoming some limitations of current state-of-the-art detection systems, allowing for reliable slab detection, outside and/or inside the machine, while maintaining low complexity and at the same time robustness to industrial harsh conditions. The proposed sensing devices may implement a wireless or wired sensor network feeding detection data to the machine controller. Data integrity check and process control algorithms have to be implemented for the safety and reliability of the overall industrial process.

  9. Structured IR illumination for relative depth sensing in virtual interfaces

    Science.gov (United States)

    Kress, Bernard; Raulot, Victorien; Grossman, Michel

    2012-06-01

    Depth mapping or depth sensing has become a popular field, applied not only to automotive sensing for collision avoidance (radar) but also to gesture sensing for gaming and virtual interfaces (optical). Popular gesture sensing devices such as the Kinect from Microsoft's Xbox gaming device produce a full absolute depth map, which is in most cases not adapted to the task on hand (relative gesture sensing). We propose in this paper a new gesture sensing technique through structured IR illumination to provide a relative depth mapping rather than an absolute one, and this reducing the requirements on computing power and therefore enabling this technology for wearable computing such as see through display.

  10. High resolution space quartz-flexure accelerometer based on capacitive sensing and electrostatic control technology.

    Science.gov (United States)

    Tian, W; Wu, S C; Zhou, Z B; Qu, S B; Bai, Y Z; Luo, J

    2012-09-01

    High precision accelerometer plays an important role in space scientific and technical applications. A quartz-flexure accelerometer operating in low frequency range, having a resolution of better than 1 ng/Hz(1/2), has been designed based on advanced capacitive sensing and electrostatic control technologies. A high precision capacitance displacement transducer with a resolution of better than 2 × 10(-6) pF/Hz(1/2) above 0.1 Hz, is used to measure the motion of the proof mass, and the mechanical stiffness of the spring oscillator is compensated by adjusting the voltage between the proof mass and the electrodes to induce a proper negative electrostatic stiffness, which increases the mechanical sensitivity and also suppresses the position measurement noise down to 3 × 10(-10) g/Hz(1/2) at 0.1 Hz. A high resolution analog-to-digital converter is used to directly readout the feedback voltage applied on the electrodes in order to suppress the action noise to 4 × 10(-10) g/Hz(1/2) at 0.1 Hz. A prototype of the quartz-flexure accelerometer has been developed and tested, and the preliminary experimental result shows that its resolution comes to about 8 ng/Hz(1/2) at 0.1 Hz, which is mainly limited by its mechanical thermal noise due to low quality factor.

  11. Capacitive humidity sensing properties of carbon nanotubes grown on silicon nanoporous pillar array

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Multi-walled carbon nanotubes (CNTs) were grown on silicon nanoporous pillar array (Si-NPA) by thermal chemical vapor deposition method, and the structural and capacitive humidity sensing properties of CNT/Si-NPA were studied. It was found that with the relative humidity (RH) changing from 11% to 95%, a device re-sponse of ~480% was achieved at the frequency of 50000 Hz, and a linear device response curve could be obtained by adopting longitudinal logarithmic coordinate. The response/recovery times were measured to be ~20 s and ~10 s, respectively, which indicated a rather fast response/recovery rate. The adsorption-desorption dynamic cycle experiments demonstrated the high measurement reproducibility of CNT/Si-NPA sensors. These excellent performances were attributed to the unique surface structure, morphology and chemical inertness of CNT/Si-NPA.

  12. Capacitive humidity sensing properties of carbon nanotubes grown on silicon nanoporous pillar array

    Institute of Scientific and Technical Information of China (English)

    JIANG WeiFen; XIAO ShunHua; ZHANG HuanYun; DONG YongFen; LI XinJian

    2007-01-01

    Multi-walled carbon nanotubes (CNTs) were grown on silicon nanoporous pillar array (Si-NPA) by thermal chemical vapor deposition method, and the structural and capacitive humidity sensing properties of CNT/Si-NPA were studied. It was found that with the relative humidity (RH) changing from 11% to 95%, a device response of ~480% was achieved at the frequency of 50000 Hz, and a linear device response curve could be obtained by adopting longitudinal logarithmic coordinate. The response/recovery times were measured to be ~20 s and ~10 s, respectively, which indicated a rather fast response/recovery rate. The adsorption-desorption dynamic cycle experiments demonstrated the high measurement reproducibility of CNT/Si-NPA sensors. These excellent performances were attributed to the unique surface structure, morphology and chemical inertness of CNT/Si-NPA.

  13. Embedded Touch Sensing Circuit Using Mutual Capacitance for Active-Matrix Organic Light-Emitting Diode Display

    Science.gov (United States)

    Park, Young-Ju; Seok, Su-Jeong; Park, Sang-Ho; Kim, Ohyun

    2011-03-01

    We propose and simulate an embedded touch sensing circuit for active-matrix organic light-emitting diode (AMOLED) displays. The circuit consists of three thin-film transistors (TFTs), one fixed capacitor, and one variable capacitor. AMOLED displays do not have a variable capacitance characteristic, so we realized a variable capacitor to detect touches in the sensing pixel by exploiting the change in the mutual capacitance between two electrodes that is caused by touch. When a dielectric substance approaches two electrodes, the electric field is shunted so that the mutual capacitance decreases. We use the existing TFT process to form the variable capacitor, so no additional process is needed. We use advanced solid-phase-crystallization TFTs because of their stability and uniformity. The proposed circuit detects multi-touch points by a scanning process.

  14. Crowding and Anomalous Capacitance at an Electrode-Ionic Liquid Interface Observed Using Operando X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Miaoqi; Miller, Mitchell; Dutta, Pulak (NWU)

    2016-04-11

    Room temperature ionic liquids are widely recognized as novel electrolytes with properties very different from those of aqueous solutions, and thus with many potential applications, but observing how they actually behave at electrolytic interfaces has proved to be challenging. We have studied the voltage-dependent structure of [TDTHP]+[NTF2]- near its interface with an electrode, using in situ synchrotron X-ray reflectivity. An anion-rich layer develops at the interface above a threshold voltage of +1.75 V, and the layer thickness increases rapidly with voltage, reaching ~6 nm (much larger that the anion dimensions) at +2.64 V. Our results provide direct confirmation of the theoretical prediction of “crowding” of ions near the interface. The interfacial layer is not purely anionic but a mixture of up to ~80% anions and the rest cations. Moreover, the static differential capacitance calculated from X-ray measurements shows an increase at higher voltages, consistent with a recent zero-frequency capacitance measurement but inconsistent with ac capacitance measurements.

  15. 3D printed biomimetic whisker-based sensor with co-planar capacitive sensing

    NARCIS (Netherlands)

    Delamare, John; Sanders, Remco; Krijnen, Gijs

    2016-01-01

    This paper describes the development of a whisker sensor for tactile purposes and which is fabricated by 3D printing. Read-out consists of a capacitive measurement of a co-planar capacitance which is affected by a dielectric that is driven into the electric field of the capacitance. The current impl

  16. Macromolecular sensing at the liquid-liquid interface

    Energy Technology Data Exchange (ETDEWEB)

    Herzog, Gregoire; Flynn, Shane [Tyndall National Institute, Lee Maltings, University College, Cork (Ireland); Arrigan, Damien W M, E-mail: gregoire.herzog@tyndall.ie [Nanochemistry Research Institute, Department of Chemistry, Curtin University, Perth (Australia)

    2011-08-17

    We report here the electrochemical sensing of macromolecules, such as polyLysine dendrimers, at the polarised liquid | liquid interface. Electrochemistry at the liquid | liquid interface is a powerful analytical technique which allows the detection of non-redox active molecules via ion transfer reactions at a polarised water - oil interface. We demonstrate here that different parameters of the polyLysine dendrimers (charge number, molecular weight) have a strong influence on the sensitivity and limit of detection of these macromolecules. This work will help to the development of sensors based on charge transfer at the liquid | liquid interface.

  17. Highly Sensitive Temperature Sensors Based on Fiber-Optic PWM and Capacitance Variation Using Thermochromic Sensing Membrane.

    Science.gov (United States)

    Khan, Md Rajibur Rahaman; Kang, Shin-Won

    2016-07-09

    In this paper, we propose a temperature/thermal sensor that contains a Rhodamine-B sensing membrane. We applied two different sensing methods, namely, fiber-optic pulse width modulation (PWM) and an interdigitated capacitor (IDC)-based temperature sensor to measure the temperature from 5 °C to 100 °C. To the best of our knowledge, the fiber-optic PWM-based temperature sensor is reported for the first time in this study. The proposed fiber-optic PWM temperature sensor has good sensing ability; its sensitivity is ~3.733 mV/°C. The designed temperature-sensing system offers stable sensing responses over a wide dynamic range, good reproducibility properties with a relative standard deviation (RSD) of ~0.021, and the capacity for a linear sensing response with a correlation coefficient of R² ≈ 0.992 over a wide sensing range. In our study, we also developed an IDC temperature sensor that is based on the capacitance variation principle as the IDC sensing element is heated. We compared the performance of the proposed temperature-sensing systems with different fiber-optic temperature sensors (which are based on the fiber-optic wavelength shift method, the long grating fiber-optic Sagnac loop, and probe type fiber-optics) in terms of sensitivity, dynamic range, and linearity. We observed that the proposed sensing systems have better sensing performance than the above-mentioned sensing system.

  18. Absolute Position Sensing Based on a Robust Differential Capacitive Sensor with a Grounded Shield Window.

    Science.gov (United States)

    Bai, Yang; Lu, Yunfeng; Hu, Pengcheng; Wang, Gang; Xu, Jinxin; Zeng, Tao; Li, Zhengkun; Zhang, Zhonghua; Tan, Jiubin

    2016-05-11

    A simple differential capacitive sensor is provided in this paper to measure the absolute positions of length measuring systems. By utilizing a shield window inside the differential capacitor, the measurement range and linearity range of the sensor can reach several millimeters. What is more interesting is that this differential capacitive sensor is only sensitive to one translational degree of freedom (DOF) movement, and immune to the vibration along the other two translational DOFs. In the experiment, we used a novel circuit based on an AC capacitance bridge to directly measure the differential capacitance value. The experimental result shows that this differential capacitive sensor has a sensitivity of 2 × 10(-4) pF/μm with 0.08 μm resolution. The measurement range of this differential capacitive sensor is 6 mm, and the linearity error are less than 0.01% over the whole absolute position measurement range.

  19. Interface Defect Hydrogen Depassivation and Capacitance-Voltage Hysteresis of Al2O3/InGaAs Gate Stacks.

    Science.gov (United States)

    Tang, Kechao; Palumbo, Felix Roberto; Zhang, Liangliang; Droopad, Ravi; McIntyre, Paul C

    2017-03-01

    We investigate the effects of pre- and postatomic layer deposition (ALD) defect passivation with hydrogen on the trap density and reliability of Al2O3/InGaAs gate stacks. Reliability is characterized by capacitance-voltage hysteresis measurements on samples prepared using different fabrication procedures and having different initial trap densities. Despite its beneficial capability to passivate both interface and border traps, a final forming gas (H2/N2) anneal (FGA) step is correlated with a significant hysteresis. This appears to be caused by hydrogen depassivation of defects in the gate stack under bias stress, supported by the observed bias stress-induced increase of interface trap density, and strong hydrogen isotope effects on the measured hysteresis. On the other hand, intentional air exposure of the InGaAs surface prior to Al2O3 ALD increases the initial interface trap density (Dit) but considerably lowers the hysteresis.

  20. Interface and permittivity simultaneous reconstruction in electrical capacitance tomography based on boundary and finite-elements coupling method.

    Science.gov (United States)

    Ren, Shangjie; Dong, Feng

    2016-06-28

    Electrical capacitance tomography (ECT) is a non-destructive detection technique for imaging the permittivity distributions inside an observed domain from the capacitances measurements on its boundary. Owing to its advantages of non-contact, non-radiation, high speed and low cost, ECT is promising in the measurements of many industrial or biological processes. However, in the practical industrial or biological systems, a deposit is normally seen in the inner wall of its pipe or vessel. As the actual region of interest (ROI) of ECT is surrounded by the deposit layer, the capacitance measurements become weakly sensitive to the permittivity perturbation occurring at the ROI. When there is a major permittivity difference between the deposit and the ROI, this kind of shielding effect is significant, and the permittivity reconstruction becomes challenging. To deal with the issue, an interface and permittivity simultaneous reconstruction approach is proposed. Both the permittivity at the ROI and the geometry of the deposit layer are recovered using the block coordinate descent method. The boundary and finite-elements coupling method is employed to improve the computational efficiency. The performance of the proposed method is evaluated with the simulation tests. This article is part of the themed issue 'Supersensing through industrial process tomography'.

  1. Analytical development and optimization of a graphene–solution interface capacitance model

    Directory of Open Access Journals (Sweden)

    Hediyeh Karimi

    2014-05-01

    Full Text Available Graphene, which as a new carbon material shows great potential for a range of applications because of its exceptional electronic and mechanical properties, becomes a matter of attention in these years. The use of graphene in nanoscale devices plays an important role in achieving more accurate and faster devices. Although there are lots of experimental studies in this area, there is a lack of analytical models. Quantum capacitance as one of the important properties of field effect transistors (FETs is in our focus. The quantum capacitance of electrolyte-gated transistors (EGFETs along with a relevant equivalent circuit is suggested in terms of Fermi velocity, carrier density, and fundamental physical quantities. The analytical model is compared with the experimental data and the mean absolute percentage error (MAPE is calculated to be 11.82. In order to decrease the error, a new function of E composed of α and β parameters is suggested. In another attempt, the ant colony optimization (ACO algorithm is implemented for optimization and development of an analytical model to obtain a more accurate capacitance model. To further confirm this viewpoint, based on the given results, the accuracy of the optimized model is more than 97% which is in an acceptable range of accuracy.

  2. Feasibility of novel four degrees of freedom capacitive force sensor for skin interface force

    Directory of Open Access Journals (Sweden)

    Murakami Chisato

    2012-11-01

    Full Text Available Abstract Background The objective of our study was to develop a novel capacitive force sensor that enables simultaneous measurements of yaw torque around the pressure axis and normal force and shear forces at a single point for the purpose of elucidating pressure ulcer pathogenesis and establishing criteria for selection of cushions and mattresses. Methods Two newly developed sensors (approximately 10 mm×10 mm×5 mm (10 and 20 mm×20 mm×5 mm (20 were constructed from silicone gel and four upper and lower electrodes. The upper and lower electrodes had sixteen combinations that had the function as capacitors of parallel plate type. The full scale (FS ranges of force/torque were defined as 0–1.5 N, –0.5-0.5 N and −1.5-1.5 N mm (10 and 0–8.7 N, –2.9-2.9 N and −16.8-16.8 N mm (20 in normal force, shear forces and yaw torque, respectively. The capacitances of sixteen capacitors were measured by an LCR meter (AC1V, 100 kHz when displacements corresponding to four degrees of freedom (DOF forces within FS ranges were applied to the sensor. The measurement was repeated three times in each displacement condition (10 only. Force/torque were calculated by corrected capacitance and were evaluated by comparison to theoretical values and standard normal force measured by an universal tester. Results In measurements of capacitance, the coefficient of variation was 3.23% (10. The Maximum FS errors of estimated force/torque were less than or equal to 10.1 (10 and 16.4% (20, respectively. The standard normal forces were approximately 1.5 (10 and 9.4 N (20 when pressure displacements were 3 (10 and 2 mm (20, respectively. The estimated normal forces were approximately 1.5 (10 and 8.6 N (10 in the same condition. Conclusions In this study, we developed a new four DOF force sensor for measurement of force/torque that occur between the skin and a mattress. In measurement of capacitance, the repeatability was good and it was confirmed that the sensor had

  3. A 45.8fJ/Step, energy-efficient, differential SAR capacitance-to-digital converter for capacitive pressure sensing

    KAUST Repository

    Alhoshany, Abdulaziz

    2016-05-03

    An energy-efficient readout circuit for a capacitive sensor is presented. The capacitive sensor is digitized by a 12-bit energy efficient capacitance-to-digital converter (CDC) that is based on a differential successive-approximation architecture. This CDC meets extremely low power requirements by using an operational transconductance amplifier (OTA) that is based on a current-starved inverter. It uses a charge-redistribution DAC that involves coarse-fine architecture. We split the DAC into a coarse-DAC and a fine-DAC to allow a wide capacitance range in a compact area. It covers a wide range of capacitance of 16.14 pF with a 4.5 fF absolute resolution. An analog comparator is implemented by cross-coupling two 3-input NAND gates to enable power and area efficient operation. The prototype CDC was fabricated using a standard 180 nm CMOS technology. The 12-bit CDC has a measurement time of 42.5 μs, and consumes 3.54 μW and 0.29 μW from analog and digital supplies, respectively. This corresponds to a state-of-the-art figure-of-merit (FoM) of 45.8 fJ/conversion-step. © 2016 Elsevier B.V. All rights reserved.

  4. Interface circuit with adjustable bias voltage enabling maximum power point tracking of capacitive energy harvesting devices

    Science.gov (United States)

    Wei, J.; Lefeuvre, E.; Mathias, H.; Costa, F.

    2016-12-01

    The operation analysis of a new interface circuit for electrostatic vibration energy harvesting with adjustable bias voltage is carried out in this paper. Two configurations determined by the open or closed states of an electronic switch are examined. The increase of the voltage across a biasing capacitor, occurring when the switch is open, is proved theoretically and experimentally. With the decrease of this biasing voltage which occurs naturally when the switch is closed due to imperfections of the circuit, the bias voltage can be maintained close to a target value by appropriate ON and OFF control of the switch. As the energy converted by the variable capacitor on each cycle depends on the bias voltage, this energy can be therefore accurately controlled. This feature opens up promising perspectives for optimization the power harvested by electrostatic devices. Simulation results with and without electromechanical coupling effect are presented. In experimental tests, a simple switch control enabling to stabilize the bias voltage is described.

  5. Noise analysis and characterization of a full differential CMOS interface circuit for capacitive closed-loop micro-accelerometer

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-wei; LI Hai-tao; YIN Liang; CHEN Wei-ping; SUO Chun-guang; ZHOU Zhi-ping

    2010-01-01

    To achieve a high precision capacitive closed-loop micro-accelerometer,a full differential CMOS based on switched-capacitor circuit was presented in this paper as the sensor interface circuit.This circuit consists of a balance-bridge module,a charge sensitive amplifier,a correlated-double-sampling module,and a logic timing control module.A special two-path feedback circuit configuration was given to improve the system linearity.The quantitative analysis of error voltage and noise shows that there is tradeoff around circuit's noise,speed and accuracy.A detailed design method was given for this tradeoff.The noise performance optimized circuit has a noise root spectral density of 1.0 μV/√Hz,equivalent to rms noise root spectral density of1.63 μg/√Hz.Therefore,the sensor' s Brown noise becomes the main noise source in this design.This circuit is designed with 0.5 μm n-well CMOS process.Under a ± 5 V supply,the Hspice simulation shows that the system sensitivity achieves 0.616 V/g,the system offset is as low as 1.456 mV,the non-linearity is below0.03%,and the system linear range achieves ±5 g.

  6. Sensing of electrically conductive textiles and capacitance sensor-embedded fabrics for parachutes

    Science.gov (United States)

    Damplo, Mark; Niezrecki, Christopher; Willis, David; Chen, Julie; Niemi, Eugene; Agnihotra, Srikanthrao; Manohar, Sanjeev K.; Desabrais, Kenneth; Charette, Christine

    2012-04-01

    This paper evaluates the conductive properties and sensing capabilities of various smart materials being considered for enhancing parachute performance. In a previous review of sensing technologies, several materials showed potential for parachute implementation - specifically, electrically conductive textiles and dielectric electro-active polymers (DEAPs). Past efforts have been focused on mechanically testing and evaluating the sensing performance of conductive fabrics (coated with carbon nanotubes, polypyrrole and polyaniline) and DEAPs. While some of the conductive fabrics demonstrated sufficient sensing capability, they were not conductive enough to implement into an intelligent parachute sensor network for transmitting power or data. Also, attaching or stitching DEAPs to the parachute fabric has proven to be a challenge. The primary goal of this paper is to investigate the use of highly-conductive textiles in an intelligent textile sensor network for sensing and as a means to transmit power or electrical signals. The applications of the materials investigated in this paper may also extend beyond parachutes to any large-scale textile structure.

  7. Sensing and Control Electronics for Low-Mass Low-Capacitance MEMS Accelerometers

    Science.gov (United States)

    2002-05-01

    frequency is close to the best achievable noise floor without vacuum packaging . The experiments also show that the input-referred noise floor of the...One major difficulty in vacuum packaging MEMS sensors is that the structure has modes of vibration other than the sensing mode. Low-damping operation

  8. Capacitive chemical sensor

    Science.gov (United States)

    Manginell, Ronald P; Moorman, Matthew W; Wheeler, David R

    2014-05-27

    A microfabricated capacitive chemical sensor can be used as an autonomous chemical sensor or as an analyte-sensitive chemical preconcentrator in a larger microanalytical system. The capacitive chemical sensor detects changes in sensing film dielectric properties, such as the dielectric constant, conductivity, or dimensionality. These changes result from the interaction of a target analyte with the sensing film. This capability provides a low-power, self-heating chemical sensor suitable for remote and unattended sensing applications. The capacitive chemical sensor also enables a smart, analyte-sensitive chemical preconcentrator. After sorption of the sample by the sensing film, the film can be rapidly heated to release the sample for further analysis. Therefore, the capacitive chemical sensor can optimize the sample collection time prior to release to enable the rapid and accurate analysis of analytes by a microanalytical system.

  9. Design and implementation of a novel sliding mode sensing architecture for capacitive MEMS accelerometers

    Science.gov (United States)

    Sarraf, E. H.; Cousins, B.; Cretu, E.; Mirabbasi, S.

    2011-11-01

    We propose novel feedback control and sensing schemes based on sliding mode control (SMC) for closed-loop micro-accelerometers as alternative digital control architectures to sigma-delta (ΣΔ) approaches. The under-damped micro-device has been designed in Coventorware, fabricated in SOIMUMPs (25 µm thick structural layer) technology and experimentally characterized using a Polytec MSA-500 (micro-system analyzer) equipment. To verify the system architecture robustness, the application of SMC is extended to an over-damped accelerometer model. In either case, the SMC demonstrates the repositioning of the proof mass to null position; however, the over-damped model exhibits shorter transition time (15 ms for 1g acceleration) due to the increased damping. In addition to that, we extend the usage of SMC beyond the classical actuation problem to a novel sensing problem where we demonstrate the extraction of the external acceleration measurement from the switching behavior along the sliding surface. An optimized fixed-point implementation is targeted on a field-programmable gate array (FPGA) using rapid prototyping methodology, where the new proposed method has been compared for reference with a control scheme that employs a ΣΔ modulator. The SMC-based architecture is advantageous in terms of hardware complexity, and the control of the number of degrees of freedom required by an inertial measurement unit can be accommodated on a low-cost FPGA device. SMC offers a sound theoretical framework for the nonlinear control of inertial sensors.

  10. CMOS capacitive sensors for lab-on-chip applications a multidisciplinary approach

    CERN Document Server

    Ghafar-Zadeh, Ebrahim

    2010-01-01

    The main components of CMOS capacitive biosensors including sensing electrodes, bio-functionalized sensing layer, interface circuitries and microfluidic packaging are verbosely explained in chapters 2-6 after a brief introduction on CMOS based LoCs in Chapter 1. CMOS Capacitive Sensors for Lab-on-Chip Applications is written in a simple pedagogical way. It emphasises practical aspects of fully integrated CMOS biosensors rather than mathematical calculations and theoretical details. By using CMOS Capacitive Sensors for Lab-on-Chip Applications, the reader will have circuit design methodologies,

  11. Influence of plasma-etch damage on the interface states in SOI structures investigated by capacitance-voltage measurements and simulations

    Science.gov (United States)

    Jo, Yeong-Deuk; Koh, Jung-Hyuk; Ha, Jae-Geun; Kim, Ji-Hong; Cho, Dae-Hyung; Moon, Byung-Moo; Koo, Sang-Mo

    2009-12-01

    Au/SiO2/n-Si metal-oxide-silicon-on-insulator (MOSOI) capacitors were fabricated to study the damage caused by reactive ion etching (RIE) on (1 1 0) oriented silicon-on-insulator (SOI) substrates. The MOSOI capacitors with an etch-damaged SOI layer were characterized by capacitance-voltage (C-V) measurements and compared to the sacrificial oxidation treated samples and the reference samples without etching treatment. The measurements revealed that C-V curves significantly change and a negative voltage shift occurs for plasma-damaged capacitors. The simulated band diagram profiles and potential distribution of the corresponding structures indicate that the C-V shift is mainly due to the removal of a parasitic depletion capacitance (Cp) in the substrate, when the interface charges (Qf) are present at the gate oxide/SOI interface. For etch-damaged MOSOI samples, the surface roughness and the interface charges (Qf) have been found to increase by ~1.94 × 1012 cm-2 with respect to the reference devices, whereas the increase was reduced for sacrificial-oxidation treated samples, which implies a recovery from the plasma-induced etch damage on SOI structures.

  12. Steerable Capacitive Proximity Sensor

    Science.gov (United States)

    Jenstrom, Del T.; Mcconnell, Robert L.

    1994-01-01

    Steerable capacitive proximity sensor of "capaciflector" type based partly on sensing units described in GSC-13377 and GSC-13475. Position of maximum sensitivity adjusted without moving sensor. Voltage of each driven shield adjusted separately to concentrate sensing electric field more toward one side or other.

  13. Suspended Solid-state Membranes on Glass Chips with Sub 1-pF Capacitance for Biomolecule Sensing Applications

    Science.gov (United States)

    Chien, Chen-Chi; Balan, Adrian; Engelke, Rebecca; Drndic, Marija

    Solid-state membranes are finding use in many applications in nanoelectronics and nanomedicine, from single molecule sensors to water filtration, and yet many of their electronics applications are limited by the current noise and low bandwidth stemming from the relatively high capacitance (more than 10 pF) of the membrane chips. To address this problem, we devised an integrated fabrication process to grow and define circular silicon nitride membranes on glass chips that successfully lower the chip capacitance to below 1 pF. We use these devices to demonstrate low-noise, high-bandwidth DNA translocation measurements. We also make use of this versatile, low-capacitance platform to suspend other thin, two-dimensional membranes such as graphene.

  14. Design of a robust EMG sensing interface for pattern classification.

    Science.gov (United States)

    Huang, He; Zhang, Fan; Sun, Yan L; He, Haibo

    2010-10-01

    Electromyographic (EMG) pattern classification has been widely investigated for neural control of external devices in order to assist with movements of patients with motor deficits. Classification performance deteriorates due to inevitable disturbances to the sensor interface, which significantly challenges the clinical value of this technique. This study aimed to design a sensor fault detection (SFD) module in the sensor interface to provide reliable EMG pattern classification. This module monitored the recorded signals from individual EMG electrodes and performed a self-recovery strategy to recover the classification performance when one or more sensors were disturbed. To evaluate this design, we applied synthetic disturbances to EMG signals collected from leg muscles of able-bodied subjects and a subject with a transfemoral amputation and compared the accuracies for classifying transitions between different locomotion modes with and without the SFD module. The results showed that the SFD module maintained classification performance when one signal was distorted and recovered about 20% of classification accuracy when four signals were distorted simultaneously. The method was simple to implement. Additionally, these outcomes were observed for all subjects, including the leg amputee, which implies the promise of the designed sensor interface for providing a reliable neural-machine interface for artificial legs.

  15. Design of a robust EMG sensing interface for pattern classification

    Science.gov (United States)

    Huang, He; Zhang, Fan; Sun, Yan L.; He, Haibo

    2010-10-01

    Electromyographic (EMG) pattern classification has been widely investigated for neural control of external devices in order to assist with movements of patients with motor deficits. Classification performance deteriorates due to inevitable disturbances to the sensor interface, which significantly challenges the clinical value of this technique. This study aimed to design a sensor fault detection (SFD) module in the sensor interface to provide reliable EMG pattern classification. This module monitored the recorded signals from individual EMG electrodes and performed a self-recovery strategy to recover the classification performance when one or more sensors were disturbed. To evaluate this design, we applied synthetic disturbances to EMG signals collected from leg muscles of able-bodied subjects and a subject with a transfemoral amputation and compared the accuracies for classifying transitions between different locomotion modes with and without the SFD module. The results showed that the SFD module maintained classification performance when one signal was distorted and recovered about 20% of classification accuracy when four signals were distorted simultaneously. The method was simple to implement. Additionally, these outcomes were observed for all subjects, including the leg amputee, which implies the promise of the designed sensor interface for providing a reliable neural-machine interface for artificial legs.

  16. Layer-by-layer assembled multilayer films of exfoliated layered double hydroxide and carboxymethyl-β-cyclodextrin for selective capacitive sensing of acephatemet.

    Science.gov (United States)

    Gong, Jingming; Han, Xinmei; Zhu, Xiaolei; Guan, Zhangqiong

    2014-11-15

    Novel organic-inorganic hybrid ultrathin films were fabricated by alternate assembly of cationic exfoliated Mg-Al-layered double hydroxide (LDH) nanosheets and carboxymethyl-β-cyclodextrin (CMCD) as a polyanion onto a glassy carbon electrode (GCE) via a layer-by-layer (LBL) approach. The multilayer films were then characterized by means of X-ray powder diffraction (XRD), infrared spectroscopy (IR), and scanning electron microscopy (SEM). These films were found to possess a long range stacking order in the normal direction of the substrate with a continuous and uniform morphology. Its electrochemical performance was systematically investigated. Our results demonstrate that such a newly designed (LDH/CMCD)n multilayer film, combining the individual properties of CMCD (a high supramolecule recognition and enrichment capability) together with LDH nanosheets (a rigid inorganic matrix), can be applied to a sensitive, simple, and label-free capacitive detection of acephatemet (AM). Molecular docking calculations further disclose that the selective sensing behavior toward AM may be attributed to the specific binding ability of CMCD to AM. Under the optimized conditions, the capacitive change of AM was proportional to its concentration ranging from 0.001 to 0.10 μg mL(-1) and 0.1 to 0.8 μg mL(-1) with a detection limit 0.6 ng mL(-1) (S/N=3). Toward the goal for practical applications, this simple probe was further evaluated by monitoring AM in real samples.

  17. Numerical and analytical models to investigate the AC high-frequency response of nanoelectrode/SAM/electrolyte capacitive sensing elements

    Science.gov (United States)

    Pittino, Federico; Selmi, Luca; Widdershoven, Frans

    2013-10-01

    We develop theoretical models and numerical simulators to accurately describe the AC signal response of nanoelectrodes to the presence of biomolecules, in order to aid the design of capacitive biosensors. In particular, we first develop an analytical model for the electrolyte response to AC signal stimulation, showing that it is possible to define an AC screening length as in the standard Debye-Hückel theory. We then develop a full-custom numerical simulator for a simple nanoelectrode system, where the AC part is solved in the small-signal approximation, coupled to the DC solution. We validate the solver using the analytical model, and then use it to understand the effect of a dielectric biomolecule on the biosensor admittance.

  18. Nanocrystals of zeolite act as enhanced sensing interface for biosensing of leviteracetum.

    Science.gov (United States)

    Narang, Jagriti; Chauhan, Nidhi; Malhotra, Nitesh; Pundir, C S

    2015-03-01

    In present work, nanocrystals of zeolites were employed as sensing interface for augmented electrochemical sensing of antiepileptic drug, that is, leviteracetum (LEV). Electrochemical sensing method was developed by depositing nanocrystals of zeolites and horseradish peroxidase (nanocrys zeolites-HRP) onto indium tin oxide (ITO)-coated glass surface for LEV detection. Various stages of biosensor fabrication were characterized by Transmission electron microscopy, X-ray diffraction, scanning electron microscopy, and electrochemical impedance spectroscopy. The fabricated nanocrys zeolites-HRP-modified sensor exhibited wide linear range (10-500 μM) and a low detection limit of 0.01 μM. The biosensor also showed a short response time (within 2 s). In addition, the biosensor exhibited high reproducibility, good storage stability, and anti-interference ability. The applicability of the nanocrys zeolites-HRP-modified sensor is to determine LEV level in spiked serum samples.

  19. Research on an Interface Circuit for Micro-capacitive Sensors Based on Current Mirror%基于电流镜的微电容式传感器接口电路研究

    Institute of Scientific and Technical Information of China (English)

    王宁; 王阳; 丁卫权; 徐振波

    2014-01-01

    In the research of integrated micro-capacitive sensors, because of the change in sensitive capacitance is very small, the interface circuit research is very important for improving the sensors' performance. An interface circuit for micro-capacitive sensors based on the principle of current mirror is designed. The circuit consists of the capacitance-voltage measuring circuit, subtractor circuit, pulse circuit, buffer circuit, and so on. Based on 0.18μm CMOS process library to design and simulate this circuit, the results show that the circuit is easy to be compatible with sensitive capacitor; the output voltage has a linear relationship with sensitive capacitance. The circuit has high detection precision and wide measuring range.%在集成微电容式传感器的研究中,由于敏感电容值的变化量非常微小,其接口电路的研究对传感器性能提升是至关重要的。设计了一种基于电流镜原理检测的微电容式传感器接口电路,电路由电容转换电压电路、减法器电路、脉冲电路、缓冲器电路等组成。基于0.18μm CMOS工艺库对电路进行设计仿真,结果表明该电路便于与敏感电容兼容,输出电压与敏感电容成线性关系,其检测精确度高、范围广。

  20. Magnetically controlled space charge capacitance at La{sub 1-x}Sr{sub x}MnO{sub 3}/Sr{sub x}La{sub 1-x}TiO{sub 3} interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Rainer; Garcia-Barriocanal, Javier; Leon, Carlos; Santamaria, Jacobo [Facultad de Ciencias Fisicas, Dpto. Fisica Aplicada III, Universidad Complutense de Madrid, GFMC (Spain); Unidad Asociada ' ' Laboratorio de Heteroestructuras con Aplicacion en Espintronica' ' , UCM/CSIC, Madrid (Spain); Varela, Maria [Facultad de Ciencias Fisicas, Dpto. Fisica Aplicada III, Universidad Complutense de Madrid, GFMC (Spain); Oak Ridge National Laboratory, Oak Ridge, TN (United States); Instituto Pluridisciplinar, Universidad Complutense de Madrid (Spain); Garcia-Hernandez, Mar [Instituto de Ciencia de Materiales de Madrid - Consejo Superior de Investigaciones Cientificas (ICMM-CSIC), Madrid (Spain)

    2016-08-15

    This work reports on magnetocapacitance (MC) effects in epitaxial heterostructures of nominally 15 unit cells (u.c.) LaMnO{sub 3} (LMO) and 2 u.c. SrTiO{sub 3} (STO) with an alternating layer-repetition rate of 8: (LMO{sub 15}/STO{sub 2}){sub 8}. Epitaxial multilayer growth at high temperatures (900 C) activates a selective inter-diffusion of La{sup 3+} and Sr{sup 2+} cations across the interfaces, which gives rise to Sr p-doping of the LMO and La n-doping of the STO layers. MC effects at the buried La{sub 1-x}Sr{sub x}MnO{sub 3}/Sr{sub x}La{sub 1-x}TiO{sub 3} (LSMO/SLTO) interfaces are probed by frequency, temperature and magnetic field dependent AC impedance spectroscopy. The technique is shown to be appropriate to account for the separate analysis of different resistance and capacitance contributions at the buried interfaces. As a result of the La/Sr inter-diffusion process, Schottky barriers are formed at the LSMO/SLTO interfaces, which give rise to massive MC of up to ∼ -200% in the out-of-plane film direction. The capacitance of the manganite-titanate LSMO/SLTO interfaces may be coupled indirectly to the resistance of the LSMO layers, because the Schottky space-charge layers and their capacitance can be modulated by varying the concentration of highly mobile charge carriers in the LSMO with a magnetic field. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Electrochemical Sensing and Imaging Based on Ion Transfer at Liquid/Liquid Interfaces

    Science.gov (United States)

    Amemiya, Shigeru; Kim, Jiyeon; Izadyar, Anahita; Kabagambe, Benjamin; Shen, Mei; Ishimatsu, Ryoichi

    2013-01-01

    Here we review the recent applications of ion transfer (IT) at the interface between two immiscible electrolyte solutions (ITIES) for electrochemical sensing and imaging. In particular, we focus on the development and recent applications of the nanopipet-supported ITIES and double-polymer-modified electrode, which enable the dynamic electrochemical measurements of IT at nanoscopic and macroscopic ITIES, respectively. High-quality IT voltammograms are obtainable using either technique to quantitatively assess the kinetics and dynamic mechanism of IT at the ITIES. Nanopipet-supported ITIES serves as an amperometric tip for scanning electrochemical microscopy to allow for unprecedentedly high-resolution electrochemical imaging. Voltammetric ion sensing at double-polymer-modified electrodes offers high sensitivity and unique multiple-ion selectivity. The promising future applications of these dynamic approaches for bioanalysis and electrochemical imaging are also discussed. PMID:24363454

  2. Electrochemical Sensing and Imaging Based on Ion Transfer at Liquid/Liquid Interfaces.

    Science.gov (United States)

    Amemiya, Shigeru; Kim, Jiyeon; Izadyar, Anahita; Kabagambe, Benjamin; Shen, Mei; Ishimatsu, Ryoichi

    2013-11-01

    Here we review the recent applications of ion transfer (IT) at the interface between two immiscible electrolyte solutions (ITIES) for electrochemical sensing and imaging. In particular, we focus on the development and recent applications of the nanopipet-supported ITIES and double-polymer-modified electrode, which enable the dynamic electrochemical measurements of IT at nanoscopic and macroscopic ITIES, respectively. High-quality IT voltammograms are obtainable using either technique to quantitatively assess the kinetics and dynamic mechanism of IT at the ITIES. Nanopipet-supported ITIES serves as an amperometric tip for scanning electrochemical microscopy to allow for unprecedentedly high-resolution electrochemical imaging. Voltammetric ion sensing at double-polymer-modified electrodes offers high sensitivity and unique multiple-ion selectivity. The promising future applications of these dynamic approaches for bioanalysis and electrochemical imaging are also discussed.

  3. Design of signal processing circuit for micro-displacement capacitance sensing based on CDC&ARM%基于CDC与ARM的微位移电容传感信号处理电路设计

    Institute of Scientific and Technical Information of China (English)

    程建新; 赵涛; 王志刚

    2013-01-01

    设计了基于数字电路方法,采用电容数字转换芯片AD7745和高性能ARM微控制器为核心的信号测试电路.给出了AD7745的测量原理和电路的软硬件设计.AD7745直接将微弱的电容信号转换成数字信号而非电压信号,避免了将有用电容信号同误差电容信号一起转换成电压信号,有效降低了环境中分布电容和寄生电容的干扰.实验结果表明:设计的微位移电容传感信号处理电路提高了变极距型电容传感器的稳定性和抗干扰能力,实现了0.72 μm的分辨力.%Based on digital circuit design methods, a signal test circuit is designed by using the capacitance digital conversion chip AD7745 and high-performance ARM micro-controller. The measurement principle of AD7745 and the software and hardware design of circuit are described. AD7745 directly converts capacitance signal into digital signal rather than voltage signal, which can avoid converting the useful signal together with the error signal into voltage signal, and effectively reduces the interference of distributed capacitance and parasitic capacitance in environment. The experimental results show that the signal processing circuit for micro-displacement capacitance sensing improves stability and anti-interference ability of variable pole pitch capacitive sensor,and the resolution of the system is up to 0. 72 μm.

  4. A Power-Efficient Capacitive Read-Out Circuit With Parasitic-Cancellation for MEMS Cochlea Sensors.

    Science.gov (United States)

    Wang, Shiwei; Koickal, Thomas Jacob; Hamilton, Alister; Mastropaolo, Enrico; Cheung, Rebecca; Abel, Andrew; Smith, Leslie S; Wang, Lei

    2016-02-01

    This paper proposes a solution for signal read-out in the MEMS cochlea sensors that have very small sensing capacitance and do not have differential sensing structures. The key challenge in such sensors is the significant signal degradation caused by the parasitic capacitance at the MEMS-CMOS interface. Therefore, a novel capacitive read-out circuit with parasitic-cancellation mechanism is developed; the equivalent input capacitance of the circuit is negative and can be adjusted to cancel the parasitic capacitance. Chip results prove that the use of parasitic-cancellation is able to increase the sensor sensitivity by 35 dB without consuming any extra power. In general, the circuit follows a low-degradation low-amplification approach which is more power-efficient than the traditional high-degradation high-amplification approach; it employs parasitic-cancellation to reduce the signal degradation and therefore a lower gain is required in the amplification stage. Besides, the chopper-stabilization technique is employed to effectively reduce the low-frequency circuit noise and DC offsets. As a result of these design considerations, the prototype chip demonstrates the capability of converting a 7.5 fF capacitance change of a 1-Volt-biased 0.5 pF capacitive sensor pair into a 0.745 V signal-conditioned output at the cost of only 165.2 μW power consumption.

  5. The pyramidal capacitated vehicle routing problem

    DEFF Research Database (Denmark)

    Lysgaard, Jens

    2010-01-01

    This paper introduces the pyramidal capacitated vehicle routing problem (PCVRP) as a restricted version of the capacitated vehicle routing problem (CVRP). In the PCVRP each route is required to be pyramidal in a sense generalized from the pyramidal traveling salesman problem (PTSP). A pyramidal...

  6. Expandable Fully Compliant Capacitive Tactile Sensing Array:Design and Experiment%可拼接式全柔性电容触觉阵列传感器设计与实验

    Institute of Scientific and Technical Information of China (English)

    黄英; 郭小辉; 刘家俊; 马阳洋; 刘彩霞; 刘平; 田合雷

    2015-01-01

    针对现有机器人触觉传感器存在可穿戴性与可移植性差、不易维护及扩展等缺点,提出了一种可用于机器人仿生皮肤的全柔性电容式触觉传感器,并设计成12×12正方形触觉传感阵列和正六边形触觉模块两种可拼接式阵列结构。以炭黑填充硅橡胶作为电容式触觉传感器的弹性电介质,聚酰亚胺为柔性基体,有机硅导电银胶和金属膜为上下两柔性极板,共同构成压力敏感单元。介绍了电容式柔性触觉传感器的工作原理、结构设计及两种与之对应的电容触觉阵列无线数据采集与处理系统。实验结果表明,该全柔性电容式触觉阵列传感器及信号提取系统具有良好的稳定性与灵敏度,可用作人工皮肤实现全触觉感知。%Current robot tactile sensors have shortcomings such as poor wearability and portability, as well as being unpleasant to be maintained and expanded. An expandable, fully compliant capacitive tactile sensor is presented to counteract these shortcomings, which can be used as bio-inspired skin. The structure is designed with two kinds of expandable arrays, the 12×12 square tactile sensing array and the hexagon tactile model. The pressure-sensitive unit is constituted of carbon black filled silicone rubber uniformly as the elastic dielectric of the capacitive sensor, polyimide film as the flexible substrate, as well as silver conductive adhesive and metal film as the flexible parallel-plates of capacitor. In addition, the working principle and the structure design of the capacitive flexible tactile sensor are introduced, and also the wireless signal acquisition and processing systems of two corresponding capacitive arrays are proposed. The experiment results indicate that the fully compliant capacitive sensing array and capacitive signal extraction system has good stability and sensitivity to be used as artificial skin to achieve tactile perception.

  7. Interdigitated Pt-GaN Schottky interfaces for high-temperature soot-particulate sensing

    Science.gov (United States)

    So, Hongyun; Hou, Minmin; Jain, Sambhav R.; Lim, Jongwoo; Senesky, Debbie G.

    2016-04-01

    A microscale soot-particulate sensor using interdigitated platinum-gallium nitride (Pt-GaN) Schottky interfaces was developed to monitor fine soot particles within high-temperature environments (e.g., combustion exhausts and flues). Upon exposure to soot particles (30 to 50 nm in diameter) from an experimental chimney, an increased current (∼43.6%) is observed through the back-to-back Schottky contact to n-type GaN. This is attributed to a reduction in the effective Schottky barrier height (SBH) of ∼10 meV due to the electric field from the charged soot particles in the depletion region and exposed GaN surface. Furthermore, the microfabricated sensor was shown to recover sensitivity and regenerate the sensing response (∼11 meV SBH reduction) after exposure to temperature as high as 550 °C. This study supports the feasibility of a simple and reliable soot sensor to meet the increasing market demand for particulate matter sensing in harsh environments.

  8. Interface

    DEFF Research Database (Denmark)

    Computerens interface eller grænseflade har spredt sig overalt. Mobiltelefoner, spilkonsoller, pc'er og storskærme indeholder computere – men computere indbygges også i tøj og andre hverdagslige genstande, så vi konstant har adgang til digitale data. Interface retter fokus mod, hvordan den digita...

  9. 静电驱动电容式微机械陀螺寄生Coriolis力的建模与分析%Modeling and Analysis of Coriolis Offset for Micromachined Gyroscope with Electrostatic Driving and Capacitive Sensing

    Institute of Scientific and Technical Information of China (English)

    莫冰; 郑琦; 刘晓为; 陈斯浩

    2011-01-01

    A micromachined gyroscope with electrostatic driving and capacitive sensing was investigated based on mechanical analysis of Coriolis offset, and an equivalent electrical model of micromachined gyroscope including Coriolis offset was established. This model was simulated and compared with the equivalent electrical model of micromachined gyroscope under ideal conditions. Results indicated that, for micromachined gyroscope with electrostatic driving and capacitive sensing, the Coriolis offset affected neither frequency nor phase of the desired signal, but it may reduce the amplitude of desired signal within 0. 2%o.%在静电驱动电容式微机械陀螺传感器结构的基础上,对寄生Coriolis力进行受力分析,建立了寄生Coriolis力的等效电学模型.比较分析了理想情况下微机械陀螺的等效电学模型以及包含寄生Coriolis力的等效电学模型,结果表明,对于静电驱动电容式微机械陀螺,寄生Coriolis力并不改变有用信号的频率及相位,对其峰峰值的衰减程度小于0.2‰.

  10. Kinetic Interface

    DEFF Research Database (Denmark)

    2009-01-01

    A kinetic interface for orientation detection in a video training system is disclosed. The interface includes a balance platform instrumented with inertial motion sensors. The interface engages a participant's sense of balance in training exercises.......A kinetic interface for orientation detection in a video training system is disclosed. The interface includes a balance platform instrumented with inertial motion sensors. The interface engages a participant's sense of balance in training exercises....

  11. Capacitance Measurement Methods for Integrated Sensor Applications

    Directory of Open Access Journals (Sweden)

    Alireza Hassanzadeh

    2013-09-01

    Full Text Available In this paper different measurement methods that have been used for integrated capacitance measurement are reviewed and their advantage and disadvantages are discussed. For the designers of high accuracy on chip integrated circuits for capacitive sensors, it is important to know which method will provide the best approach for high accuracy, small chip area and power consumption especially for array sensors. These methods include on chip capacitive sensor and transducer measurement techniques that have been implemented for low value capacitance evaluations using CMOS technology. After the best structure is known the designer can optimize the chip for specific application. Voltage mode and current mode, linear and switched mode techniques are reviewed and a useful comparison table comparing all figures of merit including accuracy, range of measurement, chip area, speed and complexity is provided. The provided comparison table can be used as a reference for analog designers in the design of high accuracy integrated capacitive sensor interface

  12. Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption

    Directory of Open Access Journals (Sweden)

    Ashis Tripathy

    2016-07-01

    Full Text Available Despite the many attractive potential uses of ceramic materials as humidity sensors, some unavoidable drawbacks, including toxicity, poor biocompatibility, long response and recovery times, low sensitivity and high hysteresis have stymied the use of these materials in advanced applications. Therefore, in present investigation, we developed a capacitive humidity sensor using lead-free Ca,Mg,Fe,Ti-Oxide (CMFTO-based electro-ceramics with perovskite structures synthesized by solid-state step-sintering. This technique helps maintain the submicron size porous morphology of the developed lead-free CMFTO electro-ceramics while providing enhanced water physisorption behaviour. In comparison with conventional capacitive humidity sensors, the presented CMFTO-based humidity sensor shows a high sensitivity of up to 3000% compared to other materials, even at lower signal frequency. The best also shows a rapid response (14.5 s and recovery (34.27 s, and very low hysteresis (3.2% in a 33%–95% relative humidity range which are much lower values than those of existing conventional sensors. Therefore, CMFTO nano-electro-ceramics appear to be very promising materials for fabricating high-performance capacitive humidity sensors.

  13. Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption

    Science.gov (United States)

    Tripathy, Ashis; Pramanik, Sumit; Manna, Ayan; Bhuyan, Satyanarayan; Azrin Shah, Nabila Farhana; Radzi, Zamri; Abu Osman, Noor Azuan

    2016-01-01

    Despite the many attractive potential uses of ceramic materials as humidity sensors, some unavoidable drawbacks, including toxicity, poor biocompatibility, long response and recovery times, low sensitivity and high hysteresis have stymied the use of these materials in advanced applications. Therefore, in present investigation, we developed a capacitive humidity sensor using lead-free Ca,Mg,Fe,Ti-Oxide (CMFTO)-based electro-ceramics with perovskite structures synthesized by solid-state step-sintering. This technique helps maintain the submicron size porous morphology of the developed lead-free CMFTO electro-ceramics while providing enhanced water physisorption behaviour. In comparison with conventional capacitive humidity sensors, the presented CMFTO-based humidity sensor shows a high sensitivity of up to 3000% compared to other materials, even at lower signal frequency. The best also shows a rapid response (14.5 s) and recovery (34.27 s), and very low hysteresis (3.2%) in a 33%–95% relative humidity range which are much lower values than those of existing conventional sensors. Therefore, CMFTO nano-electro-ceramics appear to be very promising materials for fabricating high-performance capacitive humidity sensors. PMID:27455263

  14. Investigation on a Novel Capacitive Electrode for Geophysical Surveys

    Directory of Open Access Journals (Sweden)

    Zhiyu Wang

    2016-01-01

    Full Text Available Nonpolarizable electrodes are applied widely in the electric field measurement for geophysical surveys. However, there are two major problems: (1 systematic errors caused by poor electrical contact in the high resistive terrains and (2 environmental damage associated with using nonpolarizable electrodes. A new alternative structure of capacitive electrode, which is capable of sensing surface potential through weak capacitive coupling, is presented to solve the above problems. A technique is introduced to neutralize distributed capacitance and input capacitance of the detection circuit. With the capacitance neutralization technique, the transmission coefficient of capacitive electrode remains stable when environmental conditions change. The simulation and field test results indicate that the new capacitive electrode has an operating bandwidth range from 0.1 Hz to 1 kHz. The capacitive electrodes have a good prospect of the applications in geophysical prospecting, especially in resistive terrains.

  15. Formation and Characterization of Self-Assembled Phenylboronic Acid Derivative Monolayers toward Developing Monosaccaride Sensing-Interface

    Directory of Open Access Journals (Sweden)

    Kwangnak Koh

    2007-08-01

    Full Text Available We designed and synthesized phenylboronic acid as a molecular recognitionmodel system for saccharide detection. The phenylboronic acid derivatives that haveboronic acid moiety are well known to interact with saccharides in aqueous solution; thus,they can be applied to a functional interface of saccharide sensing through the formation ofself-assembled monolayer (SAM. In this study, self-assembled phenylboronic acidderivative monolayers were formed on Au surface and carefully characterized by atomicforce microscopy (AFM, Fourier transform infrared reflection absorption spectroscopy(FTIR-RAS, surface enhanced Raman spectroscopy (SERS, and surface electrochemicalmeasurements. The saccharide sensing application was investigated using surface plasmonresonance (SPR spectroscopy. The phenylboronic acid monolayers showed goodsensitivity of monosaccharide sensing even at the low concentration range (1.0 × 10-12 M.The SPR angle shift derived from interaction between phenylboronic acid andmonosaccharide was increased with increasing the alkyl spacer length of synthesizedphenylboronic acid derivatives.

  16. interfaces

    Directory of Open Access Journals (Sweden)

    Dipayan Sanyal

    2005-01-01

    macroscopic conservation equations with an order parameter which can account for the solid, liquid, and the mushy zones with the help of a phase function defined on the basis of the liquid fraction, the Gibbs relation, and the phase diagram with local approximations. Using the above formalism for alloy solidification, the width of the diffuse interface (mushy zone was computed rather accurately for iron-carbon and ammonium chloride-water binary alloys and validated against experimental data from literature.

  17. Mesure de la capacité différencielle de la double couche électrique en milieu hydrocarbure. Etude de l'interface métal-additifs pour lubrifiants. Première partie Measuring the Differential Capacity of the Electric Double Layer in a Hydrocarbon Medium. Analysis of the Metal Additive Interface for Lubricants. Part One

    Directory of Open Access Journals (Sweden)

    Hipeaux J. C.

    2006-11-01

    Full Text Available Le phénomène d'adsorption d'additifs détergents-dispersants contenus dans les huiles lubrifiantes est à la base de l'action de ces produits. L'existence d'une double couche électrique est un des paramètres envisagés lors de l'étude de l'interface métal-milieu hydrocarbure. La structure de cette double couche en liaison avec le phénomène d'adsorption à l'interface (courbe électrocapillaire, énergie libre de surface, charge, capacité différentielle sont abordés. L'importance de la connaissance du potentiel de charge nulle est montrée. Une revue bibliographique des moyens d'accès à la mesure des capacités différentielles de la double couche est farte, l'objectif à atteindre étant le choix d'une technique de mesure possible en milieu hydrocarbure, sur électrode solide. Une méthode, basée sur l'étude du début de la charge de la double couche électrique et utilisant la superposition d'une tension carrée à une tension continue maintenue constante, est développée et l'étude théorique du circuit réalisée. Des courbes capacité différentielle = f (tension de polarisation sont tracées pour des solutions dans l'heptane de différents additifs utilisés en lubrification. Une réflexion sur les mécanismes d'adsorption est faite à partir de l'exploitation de ces courbes expérimentales. A titre de comparaison quelques tracés de courbes de capacité différentielle sont effectués avec un produit antistatique rendant fortement conducteur les hydrocarbures et un produit antiusure. Enfin un système de référence utilisant une électrode au calomel est proposé. The adsorption phenomena of detergent-dispersant additives contained in lubricating ails is behind for the action of such products. The existence of an electrical double layer is one of the parameters token into consideration when analyzing the métal/hydrocarbon medium interface. The structure of this double layer in connection with the adsorption phenomenon on

  18. Integration of Capacitive Micromachined Ultrasound Transducers to Microfluidic Devices

    KAUST Repository

    Viržonis, Darius

    2013-10-22

    The design and manufacturing flexibility of capacitive micromachined ultrasound transducers (CMUT) makes them attractive option for integration with microfluidic devices both for sensing and fluid manipulation. CMUT concept is introduced here by presentin

  19. Capacitance enhancement via electrode patterning

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Tuan A.; Striolo, Alberto, E-mail: a.striolo@ucl.ac.uk [School of Chemical, Biological and Materials Engineering, The University of Oklahoma, Norman, Oklahoma 73019 (United States); Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)

    2013-11-28

    The necessity of increasing the energy density in electric double layer capacitors to meet current demand is fueling fundamental and applied research alike. We report here molecular dynamics simulation results for aqueous electrolytes near model electrodes. Particular focus is on the effect of electrode patterning on the structure of interfacial electrolytes, and on the potential drop between the solid electrodes and the bulk electrolytes. The latter is estimated by numerically integrating the Poisson equation using the charge densities due to water and ions accumulated near the interface as input. We considered uniform and patterned electrodes, both positively and negatively charged. The uniformly charged electrodes are modeled as graphite. The patterned ones are obtained by removing carbon atoms from the top-most graphene layer, yielding nanoscopic squares and stripes patterns. For simplicity, the patterned electrodes are effectively simulated as insulators (the charge remains localized on the top-most layer of carbon atoms). Our simulations show that the patterns alter the structure of water and the accumulation of ions at the liquid-solid interfaces. Using aqueous NaCl solutions, we found that while the capacitance calculated for three positively charged electrodes did not change much, that calculated for the negatively charged electrodes significantly increased upon patterning. We find that both water structure and orientation, as well as ion accumulation affect the capacitance. As electrode patterning affects differently water structure and ion accumulation, it might be possible to observe ion-specific effects. These results could be useful for advancing our understanding of electric double layer capacitors, capacitive desalination processes, as well as of fundamental interfacial electrolytes properties.

  20. Capacitance enhancement via electrode patterning

    Science.gov (United States)

    Ho, Tuan A.; Striolo, Alberto

    2013-11-01

    The necessity of increasing the energy density in electric double layer capacitors to meet current demand is fueling fundamental and applied research alike. We report here molecular dynamics simulation results for aqueous electrolytes near model electrodes. Particular focus is on the effect of electrode patterning on the structure of interfacial electrolytes, and on the potential drop between the solid electrodes and the bulk electrolytes. The latter is estimated by numerically integrating the Poisson equation using the charge densities due to water and ions accumulated near the interface as input. We considered uniform and patterned electrodes, both positively and negatively charged. The uniformly charged electrodes are modeled as graphite. The patterned ones are obtained by removing carbon atoms from the top-most graphene layer, yielding nanoscopic squares and stripes patterns. For simplicity, the patterned electrodes are effectively simulated as insulators (the charge remains localized on the top-most layer of carbon atoms). Our simulations show that the patterns alter the structure of water and the accumulation of ions at the liquid-solid interfaces. Using aqueous NaCl solutions, we found that while the capacitance calculated for three positively charged electrodes did not change much, that calculated for the negatively charged electrodes significantly increased upon patterning. We find that both water structure and orientation, as well as ion accumulation affect the capacitance. As electrode patterning affects differently water structure and ion accumulation, it might be possible to observe ion-specific effects. These results could be useful for advancing our understanding of electric double layer capacitors, capacitive desalination processes, as well as of fundamental interfacial electrolytes properties.

  1. PyzoFlex: a printed piezoelectric pressure sensing foil for human machine interfaces

    Science.gov (United States)

    Zirkl, M.; Scheipl, G.; Stadlober, B.; Rendl, C.; Greindl, P.; Haller, M.; Hartmann, P.

    2013-09-01

    Ferroelectric material supports both pyro- and piezoelectric effects that can be used for sensing pressures on large, bended surfaces. We present PyzoFlex, a pressure-sensing input device that is based on a ferroelectric material (PVDF:TrFE). It is constructed by a sandwich structure of four layers that can easily be printed on any substrate. The PyzoFlex foil is sensitive to pressure- and temperature changes, bendable, energy-efficient, and it can easily be produced by a screen-printing routine. Even a hovering input-mode is feasible due to its pyroelectric effect. In this paper, we introduce this novel, fully printed input technology and discuss its benefits and limitations.

  2. EUROSPEC: at the interface between remote sensing and ecosystem CO2 flux measurements in Europe

    Directory of Open Access Journals (Sweden)

    A. Porcar-Castell

    2015-08-01

    Full Text Available Resolving the spatial and temporal dynamics of gross primary productivity (GPP of terrestrial ecosystems across different scales remains a challenge. Remote sensing is regarded as the solution to upscale point observations conducted at the ecosystem level, using the eddy covariance (EC technique, to the landscape and global levels. In addition to traditional vegetation indices, the photochemical reflectance index (PRI and the emission of solar-induced chlorophyll fluorescence (SIF, now measurable from space, provide a new range of opportunities to monitor the global carbon cycle using remote sensing. However, the scale mismatch between EC observations and the much coarser satellite-derived data complicates the integration of the two sources of data. The solution is to establish a network of in situ spectral measurements that can act as bridge between EC measurements and remote sensing data. In situ spectral measurements have been already conducted for many years at EC sites, but using variable instrumentation, setups, and measurement standards. In Europe in particular, in situ spectral measurements remain highly heterogeneous. The goal of EUROSPEC Cost Action ES0930 was to promote the development of common measuring protocols and new instruments towards establishing best practices and standardization of in situ spectral measurements. In this review we describe the background and main tradeoffs of in situ spectral measurements, review the main results of EUROSPEC Cost Action, and discuss the future challenges and opportunities of in situ spectral measurements for improved estimation of local and global carbon cycle.

  3. Electrodeposition of gold-platinum alloy nanoparticles on carbon nanotubes as electrochemical sensing interface for sensitive detection of tumor marker

    Energy Technology Data Exchange (ETDEWEB)

    Li Ya [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Yuan Ruo, E-mail: yuanruo@swu.edu.cn [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Chai Yaqin; Song Zhongju [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)

    2011-07-30

    Graphical abstract: Electrodeposition of gold-platinum alloy (Au-PtNPs) on carbon nanotubes as electrochemical sensing interface and HRP as blocking agent for the fabrication of high sensitive immunosensor. Display Omitted Highlights: > In this work, we proposed a novel electrochemical sensing surface. > The sensing surface possessed larger electro-active areas and higher conductivity due to the introduction of MWCNTs. > The signal could be amplified effectively by synergetic catalysis effect of Au-PtNPs and HRP towards the reduction of H{sub 2}O{sub 2}. > Biomolecules could be immobilized on the surface of Au-PtNPs tightly with the bioactivity kept well. > The simple fabrication method provided a new potential for the future development of practical devices for clinical diagnosis application. - Abstract: A novel electrochemical sensing interface, electrodeposition of gold-platinum alloy nanoparticles (Au-PtNPs) on carbon nanotubes, was proposed and used to fabricate a label-free amperometric immunosensor. On the one hand, the multiwalled carbon nanotubes (MWCNTs) could increase active area of the electrode and enhance the electron transfer ability between the electrode and redox probe; on the other hand, the Au-PtNPs not only could be used to assemble biomolecules with bioactivity kept well, but also could further facilitate the shuttle of electrons. In the meanwhile, horseradish peroxidase (HRP) instead of bovine serum albumin (BSA) was employed to block the possible remaining active sites and avoid the nonspecific adsorption. With the synergetic catalysis effect of Au-PtNPs and HRP towards the reduction of hydrogen peroxide (H{sub 2}O{sub 2}), the signal could be amplified and the sensitivity could be enhanced. Using alpha-fetoprotein (AFP) as model analyte, the fabricated immunosensor exhibited two wide linear ranges in the concentration ranges of 0.5-20 ng mL{sup -1} and 20-200 ng mL{sup -1} with a detection limit of 0.17 ng mL{sup -1} at a signal-to-noise of

  4. Synthesis of Ag-Au bimetallic film at liquid-liquid interface and its application in vapor sensing

    Energy Technology Data Exchange (ETDEWEB)

    Pasricha, Renu, E-mail: pasrichar@mail.nplindia.ernet.i [Material Characterization Division, National Physical Laboratory, New Delhi-110012 (India); Gupta, Shweta [Material Characterization Division, National Physical Laboratory, New Delhi-110012 (India); Sastry, M. [Tata Chemical Innovation Center, Anmol Pride, Baner Road, Pune-45 (India); Singh, Nahar; Gupta, Prabhat [Material Characterization Division, National Physical Laboratory, New Delhi-110012 (India)

    2010-11-30

    We demonstrate a novel process for preparing densely packed film of silver nanoparticles at the liquid-liquid interface followed by a transmetallation reaction with gold ion to yield a film of bimetallic nanoparticles. Films of assembled silver as well as Ag-Au bimetallic were characterized by UV-vis-spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. I-V measurement shows linear behavior for both the films with ca. five orders of magnitude drop in resistance for the Ag-Au bimetallic film. Temperature dependent I-V measurement revealed a semiconductor to metal transition after transmetallation reaction. The films where checked for their potential application in chemical vapor sensing to ammonia vapors.

  5. Method to estimate drag coefficient at the air/ice interface over drifting open pack ice from remotely sensed data

    Science.gov (United States)

    Feldman, U.

    1984-01-01

    A knowledge in near real time, of the surface drag coefficient for drifting pack ice is vital for predicting its motions. And since this is not routinely available from measurements it must be replaced by estimates. Hence, a method for estimating this variable, as well as the drag coefficient at the water/ice interface and the ice thickness, for drifting open pack ice was developed. These estimates were derived from three-day sequences of LANDSAT-1 MSS images and surface weather charts and from the observed minima and maxima of these variables. The method was tested with four data sets in the southeastern Beaufort sea. Acceptable results were obtained for three data sets. Routine application of the method depends on the availability of data from an all-weather air or spaceborne remote sensing system, producing images with high geometric fidelity and high resolution.

  6. Direct optical interfacing of CVD diamond for deported NV-based sensing experiments

    CERN Document Server

    Mayer, Ludovic

    2016-01-01

    Nitrogen-vacancy (NV) defect in diamond is a very promising tool for numerous sensing applications like magnetometry or thermometry. In this paper, we demonstrate a compact and convenient device for magnetic field imaging where a commercial single mode photonic crystal fibre is directly coupled to a commercial CVD ppm diamond. We managed to excite and detect efficiently the luminescence from an ensemble of NV centres and also to perform Electron Spin Resonance (ESR) experiments where the NV hyperfine structure is perfectly resolved under continuous excitation and measurement.

  7. Interfacing remote sensing and geographic information systems for global environmental change research

    Science.gov (United States)

    Lee, Jae K.; Randolph, J. C.; Lulla, Kamlesh P.; Helfert, Michael R.

    1993-01-01

    Because changes in the Earth's environment have become major global issues, continuous, longterm scientific information is required to assess global problems such as deforestation, desertification, greenhouse effects and climate variations. Global change studies require understanding of interactions of complex processes regulating the Earth system. Space-based Earth observation is an essential element in global change research for documenting changes in Earth environment. It provides synoptic data for conceptual predictive modeling of future environmental change. This paper provides a brief overview of remote sensing technology from the perspective of global change research.

  8. Sensing pressure distribution on a lower-limb exoskeleton physical human-machine interface.

    Science.gov (United States)

    De Rossi, Stefano Marco Maria; Vitiello, Nicola; Lenzi, Tommaso; Ronsse, Renaud; Koopman, Bram; Persichetti, Alessandro; Vecchi, Fabrizio; Ijspeert, Auke Jan; van der Kooij, Herman; Carrozza, Maria Chiara

    2011-01-01

    A sensory apparatus to monitor pressure distribution on the physical human-robot interface of lower-limb exoskeletons is presented. We propose a distributed measure of the interaction pressure over the whole contact area between the user and the machine as an alternative measurement method of human-robot interaction. To obtain this measure, an array of newly-developed soft silicone pressure sensors is inserted between the limb and the mechanical interface that connects the robot to the user, in direct contact with the wearer's skin. Compared to state-of-the-art measures, the advantage of this approach is that it allows for a distributed measure of the interaction pressure, which could be useful for the assessment of safety and comfort of human-robot interaction. This paper presents the new sensor and its characterization, and the development of an interaction measurement apparatus, which is applied to a lower-limb rehabilitation robot. The system is calibrated, and an example its use during a prototypical gait training task is presented.

  9. Sensing Pressure Distribution on a Lower-Limb Exoskeleton Physical Human-Machine Interface

    Directory of Open Access Journals (Sweden)

    Maria Chiara Carrozza

    2010-12-01

    Full Text Available A sensory apparatus to monitor pressure distribution on the physical human-robot interface of lower-limb exoskeletons is presented. We propose a distributed measure of the interaction pressure over the whole contact area between the user and the machine as an alternative measurement method of human-robot interaction. To obtain this measure, an array of newly-developed soft silicone pressure sensors is inserted between the limb and the mechanical interface that connects the robot to the user, in direct contact with the wearer’s skin. Compared to state-of-the-art measures, the advantage of this approach is that it allows for a distributed measure of the interaction pressure, which could be useful for the assessment of safety and comfort of human-robot interaction. This paper presents the new sensor and its characterization, and the development of an interaction measurement apparatus, which is applied to a lower-limb rehabilitation robot. The system is calibrated, and an example its use during a prototypical gait training task is presented.

  10. A New Type Capacitive MEMS AcceIerometer DigitaI Interface Circuit Design%新型电容式MEMS加速度计数字接口电路设计

    Institute of Scientific and Technical Information of China (English)

    李宗伟; 丛宁; 熊兴崟; 韩可都; 杨长春

    2016-01-01

    The circuit offset often causes integration saturation in the traditional sigma-delta interface of capacitive MEMS accelerometers.To address this problem,a new type of capacitive digital interface circuit used for downhole explora-tion and oil detection is designed.This paper presents a MEMS-based 5 th-order sigma-delta capacitive accelerometer,where the 3 rd-order digital loop filter is realized using FPGA.This will reduce the ASIC analog circuit layout design and chip tes-ting difficulties and is easy to optimize the loop filter parameters,which can be used to improve the system stability and opti-mize the noise performance.The analog-frond-end amplifier (AFE)is realized by using a simple correlated double sampling (CDS),which is one effective method to reduce circuit offset of AFE.According to the Gaussian distribution of AFE output signal,one new type 8-bit instantaneous floating point ADC (IFP ADC)is designed.The IFP ADC is used to convert analog signal of AFE to digital signal to feed the 3 rd-order digital loop filter.The whole system provides a significantly low noise floor 53. 09ng/rt(Hz)overall a 200 Hz bandwidth.In this work,the AFE amplifier and ADC were successfully fabricated by using XFAB XH018 mixed-signal CMOS process.Furthermore,the sensitivity and noise floor of the AFE amplifier are 0. 69V/pF and 3. 20μV/rt(Hz)in open loop measurement,respectively.%MEMS加速度计接口电路主要采用传统sigma-delta架构实现,但这种方式中的电路失调电压很容易产生积分饱和现象.为解决这个问题,本文设计了一种可以用于钻井、石油勘探等微弱信号检测的新型数字电容接口电路.该设计在电容式MEMS加速度传感器基础上,采用FPGA实现数字三阶环路滤波器,构成5阶sigma-delta系统.采用数字环路滤波器降低了ASIC模拟电路版图设计与芯片测试难度,利于快速优化环路滤波器设计参数,改善系统稳定性和优化系统噪声性能.前置

  11. Comparison of piezoresistive and capacitive ultrasonic transducers

    Science.gov (United States)

    Neumann, John J.; Greve, David W.; Oppenheim, Irving J.

    2004-07-01

    MEMS ultrasonic transducers for flaw detection have heretofore been built as capacitive diaphragm-type devices. A diaphragm forms a moveable electrode, placed at a short gap from a stationary electrode, and diaphragm movement has been detected by capacitance change. Although several research teams have successfully demonstrated that technology, the detection of capacitance change is adversely affected by stray and parasitic capacitances, limiting the sensitivity of such transducers and typically requiring relatively large diaphragm areas. We describe the design and fabrication of what to our knowledge is the first CMOS-MEMS ultrasonic phased array transducer using piezoresistive strain sensing. Piezoresistors have been patterned within the diaphragms, and diaphragm movement creates bending strain which is detected by a bridge circuit, for which conductor losses will be less significant. The prospective advantage of such piezoresistive transducers is that sufficient sensitivity may be achieved with very small diaphragms. We compare transducer response under fluid-coupled ultrasonic excitation and report the experimental gauge factor for the piezoresistors. We also discuss the phased array performance of the transducer in sensing the direction of an incoming wave.

  12. Infrared Spectroscopy of Bilberry Extract Water-in-Oil Emulsions: Sensing the Water-Oil Interface

    Directory of Open Access Journals (Sweden)

    Johannes Kiefer

    2016-04-01

    Full Text Available Water-in-oil (w/o emulsions are of great interest in many areas of the life sciences, including food technology, bioprocess engineering, and pharmaceuticals. Such emulsions are complex multi-component systems and the molecular mechanisms which lead to a stable emulsion are yet to be fully understood. In this work, attenuated total reflection (ATR infrared (IR spectroscopy is applied to a series of w/o emulsions of an aqueous anthocyanin-rich bilberry extract dispersed in a medium chain triglyceride (MCT oil phase. The content of the emulsifier polyglycerin-polyricinoleat (PGPR has been varied systematically in order to investigate whether or not its concentration has an impact on the molecular stabilization mechanisms. The molecular stabilization is accessed by a careful analysis of the IR spectrum, where changes in the vibrational frequencies and signal strengths indicate alterations of the molecular environment at the water/oil interface. The results suggest that adding emulsifier in excess of 1% by weight does not lead to an enhanced stabilization of the emulsion.

  13. Retrieval of Parameters for Three-Layer Media with Nonsmooth Interfaces for Subsurface Remote Sensing

    Directory of Open Access Journals (Sweden)

    Yuriy Goykhman

    2012-01-01

    Full Text Available A solution to the inverse problem for a three-layer medium with nonsmooth boundaries, representing a large class of natural subsurface structures, is developed in this paper using simulated radar data. The retrieval of the layered medium parameters is accomplished as a sequential nonlinear optimization starting from the top layer and progressively characterizing the layers below. The optimization process is achieved by an iterative technique built around the solution of the forward scattering problem. The forward scattering process is formulated by using the extended boundary condition method (EBCM and constructing reflection and transmission matrices for each interface. These matrices are then combined into the generalized scattering matrix for the entire system, from which radar scattering coefficients are then computed. To be efficiently utilized in the inverse problem, the forward scattering model is simulated over a wide range of unknowns to obtain a complete set of subspace-based equivalent closed-form models that relate radar backscattering coefficients to the sought-for parameters including dielectric constants of each layer and separation of the layers. The inversion algorithm is implemented as a modified conjugate-gradient-based nonlinear optimization. It is shown that this technique results in accurate retrieval of surface and subsurface parameters, even in the presence of noise.

  14. A High Performance LIA-Based Interface for Battery Powered Sensing Devices.

    Science.gov (United States)

    García-Romeo, Daniel; Valero, María R; Medrano, Nicolás; Calvo, Belén; Celma, Santiago

    2015-09-30

    This paper proposes a battery-compatible electronic interface based on a general purpose lock-in amplifier (LIA) capable of recovering input signals up to the MHz range. The core is a novel ASIC fabricated in 1.8 V 0.18 µm CMOS technology, which contains a dual-phase analog lock-in amplifier consisting of carefully designed building blocks to allow configurability over a wide frequency range while maintaining low power consumption. It operates using square input signals. Hence, for battery-operated microcontrolled systems, where square reference and exciting signals can be generated by the embedded microcontroller, the system benefits from intrinsic advantages such as simplicity, versatility and reduction in power and size. Experimental results confirm the signal recovery capability with signal-to-noise power ratios down to -39 dB with relative errors below 0.07% up to 1 MHz. Furthermore, the system has been successfully tested measuring the response of a microcantilever-based resonant sensor, achieving similar results with better power-bandwidth trade-off compared to other LIAs based on commercial off-the-shelf (COTS) components and commercial LIA equipment.

  15. Epidermal mechano-acoustic sensing electronics for cardiovascular diagnostics and human-machine interfaces

    Science.gov (United States)

    Liu, Yuhao; Norton, James J. S.; Qazi, Raza; Zou, Zhanan; Ammann, Kaitlyn R.; Liu, Hank; Yan, Lingqing; Tran, Phat L.; Jang, Kyung-In; Lee, Jung Woo; Zhang, Douglas; Kilian, Kristopher A.; Jung, Sung Hee; Bretl, Timothy; Xiao, Jianliang; Slepian, Marvin J.; Huang, Yonggang; Jeong, Jae-Woong; Rogers, John A.

    2016-01-01

    Physiological mechano-acoustic signals, often with frequencies and intensities that are beyond those associated with the audible range, provide information of great clinical utility. Stethoscopes and digital accelerometers in conventional packages can capture some relevant data, but neither is suitable for use in a continuous, wearable mode, and both have shortcomings associated with mechanical transduction of signals through the skin. We report a soft, conformal class of device configured specifically for mechano-acoustic recording from the skin, capable of being used on nearly any part of the body, in forms that maximize detectable signals and allow for multimodal operation, such as electrophysiological recording. Experimental and computational studies highlight the key roles of low effective modulus and low areal mass density for effective operation in this type of measurement mode on the skin. Demonstrations involving seismocardiography and heart murmur detection in a series of cardiac patients illustrate utility in advanced clinical diagnostics. Monitoring of pump thrombosis in ventricular assist devices provides an example in characterization of mechanical implants. Speech recognition and human-machine interfaces represent additional demonstrated applications. These and other possibilities suggest broad-ranging uses for soft, skin-integrated digital technologies that can capture human body acoustics. PMID:28138529

  16. A High Performance LIA-Based Interface for Battery Powered Sensing Devices

    Directory of Open Access Journals (Sweden)

    Daniel García-Romeo

    2015-09-01

    Full Text Available This paper proposes a battery-compatible electronic interface based on a general purpose lock-in amplifier (LIA capable of recovering input signals up to the MHz range. The core is a novel ASIC fabricated in 1.8 V 0.18 µm CMOS technology, which contains a dual-phase analog lock-in amplifier consisting of carefully designed building blocks to allow configurability over a wide frequency range while maintaining low power consumption. It operates using square input signals. Hence, for battery-operated microcontrolled systems, where square reference and exciting signals can be generated by the embedded microcontroller, the system benefits from intrinsic advantages such as simplicity, versatility and reduction in power and size. Experimental results confirm the signal recovery capability with signal-to-noise power ratios down to −39 dB with relative errors below 0.07% up to 1 MHz. Furthermore, the system has been successfully tested measuring the response of a microcantilever-based resonant sensor, achieving similar results with better power-bandwidth trade-off compared to other LIAs based on commercial off-the-shelf (COTS components and commercial LIA equipment.

  17. Nano-structured interface of graphene and h-BN for sensing applications

    Science.gov (United States)

    de Souza, Fábio A. L.; Amorim, Rodrigo G.; Scopel, Wanderlã L.; Scheicher, Ralph H.

    2016-09-01

    The atomically-precise controlled synthesis of graphene stripes embedded in hexagonal boron nitride opens up new possibilities for the construction of nanodevices with applications in sensing. Here, we explore properties related to the electronic structure and quantum transport of a graphene nanoroad embedded in hexagonal boron nitride, using a combination of density functional theory and the non-equilibrium Green's functions method to calculate the electric conductance. We find that the graphene nanoribbon signature is preserved in the transmission spectra and that the local current is mainly confined to the graphene domain. When a properly sized nanopore is created in the graphene part of the system, the electronic current becomes restricted to a carbon chain running along the border with hexagonal boron nitride. This circumstance could allow the hypothetical nanodevice to become highly sensitive to the electronic nature of molecules passing through the nanopore, thus opening up ways to detect gas molecules, amino acids, or even DNA sequences based on a measurement of the real-time conductance modulation in the graphene nanoroad.

  18. Porous Alumina Based Capacitive MEMS RH Sensor

    CERN Document Server

    Juhasz, L; Timar-Horvath, Veronika; Desmulliez, Marc; Dhariwal, Resh

    2008-01-01

    The aim of a joint research and development project at the BME and HWU is to produce a cheap, reliable, low-power and CMOS-MEMS process compatible capacitive type relative humidity (RH) sensor that can be incorporated into a state-of-the-art, wireless sensor network. In this paper we discuss the preparation of our new capacitive structure based on post-CMOS MEMS processes and the methods which were used to characterize the thin film porous alumina sensing layer. The average sensitivity is approx. 15 pF/RH% which is more than a magnitude higher than the values found in the literature. The sensor is equipped with integrated resistive heating, which can be used for maintenance to reduce drift, or for keeping the sensing layer at elevated temperature, as an alternative method for temperature-dependence cancellation.

  19. Speech through ears and eyes: interfacing the senses with the supramodal brain

    Directory of Open Access Journals (Sweden)

    Virginie evan Wassenhove

    2013-07-01

    Full Text Available The comprehension of auditory-visual (AV speech integration has greatly benefited from recent advances in neurosciences and multisensory research. AV speech integration raises numerous questions relevant to the computational rules needed for binding information (within and across sensory modalities, the representational format in which speech information is encoded in the brain (e.g. auditory vs. articulatory, or how AV speech ultimately interfaces with the linguistic system. The following non-exhaustive review provides a set of empirical findings and theoretical questions that have fed the original proposal for predictive coding in AV speech processing. More recently, predictive coding has pervaded many fields of inquiries and positively reinforced the need to refine the notion of internal models in the brain together with their implications for the interpretation of neural activity recorded with various neuroimaging techniques. However, it is argued here that the strength of predictive coding frameworks reside in the specificity of the generative internal models not in their generality; specifically, internal models come with a set of rules applied on particular representational formats themselves depending on the levels and the network structure at which predictive operations occur. As such, predictive coding in AV speech owes to specify the level(s and the kinds of internal predictions that are necessary to account for the perceptual benefits or illusions observed in the field. Among those specifications, the actual content of a prediction comes first and foremost, followed by the representational granularity of that prediction in time. This review specifically presents a focused discussion on these issues.

  20. A wireless magnetoresistive sensing system for an intraoral tongue-computer interface.

    Science.gov (United States)

    Park, Hangue; Kiani, Mehdi; Lee, Hyung-Min; Kim, Jeonghee; Block, Jacob; Gosselin, Benoit; Ghovanloo, Maysam

    2012-12-01

    Tongue drive system (TDS) is a tongue-operated, minimally invasive, unobtrusive, and wireless assistive technology (AT) that infers users' intentions by detecting their voluntary tongue motion and translating them into user-defined commands. Here we present the new intraoral version of the TDS (iTDS), which has been implemented in the form of a dental retainer. The iTDS system-on-a-chip (SoC) features a configurable analog front-end (AFE) that reads the magnetic field variations inside the mouth from four 3-axial magnetoresistive sensors located at four corners of the iTDS printed circuit board (PCB). A dual-band transmitter (Tx) on the same chip operates at 27 and 432 MHz in the Industrial/Scientific/Medical (ISM) band to allow users to switch in the presence of external interference. The Tx streams the digitized samples to a custom-designed TDS universal interface, built from commercial off-the-shelf (COTS) components, which delivers the iTDS data to other devices such as smartphones, personal computers (PC), and powered wheelchairs (PWC). Another key block on the iTDS SoC is the power management integrated circuit (PMIC), which provides individually regulated and duty-cycled 1.8 V supplies for sensors, AFE, Tx, and digital control blocks. The PMIC also charges a 50 mAh Li-ion battery with constant current up to 4.2 V, and recovers data and clock to update its configuration register through a 13.56 MHz inductive link. The iTDS SoC has been implemented in a 0.5-μm standard CMOS process and consumes 3.7 mW on average.

  1. Membrane capacitive deionization

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Wal, van der A.

    2010-01-01

    Membrane capacitive deionization (MCDI) is an ion-removal process based on applying an electrical potential difference across an aqueous solution which flows in between oppositely placed porous electrodes, in front of which ion-exchange membranes are positioned. Due to the applied potential, ions ar

  2. Negative capacitance in multidomain ferroelectric superlattices

    Science.gov (United States)

    Zubko, Pavlo; Wojdeł, Jacek C.; Hadjimichael, Marios; Fernandez-Pena, Stéphanie; Sené, Anaïs; Luk'Yanchuk, Igor; Triscone, Jean-Marc; Íñiguez, Jorge

    2016-06-01

    The stability of spontaneous electrical polarization in ferroelectrics is fundamental to many of their current applications, which range from the simple electric cigarette lighter to non-volatile random access memories. Research on nanoscale ferroelectrics reveals that their behaviour is profoundly different from that in bulk ferroelectrics, which could lead to new phenomena with potential for future devices. As ferroelectrics become thinner, maintaining a stable polarization becomes increasingly challenging. On the other hand, intentionally destabilizing this polarization can cause the effective electric permittivity of a ferroelectric to become negative, enabling it to behave as a negative capacitance when integrated in a heterostructure. Negative capacitance has been proposed as a way of overcoming fundamental limitations on the power consumption of field-effect transistors. However, experimental demonstrations of this phenomenon remain contentious. The prevalent interpretations based on homogeneous polarization models are difficult to reconcile with the expected strong tendency for domain formation, but the effect of domains on negative capacitance has received little attention. Here we report negative capacitance in a model system of multidomain ferroelectric-dielectric superlattices across a wide range of temperatures, in both the ferroelectric and paraelectric phases. Using a phenomenological model, we show that domain-wall motion not only gives rise to negative permittivity, but can also enhance, rather than limit, its temperature range. Our first-principles-based atomistic simulations provide detailed microscopic insight into the origin of this phenomenon, identifying the dominant contribution of near-interface layers and paving the way for its future exploitation.

  3. A Wearable Capacitive Sensor for Monitoring Human Respiratory Rate

    Science.gov (United States)

    Kundu, Subrata Kumar; Kumagai, Shinya; Sasaki, Minoru

    2013-04-01

    Realizing an untethered, low-cost, and comfortably wearable respiratory rate sensor for long-term breathing monitoring application still remains a challenge. In this paper, a conductive-textile-based wearable respiratory rate sensing technique based on the capacitive sensing approach is proposed. The sensing unit consists of two conductive textile electrodes that can be easily fabricated, laminated, and integrated in garments. Respiration cycle is detected by measuring the capacitance of two electrodes placed on the inner anterior and posterior sides of a T-shirt at either the abdomen or chest position. A convenient wearable respiratory sensor setup with a capacitance-to-voltage converter has been devised. Respiratory rate as well as breathing mode can be accurately identified using the designed sensor. The sensor output provides significant information on respiratory flow. The effectiveness of the proposed system for different breathing patterns has been evaluated by experiments.

  4. Full differential CMOS interface circuit for closed-loop capacitive micro-accelerometers%闭环电容式微加速度计全差分CMOS接口电路

    Institute of Scientific and Technical Information of China (English)

    刘晓为; 尹亮; 李海涛; 周治平

    2011-01-01

    提出了一种用于电容式微加速度计的低噪声、高线性度全差分接口电路.基于开关电容检测技术,该电路采用一种新的双路反馈结构来提高系统线性度,并采用2 μm n阱CMOS工艺完成芯片设计.仿真结果证明,电路中采用的双路反馈和全差分检测结构使系统的线性度达到0.01%.加入经过优化设计的比例-微分-积分控制器后,有效减小了系统稳态误差,系统响应速度提高了31%,系统线性度提高了66.7%.在±5 V工作电压下,选取64 kHz作为电路采样频率时,其电路等效输入噪声为8 μg·Hz-(1)/(2),系统灵敏度为1.22 V/g,线性度为0.03%,测量范围为±2 g.测试结果显示,提出的电路达到高精度微加速度计系统设计要求,可以应用到地震监测、石油勘探等领域中.%A CMOS full differential interface circuit with low noise and high linearity was presented for closed-loop capacitive micro-accelerometers. Based on switched-capacitor detection, the circuit was designed to improve its linearity by a 0.5 μm n-well CMOS process technology. The simulation result shows that the proposed two-path feedback structure provides a good system linearity of 0.01%. The optimized designed PID controller was added into the system, which decreases the stabilization error effectively, increases the system responding speed by 31%, and the linearity by 66.7%. With a ±5 V supply and a sampling frequency of 64 kHz, the circuit can offer the equivalent input noise in 8μg ·Hz-(1/2), system sensitivity in 1.22 V/g, system linearity in 0.03%, and the work range in ±2 g·These results prove that this circuit is suitable for applications of high performance micro-accelerome-ters to seism detection, oil exploration,etc..

  5. Multi-Channel Capacitive Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Bingnan Wang

    2016-01-01

    Full Text Available In this paper, multi-channel capacitive sensor arrays based on microstrip band-stop filters are studied. The sensor arrays can be used to detect the proximity of objects at different positions and directions. Each capacitive sensing structure in the array is connected to an inductive element to form resonance at different frequencies. The resonances are designed to be isolated in the frequency spectrum, such that the change in one channel does not affect resonances at other channels. The inductive element associated with each capacitive sensor can be surface-mounted inductors, integrated microstrip inductors or metamaterial-inspired structures. We show that by using metamaterial split-ring structures coupled to a microstrip line, the quality factor of each resonance can be greatly improved compared to conventional surface-mounted or microstrip meander inductors. With such a microstrip-coupled split-ring design, more sensing elements can be integrated in the same frequency spectrum, and the sensitivity can be greatly improved.

  6. Nanostructure-Directed Chemical Sensing: The IHSAB Principle and the Effect of Nitrogen and Sulfur Functionalization on Metal Oxide Decorated Interface Response

    Directory of Open Access Journals (Sweden)

    James L. Gole

    2013-08-01

    Full Text Available The response matrix, as metal oxide nanostructure decorated n-type semiconductor interfaces are modified in situ through direct amination and through treatment with organic sulfides and thiols, is demonstrated. Nanostructured TiO2, SnOx, NiO and CuxO (x = 1,2, in order of decreasing Lewis acidity, are deposited to a porous silicon interface to direct a dominant electron transduction process for reversible chemical sensing in the absence of significant chemical bond formation. The metal oxide sensing sites can be modified to decrease their Lewis acidity in a process appearing to substitute nitrogen or sulfur, providing a weak interaction to form the oxynitrides and oxysulfides. Treatment with triethylamine and diethyl sulfide decreases the Lewis acidity of the metal oxide sites. Treatment with acidic ethane thiol modifies the sensor response in an opposite sense, suggesting that there are thiol (SH groups present on the surface that provide a Brønsted acidity to the surface. The in situ modification of the metal oxides deposited to the interface changes the reversible interaction with the analytes, NH3 and NO. The observed change for either the more basic oxynitrides or oxysulfides or the apparent Brønsted acid sites produced from the interaction of the thiols do not represent a simple increase in surface basicity or acidity, but appear to involve a change in molecular electronic structure, which is well explained using the recently developed inverse hard and soft acids and bases (IHSAB model.

  7. A robust parasitic-insensitive successive approximation capacitance-to-digital converter

    KAUST Repository

    Omran, Hesham

    2014-09-01

    In this paper, we present a capacitive sensor digital interface circuit using true capacitance-domain successive approximation that is independent of supply voltage. Robust operation is achieved by using a charge amplifier stage and multiple comparison technique. The interface circuit is insensitive to parasitic capacitances, offset voltages, and charge injection, and is not prone to noise coupling. The proposed design achieves very low temperature sensitivity of 25ppm/oC. A coarse-fine programmable capacitance array allows digitizing a wide capacitance range of 16pF with 12.5-bit quantization limited resolution in a compact area of 0.07mm2. The fabricated prototype is experimentally verified using on-chip sensor and off-chip MEMS capacitive pressure sensor. © 2014 IEEE.

  8. Induced Charge Capacitive Deionization

    CERN Document Server

    Rubin, S; Biesheuvel, P M; Bercovici, M

    2016-01-01

    We demonstrate the phenomenon of induced-charge capacitive deionization (ICCDI) that occurs around a porous and conducting particle immersed in an electrolyte, under the action of an external electrostatic field. The external electric field induces an electric dipole in the porous particle, leading to capacitive charging of its volume by both cations and anions at opposite poles. This regime is characterized both by a large RC charging time and a small electrochemical charge relaxation time, which leads to rapid and significant deionization of ionic species from a volume which is on the scale of the particle. We show by theory and experiment that the transient response around a cylindrical particle results in spatially non-uniform charging and non-steady growth of depletion regions which emerge around the particle's poles. Potentially, ICCDI can be useful in applications where fast concentration changes of ionic species are required over large volumes.

  9. Capacitive deionization of seawater

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J.C.; Fix, D.V.; Mack, G.V. [and others

    1995-10-01

    Capacitive deionization with carbon aerogel electrodes is an efficient and economical new process for removing salt and impurities from water. Carbon aerogel is a material that enables the successful purification of water because of its high surface area, optimum pore size, and low electrical resistivity. The electrodes are maintained at a potential difference of about one volt; ions are removed from the water by the imposed electrostatic field and retained on the electrode surface until the polarity is reversed. The capacitive deionization of water with a stack of carbon aerogel electrodes has been successfully demonstrated. The overall process offers advantages when compared to conventional water-purification methods, requiring neither pumps, membranes, distillation columns, nor thermal heaters. Consequently, the overall process is both robust and energy efficient. The current state of technology development, commercialization, and potential applications of this process are reviewed.

  10. The Pyramidal Capacitated Vehicle Routing Problem

    DEFF Research Database (Denmark)

    Lysgaard, Jens

    This paper introduces the Pyramidal Capacitated Vehicle Routing Problem (PCVRP) as a restricted version of the Capacitated Vehicle Routing Problem (CVRP). In the PCVRP each route is required to be pyramidal in a sense generalized from the Pyramidal Traveling Salesman Problem (PTSP). A pyramidal...... found in many optimal solutions to CVRP instances. An optimal solution to the PCVRP may therefore be useful in itself as a heuristic solution to the CVRP. Further, an attempt can be made to find an even better CVRP solution by solving a TSP, possibly leading to a non-pyramidal route, for each...... of the routes in the PCVRP solution. This paper develops an exact branch-and-cut-and-price (BCP) algorithm for the PCVRP. At the pricing stage, elementary routes can be computed in pseudo-polynomial time in the PCVRP, unlike in the CVRP. We have therefore implemented pricing algorithms that generate only...

  11. Time dependent capacitance voltage measurements on Cu(In,Ga)Se{sub 2} solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Adler, Tobias; Klein, Andreas [Darmstadt University of Technology, Institute of Materials Science, Petersenstrasse 32, D-64287 Darmstadt (Germany); Witte, Wolfram; Hariskos, Dimitrios [Zentrum fuer Sonnenenergie- und Wasserstoff-Forschung Baden-Wuerttemberg (ZSW), Industriestrasse 6, D-70565 Stuttgart (Germany)

    2011-07-01

    Capacitance Voltage (C-V) measurements are widely used to determine the doping density of semiconductor interfaces in dependence on the width of the space charge layer. In Cu(In,Ga)Se{sub 2} (CIGS) solar cells we observe a time dependent capacitance signal, which can be explained by different models like filling and emptying of electronic (metastable) defect states or by the diffusion of copper ions. The observed capacitance transients are compared to the different models.

  12. 嵌入式容栅传感技术及轴功率测试研究%Study on embedded capacitive grating sensing technology and shaft power testing

    Institute of Scientific and Technical Information of China (English)

    谢锐; 马铁华; 武耀艳; 靳鸿

    2012-01-01

    The difficulties in power measurement of revolving shaft are difficult signal transmission, limited installation space and signal disturbance. In order to solve the above problems, an embedded capacitive grating torque/ speed sensor and related measuring system have been developed. Two capacitive grating sensors are installed on both ends of the shaft. When the revolving shaft is actuated by a torque, a twist angle is produced; and a phase difference between the outputs of the two capacitive grating sensors appears, and the phase difference represents the amount of the twist angle. Through measuring the phase difference, the torque is obtained. The differential structure of the capacitive grating sensor increases the sensitivity and decreases the measurement error. The embedded installation of the capacitive grating sensor decreases the effect on the shaft under test to the lowest. Experiment results show that the capacitive grating sensor is highly reliable and can be used under harsh environment for a long time. Besides, the capacitive grating sensor does not need to use slip ring, radio or infrared to transmit signal and power, which overcomes the shortcomings of complex installation and signal disturbance.%针对旋转轴功率测试存在的传感器信号引线困难、安装空间受限、信号易受干扰的问题,设计了一种嵌入式容栅扭矩、转速传感器和测试系统.测试时在轴的两端分别安装容栅传感器,轴在受到扭矩时产生扭角,则两容栅的输出信号会产生一个相位差,通过测量相位差的变化得到扭矩.容栅传感器的差动结构提高了灵敏度减小了误差,容栅的嵌入式安装,将对被测轴的影响降到了最低.实验证明容栅传感器可靠性高,可以在环境要求严格的情况下长时间使用,并且无需通过滑环、无线或红外进行供电和信号的传输,克服了以上方式安装复杂、信号易受干扰的缺点.

  13. Enhancement of two dimensional electron gas concentrations due to Si{sub 3}N{sub 4} passivation on Al{sub 0.3}Ga{sub 0.7}N/GaN heterostructure: strain and interface capacitance analysis

    Energy Technology Data Exchange (ETDEWEB)

    Dinara, Syed Mukulika, E-mail: smdinara.iit@gmail.com; Jana, Sanjay Kr.; Ghosh, Saptarsi; Mukhopadhyay, Partha; Kumar, Rahul [Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur, India 721302 (India); Chakraborty, Apurba; Biswas, Dhrubes [Dept. of Electronics and Electrical Communication Engineering, Indian Institute of Technology, Kharagpur, India 721 302 (India); Bhattacharya, Sekhar [SSN Research Center, Tamilnadu, India 603110 (India)

    2015-04-15

    Enhancement of two dimensional electron gas (2DEG) concentrations at Al{sub 0.3}Ga{sub 0.7}N/GaN hetero interface after a-Si{sub 3}N{sub 4} (SiN) passivation has been investigated from non-destructive High Resolution X-ray Diffraction (HRXRD) analysis, depletion depth and capacitance-voltage (C-V) profile measurement. The crystalline quality and strained in-plane lattice parameters of Al{sub 0.3}Ga{sub 0.7}N and GaN were evaluated from double axis (002) symmetric (ω-2θ) diffraction scan and double axis (105) asymmetric reciprocal space mapping (DA RSM) which revealed that the tensile strain of the Al{sub 0.3}Ga{sub 0.7}N layer increased by 15.6% after SiN passivation. In accordance with the predictions from theoretical solution of Schrödinger-Poisson’s equations, both electrochemical capacitance voltage (ECV) depletion depth profile and C-V characteristics analyses were performed which implied effective 9.5% increase in 2DEG carrier density after passivation. The enhancement of polarization charges results from increased tensile strain in the Al{sub 0.3}Ga{sub 0.7}N layer and also due to the decreased surface states at the interface of SiN/Al{sub 0.3}Ga{sub 0.7}N layer, effectively improving the carrier confinement at the interface.

  14. Capacitance of circular patch resonator

    Energy Technology Data Exchange (ETDEWEB)

    Miano, G.; Verolino, L. [Dip. di Ingegneria Elettrica, Ist. Nazionale di Fisica Nucleare, Naples (Italy); Panariello, G. [Dip. di Ingegneria Elettronica, Naples (Italy); Vaccaro, V.G. [Ist. Nazionale di Fisica Nucleare, Naples (Italy). Dipt. di Scienze Fisiche

    1995-11-01

    In this paper the capacitance of the circular microstrip patch resonator is computed. It is shown that the electrostatic problem can be formulated as a system of dual integral equations, and the most interesting techniques of solutions of these systems are reviewed. Some useful approximated formulas for the capacitance are derived and plots of the capacitance are finally given in a wide range of dielectric constants.

  15. Capacitive tool standoff sensor for dismantlement tasks

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, D.J.; Weber, T.M. [Sandia National Labs., Albuquerque, NM (United States); Liu, J.C. [Univ. of Illinois, Urbana, IL (United States)

    1996-12-31

    A capacitive sensing technology has been applied to develop a Standoff Sensor System for control of robotically deployed tools utilized in Decontamination and Dismantlement (D and D) activities. The system combines four individual sensor elements to provide non-contact, multiple degree-of-freedom control of tools at distances up to five inches from a surface. The Standoff Sensor has been successfully integrated to a metal cutting router and a pyrometer, and utilized for real-time control of each of these tools. Experiments demonstrate that the system can locate stationary surfaces with a repeatability of 0.034 millimeters.

  16. Capacitive pressure sensor in post-processing on LTCC substrates

    NARCIS (Netherlands)

    Meijerink, M.G.H.; Nieuwkoop, E.; Veninga, E.P.; Meuwissen, M.H.H.; Tijdink, M.W.W.J.

    2005-01-01

    A capacitive pressure sensor was realized by means of a post-processing step on a low temperature co-fired ceramics (LTCC) substrate. The new sensor fabrication technology allows for integration of the sensor with interface circuitry and possibly also wireless transmission circuits on LTCC substrate

  17. A versatile method to grow localized arrays of nanowires for highly sensitive capacitive devices

    DEFF Research Database (Denmark)

    Antohe, V.A.; Radu, A.; Yunus, S.

    2008-01-01

    We propose a new approach to increase the detection efficiency of the capacitive sensing devices, by growing vertically aligned nanowires arrays, localized and confined on small interdigited electrodes structures. The metallic tracks are made using optical lithography, and the nanowires are reali......We propose a new approach to increase the detection efficiency of the capacitive sensing devices, by growing vertically aligned nanowires arrays, localized and confined on small interdigited electrodes structures. The metallic tracks are made using optical lithography, and the nanowires...

  18. Optimal pricing of capacitated networks

    NARCIS (Netherlands)

    Grigoriev, Alexander; Loon, van Joyce; Sitters, René; Uetz, Marc

    2009-01-01

    We address the algorithmic complexity of a profit maximization problem in capacitated, undirected networks. We are asked to price a set of $m$ capacitated network links to serve a set of $n$ potential customers. Each customer is interested in purchasing a network connection that is specified by a si

  19. Efficiency of Capacitively Loaded Converters

    DEFF Research Database (Denmark)

    Andersen, Thomas; Huang, Lina; Andersen, Michael A. E.;

    2012-01-01

    This paper explores the characteristic of capacitance versus voltage for dielectric electro active polymer (DEAP) actuator, 2kV polypropylene film capacitor as well as 3kV X7R multi layer ceramic capacitor (MLCC) at the beginning. An energy efficiency for capacitively loaded converters...... is introduced as a definition of efficiency. The calculated and measured efficiency curves for charging DEAP actuator, polypropylene film capacitor and X7R MLCC are provided and compared. The attention has to be paid for the voltage dependent capacitive load, like X7R MLCC, when evaluating the charging...... polypropylene film capacitor can be the equivalent capacitive load. Because of the voltage dependent characteristic, X7R MLCC cannot be used to replace the DEAP actuator. However, this type of capacitor can be used to substitute the capacitive actuator with voltage dependent property at the development phase....

  20. Micromachined capacitive pressure sensor with signal conditioning electronics

    DEFF Research Database (Denmark)

    Fragiacomo, Giulio

    Micromachined capacitive pressure sensors for harsh environment together with interfacing electronic circuits have been studied in this project. Micro-electromechanical systems (MEMS) have been proposed as substitutes for macro scale sensor’s systems in many different fields and are the only...... a great deal of sensors are used. Pressure sensors are among the most successful MEMS and are used in a huge variety of applications. In this project an absolute capacitive pressure sensor has been developed with the aim to integrate it in pump control systems to improve the efficiency of the pump...

  1. Touch mode micromachined capacitive pressure sensor with signal conditioning electronics

    DEFF Research Database (Denmark)

    Fragiacomo, Giulio; Eriksen, Gert F.; Christensen, Carsten

    2010-01-01

    is one of the key challenges nowadays. In this context, house heating is a priority for environmental issues. For this reason, the possibilities of using a low power consumption technique, such as capacitive pressure sensing, in harsh environments is a concrete market opportunity. Our aim is therefore....... A measurement setup was arranged and tested for accuracy and reliability with respect to hysteresis. Finally, designs with different radii of the top plate were characterized by a capacitance versus pressure curve at different frequencies and temperatures (Fig. 3). Industrial possibilities Energy saving systems...

  2. A MEMS Interface IC With Low-Power and Wide-Range Frequency-to-Voltage Converter for Biomedical Applications.

    Science.gov (United States)

    Arefin, Md Shamsul; Redouté, Jean-Michel; Yuce, Mehmet Rasit

    2016-04-01

    This paper presents an interface circuit for capacitive and inductive MEMS biosensors using an oscillator and a charge pump based frequency-to-voltage converter. Frequency modulation using a differential crossed coupled oscillator is adopted to sense capacitive and inductive changes. The frequency-to-voltage converter is designed with a negative feedback system and external controlling parameters to adjust the sensitivity, dynamic range, and nominal point for the measurement. The sensitivity of the frequency-to-voltage converter is from 13.28 to 35.96 mV/MHz depending on external voltage and charging current. The sensitivity ranges of the capacitive and inductive interface circuit are 17.08 to 54.4 mV/pF and 32.11 to 82.88 mV/mH, respectively. A capacitive MEMS based pH sensor is also connected with the interface circuit to measure the high acidic gastric acid throughout the digestive tract. The sensitivity for pH from 1 to 3 is 191.4 mV/pH with 550 μV(pp) noise. The readout circuit is designed and fabricated using the UMC 0.18 μm CMOS technology. It occupies an area of 0.18 mm (2) and consumes 11.8 mW.

  3. Last-passage Monte Carlo algorithm for mutual capacitance.

    Science.gov (United States)

    Hwang, Chi-Ok; Given, James A

    2006-08-01

    We develop and test the last-passage diffusion algorithm, a charge-based Monte Carlo algorithm, for the mutual capacitance of a system of conductors. The first-passage algorithm is highly efficient because it is charge based and incorporates importance sampling; it averages over the properties of Brownian paths that initiate outside the conductor and terminate on its surface. However, this algorithm does not seem to generalize to mutual capacitance problems. The last-passage algorithm, in a sense, is the time reversal of the first-passage algorithm; it involves averages over particles that initiate on an absorbing surface, leave that surface, and diffuse away to infinity. To validate this algorithm, we calculate the mutual capacitance matrix of the circular-disk parallel-plate capacitor and compare with the known numerical results. Good agreement is obtained.

  4. Gallium-Based Room Temperature Liquid Metals and its Application to Single Channel Two-Liquid Hyperelastic Capacitive Strain Sensors

    Science.gov (United States)

    Liu, Shanliangzi

    Gallium-based liquid metals are of interest for a variety of applications including flexible electronics, soft robotics, and biomedical devices. Still, nano- to microscale device fabrication with these materials is challenging because of their strong adhesion to a majority of substrates. This unusual high adhesion is attributed to the formation of a thin oxide shell; however, its role in the adhesion process has not yet been established. In the first part of the thesis, we described a multiscale study aiming at understanding the fundamental mechanisms governing wetting and adhesion of gallium-based liquid metals. In particular, macroscale dynamic contact angle measurements were coupled with Scanning Electron Microscope (SEM) imaging to relate macroscopic drop adhesion to morphology of the liquid metal-surface interface. In addition, room temperature liquid-metal microfluidic devices are also attractive systems for hyperelastic strain sensing. Currently two types of liquid metal-based strain sensors exist for inplane measurements: single-microchannel resistive and two-microchannel capacitive devices. However, with a winding serpentine channel geometry, these sensors typically have a footprint of about a square centimeter, limiting the number of sensors that can be embedded into. In the second part of the thesis, firstly, simulations and an experimental setup consisting of two GaInSn filled tubes submerged within a dielectric liquid bath are used to quantify the effects of the cylindrical electrode geometry including diameter, spacing, and meniscus shape as well as dielectric constant of the insulating liquid and the presence of tubing on the overall system's capacitance. Furthermore, a procedure for fabricating the two-liquid capacitor within a single straight polydiemethylsiloxane channel is developed. Lastly, capacitance and response of this compact device to strain and operational issues arising from complex hydrodynamics near liquid-liquid and liquid

  5. CMOS MEMS capacitive absolute pressure sensor

    Science.gov (United States)

    Narducci, M.; Yu-Chia, L.; Fang, W.; Tsai, J.

    2013-05-01

    This paper presents the design, fabrication and characterization of a capacitive pressure sensor using a commercial 0.18 µm CMOS (complementary metal-oxide-semiconductor) process and postprocess. The pressure sensor is capacitive and the structure is formed by an Al top electrode enclosed in a suspended SiO2 membrane, which acts as a movable electrode against a bottom or stationary Al electrode fixed on the SiO2 substrate. Both the movable and fixed electrodes form a variable parallel plate capacitor, whose capacitance varies with the applied pressure on the surface. In order to release the membranes the CMOS layers need to be applied postprocess and this mainly consists of four steps: (1) deposition and patterning of PECVD (plasma-enhanced chemical vapor deposition) oxide to protect CMOS pads and to open the pressure sensor top surface, (2) etching of the sacrificial layer to release the suspended membrane, (3) deposition of PECVD oxide to seal the etching holes and creating vacuum inside the gap, and finally (4) etching of the passivation oxide to open the pads and allow electrical connections. This sensor design and fabrication is suitable to obey the design rules of a CMOS foundry and since it only uses low-temperature processes, it allows monolithic integration with other types of CMOS compatible sensors and IC (integrated circuit) interface on a single chip. Experimental results showed that the pressure sensor has a highly linear sensitivity of 0.14 fF kPa-1 in the pressure range of 0-300 kPa.

  6. Spin-orbit controlled capacitance of a polar heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Steffen, Kevin; Kopp, Thilo [Center for Electronic Correlations and Magnetism, EP VI, Institute of Physics, University of Augsburg, 86135 Augsburg (Germany); Loder, Florian [Center for Electronic Correlations and Magnetism, EP VI and TP III, Institute of Physics, University of Augsburg, 86135 Augsburg (Germany)

    2015-07-01

    Oxide heterostructures with polar films display special electronic properties, such as the electronic reconstruction at their internal interfaces with the formation of two-dimensional metallic states. Moreover, the electrical field from the polar layers is inversion-symmetry breaking and may generate a strong Rashba spin-orbit coupling (RSOC) in the interfacial electronic system. We investigate the capacitance of a heterostructure in which a strong RSOC at a metallic interface is controlled by the electric field of a surface electrode. Such a structure is for example given by a LaAlO{sub 3} film on a SrTiO{sub 3} substrate which is gated by a top electrode. We find that due to a strong RSOC the capacitance can be larger than the classical geometric value.

  7. High resolution capacitance detection circuit for rotor micro-gyroscope

    Directory of Open Access Journals (Sweden)

    Ming-Yuan Ren

    2014-03-01

    Full Text Available Conventional methods for rotor position detection of micro-gyroscopes include common exciting electrodes (single frequency and common sensing electrodes (frequency multiplex, but they have encountered some problems. So we present a high resolution and low noise pick-off circuit for micro-gyroscopes which utilizes the time multiplex method. The detecting circuit adopts a continuous-time current sensing circuit for capacitance measurement, and its noise analysis of the charge amplifier is introduced. The equivalent output noise power spectral density of phase-sensitive demodulation is 120 nV/Hz1/2. Tests revealed that the whole circuitry has a relative capacitance resolution of 1 × 10−8.

  8. Mass detection using capacitive resonant silicon resonator employing LC resonant circuit technique.

    Science.gov (United States)

    Kim, Sang-Jin; Ono, Takahito; Esashi, Masayoshi

    2007-08-01

    Capacitive resonant mass sensing using a single-crystalline silicon resonator with an electrical LC oscillator was demonstrated in ambient atmosphere. Using capacitive detection method, the detectable minimum mass of 1 x 10(-14) g was obtained in the self-oscillation of cantilever with a thickness of 250 nm. The noise amplitude of the sensor output corresponds to a vibration amplitude of 0.05 nm(Hz)(0.5) in the frequency domain compared with the actuation signal, which is equivalent to the detectable minimum capacitance variation of 2.4 x 10(-21) F. Using the capacitive detection method, mass/stress induced resonance frequency shift due to the adsorption of ethanol and moist vapor in a pure N(2) gas as a carrier is successfully demonstrated. These results show the high potential of capacitive silicon resonator for high mass/stress-sensitive sensor.

  9. Determination of multi-component flow process parameters based on electrical capacitance tomography data using artificial neural networks

    Science.gov (United States)

    Mohamad-Saleh, J.; Hoyle, B. S.

    2002-12-01

    Artificial neural networks (ANNs) have been used to investigate their capabilities at estimating key parameters for the characterization of flow processes, based on electrical capacitance-sensed tomographic (ECT) data. The estimations of the parameters are made directly, without recourse to tomographic images. The parameters of interest include component height and interface orientation of two-component flows, and component fractions of two-component and three-component flows. Separate multi-layer perceptron networks were trained with patterns consisting of pairs of simulated ECT data and the corresponding component heights, interface orientations and component fractions. The networks were then tested with patterns consisting of unlearned simulated ECT data of various flows and with real ECT data of gas-water flows. The neural systems provided estimations having mean absolute errors of less than 1% for oil and water heights and fractions and less than 10° for interface orientations. When tested with real plant ECT data, the mean absolute errors were less than 4% for water height, less than 15° for gas-water interface orientation and less than 3% for water fraction, respectively. The results demonstrate the feasibility of the application of ANNs for flow process parameter estimations based upon tomography data.

  10. A Capacitated Facility Location Approach for the Tanker Employment Problem

    Science.gov (United States)

    2005-03-01

    Depot (MD) Vehicle Routing Problem (VRP) ......................................... 14 2.5 Capacitated Facility Location Problem (CFLP) with Sole...service receiver groups. In this sense the problem can be viewed as a multi-depot vehicle routing problem . Anchor points are two stationary points...for future research. 2.4 Multi-Depot (MD) Vehicle Routing Problem (VRP) Another approach to the Tanker Employment Problem is to model it as a VRP

  11. Unified capacitance modelling of MOSFETs

    Science.gov (United States)

    Johannessen, O. G.; Fjeldly, T. A.; Ytterdal, T.

    1994-01-01

    A unified physics based capacitance model for MOSFETs suitable for implementation in circuit simulators is presented. This model is based on the charge conserving, so-called Meyer-like approach proposed by Turchetti et al., and utilizes a unified charge control model to assure a continuous description of the MOSFET capacitances both above and below threshold. The capacitances associated with the model are comparable to those of the well-known BSIM model in the above-threshold regime, but it is more precise in the description of near-threshold and subthreshold behaviour. Moreover, the discontinuities at the transitions between the various regimes of operation are removed. The present modelling scheme was implemented in our circuit simulator AIM-Spice, and simulations of the dynamic behaviour of various demanding benchmark circuits clearly reveal its superiority over simulations using the simple Meyer model.

  12. Bioenergetics of Mammalian Sperm Capacitation

    Directory of Open Access Journals (Sweden)

    Alessandra Ferramosca

    2014-01-01

    Full Text Available After ejaculation, the mammalian male gamete must undergo the capacitation process, which is a prerequisite for egg fertilization. The bioenergetics of sperm capacitation is poorly understood despite its fundamental role in sustaining the biochemical and molecular events occurring during gamete activation. Glycolysis and mitochondrial oxidative phosphorylation (OXPHOS are the two major metabolic pathways producing ATP which is the primary source of energy for spermatozoa. Since recent data suggest that spermatozoa have the ability to use different metabolic substrates, the main aim of this work is to present a broad overview of the current knowledge on the energy-producing metabolic pathways operating inside sperm mitochondria during capacitation in different mammalian species. Metabolism of glucose and of other energetic substrates, such as pyruvate, lactate, and citrate, is critically analyzed. Such knowledge, besides its obvious importance for basic science, could eventually translate into the development of novel strategies for treatment of male infertility, artificial reproduction, and sperm selection methods.

  13. Noise limits of CMOS current interfaces for biosensors: a review.

    Science.gov (United States)

    Crescentini, Marco; Bennati, Marco; Carminati, Marco; Tartagni, Marco

    2014-04-01

    Current sensing readout is one of the most frequent techniques used in biosensing due to the charge-transfer phenomena occurring at solid-liquid interfaces. The development of novel nanodevices for biosensing determines new challenges for electronic interface design based on current sensing, especially when compact and efficient arrays need to be organized, such as in recent trends of rapid label-free electronic detection of DNA synthesis. This paper will review the basic noise limitations of current sensing interfaces with particular emphasis on integrated CMOS technology. Starting from the basic theory, the paper presents, investigates and compares charge-sensitive amplifier architectures used in both continuous-time and discrete-time approaches, along with their design trade-offs involving noise floor, sensitivity to stray capacitance and bandwidth. The ultimate goal of this review is providing analog designers with helpful design rules and analytical tools. Also, in order to present a comprehensive overview of the state-of-the-art, the most relevant papers recently appeared in the literature about this topic are discussed and compared.

  14. Small-Molecule Fusion Inhibitors Bind the pH-Sensing Stable Signal Peptide-GP2 Subunit Interface of the Lassa Virus Envelope Glycoprotein

    Science.gov (United States)

    Shankar, Sundaresh; Whitby, Landon R.; Casquilho-Gray, Hedi E.; York, Joanne; Boger, Dale L.

    2016-01-01

    arenavirus envelope glycoprotein (GPC) have recently been identified and shown to block GPC-mediated fusion of the viral and cellular endosomal membranes, thereby preventing virus entry into the host cell. Genetic studies suggest that these inhibitors act through a unique pH-sensing intersubunit interface in GPC, but atomic-level structural information is unavailable. In this report, we utilize novel photoreactive fusion inhibitors and photoaffinity labeling to obtain direct physical evidence for inhibitor binding at this critical interface in Lassa virus GPC. Future identification of modified residues at the inhibitor-binding site will help elucidate the molecular basis for fusion activation and its inhibition and guide the development of effective therapies to treat arenaviral hemorrhagic fevers. PMID:27194767

  15. Fully integrated low-noise readout circuit with automatic offset cancellation loop for capacitive microsensors.

    Science.gov (United States)

    Song, Haryong; Park, Yunjong; Kim, Hyungseup; Cho, Dong-Il Dan; Ko, Hyoungho

    2015-10-14

    Capacitive sensing schemes are widely used for various microsensors; however, such microsensors suffer from severe parasitic capacitance problems. This paper presents a fully integrated low-noise readout circuit with automatic offset cancellation loop (AOCL) for capacitive microsensors. The output offsets of the capacitive sensing chain due to the parasitic capacitances and process variations are automatically removed using AOCL. The AOCL generates electrically equivalent offset capacitance and enables charge-domain fine calibration using a 10-bit R-2R digital-to-analog converter, charge-transfer switches, and a charge-storing capacitor. The AOCL cancels the unwanted offset by binary-search algorithm based on 10-bit successive approximation register (SAR) logic. The chip is implemented using 0.18 μm complementary metal-oxide-semiconductor (CMOS) process with an active area of 1.76 mm². The power consumption is 220 μW with 3.3 V supply. The input parasitic capacitances within the range of -250 fF to 250 fF can be cancelled out automatically, and the required calibration time is lower than 10 ms.

  16. Fully Integrated Low-Noise Readout Circuit with Automatic Offset Cancellation Loop for Capacitive Microsensors

    Directory of Open Access Journals (Sweden)

    Haryong Song

    2015-10-01

    Full Text Available Capacitive sensing schemes are widely used for various microsensors; however, such microsensors suffer from severe parasitic capacitance problems. This paper presents a fully integrated low-noise readout circuit with automatic offset cancellation loop (AOCL for capacitive microsensors. The output offsets of the capacitive sensing chain due to the parasitic capacitances and process variations are automatically removed using AOCL. The AOCL generates electrically equivalent offset capacitance and enables charge-domain fine calibration using a 10-bit R-2R digital-to-analog converter, charge-transfer switches, and a charge-storing capacitor. The AOCL cancels the unwanted offset by binary-search algorithm based on 10-bit successive approximation register (SAR logic. The chip is implemented using 0.18 μm complementary metal-oxide-semiconductor (CMOS process with an active area of 1.76 mm2. The power consumption is 220 μW with 3.3 V supply. The input parasitic capacitances within the range of −250 fF to 250 fF can be cancelled out automatically, and the required calibration time is lower than 10 ms.

  17. Microfluidic Arrayed Lab-On-A-Chip for Electrochemical Capacitive Detection of DNA Hybridization Events.

    Science.gov (United States)

    Ben-Yoav, Hadar; Dykstra, Peter H; Bentley, William E; Ghodssi, Reza

    2017-01-01

    A microfluidic electrochemical lab-on-a-chip (LOC) device for DNA hybridization detection has been developed. The device comprises a 3 × 3 array of microelectrodes integrated with a dual layer microfluidic valved manipulation system that provides controlled and automated capabilities for high throughput analysis of microliter volume samples. The surface of the microelectrodes is functionalized with single-stranded DNA (ssDNA) probes which enable specific detection of complementary ssDNA targets. These targets are detected by a capacitive technique which measures dielectric variation at the microelectrode-electrolyte interface due to DNA hybridization events. A quantitative analysis of the hybridization events is carried out based on a sensing modeling that includes detailed analysis of energy storage and dissipation components. By calculating these components during hybridization events the device is able to demonstrate specific and dose response sensing characteristics. The developed microfluidic LOC for DNA hybridization detection offers a technology for real-time and label-free assessment of genetic markers outside of laboratory settings, such as at the point-of-care or in-field environmental monitoring.

  18. Calcium-sensing receptors regulate cardiomyocyte Ca2+ signaling via the sarcoplasmic reticulum-mitochondrion interface during hypoxia/reoxygenation

    Directory of Open Access Journals (Sweden)

    Lu Fang-hao

    2010-06-01

    Full Text Available Abstract Communication between the SR (sarcoplasmic reticulum, SR and mitochondria is important for cell survival and apoptosis. The SR supplies Ca2+ directly to mitochondria via inositol 1,4,5-trisphosphate receptors (IP3Rs at close contacts between the two organelles referred to as mitochondrion-associated ER membrane (MAM. Although it has been demonstrated that CaR (calcium sensing receptor activation is involved in intracellular calcium overload during hypoxia/reoxygenation (H/Re, the role of CaR activation in the cardiomyocyte apoptotic pathway remains unclear. We postulated that CaR activation plays a role in the regulation of SR-mitochondrial inter-organelle Ca2+ signaling, causing apoptosis during H/Re. To investigate the above hypothesis, cultured cardiomyocytes were subjected to H/Re. We examined the distribution of IP3Rs in cardiomyocytes via immunofluorescence and Western blotting and found that type 3 IP3Rs were located in the SR. [Ca2+]i, [Ca2+]m and [Ca2+]SR were determined using Fluo-4, x-rhod-1 and Fluo 5N, respectively, and the mitochondrial membrane potential was detected with JC-1 during reoxygenation using laser confocal microscopy. We found that activation of CaR reduced [Ca2+]SR, increased [Ca2+]i and [Ca2+]m and decreased the mitochondrial membrane potential during reoxygenation. We found that the activation of CaR caused the cleavage of BAP31, thus generating the pro-apoptotic p20 fragment, which induced the release of cytochrome c from mitochondria and the translocation of bak/bax to mitochondria. Taken together, these results reveal that CaR activation causes Ca2+ release from the SR into the mitochondria through IP3Rs and induces cardiomyocyte apoptosis during hypoxia/reoxygenation.

  19. Calcium-sensing receptors regulate cardiomyocyte Ca2+ signaling via the sarcoplasmic reticulum-mitochondrion interface during hypoxia/reoxygenation.

    Science.gov (United States)

    Lu, Fang-hao; Tian, Zhiliang; Zhang, Wei-hua; Zhao, Ya-jun; Li, Hu-lun; Ren, Huan; Zheng, Hui-shuang; Liu, Chong; Hu, Guang-xia; Tian, Ye; Yang, Bao-feng; Wang, Rui; Xu, Chang-qing

    2010-06-17

    Communication between the SR (sarcoplasmic reticulum, SR) and mitochondria is important for cell survival and apoptosis. The SR supplies Ca2+ directly to mitochondria via inositol 1,4,5-trisphosphate receptors (IP3Rs) at close contacts between the two organelles referred to as mitochondrion-associated ER membrane (MAM). Although it has been demonstrated that CaR (calcium sensing receptor) activation is involved in intracellular calcium overload during hypoxia/reoxygenation (H/Re), the role of CaR activation in the cardiomyocyte apoptotic pathway remains unclear. We postulated that CaR activation plays a role in the regulation of SR-mitochondrial inter-organelle Ca2+ signaling, causing apoptosis during H/Re. To investigate the above hypothesis, cultured cardiomyocytes were subjected to H/Re. We examined the distribution of IP3Rs in cardiomyocytes via immunofluorescence and Western blotting and found that type 3 IP3Rs were located in the SR. [Ca2+]i, [Ca2+]m and [Ca2+]SR were determined using Fluo-4, x-rhod-1 and Fluo 5N, respectively, and the mitochondrial membrane potential was detected with JC-1 during reoxygenation using laser confocal microscopy. We found that activation of CaR reduced [Ca2+]SR, increased [Ca2+]i and [Ca2+]m and decreased the mitochondrial membrane potential during reoxygenation. We found that the activation of CaR caused the cleavage of BAP31, thus generating the pro-apoptotic p20 fragment, which induced the release of cytochrome c from mitochondria and the translocation of bak/bax to mitochondria. Taken together, these results reveal that CaR activation causes Ca2+ release from the SR into the mitochondria through IP3Rs and induces cardiomyocyte apoptosis during hypoxia/reoxygenation.

  20. Water desalination via capacitive deionization

    NARCIS (Netherlands)

    Suss, M.E.; Porada, S.; Sun, X.; Biesheuvel, P.M.; Yoon, J.; Presser, V.

    2015-01-01

    Capacitive deionization (CDI) is an emerging technology for the facile removal of charged ionic species from aqueous solutions, and is currently being widely explored for water desalination applications. The technology is based on ion electrosorption at the surface of a pair of electrically charg

  1. Voltage Dependence of Supercapacitor Capacitance

    Directory of Open Access Journals (Sweden)

    Szewczyk Arkadiusz

    2016-09-01

    Full Text Available Electronic Double-Layer Capacitors (EDLC, called Supercapacitors (SC, are electronic devices that are capable to store a relatively high amount of energy in a small volume comparing to other types of capacitors. They are composed of an activated carbon layer and electrolyte solution. The charge is stored on electrodes, forming the Helmholtz layer, and in electrolyte. The capacitance of supercapacitor is voltage- dependent. We propose an experimental method, based on monitoring of charging and discharging a supercapacitor, which enables to evaluate the charge in an SC structure as well as the Capacitance-Voltage (C-V dependence. The measurement setup, method and experimental results of charging/discharging commercially available supercapacitors in various voltage and current conditions are presented. The total charge stored in an SC structure is proportional to the square of voltage at SC electrodes while the charge on electrodes increases linearly with the voltage on SC electrodes. The Helmholtz capacitance increases linearly with the voltage bias while a sublinear increase of total capacitance was found. The voltage on SC increases after the discharge of electrodes due to diffusion of charges from the electrolyte to the electrodes. We have found that the recovery voltage value is linearly proportional to the initial bias voltage value.

  2. The modelling of a capacitive microsensor for biosensing applications

    Science.gov (United States)

    Bezuidenhout, P. H.; Schoeman, J.; Joubert, T. H.

    2014-06-01

    Microsensing is a leading field in technology due to its wide application potential, not only in bio-engineering, but in other fields as well. Microsensors have potentially low-cost manufacturing processes, while a single device type can have various uses, and this consequently helps with the ever-growing need to provide better health conditions in rural parts of the world. Capacitive biosensors detect a change in permittivity (or dielectric constant) of a biological material, usually within a parallel plate capacitor structure which is often implemented with integrated electrodes of an inert metal such as gold or platinum on a microfluidic substrate typically with high dielectric constant. There exist parasitic capacitance components in these capacitive sensors, which have large influence on the capacitive measurement. Therefore, they should be considered for the development of sensitive and accurate sensing devices. An analytical model of a capacitive sensor device is discussed, which accounts for these parasitic factors. The model is validated with a laboratory device of fixed geometry, consisting of two parallel gold electrodes on an alumina (Al2O3) substrate mounted on a glass microscope slide, and with a windowed cover layer of poly-dimethyl-siloxane (PDMS). The thickness of the gold layer is 1μm and the electrode spacing is 300μm. The alumina substrate has a thickness of 200μm, and the high relative permittivity of 11.5 is expected to be a significantly contributing factor to the total device capacitance. The 155μm thick PDMS layer is also expected to contribute substantially to the total device capacitance since the relative permittivity for PDMS is 2.7. The wideband impedance analyser evaluation of the laboratory device gives a measurement result of 2pF, which coincides with the model results; while the handheld RLC meter readout of 4pF at a frequency of 10kHz is acceptable within the measurement accuracy of the instrument. This validated model will

  3. Embedding of electrodes within a microchannel interfacing a permselective medium for sensing and active control of the concentration-polarization layer

    Science.gov (United States)

    Yossifon, Gilad; Park, Sinwook

    2016-11-01

    Previously, it has been shown that for a prescribed system, the diffusion length may be affected by any number of mechanisms including natural and forced convection, electroosmotic flow of the second kind and electro-convective instability. In all of the above mentioned cases the length of the diffusion layer is indirectly prescribed by the complicated competition between several mechanisms which are primarily dictated by the various system parameters and applied voltage. In contrast, we suggest that by embedding electrodes/heaters within a microchannel interfacing a permselective medium, the diffusion layer length may be controlled regardless of the dominating overlimiting current mechanism and system parameters. As well as demonstrating that the simple presence of electrodes can enhance mixing via induced-charge electrokinetic effects, we also offer a means of externally activating embedded electrodes and heaters to maintain external, dynamic control of the diffusion length. Such control is particularly important in applications requiring intense ion transport, such as electrodialysis. At the same time, we will also investigate means of suppressing these mechanisms which is of fundamental importance for sensing applications.

  4. A nafion coated capacitive humidity sensor on a flexible PET substrate

    KAUST Repository

    Sapsanis, Christos

    2017-03-07

    This paper reports a simple and low-cost technique for fabricating low-power capacitive humidity sensors without the use of a cleanroom environment. A maskless laser engraving system was utilized to fabricate two different gold electrode structures, interdigitated electrodes and Hilbert\\'s fifth-order fractal. The capacitive structures were implemented on a flexible PET substrate. The usage of Nafion, a well-known polymer for its hydrophilic properties as a sensing film, was attempted on the PET and outperformed the current efforts in flexible substrates. Its humidity sensing properties were evaluated in an automated gas setup with a relative humidity (RH %) ranging from 15% to 95 %.

  5. Quantum Capacitance in Topological Insulators

    Science.gov (United States)

    Xiu, Faxian; Meyer, Nicholas; Kou, Xufeng; He, Liang; Lang, Murong; Wang, Yong; Yu, Xinxin; Fedorov, Alexei V.; Zou, Jin; Wang, Kang L.

    2012-01-01

    Topological insulators show unique properties resulting from massless, Dirac-like surface states that are protected by time-reversal symmetry. Theory predicts that the surface states exhibit a quantum spin Hall effect with counter-propagating electrons carrying opposite spins in the absence of an external magnetic field. However, to date, the revelation of these states through conventional transport measurements remains a significant challenge owing to the predominance of bulk carriers. Here, we report on an experimental observation of Shubnikov-de Haas oscillations in quantum capacitance measurements, which originate from topological helical states. Unlike the traditional transport approach, the quantum capacitance measurements are remarkably alleviated from bulk interference at high excitation frequencies, thus enabling a distinction between the surface and bulk. We also demonstrate easy access to the surface states at relatively high temperatures up to 60 K. Our approach may eventually facilitate an exciting exploration of exotic topological properties at room temperature. PMID:22993694

  6. Modeling the electrified solid-liquid interface

    DEFF Research Database (Denmark)

    Rossmeisl, Jan; Skulason, Egill; Björketun, Mårten;

    2008-01-01

    A detailed atomistic model based on density functional theory calculations is presented of the charged solid-electrolyte interface. Having protons solvated in a water bilayer outside a Pt(111) slab with excess electrons, we show how the interface capacitance is well described and how the work...

  7. Redox regulation of mammalian sperm capacitation

    Directory of Open Access Journals (Sweden)

    Cristian O′Flaherty

    2015-01-01

    Full Text Available Capacitation is a series of morphological and metabolic changes necessary for the spermatozoon to achieve fertilizing ability. One of the earlier happenings during mammalian sperm capacitation is the production of reactive oxygen species (ROS that will trigger and regulate a series of events including protein phosphorylation, in a time-dependent fashion. The identity of the sperm oxidase responsible for the production of ROS involved in capacitation is still elusive, and several candidates are discussed in this review. Interestingly, ROS-induced ROS formation has been described during human sperm capacitation. Redox signaling during capacitation is associated with changes in thiol groups of proteins located on the plasma membrane and subcellular compartments of the spermatozoon. Both, oxidation of thiols forming disulfide bridges and the increase on thiol content are necessary to regulate different sperm proteins associated with capacitation. Reducing equivalents such as NADH and NADPH are necessary to support capacitation in many species including humans. Lactate dehydrogenase, glucose-6-phospohate dehydrogenase, and isocitrate dehydrogenase are responsible in supplying NAD (P H for sperm capacitation. Peroxiredoxins (PRDXs are newly described enzymes with antioxidant properties that can protect mammalian spermatozoa; however, they are also candidates for assuring the regulation of redox signaling required for sperm capacitation. The dysregulation of PRDXs and of enzymes needed for their reactivation such as thioredoxin/thioredoxin reductase system and glutathione-S-transferases impairs sperm motility, capacitation, and promotes DNA damage in spermatozoa leading to male infertility.

  8. Dual Cryogenic Capacitive Density Sensor

    Science.gov (United States)

    Youngquist, Robert; Mata, Carlos; Vokrot, Peter; Cox, Robert

    2009-01-01

    A dual cryogenic capacitive density sensor has been developed. The device contains capacitive sensors that monitor two-phase cryogenic flow density to within 1% accuracy, which, if temperature were known, could be used to determine the ratio of liquid to gas in the line. Two of these density sensors, located a known distance apart, comprise the sensor, providing some information on the velocity of the flow. This sensor was constructed as a proposed mass flowmeter with high data acquisition rates. Without moving parts, this device is capable of detecting the density change within a two-phase cryogenic flow more than 100 times a second. Detection is enabled by a series of two sets of five parallel plates with stainless steel, cryogenically rated tubing. The parallel plates form the two capacitive sensors, which are measured by electrically isolated digital electronics. These capacitors monitor the dielectric of the flow essentially the density of the flow and can be used to determine (along with temperature) the ratio of cryogenic liquid to gas. Combining this information with the velocity of the flow can, with care, be used to approximate the total two-phase mass flow. The sensor can be operated at moderately high pressures and can be lowered into a cryogenic bath. The electronics have been substantially improved over the older sensors, incorporating a better microprocessor, elaborate ground loop protection and noise limiting circuitry, and reduced temperature sensitivity. At the time of this writing, this design has been bench tested at room temperature, but actual cryogenic tests are pending

  9. Compact monolithic capacitive discharge unit

    Science.gov (United States)

    Roesler, Alexander W.; Vernon, George E.; Hoke, Darren A.; De Marquis, Virginia K.; Harris, Steven M.

    2007-06-26

    A compact monolithic capacitive discharge unit (CDU) is disclosed in which a thyristor switch and a flyback charging circuit are both sandwiched about a ceramic energy storage capacitor. The result is a compact rugged assembly which provides a low-inductance current discharge path. The flyback charging circuit preferably includes a low-temperature co-fired ceramic transformer. The CDU can further include one or more ceramic substrates for enclosing the thyristor switch and for holding various passive components used in the flyback charging circuit. A load such as a detonator can also be attached directly to the CDU.

  10. Capacitive Micro Pressure Sensor Integrated with a Ring Oscillator Circuit on Chip

    Directory of Open Access Journals (Sweden)

    Cheng-Yang Liu

    2009-12-01

    Full Text Available The study investigates a capacitive micro pressure sensor integrated with a ring oscillator circuit on a chip. The integrated capacitive pressure sensor is fabricated using the commercial CMOS (complementary metal oxide semiconductor process and a post-process. The ring oscillator is employed to convert the capacitance of the pressure sensor into the frequency output. The pressure sensor consists of 16 sensing cells in parallel. Each sensing cell contains a top electrode and a lower electrode, and the top electrode is a sandwich membrane. The pressure sensor needs a post-CMOS process to release the membranes after completion of the CMOS process. The post-process uses etchants to etch the sacrificial layers, and to release the membranes. The advantages of the post-process include easy execution and low cost. Experimental results reveal that the pressure sensor has a high sensitivity of 7 Hz/Pa in the pressure range of 0–300 kPa.

  11. Capacitive Micro Pressure Sensor Integrated with a Ring Oscillator Circuit on Chip

    Science.gov (United States)

    Dai, Ching-Liang; Lu, Po-Wei; Chang, Chienliu; Liu, Cheng-Yang

    2009-01-01

    The study investigates a capacitive micro pressure sensor integrated with a ring oscillator circuit on a chip. The integrated capacitive pressure sensor is fabricated using the commercial CMOS (complementary metal oxide semiconductor) process and a post-process. The ring oscillator is employed to convert the capacitance of the pressure sensor into the frequency output. The pressure sensor consists of 16 sensing cells in parallel. Each sensing cell contains a top electrode and a lower electrode, and the top electrode is a sandwich membrane. The pressure sensor needs a post-CMOS process to release the membranes after completion of the CMOS process. The post-process uses etchants to etch the sacrificial layers, and to release the membranes. The advantages of the post-process include easy execution and low cost. Experimental results reveal that the pressure sensor has a high sensitivity of 7 Hz/Pa in the pressure range of 0–300 kPa. PMID:22303167

  12. Flexible PVDF ferroelectric capacitive temperature sensor

    KAUST Repository

    Khan, Naveed

    2015-08-02

    In this paper, a capacitive temperature sensor based on polyvinylidene fluoride (PVDF) capacitor is explored. The PVDF capacitor is characterized below its Curie temperature. The capacitance of the PVDF capacitor changes vs temperature with a sensitivity of 16pF/°C. The linearity measurement of the capacitance-temperature relation shows less than 0.7°C error from a best fit straight line. An LC oscillator based temperature sensor is demonstrated based on this capacitor.

  13. Investigation of capacitively coupled ultrasonic transducer system for nondestructive evaluation.

    Science.gov (United States)

    Zhong, Cheng Huan; Wilcox, Paul D; Croxford, Anthony J

    2013-12-01

    Capacitive coupling offers a simple solution to wirelessly probe ultrasonic transducers. This paper investigates the theory, feasibility, and optimization of such a capacitively coupled transducer system (CCTS) in the context of nondestructive evaluation (NDE) applications. The noncontact interface relies on an electric field formed between four metal plates-two plates are physically connected to the electrodes of a transducer, the other two are in a separate probing unit connected to the transmit/receive channel of the instrumentation. The complete system is modeled as an electric network with the measured impedance of a bonded piezoelectric ceramic disc representing a transducer attached to an arbitrary solid substrate. A transmission line model is developed which is a function of the physical parameters of the capacitively coupled system, such as the permittivity of the material between the plates, the size of the metal plates, and their relative positions. This model provides immediate prediction of electric input impedance, pulse-echo response, and the effect of plate misalignment. The model has been validated experimentally and has enabled optimization of the various parameters. It is shown that placing a tuning inductor and series resistor on the transmitting side of the circuit can significantly improve the system performance in terms of the signal-to-crosstalk ratio. Practically, bulk-wave CCTSs have been built and demonstrated for underwater and through-composite testing. It has been found that electrical conduction in the media between the plates limits their applications.

  14. 多感官人机交互界面的视觉设计原则%Discussion on the Visual Design Pinciples of Multi-Sense Human-Computer Interface

    Institute of Scientific and Technical Information of China (English)

    肖红; 郭歌

    2012-01-01

    通过阐述多感官人机交互界面的概念,分析了交互界面的视觉设计发展趋势——动态化、多维化、综合化。在此基础上,提出了人机交互界面的视觉设计应遵守"简洁易用"的总原则,并根据多感官人机交互界面的功能与特点,依次提出了:简洁性与美观性并存,统一性与多样性并存,易用性与交互性并存,静态与动态并存,理性与感性并存这5条设计原则。%Through expounding the concept and definition of "Multi-Sense Human-Computer Interface",it analyzed the visual trend of interface design was interactive,dynamic,comprehensiveness.On this basis,according to the functions and features of the multi-sense human-computer interface,it proposed the human-computer interface design should comply with the general principles of "Keep It Simple And Stupid".To put it concretely,the visual design of multi-sense human-computer interface should: simplicity and aesthetic property;unity and diversity;ease of use and interactive;statics and dynamic;rational and perceptual.

  15. Locating Depots for Capacitated Vehicle Routing

    DEFF Research Database (Denmark)

    Gørtz, Inge Li; Nagarajan, Viswanath

    2016-01-01

    We study a location-routing problem in the context of capacitated vehicle routing. The input to the k-location capacitated vehicle routing problem (k-LocVRP) consists of a set of demand locations in a metric space and a fleet of k identical vehicles, each of capacity Q. The objective is to locate k...

  16. Novel RF-MEMS capacitive switching structures

    NARCIS (Netherlands)

    Rottenberg, X.; Jansen, H.; Fiorini, P.; De Raedt, W.; Tilmans, H.A.C.

    2002-01-01

    This paper reports on novel RF-MEMS capacitive switching devices implementing an electrically floating metal layer covering the dielectric to ensure intimate contact with the bridge in the down state. This results in an optimal switch down capacitance and allows optimisation of the down/up capacitan

  17. Capacitively-coupled chopper amplifiers

    CERN Document Server

    Fan, Qinwen; Huijsing, Johan H

    2017-01-01

    This book describes the concept and design of the capacitively-coupled chopper technique, which can be used in precision analog amplifiers. Readers will learn to design power-efficient amplifiers employing this technique, which can be powered by regular low supply voltage such as 2V and possibly having a +\\-100V input common-mode voltage input. The authors provide both basic design concepts and detailed design examples, which cover the area of both operational and instrumentation amplifiers for multiple applications, particularly in power management and biomedical circuit designs. Discusses basic working principles and details of implementation for proven designs; Includes a diverse set of applications, along with measurement results to demonstrate the effectiveness of the technique; Explains advantages and drawbacks of the technique, given particular circumstances.

  18. Extremely robust and conformable capacitive pressure sensors based on flexible polyurethane foams and stretchable metallization

    Science.gov (United States)

    Vandeparre, H.; Watson, D.; Lacour, S. P.

    2013-11-01

    Microfabricated capacitive sensors prepared with elastomeric foam dielectric films and stretchable metallic electrodes display robustness to extreme conditions including stretching and tissue-like folding and autoclaving. The open cellular structure of the elastomeric foam leads to significant increase of the capacitance upon compression of the dielectric membrane. The sensor sensitivity can be adjusted locally with the foam density to detect normal pressure in the 1 kPa to 100 kPa range. Such pressure transducers will find applications in interfaces between the body and support surfaces such as mattresses, joysticks or prosthetic sockets, in artificial skins and wearable robotics.

  19. USAF Space Sensing Cryogenic Considerations

    Science.gov (United States)

    2010-01-01

    capacitance dilatometer for measuring thermal expansion and magnetostriction Rev. Sci. Instrum. 83, 095102 (2012) Compact radio-frequency resonator...enhancing when the refrigeration system is considered as part of an overall optimization problem. INTRODUCTION The use of cryogenics in space sensing

  20. High resolution interface circuit for closed-loop accelerometer*

    Institute of Scientific and Technical Information of China (English)

    Yin Liang; Liu Xiaowei; Chen Weiping; Zhou Zhiping

    2011-01-01

    This paper reports a low noise switched-capacitor CMOS interface circuit for the closed-loop operation of a capacitive accelerometer. The time division multiplexing of the same electrode is adopted to avoid the strong feedthrough between capacitance sensing and electrostatic force feedback. A PID controller is designed to ensure the stability and dynamic response o fa high Q closed-loop accelerometer with a vacuum package. The architecture only requires single ended operational amplifiers, transmission gates and capacitors. Test results show that a full scale acceleration of ±3 g, non-linearity of 0.05% and signal bandwidth of 1000 Hz are achieved. The complete module operates from a ±5 V supply and has a measured sensitivity of 1.2 V/g with a noise of floor of 0.8μg/√(Hz) in closed-loop. The chip is fabricated in the 2 μm two-metal and two-poly n-well CMOS process with an area of 15.2 mm2. These results prove that this circuit is suitable for high performance micro-accelerometer applications like seismic detection and oil exploration.

  1. Design and fabrication of capacitive interdigitated electrodes for smart gas sensors

    KAUST Repository

    Omran, Hesham

    2016-09-05

    In this paper, we study the design parameters of capacitive interdigitated electrodes (IDEs) and the effect of these parameters on the sensitivity of the IDEs when employed as a capacitive gas sensor. Finite element simulations using COMSOL Multiphysics were carried out to evaluate the sensitivity of the capacitive sensor. Simulations show that for permittivity-based sensing, the optimum thickness of the sensing film is slightly more than half the wavelength of the IDEs structure. On the other hand, sensing films that are thinner than half wavelength should be used if the required sensing mechanism is based on structural swelling. Increasing the IDEs metal thickness can increase the sensitivity by increasing the sidewall electric field, but this is only true if the sensing film is thick enough to completely fill the spacing between the electrodes. A simple and reliable IDEs structure and fabrication process are proposed. Physical dry etching provides good yield and fine resolution compared to liftoff technique. Fabricated and packaged prototype sensors are presented. © 2015 IEEE.

  2. Demonstration of a Packaged Capacitive Pressure Sensor System Suitable for Jet Turbofan Engine Health Monitoring

    Science.gov (United States)

    Scardelletti, Maximilian C.; Jordan, Jennifer L.; Meredith, Roger D.; Harsh, Kevin; Pilant, Evan; Usrey, Michael W.; Beheim, Glenn M.; Hunter, Gary W.; Zorman, Christian A.

    2016-01-01

    In this paper, the development and characterization of a packaged pressure sensor system suitable for jet engine health monitoring is demonstrated. The sensing system operates from 97 to 117 MHz over a pressure range from 0 to 350 psi and a temperature range from 25 to 500 deg. The sensing system consists of a Clapp-type oscillator that is fabricated on an alumina substrate and is comprised of a Cree SiC MESFET, MIM capacitors, a wire-wound inductor, chip resistors and a SiCN capacitive pressure sensor. The pressure sensor is located in the LC tank circuit of the oscillator so that a change in pressure causes a change in capacitance, thus changing the resonant frequency of the sensing system. The chip resistors, wire-wound inductors and MIM capacitors have all been characterized at temperature and operational frequency, and perform with less than 5% variance in electrical performance. The measured capacitive pressure sensing system agrees very well with simulated results. The packaged pressure sensing system is specifically designed to measure the pressure on a jet turbofan engine. The packaged system can be installed by way of borescope plug adaptor fitted to a borescope port exposed to the gas path of a turbofan engine.

  3. Sperm capacitation in the porcine oviduct.

    Science.gov (United States)

    Tienthai, P; Johannisson, A; Rodriguez-Martinez, H

    2004-01-01

    In vitro studies suggests that sperm capacitation occurs in the sperm reservoir (SR) of the pig, with spermatozoa progressing towards the ampullary-isthmic junction (AIJ) around ovulation as a consequence of capacitation/hyperactivation. In contrast, in vivo studies are scarce. Consequently, we determined the degree of capacitation in boar spermatozoa that were retrieved from the SR of sows at well-defined periods of spontaneous standing oestrus, namely pre-, peri- and post-ovulation, using flow cytometry of Merocyanine-540/Yo-Pro-1-loaded spermatozoa. SR-spermatozoa retrieved and incubated in non-capacitating medium (bicarbonate-free mBO [mBO-]) were largely viable (70-85%) and uncapacitated (69-73%), irrespective of the stage of oestrus considered. Those undergoing capacitation were a minor proportion (1-5%) during pre- and peri-ovulation, but they significantly increased (14%) in post-ovulation oestrus. To clarify whether these SR-spermatozoa were able to undergo capacitation under stimuli, sperm aliquots were challenged in vitro either by incubation in a bicarbonate-rich medium (capacitation medium, mBO+), then further in mBO+ with 20% (v/v) of in vivo collected homologous pre-ovulatory isthmic oviductal fluid (IOF), or incubation with hyaluronan (HA, 500 microg/ml). Exposure to mBO+ significantly increased the sub-population of capacitated spermatozoa from the pre- and peri-ovulation SR, indicating that the uncapacitated SR-spermatozoa were responsive to the effector/inducer bicarbonate at levels recorded in peri-ovulatory AIJ/ampulla in vivo. While addition of IOF or HA to SR-spermatozoa incubated in capacitating medium (mBO+) maintained sperm viability without obviously inducing capacitation in pre- or peri-ovulatory SR-spermatozoa, they significantly increased these percentages during post-ovulation, when compared to baseline values of control incubations (mBO-). The results suggest that massive sperm capacitation does not occur in vivo in the porcine SR

  4. Nanomaterial-Enabled Dry Electrodes for Electrophysiological Sensing: A Review

    Science.gov (United States)

    Yao, Shanshan; Zhu, Yong

    2016-04-01

    Long-term, continuous, and unsupervised tracking of physiological data is becoming increasingly attractive for health/wellness monitoring and ailment treatment. Nanomaterials have recently attracted extensive attention as building blocks for flexible/stretchable conductors and are thus promising candidates for electrophysiological electrodes. Here we provide a review on nanomaterial-enabled dry electrodes for electrophysiological sensing, focusing on electrocardiography (ECG). The dry electrodes can be classified into contact surface electrodes, contact-penetrating electrodes, and noncontact capacitive electrodes. Different types of electrodes including their corresponding equivalent electrode-skin interface models and the sources of the noise are first introduced, followed by a review on recent developments of dry ECG electrodes based on various nanomaterials, including metallic nanowires, metallic nanoparticles, carbon nanotubes, and graphene. Their fabrication processes and performances in terms of electrode-skin impedance, signal-to-noise ratio, resistance to motion artifacts, skin compatibility, and long-term stability are discussed.

  5. Effect of surface asperities on the capacitances of capacitive RF MEMS switches

    Science.gov (United States)

    Chen, Zhiqiang; Tian, Wenchao; Zhang, Xiaotong

    2017-03-01

    The effects of surface asperities on the up- and down-state capacitances of the capacitive radio frequency (RF) micro electromechanical system (MEMS) switches were studied in this paper based on the single asperity model and statics. The research results demonstrated that surface asperities effects on the up-state capacitance could be neglected, whereas surface asperities must be taken into consideration at the down-state position in the RF MEMS switches because the surface asperities significantly affected the down-state capacitance. The down-state capacitance typically decreased as the root mean square (RMS) roughness and asperity radius increased. The down-state capacitance was approximately 26% of the theoretical value when the RMS roughness was 20 nm, and 32% of the theoretical value when the asperity radius was 100 nm. The experimental results were in good agreement with the simulation results.

  6. A new touch mode capacitive pressure sensor with two deformable diaphragms

    Institute of Scientific and Technical Information of China (English)

    JIAO Yu-zhong

    2003-01-01

    To achieve the characteristics of better linearity, a new type of touch mode capacitive pressure sensor named as DDTMCPS is devised, which has a pair of deformable sensing diaphragms. Compared to present touch mode capacitive pressure sensors, the new sensor is characterized by better linearity, and large linear operation range. Such a device also has high sensitivity, and other advantages of normal touch mode capacitive pressure sensor. In the case of such a novel sensor, the second diaphragm served as bottom electrode plays great roles in modifying the deflection of the first diaphragm served as top electrode, furthermore optimizing the performance of touch mode sensors. Silicon fusion bonding technology is advised to fabricate the novel device.

  7. Greatly improved small inductance measurement using quartz crystal parasitic capacitance compensation.

    Science.gov (United States)

    Matko, Vojko; Jezernik, Karel

    2010-01-01

    Generally, quartz crystal inductance frequency pulling in oscillators is very low and therefore is not often used in practice. The new method of improving frequency pullability uses inductance to compensate for quartz stray capacitances. To this end, a special AT fundamental quartz crystal working near the antiresonance frequency is selected. By modifying its equivalent circuit with load inductance and series tuning capacitance, the magnetic sensing of the circuit can be highly improved. The experimental results show that the new approach using the quartz crystal stray capacitance compensation method increases the frequency pulling range (from ≅2 kHz/μH to ≅600 kHz/μH) by ×300 depending on the type of oscillator, making possible the measurement of nano-magnetic changes.

  8. Capacitive Cells for Dielectric Constant Measurement

    Science.gov (United States)

    Aguilar, Horacio Munguía; Maldonado, Rigoberto Franco

    2015-01-01

    A simple capacitive cell for dielectric constant measurement in liquids is presented. As an illustrative application, the cell is used for measuring the degradation of overheated edible oil through the evaluation of their dielectric constant.

  9. Complementary surface charge for enhanced capacitive deionization

    NARCIS (Netherlands)

    Gao, X.; Porada, S.; Omosebi, A.; Liu, K.L.; Biesheuvel, P.M.; Landon, J.

    2016-01-01

    Commercially available activated carbon cloth electrodes are treated using nitric acid and ethylenediamine solutions, resulting in chemical surface charge enhanced carbon electrodes for capacitive deionization (CDI) applications. Surface charge enhanced electrodes are then configured in a CDI cel

  10. Highly sensitive micromachined capacitive pressure sensor with reduced hysteresis and low parasitic capacitance

    DEFF Research Database (Denmark)

    Pedersen, Thomas; Fragiacomo, Giulio; Hansen, Ole

    2009-01-01

    This paper describes the design and fabrication of a capacitive pressure sensor that has a large capacitance signal and a high sensitivity of 76 pF/bar in touch mode operation. Due to the large signal, problems with parasitic capacitances are avoided and hence it is possible to integrate the sens...... bonding to create vacuum cavities. The exposed part of the sensor is perfectly flat such that it can be coated with corrosion resistant thin films. Hysteresis is an inherent problem in touch mode capacitive pressure sensors and a technique to significantly reduce it is presented....

  11. Electropolymerized Star-Shaped Benzotrithiophenes Yield π-Conjugated Hierarchical Networks with High Areal Capacitance

    KAUST Repository

    Ringk, Andreas

    2016-03-30

    High-surface-area π-conjugated polymeric networks have the potential to lend outstanding capacitance to supercapacitors because of the pronounced faradaic processes that take place across the dense intimate interface between active material and electrolytes. In this report, we describe how benzo[1,2-b:3,4-b’:5,6-b’’]trithiophene (BTT) and tris-EDOT-benzo[1,2-b:3,4-b’:5,6-b’’]trithiophene (TEBTT) can serve as 2D (trivalent) building blocks in the development of electropolymerized hierarchical π-conjugated frameworks with particularly high areal capacitance. In comparing electropolymerized networks of BTT, TEBTT, and their copolymers with EDOT, we show that P(TEBTT/EDOT)-based frameworks can achieve higher areal capacitance (e.g., as high as 443.8 mF cm-2 at 1 mA cm-2) than those achieved by their respective homopolymers (PTEBTT and PEDOT) in the same experimental conditions of electrodeposition (PTEBTT: 271.1 mF cm-2 (at 1 mA cm-2) and PEDOT: 12.1 mF cm-2 (at 1 mA cm-2)). For example, P(TEBTT/EDOT)-based frameworks synthesized in a 1:1 monomer-to-comonomer ratio show a ca. 35x capacitance improvement over PEDOT. The high areal capacitance measured for P(TEBTT/EDOT) copolymers can be explained by the open, highly porous hierarchical morphologies formed during the electropolymerization step. With >70% capacitance retention over 1,000 cycles (up to 89% achieved), both PTEBTT- and P(TEBTT/EDOT)-based frameworks are resilient to repeated electrochemical cycling and can be considered promising systems for high life cycle capacitive electrode applications.

  12. Analysis, Control and Experimental Verification of a Single-Phase Capacitive-Coupling Grid-Connected Inverter

    DEFF Research Database (Denmark)

    Dai, Ning-Yi; Zhang, Wen-Chen; Wong, Man-Chung;

    2015-01-01

    This study proposes a capacitive-coupling grid-connected inverter (CGCI), which consists of a full-bridge single-phase inverter coupled to a power grid via one capacitor in series with an inductor. The fundamental-frequency impedance of the coupling branch is capacitive. In contrast with the conv......This study proposes a capacitive-coupling grid-connected inverter (CGCI), which consists of a full-bridge single-phase inverter coupled to a power grid via one capacitor in series with an inductor. The fundamental-frequency impedance of the coupling branch is capacitive. In contrast...... with the conventional inductive-coupling grid-connected inverter (IGCI), this structure provides an alternative interface for use between a low-voltage DC microgrid and an AC grid. A comparison between the CGCI and the IGCI is performed. It is concluded that the CGCI is able to transfer active power and provide lagging...

  13. A novel approach for correlating capacitance data with performance during thin-film device stress studies

    Science.gov (United States)

    Graham, Rebekah L.; Clark, Laura A.; Albin, David S.

    2011-09-01

    A new data mining algorithm was developed to identify the strongest correlations between capacitance data (measured between -1.5 V and +0.49 V) and first- and second-level performance metrics (efficiency [η%], open-circuit voltage [VOC], short-circuit current density [JSC], and fill-factor [FF]) during the stress testing of voltage-stabilized CdS/CdTe devices. When considering only correlations between first- and second-level metrics, 96.5% of the observed variation in η% was attributed to FF. The overall decrease in VOC after 1,000 hours of open-circuit, light-soak stress at 60°C was about -1.5%. As determined by our algorithm, the most consistent correlation existing between FF and third-level metric capacitance data at all stages during stress testing was between FF and the apparent CdTe acceptor density (Na) calculated at a voltage of +0.49 V during forward voltage scans. Since the contribution of back-contact capacitance to total capacitance increases with increasing positive voltage, this result suggests that FF degradation is associated with decreases in Na near the CdTe/back contact interface. Also of interest, it appears that capacitance data at these higher voltages appears to more accurately fit the one-sided abrupt junction model.

  14. Novel Approach for Correlating Capacitance Data with Performance During Thin-Film Device Stress Studies: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Graham, R. L.; Albin, D. S.; Clark, L. A.

    2011-08-01

    A new data mining algorithm was developed to identify the strongest correlations between capacitance data (measured between -1.5 V and +0.49 V) and 1st and 2nd level performance metrics (efficiency, open-circuit voltage (VOC), short-circuit current density (JSC), and fill-factor (FF)) during the stress testing of voltage-stabilized CdS/CdTe devices. When considering only correlations between 1st and 2nd level metrics, 96.5% of the observed variation in efficiency was attributed to FF. The overall decrease in VOC after 1000 hours of open-circuit, light-soak stress at 60 degrees C was about 1.5%. As determined by our algorithm, the most consistent correlation existing between FF and 3rd level metric capacitance data at all stages during stress testing was between FF and the apparent CdTe acceptor density (Na) calculated at a voltage of +0.49 V during forward voltage scans. Since the contribution of back contact capacitance to total capacitance increases with increasing positive voltage, this result suggests that FF degradation is associated with decreases in Na near the CdTe/back contact interface. Also of interest, it appears that capacitance data at these higher voltages appears to more accurately fit the one-sided abrupt junction model.

  15. Electrical Capacitance Volume Tomography with High-Contrast Dielectrics

    Science.gov (United States)

    Nurge, Mark

    2010-01-01

    The Electrical Capacitance Volume Tomography (ECVT) system has been designed to complement the tools created to sense the presence of water in nonconductive spacecraft materials, by helping to not only find the approximate location of moisture but also its quantity and depth. The ECVT system has been created for use with a new image reconstruction algorithm capable of imaging high-contrast dielectric distributions. Rather than relying solely on mutual capacitance readings as is done in traditional electrical capacitance tomography applications, this method reconstructs high-resolution images using only the self-capacitance measurements. The image reconstruction method assumes that the material under inspection consists of a binary dielectric distribution, with either a high relative dielectric value representing the water or a low dielectric value for the background material. By constraining the unknown dielectric material to one of two values, the inverse math problem that must be solved to generate the image is no longer ill-determined. The image resolution becomes limited only by the accuracy and resolution of the measurement circuitry. Images were reconstructed using this method with both synthetic and real data acquired using an aluminum structure inserted at different positions within the sensing region. The cuboid geometry of the system has two parallel planes of 16 conductors arranged in a 4 4 pattern. The electrode geometry consists of parallel planes of copper conductors, connected through custom-built switch electronics, to a commercially available capacitance to digital converter. The figure shows two 4 4 arrays of electrodes milled from square sections of copper-clad circuit-board material and mounted on two pieces of glass-filled plastic backing, which were cut to approximately square shapes, 10 cm on a side. Each electrode is placed on 2.0-cm centers. The parallel arrays were mounted with the electrode arrays approximately 3 cm apart. The open ends

  16. Opening of K+ channels by capacitive stimulation from silicon chip

    Science.gov (United States)

    Ulbrich, M. H.; Fromherz, P.

    2005-10-01

    The development of stable neuroelectronic systems requires a stimulation of nerve cells from semiconductor devices without electrochemical effects at the electrolyte/solid interface and without damage of the cell membrane. The interaction must rely on a reversible opening of voltage-gated ion channels by capacitive coupling. In a proof-of-principle experiment, we demonstrate that Kv1.3 potassium channels expressed in HEK293 cells can be opened from an electrolyte/oxide/silicon (EOS) capacitor. A sufficient strength of electrical coupling is achieved by insulating silicon with a thin film of TiO2 to achieve a high capacitance and by removing NaCl from the electrolyte to enhance the resistance of the cell-chip contact. When a decaying voltage ramp is applied to the EOS capacitor, an outward current through the attached cell membrane is observed that is specific for Kv1.3 channels. An open probability up to fifty percent is estimated by comparison with a numerical simulation of the cell-chip contact.

  17. Flexible Bond Wire Capacitive Strain Sensor for Vehicle Tyres

    Directory of Open Access Journals (Sweden)

    Siyang Cao

    2016-06-01

    Full Text Available The safety of the driving experience and manoeuvrability of a vehicle can be improved by detecting the strain in tyres. To measure strain accurately in rubber, the strain sensor needs to be flexible so that it does not deform the medium that it is measuring. In this work, a novel flexible bond wire capacitive strain sensor for measuring the strain in tyres is developed, fabricated and calibrated. An array of 25 micron diameter wire bonds in an approximately 8 mm × 8 mm area is built to create an interdigitated structure, which consists of 50 wire loops resulting in 49 capacitor pairs in parallel. Laser machining was used to pattern copper on a flexible printed circuit board PCB to make the bond pads for the wire attachment. The wire array was finally packaged and embedded in polydimethylsiloxane (PDMS, which acts as the structural material that is strained. The capacitance of the device is in a linear like relationship with respect to the strain, which can measure the strain up to at least ±60,000 micro-strain (±6% with a resolution of ~132 micro-strain (0.013%. In-tyre testing under static loading has shown the ability of the sensor to measure large tyre strains. The technology used for sensor fabrication lends itself to mass production and so the design is considered to be consistent with low cost commercialisable strain sensing technology.

  18. Carbon flow electrodes for continuous operation of capacitive deionization and capacitive mixing energy generation

    NARCIS (Netherlands)

    Porada, S.; Hamelers, H.V.M.; Bryjak, M.; Presser, V.; Biesheuvel, P.M.; Weingarth, D.

    2014-01-01

    Capacitive technologies, such as capacitive deionization and energy harvesting based on mixing energy (“capmix” and “CO2 energy”), are characterized by intermittent operation: phases of ion electrosorption from the water are followed by system regeneration. From a system application point of view, c

  19. Pervasive sensing

    Science.gov (United States)

    Nagel, David J.

    2000-11-01

    The coordinated exploitation of modern communication, micro- sensor and computer technologies makes it possible to give global reach to our senses. Web-cameras for vision, web- microphones for hearing and web-'noses' for smelling, plus the abilities to sense many factors we cannot ordinarily perceive, are either available or will be soon. Applications include (1) determination of weather and environmental conditions on dense grids or over large areas, (2) monitoring of energy usage in buildings, (3) sensing the condition of hardware in electrical power distribution and information systems, (4) improving process control and other manufacturing, (5) development of intelligent terrestrial, marine, aeronautical and space transportation systems, (6) managing the continuum of routine security monitoring, diverse crises and military actions, and (7) medicine, notably the monitoring of the physiology and living conditions of individuals. Some of the emerging capabilities, such as the ability to measure remotely the conditions inside of people in real time, raise interesting social concerns centered on privacy issues. Methods for sensor data fusion and designs for human-computer interfaces are both crucial for the full realization of the potential of pervasive sensing. Computer-generated virtual reality, augmented with real-time sensor data, should be an effective means for presenting information from distributed sensors.

  20. Ion channels, phosphorylation and mammalian sperm capacitation

    Institute of Scientific and Technical Information of China (English)

    Pablo E Visconti; Dario Krapf; José Luis de la Vega-Beltrán; Juan José Acevedo; Alberto Darszon

    2011-01-01

    Sexually reproducing animals require an orchestrated communication between spermatozoa and the egg to generate a new individual. Capacitation, a maturational complex phenomenon that occurs in the female reproductive tract, renders spermatozoa capable of binding and fusing with the oocyte, and it is a requirement for mammalian fertilization. Capacitation encompasses plasma membrane reorganization, ion permeability regulation, cholesterol loss and changes in the phosphorylation state of many proteins. Novel tools to study sperm ion channels, image intracellular ionic changes and proteins with better spatial and temporal resolution, are unraveling how modifications in sperm ion transport and phosphorylation states lead to capacitation. Recent evidence indicates that two parallel pathways regulate phosphorylation events leading to capacitation, one of them requiring activation of protein kinase A and the second one involving inactivation of ser/thr phosphatases. This review examines the involvement of ion transporters and phosphorylation signaling processes needed for spermatozoa to achieve capacitation. Understanding the molecular mechanisms leading to fertilization is central for societies to deal with rising male infertility rates, to develop safe male gamete-based contraceptives and to preserve biodiversity through better assisted fertilization strategies.

  1. Ion channels, phosphorylation and mammalian sperm capacitation.

    Science.gov (United States)

    Visconti, Pablo E; Krapf, Dario; de la Vega-Beltrán, José Luis; Acevedo, Juan José; Darszon, Alberto

    2011-05-01

    Sexually reproducing animals require an orchestrated communication between spermatozoa and the egg to generate a new individual. Capacitation, a maturational complex phenomenon that occurs in the female reproductive tract, renders spermatozoa capable of binding and fusing with the oocyte, and it is a requirement for mammalian fertilization. Capacitation encompasses plasma membrane reorganization, ion permeability regulation, cholesterol loss and changes in the phosphorylation state of many proteins. Novel tools to study sperm ion channels, image intracellular ionic changes and proteins with better spatial and temporal resolution, are unraveling how modifications in sperm ion transport and phosphorylation states lead to capacitation. Recent evidence indicates that two parallel pathways regulate phosphorylation events leading to capacitation, one of them requiring activation of protein kinase A and the second one involving inactivation of ser/thr phosphatases. This review examines the involvement of ion transporters and phosphorylation signaling processes needed for spermatozoa to achieve capacitation. Understanding the molecular mechanisms leading to fertilization is central for societies to deal with rising male infertility rates, to develop safe male gamete-based contraceptives and to preserve biodiversity through better assisted fertilization strategies.

  2. Interface potential sensing from adsorption of human serum albumin (HSA) on carbon nanotube (CNT) monitored by zero current potentiometry for HSA determination.

    Science.gov (United States)

    Wang, Huan; Wu, Yi; Song, Jun-Feng

    2015-10-15

    In this work, the adsorption of human serum albumin (HSA) on the bare multiwall carbon nanotube (MWNT) was investigated by a new electrochemical method, termed as zero current potentiometry. For this, a MWNT strip was prepared by directly adhering MWNTs on the transparent adhesive tape surface. Moreover, when HSA adsorbed onto MWNT at the MWNT/solution interface, an interface potential Ψ yielded. The interface potential Ψ as the zero current potential Ezcp simply related to it was monitored by zero current potentiometry. The relationship between the zero current potential Ezcp, the HSA concentration and others was established in simple stoichiometric relation. Based on this, both the adsorption of HSA on MWNT and the HSA determination can be studied. For the HSA determination, the theoretic conclusion consisted with experimental results. The zero current potential Ezcp was proportional to the HSA concentration in the range of 2.8 × 10(-8) - 3.4 × 10(-7)M with the limit of detection 2 × 10(-8)M. The linear regression equation was Ezcp/V (vs, SCE) = (0.159 ± 0.01) + (0.358 ± 0.02) × 10(6)CHSA (µM). This determination was fast, high sensitive and good selective.

  3. Wide dynamic range microwave planar coupled ring resonator for sensing applications

    Science.gov (United States)

    Zarifi, Mohammad Hossein; Daneshmand, Mojgan

    2016-06-01

    A highly sensitive, microwave-coupled ring resonator with a wide dynamic range is studied for use in sensing applications. The resonator's structure has two resonant rings and, consequently, two resonant frequencies, operating at 2.3 and 2.45 GHz. Inductive and capacitive coupling mechanisms are explored and compared to study their sensing performance. Primary finite element analysis and measurement results are used to compare the capacitive and inductive coupled ring resonators, demonstrating sensitivity improvements of up to 75% and dynamic range enhancement up to 100% in the capacitive coupled structure. In this work, we are proposing capacitive coupled planar ring resonators as a wide dynamic range sensing platform for liquid sensing applications. This sensing device is well suited for low-cost, real-time low-power, and CMOS compatible sensing technologies.

  4. Frequency scanning capaciflector for capacitively determining the material properties

    Science.gov (United States)

    Campbell, Charles E. (Inventor)

    1996-01-01

    A capaciflector sensor system scanned in frequency is used to detect the permittivity of the material of an object being sensed. A capaciflector sensor element, coupled to current-measuring voltage follower circuitry, is driven by a frequency swept oscillator and generates an output which corresponds to capacity as a function of the input frequency. This swept frequency information is fed into apparatus e.g. a digital computer for comparing the shape of the capacitance vs. frequency curve against characteristic capacitor vs. frequency curves for a variety of different materials which are stored, for example, in a digital memory of the computer or a database. Using a technique of pattern matching, a determination is made as to the identification of the material. Also, when desirable, the distance between the sensor and the object can be determined.

  5. Anomalously large capacitance of an ionic liquid described by the restricted primitive model

    CERN Document Server

    Loth, M S; Shklovskii, B I

    2010-01-01

    We use Monte Carlo simulations to examine the simplest model of an ionic liquid, called the restricted primitive model, at a metal surface. We find that at moderately low temperatures the capacitance of the metal/ionic liquid interface is so large that the effective thickness of the electrostatic double-layer is smaller than the ion radius. We suggest a semi-quantitative theory to describe these results.

  6. First-principles simulation of capacitive charging of graphene and implications for supercapacitor design

    OpenAIRE

    Radin, Maxwell D.; Ogitsu, Tadashi; Otani, Minoru; Biener, Juergen; Wood, Brandon C.

    2014-01-01

    Supercapacitors store energy via the formation of an electric double layer, which generates a strong electric field at the electrode-electrolyte interface. Unlike conventional metallic electrodes, graphene-derived materials suffer from a low electronic density of states (i.e., quantum capacitance), which limits their ability to redistribute charge and efficiently screen this field. To explore these effects, we introduce a first-principles approach based on the effective screening medium frame...

  7. Metal nanoparticle-directed NiCo2O4 nanostructure growth on carbon nanofibers with high capacitance.

    Science.gov (United States)

    Chen, Long; Zhu, Jiahua

    2014-08-04

    Metal nanoparticles (Ni, Co) decorated on an electrospun carbon nanofiber surface directed the growth of NiCo2O4 into nanorod and nanosheet morphologies. These metal nanoparticles served as a transition layer to strengthen the interface and promote charge transfer between carbon and NiCo2O4 to achieve a high capacitance of 781 F g(-1).

  8. Carbon nanofiber supercapacitors with large areal capacitances

    KAUST Repository

    McDonough, James R.

    2009-01-01

    We develop supercapacitor (SC) devices with large per-area capacitances by utilizing three-dimensional (3D) porous substrates. Carbon nanofibers (CNFs) functioning as active SC electrodes are grown on 3D nickel foam. The 3D porous substrates facilitate a mass loading of active electrodes and per-area capacitance as large as 60 mg/ cm2 and 1.2 F/ cm2, respectively. We optimize SC performance by developing an annealing-free CNF growth process that minimizes undesirable nickel carbide formation. Superior per-area capacitances described here suggest that 3D porous substrates are useful in various energy storage devices in which per-area performance is critical. © 2009 American Institute of Physics.

  9. Microphonics in biopotential measurements with capacitive electrodes.

    Science.gov (United States)

    Luna-Lozano, Pablo S; Pallas-Areny, Ramon

    2010-01-01

    Biopotential measurements with capacitive electrodes do not need any direct contact between electrode and skin, which saves the time devoted to expose and prepare the contact area when measuring with conductive electrodes. However, mechanical vibrations resulting from physiological functions such as respiration and cardiac contraction can change the capacitance of the electrode and affect the recordings. This transformation of mechanical vibrations into undesired electric signals is termed microphonics. We have evaluated microphonics in capacitive ECG recordings obtained from a dressed subject seated on a common chair with electrodes placed on the front side of the backrest of the chair. Depending on the softness of the backrest, the recordings may be clearly affected by the displacement of the thorax back wall due to the respiration and to the heart's mechanical activity.

  10. Role of the oviduct in sperm capacitation.

    Science.gov (United States)

    Rodriguez-Martinez, H

    2007-09-01

    Following insemination of spermatozoa pre-ovulation, the mammalian oviduct ensures, by the formation of a functional sperm reservoir (SR), that suitable (low) numbers of viable and potentially fertile spermatozoa are available for fertilization at the ampullary isthmic junction (AIJ). As ovulation approaches, a proportion of the SR-stored spermatozoa is continuously distributed towards the AIJ and individually activated leading to step-wise capacitation and the attainment of hyperactivated motility. This paper reviews in vivo changes in the intra-luminal milieu of the oviduct of pigs and cows, in particular the SR and the AIJ which relate to the modulation of sperm capacitation around spontaneous ovulation. In vivo, most viable spermatozoa in the pre-ovulatory SR are uncapacitated. Capacitation rates significantly increase after ovulation, apparently not massively but concurrent with the individual, continuous sperm dislocation from the SR. Bicarbonate, whose levels differ between the SR and the AIJ, appears as the common primary effector of the membrane destabilizing changes that encompasses the first stages of capacitation. Sperm activation can be delayed or even reversed by co-incubation with membrane proteins of the tubal lining, isthmic fluid or specific tubal glycosaminoglycans, such as hyaluronan. Although the pattern of response to in vitro induction of sperm activation - capacitation in particular - is similar for all spermatozoa, the capacity and speed of the response is very individual. Such diversity in responsiveness among spermatozoa insures full sperm viability before ovulation and the presence of spermatozoa at different stages of capacitation at the AIJ, thus maximizing the chances of normal fertilization.

  11. SnO2 Nanoparticle-Based Passive Capacitive Sensor for Ethylene Detection

    Directory of Open Access Journals (Sweden)

    Mangilal Agarwal

    2012-01-01

    Full Text Available A passive capacitor-based ethylene sensor using SnO2 nanoparticles is presented for the detection of ethylene gas. The nanoscale particle size (10 nm to 15 nm and film thickness (1300 nm of the sensing dielectric layer in the capacitor model aid in sensing ethylene at room temperature and eliminate the need for microhotplates used in existing bulk SnO2-resistive sensors. The SnO2-sensing layer is deposited using room temperature dip coating process on flexible polyimide substrates with copper as the top and bottom plates of the capacitor. The capacitive sensor fabricated with SnO2 nanoparticles as the dielectric showed a total decrease in capacitance of 5 pF when ethylene gas concentration was increased from 0 to 100 ppm. A 7 pF decrease in capacitance was achieved by introducing a 10 nm layer of platinum (Pt and palladium (Pd alloy deposited on the SnO2 layer. This also improved the response time by 40%, recovery time by 28%, and selectivity of the sensor to ethylene mixed in a CO2 gas environment by 66%.

  12. Capacitance sensor for automatic soil retreat measurements

    Institute of Scientific and Technical Information of China (English)

    GU Jun; YANG Juan; YIN Wu-liang; WANG Chao; WANG Hua-xiang; LIU Ze; CHENG Su-sen

    2008-01-01

    To continuously monitor the soil retreat due to erosion in field, provide valuable information about the erosion processes and overcome the disadvantages of inefficiency, high time-consumption and labor-intensity of existing methods, this paper describes a novel capacitance sensor for measuring the soil retreat. A capaci-tance sensor based probe is proposed, which can measure the depth of the soil around it automatically and the data can be recorded by a data logger. Experimental results in the lab verify its usefulness.

  13. Experimental study of negative capacitance in LEDs

    Institute of Scientific and Technical Information of China (English)

    FENG Lie-feng; WANG Jun; ZHU Chuan-yun; CONG Hong-xia; CHEN Yong; WANG Cun-da

    2005-01-01

    The experimental study on negative capacitance(NC) of various light-emitting diodes(LEDs) is presented.Experimental result shows that all LEDs display the NC phenomenon.The voltage modulated electroluminescence(VMEL) experiment confirms that the reason of negative capacitance is the strong recombination of the injected carriers in the active region of luminescence.The measures also verify that the dependence of NC on voltage and frequency in different LEDs is similar: NC phenomenon is more obvious with higher voltage or lower frequency.

  14. The co-design of interface sensing and tailoring of ultra-thin film with ultrasonic vibration-assisted AFM system.

    Science.gov (United States)

    Shi, Jialin; Liu, Lianqing; Li, Guangyong

    2016-06-10

    Ultra-thin films (e.g., graphene, MoS2, and black phosphorus) have shown amazing performance in a variety of applications. The tailoring or machining of these ultra-thin films is often the preliminary step to manufacturing them into functional devices. Atomic force microscopy (AFM) is a flexible, high-efficiency and low-cost tailoring or machining tool with the advantages of high resolution and precision. However, the current AFM-based tailoring methods are often set up as an open loop regarding the machined depth and state. Thus, because of a lack of real-time feedback, an inappropriate applied force leads to over-cutting or under-cutting, which limits the performance of the manufactured devices. In this study, we propose a real-time tailoring and sensing method based on an ultrasonic vibration-assisted (USV-assisted) AFM system to solve the above problems. With the proposed method, the machined depth and state can be sensed in real time by detecting the phase value of the vibrating cantilever. To characterize and gain insight into the phase responses of the cantilever to the machined depth and sample material, a theoretical dynamic model of a cantilever-film vibrating system is introduced to model the machining process, and a sensing theory of machined depth and state is developed based on a USV-assisted AFM system. The experimental results verify the feasibility and effectiveness of the proposed method, which in turn lay the foundation for a closed-loop tailoring control strategy for ultra-thin films.

  15. CONCENTRATION DEPENDENCE OF STERN LAYER CAPACITANCES AND SURFACE EQUILIBRIUM CONSTANTS IN SILICA-BASED NANOFLUIDIC CHANNELS

    DEFF Research Database (Denmark)

    Andersen, Mathias Bækbo; Frey, J.; Bruus, Henrik;

    2010-01-01

    Fundamental understanding of the unique physics at the solid-liquid interface in nanofluidic channels is essential for the advancement of basic scientific knowledge and the development of novel applications for pharmaceuticals, environmental health and safety, energy harvesting and biometrics [1......]. The current models used to describe surface phenomena in nanofluidics can differ by orders of magnitude from experimentally measured values [2]. To mitigate the discrepancies, we hypothesize that the Stern-layer capacitance Cs and the surface equilibrium constants pKa, vary with the composition of the solid......-liquid interface. We quantify these dependencies combining theoretical modeling and nanofluidic capillary filling experiments....

  16. Field-effect and capacitive properties of water-gated transistors based on polythiophene derivatives

    Directory of Open Access Journals (Sweden)

    R. Porrazzo

    2015-01-01

    Full Text Available Recently, water-gated organic field-effect transistors (WGOFET have been intensively studied for their application in the biological field. Surprisingly, a very limited number of conjugated polymers have been reported so far. Here, we systematically explore a series of polythiophene derivatives, presenting different alkyl side chains lengths and orientation, and characterized by various morphologies: comparative evaluation of their performances allows highlighting the critical role played by alkyl side chains, which significantly affects the polymer/water interface capacitance. Reported results provide useful guidelines towards further development of WGOFETs and represent a step forward in the understanding of the polymer/water interface phenomena.

  17. Split-Capacitance and Conductance-Frequency Characteristics of SOI Wafers in Pseudo-MOSFET Configuration

    KAUST Repository

    Pirro, Luca

    2015-09-01

    Recent experimental results have demonstrated the possibility of characterizing silicon-on-insulator (SOI) wafers through split C-V measurements in the pseudo-MOSFET configuration. This paper analyzes the capacitance and conductance versus frequency characteristics. We discuss the conditions under which it is possible to extract interface trap density in bare SOI wafers. The results indicate, through both measurements and simulations, that the signature due to interface trap density is present in small-area samples, but is masked by the RC response of the channel in regular, large-area ones, making the extraction in standard samples problematic. © 1963-2012 IEEE.

  18. Locating Depots for Capacitated Vehicle Routing

    DEFF Research Database (Denmark)

    Gørtz, Inge Li; Nagarajan, Viswanath

    2011-01-01

    We study a location-routing problem in the context of capacitated vehicle routing. The input to k-LocVRP is a set of demand locations in a metric space and a fleet of k vehicles each of capacity Q. The objective is to locate k depots, one for each vehicle, and compute routes for the vehicles so...

  19. Thermodynamic cycle analysis for capacitive deionization

    NARCIS (Netherlands)

    Biesheuvel, P.M.

    2009-01-01

    Capacitive deionization (CDI) is an ion removal technology based on temporarily storing ions in the polarization layers of two oppositely positioned electrodes. Here we present a thermodynamic model for the minimum work required for ion separation in the fully reversible case by describing the ionic

  20. Inside-out electrical capacitance tomography

    DEFF Research Database (Denmark)

    Kjærsgaard-Rasmussen, Jimmy; Meyer, Knud Erik

    2011-01-01

    In this work we demonstrate the construction of an ‘inside-out’ sensor geometry for electrical capacitance tomography (ECT). The inside-out geometry has the electrodes placed around a tube, as usual, but measuring ‘outwards’. The flow between the electrodes and an outer tube is reconstructed...

  1. Quantum capacitance of the armchair-edge graphene nanoribbon

    Indian Academy of Sciences (India)

    Ling-Feng Mao

    2013-08-01

    The quantum capacitance, an important parameter in the design of nanoscale devices, is derived for armchair-edge single-layer graphene nanoribbon with semiconducting property. The quantum capacitance oscillations are found and these capacitance oscillations originate from the lateral quantum confinement in graphene nanoribbon. Detailed studies of the capacitance oscillations demonstrate that the local channel electrostatic potential at the capacitance peak, the height and the number of the capacitance peak strongly depend on the width, especially a few nanometres, of the armchair-edge graphene nanoribbon. It implies that the capacitance oscillations observed in the experiments can be utilized to measure the width of graphene nanoribbon. The results also show that the capacitance oscillations are not seen when the width is larger than 30 nm.

  2. Sulfur-H{sub z}(CH{sub x}){sub y}(z = 0,1) functionalized metal oxide nanostructure decorated interfaces: Evidence of Lewis base and Brönsted acid sites – Influence on chemical sensing

    Energy Technology Data Exchange (ETDEWEB)

    Laminack, William; Baker, Caitlin [Department of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Gole, James, E-mail: james.gole@physics.gatech.edu [Department of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Department of Mechanical Engineering, Georgia Tech, Atlanta, GA 30332 (United States)

    2015-06-15

    Nanostructure metal oxide decorated n-type extrinsic porous silicon (PS) semiconductor interfaces are modified through in-situ interaction with acidic ethane and butane thiols (EtSH, BuSH) and basic diethyl sulfide (Et{sub 2}S). Highly sensitive conductometric sensor evaluations and X-ray Photoelectron Spectroscopy demonstrate the effect of sulfur group functionalization modifying the acidity of the metal oxides and their interaction with NH{sub 3}. SEM micrographs demonstrate that the sulfur treated particles are less than 30 nm in size. EDAX studies confirm the chemical composition of the modified nanoparticles and suggest the surface interaction of the sulfides and thiols. The acidic thiols can form Brönsted acidic sites enhancing the acidity of the metal oxides, thus broadening the initial metal oxide acidity range. The sulfides interact to lower the Lewis acidity of nanostructured metal oxide sites. Conductometric response matrices with NH{sub 3} at room temperature, corresponding to the thiol and sulfide treated nanostructures of the metal oxides TiO{sub 2}, SnO{sub x}, Ni{sub x}O, Cu{sub x}O, and Au{sub x}O (x >> 1) are evaluated for a dominant electron transduction process forming the basis for reversible chemical sensing in the absence of chemical bond formation. Treatment with the acidic thiols enhances the metal center acidity. It is suggested that the thiols can interact to increase the Brönsted acidity of the doped metal oxide surface if they maintain SH bonds. This process may account for the shift in Lewis acidity as the Brönsted acid sites counter the decrease in Lewis acidity resulting from the interaction of S-(CH{sub x}){sub y} groups. In contrast, treatment with basic Et{sub 2}S decreases the Lewis acidity of the metal oxide sites, enhancing the basicity of the decorated interface. XPS measurements indicate a change in binding energy (BE) of the metal and oxygen centers. The observed changes in conductometric response do not represent a

  3. Synthesis of silver nanoparticle at a gas/liquid interface in the presence of silver seeds and its application for electrochemical sensing.

    Science.gov (United States)

    Yang, Ziyin; Qi, Chengcheng; Zheng, Xiaohui; Zheng, Jianbin

    2015-08-01

    Silver nanoparticles were synthesized by reducing [Ag(NH3)2](+) at a gas/liquid interface in the presence of silver seeds. Transmission electron microscopy (TEM) observations reveal that the size of these silver nanoparticles is around 35-40 nm with the average particle size of 37 nm. The silver nanoparticles were applied for the electrochemical sensor and electrochemical investigations indicate that the nanoparticles possess an excellent performance toward H2O2. The linear range is estimated to be from 5.0 μM to 4.0 mM with a low detection limit of 1.7 μM, a sensitivity of 166.7 μA mM(-1) cm(-2) and a response time of 3 s. Additionally, the sensor exhibits good anti-interference.

  4. Conversational sensing

    Science.gov (United States)

    Preece, Alun; Gwilliams, Chris; Parizas, Christos; Pizzocaro, Diego; Bakdash, Jonathan Z.; Braines, Dave

    2014-05-01

    Recent developments in sensing technologies, mobile devices and context-aware user interfaces have made it pos- sible to represent information fusion and situational awareness for Intelligence, Surveillance and Reconnaissance (ISR) activities as a conversational process among actors at or near the tactical edges of a network. Motivated by use cases in the domain of Company Intelligence Support Team (CoIST) tasks, this paper presents an approach to information collection, fusion and sense-making based on the use of natural language (NL) and controlled nat- ural language (CNL) to support richer forms of human-machine interaction. The approach uses a conversational protocol to facilitate a ow of collaborative messages from NL to CNL and back again in support of interactions such as: turning eyewitness reports from human observers into actionable information (from both soldier and civilian sources); fusing information from humans and physical sensors (with associated quality metadata); and assisting human analysts to make the best use of available sensing assets in an area of interest (governed by man- agement and security policies). CNL is used as a common formal knowledge representation for both machine and human agents to support reasoning, semantic information fusion and generation of rationale for inferences, in ways that remain transparent to human users. Examples are provided of various alternative styles for user feedback, including NL, CNL and graphical feedback. A pilot experiment with human subjects shows that a prototype conversational agent is able to gather usable CNL information from untrained human subjects.

  5. MOS Capacitance-Voltage Characteristics:V.Methods to Enhance the Trapping Capacitance

    Institute of Scientific and Technical Information of China (English)

    揭斌斌; 薩支唐

    2012-01-01

    Low-frequency and High-frequency Capacitance-Voltage (C-V) curves of Silicon Metal-Oxide-Semiconductor Capacitors,showing electron and hole trapping at shallow-level dopant and deep-level generationrecombination-trapping impurities,are presented to illustrate the enhancement of the giant trapping capacitances by physical means via device and circuit designs,in contrast to chemical means via impurity characteristics previously reported.Enhancement is realized by masking the electron or/and hole storage capacitances to make the trapping capacitances dominant at the terminals.Device and materials properties used in the computed CV curves are selected to illustrate experimental realizations for fundamental trapping parameter characterizations and for electrical and optical signal processing applications.

  6. Winding Capacitance Dividing Method for Powerformer

    Institute of Scientific and Technical Information of China (English)

    TIAN Qing; LIN Xiang-ning; LI Jian-jian; TAO Yong-hong

    2008-01-01

    It presents a method which can equivalently arrange the capacitance distribution along with the winding ofthe generator on the terminal and neutral respectively in a reasonable partition, particularly for a type of high-voltagegraded insulated cable wound generator, Powerformer. The winding of the Powerformer adopts graded insulation,which leads to the various cable thicknesses in different portion of the winding, and thus, the uneven capacitancedistribution. The large capacitive currents and large transient outrush currents resulting from the cable consisting ofthe stator winding of Powerformer may cause problems to the generator differential protection. Most of literatures a-vailable in the field of compensated differential protection focus on the charging current compensation for long trans-mission line, instead of for generator. The authors give a method which can be used to compensate the capacitivecurrent wholly to improve the reliability of the differential protection of Powerformer. It is proved that the distribu-ted capacitance can be equivalent as the lump circuit with a capacitance partition coefficient p, and p is proved as aconstant no matter whether the generator experiences the normal operation, external phase(s) fault or internal phase(s) fault. The formula of the partition coefficient is provided and the corresponding equivalent circuit of the Power-former cable to calculate capacitance currents is given. An analysis programming resolving the minimum value of thecoefficient p is written in MATLAB 7. 0/m according to this formula, using the function fmincon() which can workin any type of constraint condition. The program always gets the same global minimum points under the different in-itial values condition which proves our point by mathematical test. With this new approach to winding capacitancedividing method, the protection scheme used for Powerformer can be validated and improved accordingly.

  7. CAPACITIVE TOMOGRAPHY FOR THE LOCATION OF PLASTIC PIPE

    Energy Technology Data Exchange (ETDEWEB)

    Brian J. Huber

    2002-10-30

    Throughout the utility industry, there is high interest in subsurface imaging of plastic, ceramic, and metallic objects because of the cost, reliability, and safety benefits available in avoiding impacts with the existing infrastructure and in reducing inappropriate excavations. Industry interest in locating plastic pipe has resulted in funding available for the development of technologies that enable this imaging. Gas Technology Institute (GTI) proposes to develop a compact and inexpensive capacitive tomography imaging sensor that takes the form of a flat plate or flexible mat that can be placed on the ground to image objects embedded in the soil. A compact, low-cost sensor that can image objects through soil could be applied to multiple operations and will produce a number of cost savings for the gas industry. In a stand-alone mode, it could be used to survey an area prior to excavation. The technology would improve the accuracy and reliability of any operation that involves excavation by locating or avoiding buried objects. An accurate subsurface image of an area will enable less costly keyhole excavations and other cost-saving techniques. Ground penetrating radar (GPR) has been applied to this area with limited success. Radar requires a high-frequency carrier to be injected into the soil: the higher the frequency, the greater the image resolution. Unfortunately, high-frequency radio waves are more readily absorbed by soil. Also, high-frequency operation raises the cost of the associated electronics. By contrast, the capacitive tomography sensor uses low frequencies with a multiple-element antenna to obtain good resolution. Low-frequency operation lowers the cost of the associated electronics while improving depth of penetration. The objective of this project is to combine several existing techniques in the area of capacitive sensing to quickly produce a demonstrable prototype. The sensor itself will take the form of a flat array of electrodes that can be

  8. Automatic Power Factor Correction Using Capacitive Bank

    Directory of Open Access Journals (Sweden)

    Mr.Anant Kumar Tiwari,

    2014-02-01

    Full Text Available The power factor correction of electrical loads is a problem common to all industrial companies. Earlier the power factor correction was done by adjusting the capacitive bank manually [1]. The automated power factor corrector (APFC using capacitive load bank is helpful in providing the power factor correction. Proposed automated project involves measuring the power factor value from the load using microcontroller. The design of this auto-adjustable power factor correction is to ensure the entire power system always preserving unity power factor. The software and hardware required to implement the suggested automatic power factor correction scheme are explained and its operation is described. APFC thus helps us to decrease the time taken to correct the power factor which helps to increase the efficiency.

  9. CMOS Integrated Capacitive DC-DC Converters

    CERN Document Server

    Van Breussegem, Tom

    2013-01-01

    This book provides a detailed analysis of all aspects of capacitive DC-DC converter design: topology selection, control loop design and noise mitigation. Readers will benefit from the authors’ systematic overview that starts from the ground up, in-depth circuit analysis and a thorough review of recently proposed techniques and design methodologies.  Not only design techniques are discussed, but also implementation in CMOS is shown, by pinpointing the technological opportunities of CMOS and demonstrating the implementation based on four state-of-the-art prototypes.  Provides a detailed analysis of all aspects of capacitive DC-DC converter design;  Analyzes the potential of this type of DC-DC converter and introduces a number of techniques to unleash their full potential; Combines system theory with practical implementation techniques; Includes unique analysis of CMOS technology for this application; Provides in-depth analysis of four fabricated prototypes.

  10. Evaluation of a Capacitance Scaling System

    Science.gov (United States)

    2007-01-01

    2009 at 11:32 from IEEE Xplore . Restrictions apply. Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the...Downloaded on January 30, 2009 at 11:32 from IEEE Xplore . Restrictions apply. 2162 IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 56, NO. 6...30, 2009 at 11:32 from IEEE Xplore . Restrictions apply. AVRAMOV-ZAMUROVIC et al.: EVALUATION OF A CAPACITANCE SCALING SYSTEM 2163 measured to vary by

  11. THERMAL DRIFT CHARACTERISTICS OF CAPACITIVE PRESSURE SENSORS

    OpenAIRE

    2016-01-01

    The capacitive pressure sensors based on silicon are characterized by their very high sensitivities and their low power consumption. Nevertheless, their thermal behavior remains more or less unpredictable because they can indicate very high thermal coefficients. The study of the thermal behavior of these sensors is essential to define the parameters that cause the output characteristics drift. In this study, we modeled the thermal behavior of this sensors, using Finite Element Analysis (FE...

  12. A new desalination technique using capacitive deionization

    Science.gov (United States)

    Rostamy, Mohammad Sajjad; Khashechi, Morteza; Pipelzadeh, Ehsan; desalination Team

    2016-11-01

    Capacitive deionization (CDI) is an emerging energy efficient, low pressure and low capital intensive desalination process where ions are separated by a pure electrostatic force imposed by a small bias potential as low as 1 V That funded by an external Renewable (Solar) power supply to materials with high specific surface area. The main objective of this configuration is to separate the cation and anions on oppositely charged electrodes. Various electrode materials have been developed in the past, which have suffered from instability and lack of performance. Preliminary experimental results using carbon black, graphite powder, graphene ∖graphite ∖PTFE (Active ∖Conductive ∖binder), show that the graphene reduced via urea method is a suitable method to develop CDI electrode materials with capacitance as high as 52.2 mg/g for free standing graphene electrode. The focus of these studies has been mainly on developing electrodes with high specific surface area, high capacitance, excellent electronic conductivity and fast charge discharge cycles for desalination. Although some progress has been made, production of efficient and stable carbon based electrode materials for large scale desalination has not been fully realized.

  13. Evaluation of EHD films by electrical capacitance

    Science.gov (United States)

    Jablonka, Karolina; Glovnea, Romeo; Bongaerts, Jeroen

    2012-09-01

    The elastohydrodynamic (EHD) lubrication regime occurs in many machine elements where a combination of hydrodynamic effect, elastic deformation of the loaded surfaces and increase in the viscosity of the lubricant with pressure ensures the formation of a very thin, but continuous film of lubricant separating the contacting surfaces. Electrical methods to determine this film's thickness have preceded optical methods, which are widely used today. Although they generally give more qualitative thickness information, electrical methods have the main advantage that they can be applied to metallic contacts in machines, which makes them useful tools in the study of elastohydrodynamically lubricated contacts. This paper is part of a larger study on the application of electrical capacitance for the evaluation of film formation in EHD contacts. The main focus is on the quantitative measurements of film thickness using electrical capacitance. A new approach allowing the lubricant film thickness to be extracted from the measured capacitance is developed using a chromium-coated glass disc and subsequently applied to a steel-on-steel contact. The results show good agreement with optical measurements and theoretical models over a range of film thickness.

  14. Effect of Astaxanthin on Human Sperm Capacitation

    Directory of Open Access Journals (Sweden)

    Luciana Bordin

    2013-06-01

    Full Text Available In order to be able to fertilize oocytes, human sperm must undergo a series of morphological and structural alterations, known as capacitation. It has been shown that the production of endogenous sperm reactive oxygen species (ROS plays a key role in causing cells to undergo a massive acrosome reaction (AR. Astaxanthin (Asta, a photo-protective red pigment belonging to the carotenoid family, is recognized as having anti-oxidant, anti-cancer, anti-diabetic and anti-inflammatory properties and is present in many dietary supplements. This study evaluates the effect of Asta in a capacitating buffer which induces low ROS production and low percentages of acrosome-reacted cells (ARC. Sperm cells were incubated in the presence or absence of increasing concentrations of Asta or diamide (Diam and analyzed for their ROS production, Tyr-phosphorylation (Tyr-P pattern and percentages of ARC and non-viable cells (NVC. Results show that Asta ameliorated both sperm head Tyr-P and ARC values without affecting the ROS generation curve, whereas Diam succeeded in enhancing the Tyr-P level but only of the flagellum without increasing ARC values. It is suggested that Asta can be inserted in the membrane and therefore create capacitation-like membrane alteration which allow Tyr-P of the head. Once this has occurred, AR can take place and involves a higher numbers of cells.

  15. An Algorithm of Calculating the Position in a Self-Capacitance Touch Screen

    Science.gov (United States)

    Zhang, Huan; Peng, Haiyan; Qian, Xiaoli; Ren, Can; Wang, Wentao; Li, Jianjun

    Touch screens have been widely used in many kinds of electronic products. For many capacitive touch sensing devices, they always suffer from a variety of electronic signal noises. So when a finger touches the screen, it is difficult to calculate the exact touch position on the screen. We proposed an algorithm of calculating the position in a self-capacitance touch screen to alleviate noise interference. We determined the touch region by calculating the differences between current data and reference data in every channel. In the touch region we divided it into different ranges to calculate the touch point. The simulation results show that the algorithm that we proposed can alleviate noise interference effectively and obtain the exact positioning on touch screen accurately.

  16. Frustration of Negative Capacitance in Al2O3/BaTiO3 Bilayer Structure

    Science.gov (United States)

    Kim, Yu Jin; Park, Min Hyuk; Lee, Young Hwan; Kim, Han Joon; Jeon, Woojin; Moon, Taehwan; Do Kim, Keum; Jeong, Doo Seok; Yamada, Hiroyuki; Hwang, Cheol Seong

    2016-01-01

    Enhancement of capacitance by negative capacitance (NC) effect in a dielectric/ferroelectric (DE/FE) stacked film is gaining a greater interest. While the previous theory on NC effect was based on the Landau-Ginzburg-Devonshire theory, this work adopted a modified formalism to incorporate the depolarization effect to describe the energy of the general DE/FE system. The model predicted that the SrTiO3/BaTiO3 system will show a capacitance boost effect. It was also predicted that the 5 nm-thick Al2O3/150 nm-thick BaTiO3 system shows the capacitance boost effect with no FE-like hysteresis behavior, which was inconsistent with the experimental results; the amorphous-Al2O3/epitaxial-BaTiO3 system showed a typical FE-like hysteresis loop in the polarization – voltage test. This was due to the involvement of the trapped charges at the DE/FE interface, originating from the very high field across the thin Al2O3 layer when the BaTiO3 layer played a role as the NC layer. Therefore, the NC effect in the Al2O3/BaTiO3 system was frustrated by the involvement of reversible interface charge; the highly stored charge by the NC effect of the BaTiO3 during the charging period could not be retrieved during the discharging process because integral part of the polarization charge was retained within the system as a remanent polarization.

  17. Energy-Efficient Capacitance-to-Digital Converters for Low-Energy Sensor Nodes

    KAUST Repository

    Omran, Hesham

    2015-11-01

    Energy efficiency is a key requirement for wireless sensor nodes, biomedical implants, and wearable devices. The energy consumption of the sensor node needs to be minimized to avoid battery replacement, or even better, to enable the device to survive on energy harvested from the ambient. Capacitive sensors do not consume static power; thus, they are attractive from an energy efficiency perspective. In addition, they can be employed in a wide range of sensing applications. However, the sensor readout circuit–i.e., the capacitance-to-digital converter (CDC)–can be the dominant source of energy consumption in the system. Thus, the development of energy-efficient CDCs is crucial to minimizing the energy consumption of capacitive sensor nodes. In the first part of this dissertation, we propose several energy-efficient CDC architectures for low-energy sensor nodes. First, we propose a digitally-controlled coarsefine multislope CDC that employs both current and frequency scaling to achieve significant improvement in energy efficiency. Second, we analyze the limitations of successive approximation (SAR) CDC, and we address these limitations by proposing a robust parasitic-insensitive opamp-based SAR CDC. Third, we propose an inverter-based SAR CDC that achieves an energy efficiency figure-of-merit (FoM) of 31fJ/Step, which is the best energy efficiency FoM reported to date. Fourth, we propose a differential SAR CDC with quasi-dynamic operation to maintain excellent energy efficiency for a scalable sample rate. In the second part of this dissertation, we study the matching properties of small integrated capacitors, which are an integral component of energy-efficient CDCs. Despite conventional wisdom, we experimentally illustrate that the mismatch of small capacitors can be directly measured, and we report mismatch measurements for subfemtofarad integrated capacitors. We also correct the common misconception that lateral capacitors match better than vertical capacitors

  18. HORIZON SENSING

    Energy Technology Data Exchange (ETDEWEB)

    Larry G. Stolarczyk

    2003-03-18

    With the aid of a DOE grant (No. DE-FC26-01NT41050), Stolar Research Corporation (Stolar) developed the Horizon Sensor (HS) to distinguish between the different layers of a coal seam. Mounted on mining machine cutter drums, HS units can detect or sense the horizon between the coal seam and the roof and floor rock, providing the opportunity to accurately mine the section of the seam most desired. HS also enables accurate cutting of minimum height if that is the operator's objective. Often when cutting is done out-of-seam, the head-positioning function facilitates a fixed mining height to minimize dilution. With this technology, miners can still be at a remote location, yet cut only the clean coal, resulting in a much more efficient overall process. The objectives of this project were to demonstrate the feasibility of horizon sensing on mining machines and demonstrate that Horizon Sensing can allow coal to be cut cleaner and more efficiently. Stolar's primary goal was to develop the Horizon Sensor (HS) into an enabling technology for full or partial automation or ''agile mining''. This technical innovation (R&D 100 Award Winner) is quickly demonstrating improvements in productivity and miner safety at several prominent coal mines in the United States. In addition, the HS system can enable the cutting of cleaner coal. Stolar has driven the HS program on the philosophy that cutting cleaner coal means burning cleaner coal. The sensor, located inches from the cutting bits, is based upon the physics principles of a Resonant Microstrip Patch Antenna (RMPA). When it is in proximity of the rock-coal interface, the RMPA impedance varies depending on the thickness of uncut coal. The impedance is measured by the computer-controlled electronics and then sent by radio waves to the mining machine. The worker at the machine can read the data via a Graphical User Interface, displaying a color-coded image of the coal being cut, and direct the machine

  19. A 33fJ/Step SAR Capacitance-to-Digital Converter Using a Chain of Inverter-Based Amplifiers

    KAUST Repository

    Omran, Hesham

    2016-11-16

    A 12 - bit energy-efficient capacitive sensor interface circuit that fully relies on capacitance-domain successive approximation (SAR) technique is presented. Analysis shows that for SAR capacitance-to-digital converter (CDC) comparator offset voltage will result in parasitic-dependent conversion errors, which necessitates using an offset cancellation technique. Based on the presented analysis, a SAR CDC that uses a chain of cascode inverter-based amplifiers with near-threshold biasing is proposed to provide robust, energy-efficient, and fast operation. A hybrid coarse-fine capacitive digital-to-analog converter (CapDAC) achieves 11.7 - bit effective resolution, and provides 83% area saving compared to a conventional binary weighted implementation. The prototype fabricated in a 0.18μm CMOS technology is experimentally verified using MEMS capacitive pressure sensor. Experimental results show an energy efficiency figure-of-merit (FoM) of 33 f J/Step which outperforms the state-of-the-art. The CDC output is insensitive to analog references; thus, a very low temperature sensitivity of 2.3 ppm/°C is achieved without the need for calibration.

  20. Computer-assisted system for measuring capacitance and conductance of a diode using a phase sensitive technique

    Science.gov (United States)

    Ketelsen, L. J. P.; Serway, R. A.

    1981-12-01

    This paper describes a system for making accurate and reliable ac measurements of capacitance as a function of frequency, bias voltage, and temperature. The experimental apparatus consists of the basic capacitance measuring circuit and an information gathering device. The basic circuit includes a constant ac voltage source in series with the cell, a dc source for biasing the cell, an ac current amplifier in series with the cell for monitoring the current, and a lock-in amplifier to measure the ac current. The capacitance device is interfaced with a microcomputer to facilitate handling large quantities of data in a short time. The computer is also used to increment the bias voltage for C-V measurements. The system has the capability of measuring capacitance to an accuracy of about 5 digits. We have used this system to study deep impurity levels in thin-film, polycrystalline CdS/CuxS solar cells. The deep traps appear as anomalies in the otherwise linear l/C2 versus V plots. These levels play an important role in determining cell characteristics and may also influence the cell's efficiency. The advantages of the capacitance-conductance system described in this paper are: (1) simple construction; (2) accurate calibration procedure; (3) ability to take data with 4 1/2 stable digits; (4) the admittance can be measured as a function of bias voltage, frequency, and temperature; (5) automation, i.e., computer controlled, and (6) the ability to accurately provide information on unstable samples.

  1. Novel capacitance-type humidity sensor based on multi-wall carbon nanotube/SiO2 composite films

    Institute of Scientific and Technical Information of China (English)

    Liu Xiaowei; Zhao Zhengang; Li Tuo; Wang Xin

    2011-01-01

    A novel capacitance-type relative humidity (RH) sensor based on multi-wall carbon nanotubc/SiO2 (MWCNTs/SiO2) composite film is reported.Details of the fabrication process,possible sensing mechanism and sensing characteristics,such as linearity and sensitivity,are described.The capacitance of the MWCNTs/SiO2 composite film shows typical concentration percolation behavior with increasing MWCNT loading.At loadings below the percolation threshold (1.842wt%),the sensor capacitance increases obviously with increasing MWCNTs.The water condensed in the MWCNTs/SiO2 layer can lower the percolation threshold and increase the sensor capacitance.The sensor with MWCNT concentration of 1 wt% has the best properties.The sensor has a humidity sensitivity of about 673 pF/% RH and a linearity correlation of 0.98428.The response time of the sensor to RH is about 40 s and the recovery time is about 2 s.

  2. DLTS investigations of Si-SiO/sub 2/ interface states of electron-beam irradiated MOS structures

    Energy Technology Data Exchange (ETDEWEB)

    Huebner, K.; Koester, H.; Derlich, B. (Rostock Univ. (German Democratic Republic). Sektion Physik); Ecke, W. (Akademie der Wissenschaften der DDR, Jena. Physikalisch-Technisches Inst.)

    1983-08-01

    Results of CC-DLTS (constant-capacitance-deep-level-transient-spectroscopy) investigations of MOS structures are presented, which show the influence of electron-beam irradiation on the spectrum of interface states in the silicon gap at the Si-SiO/sub 2/ interface. They lead to a clear identification of a special interface state as a radiation induced one.

  3. Tunable Lowpass Filter with RF MEMS Capacitance and Transmission Line

    Directory of Open Access Journals (Sweden)

    Shimul C. Saha

    2012-01-01

    Full Text Available We have presented an RF MEMS tuneable lowpass filter. Both distributed transmission lines and RF MEMS capacitances were used to replace the lumped elements. The use of RF MEMS capacitances gives the flexibility of tuning the cutoff frequency of the lowpass filter. We have designed a low-pass filter at 9–12 GHz cutoff frequency using the theory of stepped impedance transmission lines. A prototype of the filter has been fabricated using parallel plate capacitances. The variable shunt capacitances are formed by a combination of a number of parallel plate RF MEMS capacitances. The cutoff frequency is tuned from C to X band by actuating different combinations of parallel capacitive bridges. The measurement results agree well with the simulation result.

  4. Numerical analysis of capacitive pressure micro-sensors

    Institute of Scientific and Technical Information of China (English)

    WANG; Xiaomin; LI; Mingxuan; WANG; Chenghao

    2005-01-01

    Pseudo-spectral method is used to numerically model the diaphragm deflection of capacitive pressure micro-sensor under uniform load. The relationship between the capacitance of the micro-sensor and the load is then analyzed after the description of the computational principle. For normal mode micro-sensor, the tensile force on the diaphragm can be ignored and thereby the capacitance increases linearly with the load increase only when the load is so small that the resultant deflection is less than the diaphragm thickness. The linear relationship between the capacitance and the load turns to be nonlinear thereafter and the capacitance rises dramatically with the constant increase of the load. For touch mode micro-sensor, an algorithm to determine the touch radius of the diaphragm and substrate is presented and the curve of capacitance versus load is shown on the numerical results laying a theoretical foundation for micro-sensor design.

  5. Interface dermatitis

    Directory of Open Access Journals (Sweden)

    Rajiv Joshi

    2013-01-01

    Full Text Available Interface dermatitis includes diseases in which the primary pathology involves the dermo-epidermal junction. The salient histological findings include basal cell vacuolization, apoptotic keratinocytes (colloid or Civatte bodies, and obscuring of the dermo-epidermal junction by inflammatory cells. Secondary changes of the epidermis and papillary dermis along with type, distribution and density of inflammatory cells are used for the differential diagnoses of the various diseases that exhibit interface changes. Lupus erythematosus, dermatomyositis, lichen planus, graft versus host disease, erythema multiforme, fixed drug eruptions, lichen striatus, and pityriasis lichenoides are considered major interface diseases. Several other diseases (inflammatory, infective, and neoplastic may show interface changes.

  6. Magnetic field tunable capacitive dielectric:ionic-liquid sandwich composites

    Science.gov (United States)

    Wu, Ye; Bhalla, Amar; Guo, Ruyan

    2016-03-01

    We examined the tunability of the capacitance for GaFeO3-ionic liquid-GaFeO3 composite material by external magnetic and electric field. Up to 1.6 folds of capacitance tunability could be achieved at 957 kHz with voltage 4 V and magnetic field 0.02 T applied. We show that the capacitance enhancement is due to the polarization coupling between dielectric layer and ionic liquid layer.

  7. Carrier Statistics and Quantum Capacitance Models of Graphene Nanoscroll

    Directory of Open Access Journals (Sweden)

    M. Khaledian

    2014-01-01

    schematic perfect scroll-like Archimedes spiral. The DOS model was derived at first, while it was later applied to compute the carrier concentration and quantum capacitance model. Furthermore, the carrier concentration and quantum capacitance were modeled for both degenerate and nondegenerate regimes, along with examining the effect of structural parameters and chirality number on the density of state and carrier concentration. Latterly, the temperature effect on the quantum capacitance was studied too.

  8. Circuit analysis and simulation of an ultrahigh-frequency capacitance sensor for scanning capacitance microscopy

    Science.gov (United States)

    Yang, Jing; Postula, A.; Bialkowski, M.

    2004-03-01

    Quantitative two-dimensional dopant profiling tools are urgently needed for nowadays semiconductor industry. Scanning Capacitance Microscopy (SCM) holds most promise to become such a tool. The key component of SCM is an ultra high frequency (UHF) capacitance sensor. The output of the sensor has been approximately regarded as dC/dV, the derivative of the capacitance between the SCM tip and the sample versus the applied bias voltage. The SCM dopant profiling involves extracting the dopant profile from the SCM signal using analytic or numerical simulation models of Metal-Oxide-Semiconductor physics. To achieve a quantitative SCM dopant profiling, the operational principle of the whole SCM measurement has to be well understood and correctly included in those models. Recently, experimental evidences show the SCM signal is dramatically affected by many SCM experimental factors, including the behavior of the UHF capacitance sensor. However, till now, very little research has been reported on the behavior of the sensor in SCM measurement of semiconductors. In this paper, we derive an analytic expression of the sensor output, a circuit simulation model of the sensor is established using Advanced Design System 2003, and the dependences of the sensor output on the SCM operational factors are simulated.

  9. Chemical vapor detection using a capacitive micromachined ultrasonic transducer.

    Science.gov (United States)

    Lee, Hyunjoo J; Park, Kwan Kyu; Kupnik, Mario; Oralkan, O; Khuri-Yakub, Butrus T

    2011-12-15

    Distributed sensing of gas-phase chemicals using highly sensitive and inexpensive sensors is of great interest for many defense and consumer applications. In this paper we present ppb-level detection of dimethyl methylphosphonate (DMMP), a common simulant for sarin gas, with a ppt-level resolution using an improved capacitive micromachined ultrasonic transducer (CMUT) as a resonant chemical sensor. The improved CMUT operates at a higher resonant frequency of 47.7 MHz and offers an improved mass sensitivity of 48.8 zg/Hz/μm(2) by a factor of 2.7 compared to the previous CMUT sensors developed. A low-noise oscillator using the CMUT resonant sensor as the frequency-selective device was developed for real-time sensing, which exhibits an Allan deviation of 1.65 Hz (3σ) in the presence of a gas flow; this translates into a mass resolution of 80.5 zg/μm(2). The CMUT resonant sensor is functionalized with a 50-nm thick DKAP polymer developed at Sandia National Laboratory for dimethyl methylphosphonate (DMMP) detection. To demonstrate ppb-level detection of the improved chemical sensor system, the sensor performance was tested at a certified lab (MIT Lincoln Laboratory), which is equipped with an experimental chemical setup that reliably and accurately delivers a wide range of low concentrations down to 10 ppb. We report a high volume sensitivity of 34.5 ± 0.79 pptv/Hz to DMMP and a good selectivity of the polymer to DMMP with respect to dodecane and 1-octanol.

  10. Dynamics of the YSZ-Pt Interface

    DEFF Research Database (Denmark)

    Bay, Lasse; Jacobsen, Torben

    1997-01-01

    Yttria stabilized zirconia (YSZ)-Pt point electrodes were examined by linear potential sweep, potential step and impedance measurements at 1000 degrees C in air. Inductive loops and hysteresis phenomena with long relaxation times were found. Atomic force microscopy showed changes of the interface...... between Pt and YSZ induced by the current passage. These changes involve transport of solid and are slow enough to explain the large time constants. The low frequency capacitance and inductive loop forming an entire circle indicate the presence of gas reservoirs at the YSZ-Pt interface....

  11. A capacitive biosensor based on an interdigitated electrode with nanoislands.

    Science.gov (United States)

    Jung, Ha-Wook; Chang, Young Wook; Lee, Ga-yeon; Cho, Sungbo; Kang, Min-Jung; Pyun, Jae-Chul

    2014-09-24

    A capacitive biosensor based on an interdigitated electrode (IDE) with nanoislands was developed for label-free detection of antigen-antibody interactions. To enable sensitive capacitive detection of protein adsorption, the nanoislands were fabricated between finger electrodes of the IDE. The effect of the nanoislands on the sensitive capacitive measurement was estimated using horseradish peroxidase (HRP) as a model protein. Additionally, a parylene-A film was coated on the IDE with nanoislands to improve the efficiency of protein immobilization. By using HRP and hepatitis B virus surface antigen (HBsAg) as model analytes, the effect of the parylene-A film on the capacitive detection of protein adsorption was demonstrated.

  12. Metal oxide nanostructures as gas sensing devices

    CERN Document Server

    Eranna, G

    2011-01-01

    Metal Oxide Nanostructures as Gas Sensing Devices explores the development of an integrated micro gas sensor that is based on advanced metal oxide nanostructures and is compatible with modern semiconductor fabrication technology. This sensor can then be used to create a compact, low-power, handheld device for analyzing air ambience. The book first covers current gas sensing tools and discusses the necessity for miniaturized sensors. It then focuses on the materials, devices, and techniques used for gas sensing applications, such as resistance and capacitance variations. The author addresses th

  13. A highly elastic, capacitive strain gauge based on percolating nanotube networks.

    Science.gov (United States)

    Cohen, Daniel J; Mitra, Debkishore; Peterson, Kevin; Maharbiz, Michel M

    2012-04-11

    We present a highly elastic strain gauge based on capacitive sensing of parallel, carbon nanotube-based percolation electrodes separated by a dielectric elastomer. The fabrication, relying on vacuum filtration of single-walled carbon nanotubes and hydrophobic patterning of silicone, is both rapid and inexpensive. We demonstrate reliable, linear performance over thousands of cycles at up to 100% strain with less than 3% variability and the highest reported gauge factor for a device of this class (0.99). We further demonstrate use of this sensor in a robotics context to transduce joint angles.

  14. Charge Efficiency: A Functional Tool to Probe the Double-Layer Structure Inside of Porous Electrodes and Application in the Modeling of Capacitive Deionization

    NARCIS (Netherlands)

    Zhao, R.; Biesheuvel, P.M.; Miedema, H.; Bruning, H.; Wal, van der A.

    2010-01-01

    Porous electrodes are important in many physical-chemical processes including capacitive deionization (CDI), a desalination technology where ions are adsorbed from solution into the electrostatic double layers formed at the electrode/solution interface inside of two juxtaposed porous electrodes. A k

  15. The role of Stern layer in the interplay of dielectric saturation and ion steric effects for the capacitance of graphene in aqueous electrolytes

    Science.gov (United States)

    Daniels, Lindsey; Scott, Matthew; Mišković, Z. L.

    2017-03-01

    Nano-scale devices continue to challenge our theoretical understanding of microscopic systems. Of particular interest is the characterization of the interface electrochemistry of graphene-based sensors. Typically operated in a regime of high ion concentration and high surface charge density, dielectric saturation and ion crowding become non-negligible at the interface, complicating continuum treatments based upon the Poisson-Boltzmann equation. Using the Poisson-Boltzmann equation, modified with the Bikerman-Freise model to account for non-zero ion size and the Booth model to account for dielectric saturation at the interface, we characterize the diffuse layer capacitance of both metallic and graphene electrodes immersed in an aqueous electrolyte. We find that the diffuse layer capacitance exhibits two peaks when the surface charge density of the electrode is increased, in contrast with experimental results. We propose a self-consistent (and parameter-free) method to include the Stern layer which eliminates the spurious secondary peak in the capacitance and restores the correspondence of the model with experimental observations. This study sheds light on the interplay between the ion steric effects and the dielectric saturation in solvent, exposes the importance of quantum capacitance when graphene is used as an electrode, and demonstrates the importance of a self-consistent treatment of the Stern layer in continuum models of the electrode-electrolyte interface. Furthermore, the theoretical foundation provides a base upon which more detailed models of graphene-based sensors can be built.

  16. Interface models

    DEFF Research Database (Denmark)

    Ravn, Anders P.; Staunstrup, Jørgen

    1994-01-01

    This paper proposes a model for specifying interfaces between concurrently executing modules of a computing system. The model does not prescribe a particular type of communication protocol and is aimed at describing interfaces between both software and hardware modules or a combination of the two...

  17. Fluid Interfaces

    DEFF Research Database (Denmark)

    Hansen, Klaus Marius

    2001-01-01

    Fluid interaction, interaction by the user with the system that causes few breakdowns, is essential to many user interfaces. We present two concrete software systems that try to support fluid interaction for different work practices. Furthermore, we present specificity, generality, and minimality...... as design goals for fluid interfaces....

  18. Nanostructured conducting polymer based reagentless capacitive immunosensor.

    Science.gov (United States)

    Bandodkar, Amay Jairaj; Dhand, Chetna; Arya, Sunil K; Pandey, M K; Malhotra, Bansi D

    2010-02-01

    Nanostructured polyaniline (PANI) film electrophoretically fabricated onto indium-tin-oxide (ITO) coated glass plate has been utilized for development of an immunosensor based on capacitance change of a parallel plate capacitor (PPC) by covalently immobilizing anti-human IgG (Anti-HIgG) using N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide chemistry. These fabricated PANI/ITO and Anti-HIgG/PANI/ITO plates have been characterized using scanning electron microscopy, cyclic voltammetry, differential pulse voltammetry and Fourier transform infra-red studies. The capacitance measurements indicate that dielectric medium of this biologically modified PPC (Anti-HIgG/PANI/ITO) is sensitive to HIgG in 5 - 5 x 10(5) ng mL(-1) range and has lower detection limit of 1.87 ng mL(-1). The observed results reveal that this Anti-HIgG modified PPC can be used as a robust, easy-to-use, reagentless, sensitive and selective immunosensor for estimation of human IgG.

  19. THERMAL DRIFT CHARACTERISTICS OF CAPACITIVE PRESSURE SENSORS

    Directory of Open Access Journals (Sweden)

    ABDELAZIZ BEDDIAF

    2016-03-01

    Full Text Available The capacitive pressure sensors based on silicon are characterized by their very high sensitivities and their low power consumption. Nevertheless, their thermal behavior remains more or less unpredictable because they can indicate very high thermal coefficients. The study of the thermal behavior of these sensors is essential to define the parameters that cause the output characteristics drift. In this study, we modeled the thermal behavior of this sensors, using Finite Element Analysis (FEA made in COMSOL. The model solved by COMSOL environment takes into account the entire sensor and thermal effects due to the temperature considering the materials’ properties, the geometric shape and also the heat transfer mechanisms. By COMSOL we determine how the temperature affects the sensor during the manufacturing process. For that end, we calculated the thermal drift of capacitance at rest, the thermal coefficients and we compared them with experimental results to validate our model. Further, we studied the thermal drift of sensor characteristics both at rest and under constant and uniform pressure. Further, our study put emphasis on the geometric influence parameters on these characteristics to optimize the sensor performance. Finally, this study allows us to predict the sensor behavior against temperature and to minimize this effect by optimizing the geometrical parameters.

  20. Reinterpretation of defect levels derived from capacitance spectroscopy of CIGSe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Igalson, Malgorzata [Faculty of Physics, Warsaw University of Technology, Koszykowa 75, PL 00 662 Warszawa (Poland)], E-mail: igalson@if.pw.edu.pl; Urbaniak, Aleksander [Faculty of Physics, Warsaw University of Technology, Koszykowa 75, PL 00 662 Warszawa (Poland); Edoff, Marika [Angstroem Solar Center, Uppsala University, P.O. Box 534, SE-751 21, Uppsala (Sweden)

    2009-02-02

    In this work we make an attempt to clarify ambiguities and to present our present understanding of defects and defect-related phenomena affecting the capacitance characteristics of Cu(In,Ga)Se{sub 2}-based solar cells. We discuss deep defect levels derived from admittance and deep level transient spectroscopy, as well as shallow levels affecting the charge distributions by capacitance-voltage profiling. The discussion includes two types of metastable effects affecting capacitance characteristics: one induced at room temperature by light or voltage bias, and one created at low temperature by red illumination of reverse-biased junction (ROB effect). Recent theoretical achievements on negative-U properties of such intrinsic defects as selenium vacancies and In{sub Cu} antisites are used to explain the experimental data. We show that the most prominent level in the admittance spectra is due to the response of interface states combined with contribution of deep V{sub Se}-V{sub Cu}{sup -/2-} acceptor level. We attribute the ROB metastability to the relaxation of In{sub Cu} defects upon electron capture. Finally we discuss the influence of these defects on the device efficiency.

  1. Charge recombination mechanism to explain the negative capacitance in dye-sensitized solar cells

    Science.gov (United States)

    Lie-Feng, Feng; Kun, Zhao; Hai-Tao, Dai; Shu-Guo, Wang; Xiao-Wei, Sun

    2016-03-01

    Negative capacitance (NC) in dye-sensitized solar cells (DSCs) has been confirmed experimentally. In this work, the recombination behavior of carriers in DSC with semiconductor interface as a carrier’s transport layer is explored theoretically in detail. Analytical results indicate that the recombination behavior of carriers could contribute to the NC of DSCs under small signal perturbation. Using this recombination capacitance we propose a novel equivalent circuit to completely explain the negative terminal capacitance. Further analysis based on the recombination complex impedance show that the NC is inversely proportional to frequency. In addition, analytical recombination resistance is composed by the alternating current (AC) recombination resistance (Rrac) and the direct current (DC) recombination resistance (Rrdc), which are caused by small-signal perturbation and the DC bias voltage, respectively. Both of two parts will decrease with increasing bias voltage. Project supported by the National Natural Science Foundation of China (Grant Nos. 11204209 and 60876035) and the Natural Science Foundation of Tianjin City, China (Grant No. 13JCZDJC32800).

  2. Testing Interfaces

    DEFF Research Database (Denmark)

    Holbøll, Joachim T.; Henriksen, Mogens; Nilson, Jesper K.;

    1999-01-01

    The wide use of solid insulating materials combinations in combinations has introduced problems in the interfaces between components. The most common insulating materials are cross-linked polyethylene (XLPE), silicone rubber (SIR) and ethylene-propylene rubbers (EPR). Assemblies of these materials...... have caused major failures. In the Netherlands, a major black out was caused by interface problems in 150kV cable terminations, causing a cascade of breakdowns. There is a need to investigate the reasons for this and other similar breakdowns.The major problem is expected to lie in the interface between...... two different materials. Environmental influence, surface treatment, defects in materials and interface, design, pressure and rubbing are believed to have an effect on interface degradation. These factors are believed to increase the possibility of partial discharges (PD). PD will, with time, destroy...

  3. Focal length measurement of a varifocal liquid lens with capacitance detection

    Science.gov (United States)

    Noda, Kentaro; Binh-Khiem, Nguyen; Takei, Yusuke; Takahata, Tomoyuki; Matsumoto, Kiyoshi; Shimoyama, Isao

    2014-04-01

    This paper reports on a detailed deformation model of varifocal liquid lenses fabricated by Parylene-on-liquid-deposition (POLD), which can be applied to measure and adjust the focal length of such lenses without using extra sensors or sensing mechanisms. The lens was fabricated by encapsulating a liquid between a transparent electrode and a polymer film that was covered with a metal electrode. When voltage is applied to the two electrodes, the lens deforms due to the electrostatic force, and its focal length and the capacitance between the two electrodes change simultaneously. This characteristic enables the focal length of the lens to be adjusted and detected by measuring the capacitance change. The focal length of the fabricated varifocal liquid lens changed from 153.6 to 82.6 mm by applying 150-V. The focal length change of the liquid lens was calculated from the change in its capacitance. Finally, to confirm the efficiency of this varifocal liquid lens, we fabricated a confocal distance sensor using the lens for laser scanning and demonstrated that this system can be used to measure distances of 94-140 mm with an average error of 0.83 mm and a standard deviation of 0.77 mm.

  4. Polymer-based flexible capacitive sensor for three-axial force measurements

    Science.gov (United States)

    Dobrzynska, J. A.; Gijs, M. A. M.

    2013-01-01

    We have developed a flexible-substrate-based three-axial force sensor, composed of finger-shaped electrode capacitors, whose operation is based on the measurement of a capacitance change induced upon applying a three-axial load. The electrode design supports high sensitivity to shear forces. An overall flexibility of the sensor and elasticity of the capacitor's dielectric is obtained by integrating three polymers in the sensor's technology process, namely polyimide, parylene-C, and polydimethylsiloxane, combined with standard metallization processes. We have theoretically modeled the sensor's capacitance and its three-axial force sensitivity. The unit capacitors have static capacitances in the range of 20 pF. The electro-mechanical characterization of the capacitors reveals in the normal direction a sensitivity Sz = 0.024 kPa-1 for pressures <10 kPa, whereas for higher pressures the measured sensitivity Sz = 6.6 × 10-4 kPa-1. Typical measured shear force sensitivity Sx = 2.8 × 10-4 kPa-1. These values give our transducer high potential for use in skin-like sensing applications.

  5. The capacitive sensor for liquid level measurement, fabricated with the inkjet printing technology

    Science.gov (United States)

    Paczesny, Daniel; Tarapata, Grzegorz; Marzecki, Michał; Woyke, Michał; Jachowicz, Ryszard

    2016-11-01

    The paper reports a capacitive multisection sensor for measuring level of various liquids. Presented sensor was fully fabricated with the inkjet printing technology on thin Kapton substrate. The measurement of liquids level based on capacitive sensing is already well known technique, however the novelty of presented sensor is the technology of fabrication that was used, approach to the pattern design which combines analog and digital capacitive section and obtained self-calibration feature of whole system independently on measured liquid type. Fabricated sensor structure has dimension of 210 mm x 12 mm and the thickness approximately of 27 μm. It contains 8 digital-like sections along the sensor and one analog section which allows to fine measurements. The sensor was tested in a vessel during filling and emptying with various liquids. Performed tests exhibited the linearity of the sensor characteristic and the lack of hysteresis. Obtained sensitivity of the sensor prototype was approximately 6.8 pF/mm, but it could be easily modify on the design stage due to the fast prototyping feature of inkjet printing technology. Thanks to the flexibility of the substrate, the sensor structure can be applied to any shape of vessel. Furthermore, the sensor construction is fairly simple and costs in mass production could be extremely low. This type of sensor was design especially for autonomous cleaning and washing robots for large areas operation.

  6. A comparative study on the mechatronic and electronic self-powered synchronized switch interfaces for piezoelectric energy harvesting systems

    Science.gov (United States)

    Liu, Haili; Ge, Cong; Liang, Junrui; Wang, Ya

    2016-04-01

    By scavenging the vibration energy from the ambience, the piezoelectric energy harvesting (PEH) technology provides one of the most promising solutions towards the everlasting power supplies for distributed wireless sensors. Given the capacitive characteristics of the piezoelectric devices, synchronized switch interface circuits, such as the synchronized switch harvesting on inductor (SSHI), have been developed towards the harvested power enhancement. The self-powered sensing and control issue is essential for implementing these circuit innovations in practical applications. This paper provides a comparative study on the recently proposed mechatronic self-powered SSHI (MSP-SSHI) and the existing electronic self-powered SSHI (ESP-SSHI). The MSP-SSHI uses a single-pole double-throw switch to simultaneously perform the sensing and switching functions in the SSHI interface. It can reduce the switching threshold and energy losses caused in the semiconductors of the electronic solution, and no need to care about the high-voltage breakdown problems in the ESP-SSHI. On the other hand, the distance between the pole and throws will introduce certain switching phase difference under the larger range of excitation. A piecewise linear model of the MSP-SSHI is built to analyze the switching phase difference. It was found that the damping ratio and stiffness in the mechanical switch can significantly influence the switching phase difference. Simulations show that well-designed damping ratio and stiffness can help the MSP-SSHI maintain smaller switching phase difference, and therefore improve the output power.

  7. A 3D Faraday Shield for Interdigitated Dielectrometry Sensors and Its Effect on Capacitance.

    Science.gov (United States)

    Risos, Alex; Long, Nicholas; Hunze, Arvid; Gouws, Gideon

    2016-12-31

    Interdigitated dielectrometry sensors (IDS) are capacitive sensors investigated to precisely measure the relative permittivity ( ϵ r ) of insulating liquids. Such liquids used in the power industry exhibit a change in ϵ r as they degrade. The IDS ability to measure ϵ r in-situ can potentially reduce maintenance, increase grid stability and improve safety. Noise from external electric field sources is a prominent issue with IDS. This paper investigates the novelty of applying a Faraday cage onto an IDS as a 3D shield to reduce this noise. This alters the spatially distributed electric field of an IDS affecting its sensing properties. Therefore, dependency of the sensor's signal with the distance to a shield above the IDS electrodes has been investigated experimentally and theoretically via a Green's function calculation and FEM. A criteria of the shield's distance s = s 0 has been defined as the distance which gives a capacitance for the IDS equal to 1 - e - 2 = 86.5 % of its unshielded value. Theoretical calculations using a simplified geometry gave a constant value for s 0 / λ = 1.65, where λ is the IDS wavelength. In the experiment, values for s 0 were found to be lower than predicted as from theory and the ratio s 0 / λ variable. This was analyzed in detail and it was found to be resulting from the specific spatial structure of the IDS. A subsequent measurement of a common insulating liquid with a nearby noise source demonstrates a considerable reduction in the standard deviation of the relative permittivity from σ unshielded = ± 9.5% to σ shielded = ± 0.6%. The presented findings enhance our understanding of IDS in respect to the influence of a Faraday shield on the capacitance, parasitic capacitances of the IDS and external noise impact on the measurement of ϵ r .

  8. Microprocessor interfacing

    CERN Document Server

    Vears, R E

    2014-01-01

    Microprocessor Interfacing provides the coverage of the Business and Technician Education Council level NIII unit in Microprocessor Interfacing (syllabus U86/335). Composed of seven chapters, the book explains the foundation in microprocessor interfacing techniques in hardware and software that can be used for problem identification and solving. The book focuses on the 6502, Z80, and 6800/02 microprocessor families. The technique starts with signal conditioning, filtering, and cleaning before the signal can be processed. The signal conversion, from analog to digital or vice versa, is expl

  9. Tactile melodies in user interfaces

    NARCIS (Netherlands)

    Veen, H.A.H.C. van; Erp, J.B.F. van

    2003-01-01

    The application of dynamic vibrotactile displays in user interfaces is still a rare situation. There are, however, several important advantages of using the sense of touch as an information channel, especially in relation to overloaded or unavailable visual and auditory channels. We propose here to

  10. Large Capacitance Measurement by Multiple Uses of MBL Charge Sensor

    Science.gov (United States)

    Lee, Jung Sook; Chae, Min; Kim, Jung Bog

    2010-01-01

    A recent article by Morse described interesting electrostatics experiments using an MBL charge sensor. In this application, the charge sensor has a large capacitance compared to the charged test object, so nearly all charges can be transferred to the sensor capacitor from the capacitor to be measured. However, the typical capacitance of commercial…

  11. Electric field theory and the fallacy of void capacitance

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson

    1991-01-01

    The concept of the capacitance of a gaseous void is discussed as applied to electrical insulation science. The most pertinent aspect of the capacitance definition is that of reference to a single-valued potential difference between surfaces. This implies that these surfaces must be surfaces...

  12. Capacitance tuning of nanoscale split-ring resonators

    DEFF Research Database (Denmark)

    Jeppesen, Claus; Xiao, Sanshui; Mortensen, Niels Asger;

    2010-01-01

    In this paper, we investigate the capacitance tuning of nanoscale split-ring resonators. Based on a simple LC circuit model (LC-model), we derive an expression where the inductance is proportional to the area while the capacitance reflects the aspect ratio of the slit. The resonance frequency may...

  13. Capacitance tuning of nanoscale split-ring resonators

    DEFF Research Database (Denmark)

    Jeppesen, Claus; Mortensen, Asger; Kristensen, Anders

    2009-01-01

    We investigate the capacitance tuning of nanoscale split-ring resonators. Based on a simple inductor-capacitor circuit model, we derive an expression, where the inductance is proportional to the area while the capacitance reflects the aspect ratio of the slit. The resonance frequency may thus be ...

  14. Human body capacitance: static or dynamic concept? [ESD

    DEFF Research Database (Denmark)

    Jonassen, Niels M

    1998-01-01

    A standing human body insulated from ground by footwear and/or floor covering is in principle an insulated conductor and has, as such, a capacitance, i.e. the ability to store a charge and possibly discharge the stored energy in a spark discharge. In the human body, the human body capacitance (HBC...

  15. Distributed Capacitance of Coaxial Line With Perturbed Walls

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Perturbation method of boundary geometry(PMOBG) used in Laplacian problems is dealt with and the three-term perturbation expression of distributed capacitance of a coaxial line with perturbed walls is obtained. As an example,four-order expression of distributed capacitance of a elliptic coaxial line with small eccentricity is given.

  16. Nanoscale capacitance: A quantum tight-binding model

    Science.gov (United States)

    Zhai, Feng; Wu, Jian; Li, Yang; Lu, Jun-Qiang

    2017-01-01

    Landauer-Buttiker formalism with the assumption of semi-infinite electrodes as reservoirs has been the standard approach in modeling steady electron transport through nanoscale devices. However, modeling dynamic electron transport properties, especially nanoscale capacitance, is a challenging problem because of dynamic contributions from electrodes, which is neglectable in modeling macroscopic capacitance and mesoscopic conductance. We implement a self-consistent quantum tight-binding model to calculate capacitance of a nano-gap system consisting of an electrode capacitance C‧ and an effective capacitance Cd of the middle device. From the calculations on a nano-gap made of carbon nanotube with a buckyball therein, we show that when the electrode length increases, the electrode capacitance C‧ moves up while the effective capacitance Cd converges to a value which is much smaller than the electrode capacitance C‧. Our results reveal the importance of electrodes in modeling nanoscale ac circuits, and indicate that the concepts of semi-infinite electrodes and reservoirs well-accepted in the steady electron transport theory may be not applicable in modeling dynamic transport properties.

  17. Nonlinear dynamics of capacitive charging and desalination by porous electrodes

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Bazant, M.Z.

    2010-01-01

    The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by supercapacitors, water desalination and purification by capacitive deionization, and capacitive extraction of renewable energy from a salin

  18. Characterizing Inductive and Capacitive Nonlinear RLC Circuits : A Passivity Test

    NARCIS (Netherlands)

    García-Canseco, Eloísa; Jeltsema, Dimitri; Ortega, Romeo; Scherpen, Jacquelien M.A.

    2004-01-01

    Linear time-invariant RLC circuits are said to be inductive (capacitive) if the current waveform in sinusoidal steady-state has a negative (resp., positive) phase shift with respect to the voltage. Furthermore, it is known that the circuit is inductive (capacitive) if and only if the magnetic energy

  19. Effect of estrogens on boar sperm capacitation in vitro

    Directory of Open Access Journals (Sweden)

    Ded Lukas

    2010-07-01

    Full Text Available Abstract Background Mammalian sperm must undergo a series of controlled molecular processes in the female reproductive tract called capacitation before they are capable of penetrating and fertilizing the egg. Capacitation, as a complex biological process, is influenced by many molecular factors, among which steroidal hormone estrogens play their role. Estrogens, present in a high concentration in the female reproductive tract are generally considered as primarily female hormones. However, there is increasing evidence of their important impact on male reproductive parameters. The purpose of this study is to investigate the effect of three natural estrogens such as estrone (E1, 17beta-estradiol (E2 and estriol (E3 as well as the synthetical one, 17alpha-ethynylestradiol (EE2 on boar sperm capacitation in vitro. Methods Boar sperm were capacitated in vitro in presence of estrogens. Capacitation progress in control and experimental samples was analyzed by flow cytometry with the anti-acrosin monoclonal antibody (ACR.2 at selected times of incubation. Sperm samples were analyzed at 120 min of capacitation by CTC (chlortetracycline assay, immunocytochemistry and flow cytometry with anti-acrosin ACR.2 antibody. Furthermore, sperm samples and capacitating media were analyzed by immunocytochemistry, ELISA with the ACR.2 antibody, and the acrosin activity assay after induced acrosomal reaction (AR. Results Estrogens stimulate sperm capacitation of boar sperm collected from different individuals. The stimulatory effect depends on capacitation time and is highly influenced by differences in the response to estrogens such as E2 by individual animals. Individual estrogens have relatively same effect on capacitation progress. In the boar samples with high estrogen responsiveness, estrogens stimulate the capacitation progress in a concentration-dependent manner. Furthermore, estrogens significantly increase the number of acrosome-reacted sperm after zona

  20. CAPACITIVE TOMOGRAPHY FOR THE LOCATION OF PLASTIC PIPE

    Energy Technology Data Exchange (ETDEWEB)

    Brian J. Huber

    2003-07-29

    Throughout the utility industry, there is high interest in subsurface imaging of plastic, ceramic, and metallic objects because of the cost, reliability, and safety benefits available in avoiding impacts with the existing infrastructure and in reducing inappropriate excavations. Industry interest in locating plastic pipe has resulted in funding available for the development of technologies that enable this imaging. Gas Technology Institute (GTI) proposes to develop a compact and inexpensive capacitive tomography imaging sensor that takes the form of a flat plate or flexible mat that can be placed on the ground to image objects embedded in the soil. A compact, low-cost sensor that can image objects through soil could be applied to multiple operations and will produce a number of cost savings for the gas industry. In a stand-alone mode, it could be used to survey an area prior to excavation. The technology would improve the accuracy and reliability of any operation that involves excavation by locating or avoiding buried objects. An accurate subsurface image of an area will enable less costly keyhole excavations and other cost-saving techniques. Ground penetrating radar (GPR) has been applied to this area with limited success. Radar requires a high-frequency carrier to be injected into the soil: the higher the frequency, the greater the image resolution. Unfortunately, high-frequency radio waves are more readily absorbed by soil. Also, high-frequency operation raises the cost of the associated electronics. By contrast, the capacitive tomography sensor uses low frequencies with a multiple-element antenna to obtain good resolution. Low-frequency operation lowers the cost of the associated electronics while improving depth of penetration. The objective of this project is to combine several existing techniques in the area of capacitive sensing to quickly produce a demonstrable prototype. The sensor itself will take the form of a flat array of electrodes that can be

  1. CAPACITIVE TOMOGRAPHY FOR THE LOCATION OF PLASTIC PIPE

    Energy Technology Data Exchange (ETDEWEB)

    Brian J. Huber

    2002-07-15

    Throughout the utility industry, there is high interest in subsurface imaging of plastic, ceramic, and metallic objects because of the cost, reliability, and safety benefits available in avoiding impacts with the existing infrastructure and in reducing inappropriate excavations. Industry interest in locating plastic pipe has resulted in funding available for the development of technologies that enable this imaging. Gas Technology Institute (GTI) proposes to develop a compact and inexpensive capacitive tomography imaging sensor that takes the form of a flat plate or flexible mat that can be placed on the ground to image objects embedded in the soil. A compact, low-cost sensor that can image objects through soil could be applied to multiple operations and will produce a number of cost savings for the gas industry. In a stand-alone mode, it could be used to survey an area prior to excavation. The technology would improve the accuracy and reliability of any operation that involves excavation by locating or avoiding buried objects. An accurate subsurface image of an area will enable less costly keyhole excavations and other cost-saving techniques. Ground penetrating radar (GPR) has been applied to this area with limited success. Radar requires a high-frequency carrier to be injected into the soil: the higher the frequency, the greater the image resolution. Unfortunately, high-frequency radio waves are more readily absorbed by soil. Also, high-frequency operation raises the cost of the associated electronics. By contrast, the capacitive tomography sensor uses low frequencies with a multiple-element antenna to obtain good resolution. Low-frequency operation lowers the cost of the associated electronics while improving depth of penetration. The objective of this project is to combine several existing techniques in the area of capacitive sensing to quickly produce a demonstrable prototype. The sensor itself will take the form of a flat array of electrodes that can be

  2. Capacitated dynamic lot sizing with capacity acquisition

    DEFF Research Database (Denmark)

    Li, Hongyan; Meissner, Joern

    2011-01-01

    batch, along with inventory carrying costs. The production per period is limited by a capacity restriction. The underlying capacity must be purchased up front for the upcoming season and remains constant over the entire season. We assume that the capacity acquisition cost is smooth and convex......One of the fundamental problems in operations management is determining the optimal investment in capacity. Capacity investment consumes resources and the decision, once made, is often irreversible. Moreover, the available capacity level affects the action space for production and inventory...... planning decisions directly. In this article, we address the joint capacitated lot-sizing and capacity-acquisition problems. The firm can produce goods in each of the finite periods into which the production season is partitioned. Fixed as well as variable production costs are incurred for each production...

  3. Capacitated Dynamic Lot Sizing with Capacity Acquisition

    DEFF Research Database (Denmark)

    Li, Hongyan; Meissner, Joern

    with inventory carrying costs. The production per period limited by a capacity restriction. The underlying capacity must be purchased up front for the upcoming season and remains constant over the entire season. We assume that the capacity acquisition cost is smooth and convex. For this situation, we develop......One of the fundamental problems in operations management is to determine the optimal investment in capacity. Capacity investment consumes resources and the decision is often irreversible. Moreover, the available capacity level affects the action space for production and inventory planning decisions...... directly. In this paper, we address the joint capacitated lot sizing and capacity acquisition problem. The firm can produce goods in each of the finite periods into which the production season is partitioned. Fixed as well as variable production costs are incurred for each production batch, along...

  4. Fund allocation using capacitated vehicle routing problem

    Science.gov (United States)

    Mamat, Nur Jumaadzan Zaleha; Jaaman, Saiful Hafizah; Ahmad, Rokiah Rozita; Darus, Maslina

    2014-09-01

    In investment fund allocation, it is unwise for an investor to distribute his fund into several assets simultaneously due to economic reasons. One solution is to allocate the fund into a particular asset at a time in a sequence that will either maximize returns or minimize risks depending on the investor's objective. The vehicle routing problem (VRP) provides an avenue to this issue. VRP answers the question on how to efficiently use the available fleet of vehicles to meet a given service demand, subjected to a set of operational requirements. This paper proposes an idea of using capacitated vehicle routing problem (CVRP) to optimize investment fund allocation by employing data of selected stocks in the FTSE Bursa Malaysia. Results suggest that CRVP can be applied to solve the issue of investment fund allocation and increase the investor's profit.

  5. Creatinine Diffusion Modeling in Capacitive Sensors

    Science.gov (United States)

    Mohabbati-Kalejahi, Elham; Azimirad, Vahid; Bahrami, Manouchehr

    2016-12-01

    In this paper, creatinine diffusion in capacitive sensors is discussed. The factors influencing the response time of creatinine biosensors are mathematically formulated and then three novel approaches for decreasing the response time are presented. At first, a piezoelectric actuator is used to vibrate the microtube that contains the blood sample, in order to reduce the viscosity of blood, and thus to increase the coefficient of diffusion. Then, the blood sample is assumed to be pushed through a porous medium, and the relevant conditions are investigated. Finally, the effect of the dentate shape of dielectric on response time is studied. The algorithms and the mathematical models are presented and discussed, and the results of simulations are illustrated. The response times for the first, second and third method are 60, 0.036 and about 31 s, respectively. It is also found that pumping results in very fast responses.

  6. [Wireless ECG measurement system with capacitive coupling].

    Science.gov (United States)

    Aleksandrowicz, Adrian; Walter, Marian; Leonhardt, Steffen

    2007-04-01

    This paper describes a measurement system that captures an electrocardiogram (ECG) using capacitively coupled electrodes. The measurement system was integrated into an off-the-shelf office chair (so-called "Aachen SmartChair"). Whereas for classical ECG measurement adhesive is used to attach conductively coupled electrodes to bare skin, the system presented allows ECG measurement through clothing without direct skin contact. Furthermore, a ZigBee communication module was integrated to allow wireless transmission of ECG data to a PC or an ICU patient monitor. For system validation, classical ECG using conductive electrodes was obtained simultaneously. First measurement results, including variations of cloth thickness and material, are presented and some of the system-specific problems of this approach are discussed.

  7. Nonlinear Dynamics of Capacitive Charging and Desalination by Porous Electrodes

    CERN Document Server

    Biesheuvel, P M

    2009-01-01

    The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by super-capacitors, water desalination and purification by capacitive deionization (or desalination), and capacitive extraction of renewable energy from a salinity difference. Here, we present a unified mean-field theory for capacitive charging and desalination by ideally polarizable porous electrodes (without Faradaic reactions or specific adsorption of ions) in the limit of thin double layers (compared to typical pore dimensions). We illustrate the theory in the case of a dilute, symmetric, binary electrolyte using the Gouy-Chapman-Stern (GCS) model of the double layer, for which simple formulae are available for salt adsorption and capacitive charging of the diffuse part of the double layer. We solve the full GCS mean-field theory numerically for realistic parameters in capacitive deionization, and we derive reduced models for two limiting regimes wi...

  8. Study of CMOS integrated signal processing circuit in capacitive sensors

    Institute of Scientific and Technical Information of China (English)

    CAO Yi-jiang; YU Xiang; WANG Lei

    2007-01-01

    A CMOS integrated signal processing circuit based on capacitance resonance principle whose structure is simple in capacitive sensors is designed. The waveform of output voltage is improved by choosing bootstrap reference current mirror with initiate circuit, CMOS analogy switch and positive feedback of double-stage inverter in the circuit. Output voltage of this circuit is a symmetric square wave signal. The variation of sensitive capacitance, which is part of the capacitive sensors, can be denoted by the change of output voltage's frequency. The whole circuit is designed with 1.5 μm P-well CMOS process and simulated by PSpice software.Output frequency varies from 261.05 kHz to 47.93 kHz if capacitance varies in the range of 1PF~15PF. And the variation of frequency can be easily detected using counter or SCU.

  9. Study of High Capacitance Ratios CPW MEMS Shunt Switches

    Institute of Scientific and Technical Information of China (English)

    Jianhai Sun; Dafu Cui

    2006-01-01

    This paper describes a fixed-fixed beam ohmic switch in series with a fixed capacitor as a replacement for a capacitive switch. In this switch, a metal plate deposited on the dielectric ensures perfectly contact with the dielectric layer in the down state. The area size of the metal plate directly influences the capacitance ratio of the switch, as the area size of the metal cap decreases, the capacitance ratio dramatically rises up. The down/up capacitance ratio can exceed 800 times over the conventional designs using the same materials and the equal size. Measurement results show that high capacitance ratio of the switches has a large effect on the isolation, and can actually improve the performance of the switches.

  10. Interface Realisms

    DEFF Research Database (Denmark)

    Pold, Søren

    2005-01-01

    This article argues for seeing the interface as an important representational and aesthetic form with implications for postmodern culture and digital aesthetics. The interface emphasizes realism due in part to the desire for transparency in Human-Computer Interaction (HCI) and partly to the devel......This article argues for seeing the interface as an important representational and aesthetic form with implications for postmodern culture and digital aesthetics. The interface emphasizes realism due in part to the desire for transparency in Human-Computer Interaction (HCI) and partly...... to the development of illusionistic realism within computer graphics and games. The article compares the pragmatic realism of HCI with aesthetic notions of realism in the computer game Max Payne (illusionistic realism), the artist Jodi's game modifications (media realism), and Adrian Ward's software art work......, "Signwave Auto Illustrator" (functional realism)....

  11. MOS Capacitance-Voltage Characteristics Ⅲ.Trapping Capacitance from 2-Charge-State Impurities

    Institute of Scientific and Technical Information of China (English)

    Jie Binbin; Sah Chihtang

    2011-01-01

    Low-frequency and high-frequency capacitance-voltage curves of Metal-Oxide-Semiconductor Capacitors are presented to illustrate giant electron and hole trapping capacitances at many simultaneously present two-charge-state and one-trapped-carrier,or one-energy-level impurity species.Models described include a donor electron trap and an acceptor hole trap,both donors,both acceptors,both shallow energy levels,both deep,one shallow and one deep,and the identical donor and acceptor.Device and material parameters are selected to simulate chemically and physically realizable capacitors for fundamental trapping parameter characterizations and for electrical and optical signal processing applications.

  12. Frequency dependent capacitance and conductance properties of Schottky diode based on rubrene organic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Barış, Behzad, E-mail: behzadbaris@gmail.com

    2013-10-01

    Al/rubrene/p-Si Schottky diode has been fabricated by forming a rubrene layer on p type Si by using the spin coating method. The frequency dependent capacitance–voltage (C–V–f) and conductance–voltage (G–V–f) characteristics of Al/rubrene/p-Si Schottky diyotes has been investigated in the frequency range of 5 kHz–500 kHz at room temperature. The C–V plots show a peak for each frequency. The capacitance of the device decreased with increasing frequency. The decrease in capacitance results from the presence of interface states. The plots of series resistance–voltage (R{sub s}−V) gave a peak in the depletion region at all frequencies. The density of interface states (N{sub ss}) and relaxation time (τ) distribution profiles as a function of applied voltage bias have been determined from the C–V and G–V measurements. The values of the N{sub ss} and τ have been calculated in the ranges of 8.37×10{sup 11}–4.85×10{sup 11} eV{sup −1} cm{sup −2} and 5.17×10{sup −6}–1.02×10{sup −5} s, respectively.

  13. Sensitivity enhancement of capacitive tumor necrosis factor-α detection by deposition of nanoparticles on interdigitated electrode

    Science.gov (United States)

    Yagati, Ajay Kumar; Park, Jinsoo; Kim, Jungsuk; Ju, Heongkyu; Chang, Keun-A.; Cho, Sungbo

    2016-06-01

    An interdigitated electrodes (IDE) modified with gold nanoparticles (AuNPs) was fabricated to enhance the capacitive detection of tumor necrosis factor-α (TNF-α) and compared with a bare IDE. A TNF-α immunosensor was developed by covalently conjugating TNF-α antibodies with 3-mercaptopropionic acid by a carbodiimide/N-hydroxysuccinimide reaction on the AuNP/IDE. After the application of human serum samples containing various concentrations of TNF-α to the sensing electrode, changes in both the impedance spectrum and the electrode interfacial capacitance were measured. The capacitance changes were dependent on the TNF-α concentration in the range of 1 pg ml-1 to 10 ng ml-1, and the device had the calculated detection limit of 0.83 pg ml-1. The developed AuNP/IDE-based immunosensor was successfully used for the capacitive detection of the binding of TNF-α to its antibody, and was found to be feasible for the analysis of TNF-α in human blood serum.

  14. Characterization of electrical and mechanical activities of rabbit uterus associated with the presence of capacitated and non-capacitated spermatozoa

    Directory of Open Access Journals (Sweden)

    J.F. Lazcano-Reyes

    2013-12-01

    Full Text Available To investigate the effects capacitated spermatozoa may exert upon motility of the rabbit uterus, both contractility and electrical activity (frequency and intensity were measured in 3 distinctive uterine segments of anaesthetized does: horn (UH, uterotubal junction (UTJ and tube (UT after 1 natural mating, 2 infusion of either seminal plasma or PBS, 3 infusion of either capacitated or non-capacitated spermatozoa. Basal values were: 17.1, 15.7, 16.4 g (contractility, P>0.05; 3.5, 3.5, 3.4 Hz (frequency, P>0.05; 0.49, 0.50, 0.57 μV (intensity, P>0.05 for UH, UTJ, UT, respectively. Seminal plasma caused an increase (P<0.05 in the UH contractility: 26.3 vs. 11.7 (natural mating and 17.0 g (PBS; it also caused a decrease (P<0.05 in electrical intensity at the UTJ: 0.24 vs. 0.67 (natural mating and 0.58 μV (PBS. The presence of either capacitated or non-capacitated spermatozoa caused no changes in contractility and electrical frequency in any of the uterine segments. However, there was a change in electrical intensity at UTJ (0.37 vs. 0.57 μV for non-capacitated and capacitated spermatozoa, respectively; P<0.05. There were also differences between segments by treatment: UTJ (0.37 vs. UT (0.59 μV for non-capacitated; UH (0.46 vs. UT (0.71 μV for capacitated spermatozoa (P<0.05. In conclusion, use of this experimental model showed that uterine electrical activity was slightly modified by the presence of capacitated spermatozoa.

  15. Concept of software interface for BCI systems

    Science.gov (United States)

    Svejda, Jaromir; Zak, Roman; Jasek, Roman

    2016-06-01

    Brain Computer Interface (BCI) technology is intended to control external system by brain activity. One of main part of such system is software interface, which carries about clear communication between brain and either computer or additional devices connected to computer. This paper is organized as follows. Firstly, current knowledge about human brain is briefly summarized to points out its complexity. Secondly, there is described a concept of BCI system, which is then used to build an architecture of proposed software interface. Finally, there are mentioned disadvantages of sensing technology discovered during sensing part of our research.

  16. Biomimetic Olfactory Sensing System Based on Brain-Machine Interface and Olfactory Decoding%基于脑-机接口和嗅觉解码的仿生气味识别系统

    Institute of Scientific and Technical Information of China (English)

    董琪; 秦臻; 胡靓; 庄柳静; 张斌; 王平

    2015-01-01

    Mammalian olfactory systems have merits of higher sensitivity, selectivity and faster response than current electronic nose systems based on chemical sensor array in odor recognition. The purpose of this study is to develop a biomimetic olfactory sensing system based on brain-machine interface technology for odor detection in vivo electrophysiological measurements of olfactory bulb. In this work, extracellular potentials of mitral/tufted cells in olfactory bulb were recorded by implanted 16-channel microwire electrode arrays. The odor-evoked response signals were analyzed. We found that neural activities of different neurons showed visible different firing patterns in both temporal features and rate features when stimulated by different small molecular odorants. Odors were classified by an algorithm based on population vector similarity and support vector machine. The results suggest that the novel bioelectonic nose is sensitive to odorant stimuli. With the development of BMI and olfactory decoding methods, we believe that this system will represent emerging and promising platforms for wide applications in medical diagnosis and security fields.%为了探讨利用生物嗅觉传感系统进行气味识别的可行性,提出了一种基于脑-机接口的仿生气味识别系统。该系统利用大鼠嗅觉感受细胞作为气味敏感传感单元,使用16通道植入式微丝电极记录和分析具有气味刺激特征的嗅球僧帽细胞电位响应信号。实验结果显示,该系统对气味具有高度敏感性,通过一定模式识别处理算法,不同的气味刺激具有较好的区分性,证明了该系统有望应用于气味的检测和识别。

  17. Bloch inductance in small-capacitance Josephson junctions.

    Science.gov (United States)

    Zorin, A B

    2006-04-28

    We show that the electrical impedance of a small-capacitance Josephson junction also includes, in addition to the capacitive term -i/(omega)CB, an inductive term i(omega)LB. Similar to the known Bloch capacitance CB(q), the Bloch inductance LB(q) also depends periodically on the quasicharge, q, and its maximum value achieved at q=e(mod 2e) always exceeds the value of the Josephson inductance of this junction LJ(phi) at fixed phi=0. The effect of the Bloch inductance on the dynamics of a single junction and a one-dimensional array is described.

  18. Designing Interfaces

    CERN Document Server

    Tidwell, Jenifer

    2010-01-01

    Despite all of the UI toolkits available today, it's still not easy to design good application interfaces. This bestselling book is one of the few reliable sources to help you navigate through the maze of design options. By capturing UI best practices and reusable ideas as design patterns, Designing Interfaces provides solutions to common design problems that you can tailor to the situation at hand. This updated edition includes patterns for mobile apps and social media, as well as web applications and desktop software. Each pattern contains full-color examples and practical design advice th

  19. Long-time constant-capacitance DLTS investigations of 6H SiC/MOS structures: comparison of dry and wet oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Bassler, M.; Pensl, G. [Erlangen-Nuernberg Univ., Erlangen (Germany). Inst. fuer Angewandte Physik

    1999-07-30

    A long-time constant-capacitance deep level transient spectroscopy (LT-CC-DLTS) method has been established to investigate the energy distribution D{sub it} and the capture-cross-section {sigma}{sub n/p} of states at the interface of 6H SiC/MOS structures. A comparison of dry and wet oxidation (1120 C) reveals a change in the distribution of interface states and a different magnitude of capture-cross-sections indicating that the interface states consist of at least two types of defects. (orig.)

  20. Pick-and-place process for sensitivity improvement of the capacitive type CMOS MEMS 2-axis tilt sensor

    Science.gov (United States)

    Chang, Chun-I.; Tsai, Ming-Han; Liu, Yu-Chia; Sun, Chih-Ming; Fang, Weileun

    2013-09-01

    This study exploits the foundry available complimentary metal-oxide-semiconductor (CMOS) process and the packaging house available pick-and-place technology to implement a capacitive type micromachined 2-axis tilt sensor. The suspended micro mechanical structures such as the spring, stage and sensing electrodes are fabricated using the CMOS microelectromechanical systems (MEMS) processes. A bulk block is assembled onto the suspended stage by pick-and-place technology to increase the proof-mass of the tilt sensor. The low temperature UV-glue dispensing and curing processes are employed to bond the block onto the stage. Thus, the sensitivity of the CMOS MEMS capacitive type 2-axis tilt sensor is significantly improved. In application, this study successfully demonstrates the bonding of a bulk solder ball of 100 µm in diameter with a 2-axis tilt sensor fabricated using the standard TSMC 0.35 µm 2P4M CMOS process. Measurements show the sensitivities of the 2-axis tilt sensor are increased for 2.06-fold (x-axis) and 1.78-fold (y-axis) after adding the solder ball. Note that the sensitivity can be further improved by reducing the parasitic capacitance and the mismatch of sensing electrodes caused by the solder ball.

  1. Instabilities in a capacitively coupled oxygen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Küllig, C., E-mail: kuellig@physik.uni-greifswald.de; Wegner, Th., E-mail: physics@thwegner.com; Meichsner, J., E-mail: meichsner@physik.uni-greifswald.de [Institute of Physics, University of Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany)

    2015-04-15

    Periodic fluctuations in the frequency range from 0.3 to 3 kHz were experimentally investigated in capacitively coupled radio frequency (13.56 MHz) oxygen plasma. The Gaussian beam microwave interferometry directly provides the line integrated electron density fluctuations. A system of two Langmuir probes measured the floating potential spatially (axial, radial) and temporally resolved. Hence, the floating potential fluctuation development is mapped within the discharge volume and provides a kind of discharge breathing and no wave propagation. Finally, it was measured the optical emission pattern of atomic oxygen during the fluctuation as well as the RF phase resolved optical emission intensity at selected phase position of the fluctuation by an intensified charge-coupled device camera. The deduced excitation rate pattern reveals the RF sheath dynamics and electron heating mechanisms, which is changing between low and high electronegativity during a fluctuation cycle. A perturbation calculation was taken into account using a global model with 15 elementary collision processes in the balance equations for the charged plasma species (O{sub 2}{sup +}, e, O{sup −}, O{sub 2}{sup −}) and a harmonic perturbation. The calculated frequencies agree with the experimentally observed frequencies. Whereby, the electron attachment/detachment processes are important for the generation of this instability.

  2. Design Considerations in Capacitively Coupled Plasmas

    Science.gov (United States)

    Song, Sang-Heon; Ventzek, Peter; Ranjan, Alok

    2015-11-01

    Microelectronics industry has driven transistor feature size scaling from 10-6 m to 10-9 m during the past 50 years, which is often referred to as Moore's law. It cannot be overstated that today's information technology would not have been so successful without plasma material processing. One of the major plasma sources for the microelectronics fabrication is capacitively coupled plasmas (CCPs). The CCP reactor has been intensively studied and developed for the deposition and etching of different films on the silicon wafer. As the feature size gets to around 10 nm, the requirement for the process uniformity is less than 1-2 nm across the wafer (300 mm). In order to achieve the desired uniformity, the hardware design should be as precise as possible before the fine tuning of process condition is applied to make it even better. In doing this procedure, the computer simulation can save a significant amount of resources such as time and money which are critical in the semiconductor business. In this presentation, we compare plasma properties using a 2-dimensional plasma hydrodynamics model for different kinds of design factors that can affect the plasma uniformity. The parameters studied in this presentation include chamber accessing port, pumping port, focus ring around wafer substrate, and the geometry of electrodes of CCP.

  3. Locating Depots for Capacitated Vehicle Routing

    CERN Document Server

    Goertz, Inge Li

    2011-01-01

    We study a location-routing problem in the context of capacitated vehicle routing. The input is a set of demand locations in a metric space and a fleet of k vehicles each of capacity Q. The objective is to locate k depots, one for each vehicle, and compute routes for the vehicles so that all demands are satisfied and the total cost is minimized. Our main result is a constant-factor approximation algorithm for this problem. To achieve this result, we reduce to the k-median-forest problem, which generalizes both k-median and minimum spanning tree, and which might be of independent interest. We give a (3+c)-approximation algorithm for k-median-forest, which leads to a (12+c)-approximation algorithm for the above location-routing problem, for any constant c>0. The algorithm for k-median-forest is just t-swap local search, and we prove that it has locality gap 3+2/t; this generalizes the corresponding result known for k-median. Finally we consider the "non-uniform" k-median-forest problem which has different cost ...

  4. An uncooled capacitive sensor for IR detection

    Science.gov (United States)

    Siebke, Georg; Gerngroß, Kathrin; Holik, Peter; Schmitz, Sam; Rohloff, Markus; Tätzner, Simon; Steltenkamp, Siegfried

    2014-06-01

    The beetle Melanophila acuminata detects forest fires from distances as far as 80 miles away. To accomplish this, the beetle uses highly specific IR receptors with a diameter of approximately 15 μm. These receptors are mechanoreceptors that detect deformations induced by the absorption of radiation. Although the detection mechanism is understood in principle, it is still unclear how the beetle reaches such high sensitivity. In this work, we present the biomimetic approach of an uncooled IR sensor based on the beetle's receptors. This sensor is based on a fluid-filled pressure cell and operates at room temperature. Upon absorbing IR radiation, the fluid heats up and expands. The expanding fluid deflects one electrode of a plate capacitor. By measuring the change in capacitance, the volume increase and the absorbed energy can be inferred. To prevent the risk of damage at high energy absorption, a compensation mechanism is presented in this work. The mechanism prevents large but slow volume changes inside the pressure cell by a microfluidic connection of the pressure cell with a compensation chamber. The channel and the compensation chamber act as a microfluidic low-pass filter and do not affect the overall sensitivity above an appropriate cut-off frequency. Using MEMS technology, we are able to incorporate the complete system into a silicon chip with an area of a few mm2. Here, we show a proof-of-concept and first measurements of the sensor.

  5. Electroactive polymers for sensing

    Science.gov (United States)

    2016-01-01

    Electromechanical coupling in electroactive polymers (EAPs) has been widely applied for actuation and is also being increasingly investigated for sensing chemical and mechanical stimuli. EAPs are a unique class of materials, with low-moduli high-strain capabilities and the ability to conform to surfaces of different shapes. These features make them attractive for applications such as wearable sensors and interfacing with soft tissues. Here, we review the major types of EAPs and their sensing mechanisms. These are divided into two classes depending on the main type of charge carrier: ionic EAPs (such as conducting polymers and ionic polymer–metal composites) and electronic EAPs (such as dielectric elastomers, liquid-crystal polymers and piezoelectric polymers). This review is intended to serve as an introduction to the mechanisms of these materials and as a first step in material selection for both researchers and designers of flexible/bendable devices, biocompatible sensors or even robotic tactile sensing units. PMID:27499846

  6. Testing Interfaces

    DEFF Research Database (Denmark)

    Holbøll, Joachim T.; Henriksen, Mogens; Nilson, Jesper K.;

    1999-01-01

    The wide use of solid insulating materials combinations in combinations has introduced problems in the interfaces between components. The most common insulating materials are cross-linked polyethylene (XLPE), silicone rubber (SIR) and ethylene-propylene rubbers (EPR). Assemblies of these materials...

  7. Gesture Interfaces

    NARCIS (Netherlands)

    Fikkert, F.W.

    2007-01-01

    Take away mouse and keyboard. Now, how do you interact with a computer? Especially one that has a display that is the size of an entire wall. One possibility is through gesture interfaces. Remember Minority Report? Cool stuff, but that was already five years ago.. So, what is already possible now an

  8. Manufacturing Interfaces

    NARCIS (Netherlands)

    Houten, van F.J.A.M.

    1992-01-01

    The paper identifies the changing needs and requirements with respect to the interfacing of manufacturing functions. It considers the manufacturing system, its components and their relationships from the technological and logistic point of view, against the background of concurrent engineering. Desi

  9. Frequency dependent capacitance studies of the CdS/Cu2S thin-film solar cell

    Science.gov (United States)

    Hmurcik, L. V.; Serway, R. A.

    1982-05-01

    The dark capacitance of CdS cells has been measured as a function of both bias voltage and operating signal frequency. Results indicate a frequency dependence of the dark current capacitance which can be attributed to deep trapping states in the bulk CdS and at the interface; these states can be characterized by a time constant in the simple relaxation model. Photocapacitance measurements indicate that hole trapping takes place in a narrow region of the i layer near the Cu2S/CdS junction. The results are interpreted in terms of a frequency-dependent model proposed by Schibli and Milnes (1968). It is shown that the simple planar junction model commonly used to describe the CdS cell is accurate at high frequencies.

  10. The Finite Element Analysis for Parallel-wire Capacitance Probe in Small Diameter Two-phase Flow Pipe

    Institute of Scientific and Technical Information of China (English)

    ZHAI Lusheng; JIN Ningde; GAO Zhongke; HUANG Xu

    2013-01-01

    This paper presents a novel capacitance probe,i.e.,parallel-wire capacitance probe (PWCP),for two-phase flow measurement.Using finite element method (FEM),the sensitivity field of the PWCP is investigated and the optimum sensor geometry is determiend in term of the characterisitc parameters.Then,the response of PWCP for the oil-water stratified fiow is calculated,and it is found the PWCP has better linearity and sensitivity to the variation of water-layer thickness,and is almost independant of the angle between the oil-water interface and the sensor electrode.Finally,the static experiment for oil-water stratified flow is carried out and the calibration method of liquid holdup is presented.

  11. High Voltage Bi-directional Flyback Converter for Capacitive Actuator

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    This paper presents a high voltage DC-DC converter topology for bi-directional energy transfer between a low voltage DC source and a high voltage capacitive load. The topology is a bi-directional flyback converter with variable switching frequency control during the charge mode, and constant...... switching frequency control during the discharge mode. The converter is capable of charging the capacitive load from 24 V DC source to 2.5 kV, and discharges it to 0 V. The flyback converter has been analyzed in detail during both charge and discharge modes, by considering all the parasitic elements...... in the converter, including the most dominating parameters of the high voltage transformer viz., self-capacitance and leakage inductance. The specific capacitive load for this converter is a dielectric electro active polymer (DEAP) actuator, which can be used as an effective replacement for conventional actuators...

  12. Topology Optimization of Stressed Capacitive RF MEMS Switches

    DEFF Research Database (Denmark)

    Philippine, Mandy A.; Sigmund, Ole; Rebeiz, Gabriel M.

    2013-01-01

    Geometry design can improve a capacitive radio-frequency microelectromechanical system switch's reliability by reducing the impacts of intrinsic biaxial stresses and stress gradients on the switch's membrane. Intrinsic biaxial stresses cause stress stiffening, whereas stress gradients cause out...

  13. A Review of High Voltage Drive Amplifiers for Capacitive Actuators

    DEFF Research Database (Denmark)

    Huang, Lina; Zhang, Zhe; Andersen, Michael A. E.

    2012-01-01

    This paper gives an overview of the high voltage amplifiers, which are used to drive capacitive actuators. The amplifiers for both piezoelectric and DEAP (dielectric electroactive polymer) actuator are discussed. The suitable topologies for driving capacitive actuators are illustrated in detail, ......, including linear as well as switched mode amplifiers. In the past much attention has been paid on the driver for piezoelectric actuator. As DEAP is a type of new material, there is not much literature reference for it.......This paper gives an overview of the high voltage amplifiers, which are used to drive capacitive actuators. The amplifiers for both piezoelectric and DEAP (dielectric electroactive polymer) actuator are discussed. The suitable topologies for driving capacitive actuators are illustrated in detail...

  14. Voidage measurement based on genetic algorithm and electrical capacitance tomography

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-wei; WANG Bao-liang; HUANG Zhi-yao; LI Hai-qing

    2005-01-01

    A new voidage measurement method based on electrical capacitance tomography (ECT) technique, Genetic Algorithm (GA) and Partial Least Square (PLS) method was proposed. The voidage measurement model, linear capacitance combination, was developed to measure on-line voidage. GA and PLS method were used to determine the coefficients of the voidage measurement model. GA was used to explore the optimal capacitance combination which gave significant contribution to the voidage measurement. PLS method was applied to determine the weight coefficient of the contribution of each capacitance to the voidage measurement. Flow pattern identification result was introduced to improve the voidage measurement accuracy. Experimental results showed that the proposed voidage measurement method is effective and that the measurement accuracy is satisfactory.

  15. Fringe Capacitance of a Parallel-Plate Capacitor.

    Science.gov (United States)

    Hale, D. P.

    1978-01-01

    Describes an experiment designed to measure the forces between charged parallel plates, and determines the relationship among the effective electrode area, the measured capacitance values, and the electrode spacing of a parallel plate capacitor. (GA)

  16. Structure and Capacitance of Electrical Double Layers inside Micropores

    Science.gov (United States)

    Feng, Guang; Qiao, Rui; Huang, Jingsong; Sumpter, Bobby G.; Meunier, Vincent

    2010-03-01

    Recent experiments indicate that the specific capacitance of micropores (diameter less than 2nm) increases anomalously as the pore size decreases^[1]. To understand the physical origin of this discovery, we performed a series of molecular dynamics simulations to study the electrical double layers (EDLs) in micropores with different shapes (tube vs slit) and pore sizes (0.668nm - 3.342nm). Several different aqueous electrolytes (K^+, Na^+, Cl^-, and F^- in water) were used in these micropores. We quantified the structure of EDLs inside the pores, and computed the capacitance of EDLs. The scaling of capacitance shows a qualitative agreement with the experimental observations. We attribute the anomalous enhancement of capacitance in micropores to the short-range ionelectrode and ionsolvent interactions.[1] J. Chmiola, G. Yushin, Y. Gogotsi, C. Portet, P. Simon, and P.L. Taberna, Science 2006, 313, 1760.

  17. Prostaglandin modulation of mouse and human sperm capacitation.

    Science.gov (United States)

    Herrero, M B; Viggiano, J M; Boquet, M; Gimeno, M A

    1997-09-01

    To determine whether prostaglandins produce a capacitation and/or acrosome reaction, the effect of prostaglandins on capacitated mouse spermatozoa and the effect of prostaglandin pre-incubation on human and mouse spermatozoa were studied. Prostaglandins did not induce an acrosome reaction in capacitated mouse sperm. PGE1 pre-incubation in a protein-free medium enhanced acrosome loss of mouse sperm challenged with A-23187 or solubilized mouse zona pellucida. Human sperm were pre-incubated in media containing prostaglandins, and an acrosome reaction was induced with calcium ionophore or human follicular fluid. PGE1 pre-incubation enhanced acrosome loss by human sperm when the action was induced with calcium ionophore, but had no effect on follicular fluid induction. We conclude that PGE1 acts as a capacitating factor in vitro for mouse spermatozoa, and enhances acrosome-reaction induction with calcium ionophore in human spermatozoa.

  18. Electrochemical sensing carcinogens in beverages

    CERN Document Server

    Zia, Asif Iqbal

    2016-01-01

    This book describes a robust, low-cost electrochemical sensing system that is able to detect hormones and phthalates – the most ubiquitous endocrine disruptor compounds – in beverages and is sufficiently flexible to be readily coupled with any existing chemical or biochemical sensing system. A novel type of silicon substrate-based smart interdigital transducer, developed using MEMS semiconductor fabrication technology, is employed in conjunction with electrochemical impedance spectroscopy to allow real-time detection and analysis. Furthermore, the presented interdigital capacitive sensor design offers a sufficient penetration depth of the fringing electric field to permit bulk sample testing. The authors address all aspects of the development of the system and fully explain its benefits. The book will be of wide interest to engineers, scientists, and researchers working in the fields of physical electrochemistry and biochemistry at the undergraduate, postgraduate, and research levels. It will also be high...

  19. Capacitive Coupling in Double-Circuit Transmission Lines

    Directory of Open Access Journals (Sweden)

    Zdenka Benesova

    2004-01-01

    Full Text Available The paper describes an algorithm for calculation of capacitances and charges on conductors in systems with earth wires and in double-circuit overhead lines with respect to phase arrangement. A balanced voltage system is considered. A suitable transposition of individual conductors enables to reduce the electric and magnetic fields in vicinity of overhead lines and to limit the inductive and capacitive linkage. The procedure is illustrated on examples the results of which lead to particular recommendations for designers.

  20. Current Progress of Capacitive Deionization for Removal of Pollutant Ions

    Science.gov (United States)

    Gaikwad, Mahendra S.; Balomajumder, Chandrajit

    2016-08-01

    A mini review of a recently developing water purification technology capacitive deionization (CDI) applied for removal of pollutant ions is provided. The current progress of CDI for removal of different pollutant ions such as arsenic, fluoride, boron, phosphate, lithium, copper, cadmium, ferric, and nitrate ions is presented. This paper aims at motivating new research opportunities in capacitive deionization technology for removal of pollutant ions from polluted water.

  1. Capacitance Variation of Electrolyte-Gated Bilayer Graphene Based Transistors

    OpenAIRE

    Hediyeh Karimi; Rubiyah Yusof; Mohammad Taghi Ahmadi; Mehdi Saeidmanesh; Meisam Rahmani; Elnaz Akbari; Wong King Kiat

    2013-01-01

    Quantum capacitance of electrolyte-gated bilayer graphene field-effect transistors is investigated in this paper. Bilayer graphene has received huge attention due to the fact that an energy gap could be opened by chemical doping or by applying external perpendicular electric field. So, this extraordinary property can be exploited to use bilayer graphene as a channel in electrolyte-gated field-effect transistors. The quantum capacitance of bi-layer graphene with an equivalent circuit is presen...

  2. Modeling high-frequency capacitance in SOI MOS capacitors

    Science.gov (United States)

    Łukasiak, Lidia; Jasiński, Jakub; Beck, Romuald B.; Ikraiam, Fawzi A.

    2016-12-01

    This paper presents a model of high frequency capacitance of a SOI MOSCAP. The capacitance in strong inversion is described with minority carrier redistribution in the inversion layer taken into account. The efficiency of the computational process is significantly improved. Moreover, it is suitable for the simulation of thin-film SOI structures. It may also be applied to the characterization of non-standard SOI MOSCAPS e.g. with nanocrystalline body.

  3. Metalless electrodes for capacitively coupled contactless conductivity detection on electrophoresis microchips.

    Science.gov (United States)

    Duarte Junior, Gerson F; Fracassi da Silva, José Alberto; Mendonça Francisco, Kelliton José; do Lago, Claudimir Lucio; Carrilho, Emanuel; Coltro, Wendell K T

    2015-08-01

    This paper describes the use of ionic solutions as sensing electrodes for capacitively coupled contactless conductivity detection on electrophoresis microchips. Initially, two channels were engraved in a PMMA holder by using a CO2 laser system and sealed with a thin adhesive membrane. PDMS electrophoresis chips were fabricated by soft lithography and reversibly sealed against the polymer membrane. Different ionic solutions were investigated as metalless electrodes. The electrode channels were filled with KCl solutions prepared in conductivity values from approximately 10 to 40 S/m. The best analytical response was achieved using the KCl solution with 21.9 S/m conductivity (2 mol/L). Besides KCl, we also tested NaCl and LiCl solutions for actuating as detection electrodes. Taking into account the same electrolyte concentration (2 mol/L), the best response was recorded with KCl solution due to its higher ionic conductivity. The optimum operating frequency (400 kHz) and the best sensing electrode (2 mol/L KCl) were used to monitor electrophoretic separations of a mixture containing K(+) , Na(+) , and Li(+) . The use of liquid solutions as sensing electrodes for capacitively coupled contactless conductivity detection measurements has revealed great performance to monitor separations on chip-based devices, avoiding complicated fabrication schemes to include metal deposition and encapsulation of electrodes. The LOD values were estimated to be 28, 40, and 58 μmol/L for K(+) , Na(+) , and Li(+) , respectively, what is comparable to that of conventional metal electrodes. When compared to the use metal electrodes, the proposed approach offers advantages regarding the easiness of fabrication, simplicity, and lower cost per device.

  4. Optimizing the Materials Response in Humidity Capacitive Sensors

    Directory of Open Access Journals (Sweden)

    Elham Noroozi Afshar

    2015-10-01

    Full Text Available The number of humidity outputs on the cap of a cylindrical capacitance sensor is optimized by designing three different probes with direct and indirect windows. The time interval is measured within which 30-70 % humidity can influence the dielectric constant and conductivity of the capacitance when exposed to a range of relative humidity. It is then compared with a simple set-up including a simplified equivalent circuit. The direct probes had four and double outputs on the window of the cylindrical capacitive sensor while the indirect probe had a thin plastic layer only. We observed that the dielectric constant and its conductivity depend closely to the humidity outgoing pathway and also to the increasing rate of humidity between the capacitance plates. The final variation in the materials properties alters the capacitance of the sensor which is measured simply by a LCR. This technique presents a simple method for tracking the recovery and reliability of the humidity sensors over time and assists in optimizing and controlling the materials response to the relative environment humidity. As a result, by controlling the environment humidity rate (0.02 %/s., we could measure the increment rate of capacitance with accuracy of 0.01 pf/%.

  5. Simulation Study on Quantum Capacitances of Graphene Nanoribbon VLSI Interconnects

    Science.gov (United States)

    Dutta, Arin; Rahman, Silvia; Nandy, Turja; Mahmood, Zahid Hasan

    2016-03-01

    In this paper, study on the capacitive effects of Graphene nanoribbon (GNR) in VLSI interconnect has been studied as a function of GNR width, Fermi function and gate voltage. The quantum capacitance of GNR has been simulated in terms of Fermi function for three different values of insulator thickness — 1.5nm, 2nm and 2.5nm. After that, quantum capacitance is studied in both degenerate and nondegenerate region with respect to Fermi function and gate voltage of range 1-5V. Then, the total capacitance of GNR is studied as a function of gate voltage of -2-5V range at degenerate and nondegenerate regions, where width of GNR is considered 4nm. Finally, the total capacitance of GNR is studied in both regions with varying GNR width, considering fixed gate voltage of 3V. After analyzing these simulations, it has been found that GNR in degenerate region shows nearly steady capacitance under a certain applied gate voltage.

  6. Remote Sensing

    CERN Document Server

    Khorram, Siamak; Koch, Frank H; van der Wiele, Cynthia F

    2012-01-01

    Remote Sensing provides information on how remote sensing relates to the natural resources inventory, management, and monitoring, as well as environmental concerns. It explains the role of this new technology in current global challenges. "Remote Sensing" will discuss remotely sensed data application payloads and platforms, along with the methodologies involving image processing techniques as applied to remotely sensed data. This title provides information on image classification techniques and image registration, data integration, and data fusion techniques. How this technology applies to natural resources and environmental concerns will also be discussed.

  7. Porous NiCo2O4 nanosheets/reduced graphene oxide composite: facile synthesis and excellent capacitive performance for supercapacitors.

    Science.gov (United States)

    Ma, Lianbo; Shen, Xiaoping; Ji, Zhenyuan; Cai, Xiaoqing; Zhu, Guoxing; Chen, Kangmin

    2015-02-15

    A composite with porous NiCo2O4 nanosheets attached on reduced graphene oxide (RGO) sheets is synthesized through a facile solution-based method combined with a simple thermal annealing process. The capacitive performances of the as-prepared NiCo2O4/RGO (NCG) composites as electrode materials are investigated. It is found that the NCG composites exhibit a high specific capacitance up to 1186.3 F g(-1) at the current density of 0.5 A g(-1), and superior cycling stability with about 97% of the initial capacitance after 100 cycles. The greatly enhanced capacitive performance of the NCG electrode can be attributed to the existence of RGO support, which serves as both conductive channels and active interface. The approach used in the synthesis provides a facile route for preparing graphene-binary metal oxide electrode materials. The remarkable capacitive performance of NCG composites will undoubtedly make them be attractive for high performance energy storage applications.

  8. Novel integration of ultrathin Al2O3 with low-k dielectric as bilayer liner for capacitance optimization and stress mitigation in Cu through-silicon-via

    Science.gov (United States)

    Zhang, Lin; Li, Hong Yu; Shang, Yang; Yoo, Woosik; Yu, Hao; Tan, Chuan Seng

    2016-04-01

    Through-silicon-via (TSV) used in three-dimensional (3D) stacked dies must present small electrical parasitic, such as capacitance, to allow for low latency signal transmission. Stable TSV capacitance is desired to overcome the spatial circuit performance variation caused by non-uniform hot-spot heating. In this work, a novel combination of low-k with ultrathin Al2O3 bilayer liner is successfully integrated in the TSV. The TSV capacitance is reduced by ˜26% as compared to plasma-enhanced tetrahydrothosilicate (PETEOS) oxide liner. Stable TSV capacitance within the operating voltage of interest (˜0-5 V) is achieved by operating the TSV in a stable accumulation capacitance region. The positive shift in the flat-band voltage (ΔV FB = +19 V) is achieved by utilizing Al2O3-induced negative fixed charge (|Q f| = 1.3 × 1012 cm-2) at the Si/low-k interface. Leakage current density of the bilayer liner is improved to a level comparable with the PETEOS oxide liner post annealing [forming gas (N2/H2) at 350 °C for 2 h or 400 °C for 0.5 h]. Low-k material with a smaller elastic modulus improves the thermo-mechanical stress exerted on the surrounding Si substrate compared with PETEOS oxide.

  9. Interface learning

    DEFF Research Database (Denmark)

    Thorhauge, Sally

    2014-01-01

    for students. The research focuses on the learning that the students experience in the interface of the two learning environments: The formal learning environment of the upper secondary school and the informal learning environment of the museum. Focus is also on the learning that the teachers and museum......"Interface learning - New goals for museum and upper secondary school collaboration" investigates and analyzes the learning that takes place when museums and upper secondary schools in Denmark work together in local partnerships to develop and carry out school-related, museum-based coursework...... professionals experience as a result of their collaboration. The dissertation demonstrates how a given partnership’s collaboration affects the students’ learning experiences when they are doing the coursework. The dissertation presents findings that museum-school partnerships can use in order to develop...

  10. Museets interface

    DEFF Research Database (Denmark)

    Pold, Søren

    2007-01-01

    Søren Pold gør sig overvejelser med udgangspunkt i museumsprojekterne Kongedragter.dk og Stigombord.dk. Han argumenterer for, at udviklingen af internettets interfaces skaber nye måder at se, forstå og interagere med kulturen på. Brugerne får nye medievaner og perceptionsmønstre, der må medtænkes i...

  11. Fabrication and application of a wireless inductance-capacitance coupling microsensor with electroplated high permeability material NiFe

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y H; Chang, I N [Ph. D. Program in Electrical and Communications Engineering, Feng-Chia University, Taichung 40724, Taiwan (China); Chang, H C; Lai, C C, E-mail: hcchang@fcu.edu.tw [Department of Automatic Control Engineering, Feng-Chia University, Taichung 40724, Taiwan (China)

    2011-01-01

    A fully integrated wireless inductance-capacitance (LC) coupling microsensor was designed and fabricated by MEMS technology. The sensing loop was formed by connecting a deformable parallel-plated capacitor and a planar spiral inductor with a Ni(80)Fe(20) core. Polyimide and PMMA were used to isolate and package the devices. Typical dimension of the sensors was 5 x 5 mm{sup 2} x 0.77 mm. Different electroplated inductive coils (30, 40, and 60 turns) were fabricated to connect with a 4 x 4 mm{sup 2} plate capacitor in series. The LC sensing module for measuring liquid-level induced frequency responses was setup. Experimental results show that frequency response decreased as liquid level increased and sensitivity is about 7.01 kHz/cm with deviation less than 2%. Developed planar spiral inductor with high permeability magnetic core can provide a wide range of frequency variation in LC sensing applications.

  12. Health Participatory Sensing Networks

    Directory of Open Access Journals (Sweden)

    Andrew Clarke

    2014-01-01

    Full Text Available The use of participatory sensing in relation to the capture of health-related data is rapidly becoming a possibility due to the widespread consumer adoption of emerging mobile computing technologies and sensing platforms. This has the potential to revolutionize data collection for population health, aspects of epidemiology, and health-related e-Science applications and as we will describe, provide new public health intervention capabilities, with the classifications and capabilities of such participatory sensing platforms only just beginning to be explored. Such a development will have important benefits for access to near real-time, large-scale, up to population-scale data collection. However, there are also numerous issues to be addressed first: provision of stringent anonymity and privacy within these methodologies, user interface issues, and the related issue of how to incentivize participants and address barriers/concerns over participation. To provide a step towards describing these aspects, in this paper we present a first classification of health participatory sensing models, a novel contribution to the literature, and provide a conceptual reference architecture for health participatory sensing networks (HPSNs and user interaction example case study.

  13. A cost-effective self-sensing biosensor for detection of biological species at ultralow concentrations

    Science.gov (United States)

    Faegh, Samira; Jalili, Nader; Yavuzcetin, Ozgur; Nagesha, Dattatri; Kumar, Rajiv; Sridhar, Srinivas

    2013-06-01

    the capacitance of the total interface thus changing the resonance frequency of the circuit. The amount of shift in the measured circuit's resonance frequency provides qualitative and quantitative insight into the amount of target protein concentration. The reported diagnostic platform offers a simple, cost-effective, all-electronics method of detection where the need for any bulky, expensive optical based measurement is eliminated. Utilizing this technique, physiological concentration of glucose as low as 500 nM was measured in liquid media. This sensitivity is significantly higher than what has been previously reported using other mechanical resonance techniques.

  14. Low temperature co-fired ceramic packaging of CMOS capacitive sensor chip towards cell viability monitoring

    Directory of Open Access Journals (Sweden)

    Niina Halonen

    2016-11-01

    Full Text Available Cell viability monitoring is an important part of biosafety evaluation for the detection of toxic effects on cells caused by nanomaterials, preferably by label-free, noninvasive, fast, and cost effective methods. These requirements can be met by monitoring cell viability with a capacitance-sensing integrated circuit (IC microchip. The capacitance provides a measurement of the surface attachment of adherent cells as an indication of their health status. However, the moist, warm, and corrosive biological environment requires reliable packaging of the sensor chip. In this work, a second generation of low temperature co-fired ceramic (LTCC technology was combined with flip-chip bonding to provide a durable package compatible with cell culture. The LTCC-packaged sensor chip was integrated with a printed circuit board, data acquisition device, and measurement-controlling software. The packaged sensor chip functioned well in the presence of cell medium and cells, with output voltages depending on the medium above the capacitors. Moreover, the manufacturing of microfluidic channels in the LTCC package was demonstrated.

  15. Numerical Investigations on Electric Field Characteristics with Respect to Capacitive Detection of Free-Flying Droplets

    Directory of Open Access Journals (Sweden)

    Peter Koltay

    2012-08-01

    Full Text Available In this paper a multi-disciplinary simulation of a capacitive droplet sensor based on an open plate capacitor as transducing element is presented. The numerical simulations are based on the finite volume method (FVM, including calculations of an electric field which changes according to the presence of a liquid droplet. The volume of fluid (VOF method is applied for the simulation of the ejection process of a liquid droplet out of a dispenser nozzle. The simulations were realised using the computational fluid dynamic (CFD software CFD ACE+. The investigated capacitive sensing principle enables to determine the volume of a micro droplet passing the sensor capacitor due to the induced change in capacity. It could be found that single droplets in the considered volume range of 5 nL < Vdrop < 100 nL lead to a linear change of the capacity up to ΔQ < 30 fC. The sensitivity of the focused capacitor geometry was evaluated to be Si = 0.3 fC/nL. The simulation results are validated by experiments which exhibit good agreement.

  16. Imaging metallic samples using electrical capacitance tomography: forward modelling and reconstruction algorithms

    Science.gov (United States)

    Hosani, E. Al; Zhang, M.; Abascal, J. F. P. J.; Soleimani, M.

    2016-11-01

    Electrical capacitance tomography (ECT) is an imaging technology used to reconstruct the permittivity distribution within the sensing region. So far, ECT has been primarily used to image non-conductive media only, since if the conductivity of the imaged object is high, the capacitance measuring circuit will be almost shortened by the conductivity path and a clear image cannot be produced using the standard image reconstruction approaches. This paper tackles the problem of imaging metallic samples using conventional ECT systems by investigating the two main aspects of image reconstruction algorithms, namely the forward problem and the inverse problem. For the forward problem, two different methods to model the region of high conductivity in ECT is presented. On the other hand, for the inverse problem, three different algorithms to reconstruct the high contrast images are examined. The first two methods are the linear single step Tikhonov method and the iterative total variation regularization method, and use two sets of ECT data to reconstruct the image in time difference mode. The third method, namely the level set method, uses absolute ECT measurements and was developed using a metallic forward model. The results indicate that the applications of conventional ECT systems can be extended to metal samples using the suggested algorithms and forward model, especially using a level set algorithm to find the boundary of the metal.

  17. Capacitive micropressure sensors with underneath readout circuit using a standard CMOS process

    Science.gov (United States)

    Chang, Shihchen; Dai, Chingliang; Chiou, Jinghung; Chang, Peizen

    2001-08-01

    A capacitive micropressure sensor with readout circuits on a single chip is fabricated using commercial 0.35micrometers CMOS process technology and post-processing. The main break through feature of the chip is the positioning of its readout circuits under the pressure sensor, allowing the chip to be smaller. Post-processing included anisotropic dry etching and wet etching to remove the sacrificial layer, and the use of PECVD nitride to seal the etching holes of the pressure sensor. The sacrificial layer was the metal 3 layer of the standard 0.35 micrometers CMOS process. In addition, the readout circuit is divided into analog and digital parts, with the digital part being an alternate coupled RS flip- flop with four inverters that sharpened the output wave. Moreover, the analog part is employed switched capacitor methodology. The pressure sensor contained an 8 X 8 sensing cells array, and the total area of the pressure sensor chip is 2mmx2 mm. In addition to illustrating the design and fabrication of the capacitive pressure sensor, this investigation demonstrates the simulation and testing results of the readout circuit.

  18. Numerical investigations on electric field characteristics with respect to capacitive detection of free-flying droplets.

    Science.gov (United States)

    Ernst, Andreas; Mutschler, Klaus; Tanguy, Laurent; Paust, Nils; Zengerle, Roland; Koltay, Peter

    2012-01-01

    In this paper a multi-disciplinary simulation of a capacitive droplet sensor based on an open plate capacitor as transducing element is presented. The numerical simulations are based on the finite volume method (FVM), including calculations of an electric field which changes according to the presence of a liquid droplet. The volume of fluid (VOF) method is applied for the simulation of the ejection process of a liquid droplet out of a dispenser nozzle. The simulations were realised using the computational fluid dynamic (CFD) software CFD ACE+. The investigated capacitive sensing principle enables to determine the volume of a micro droplet passing the sensor capacitor due to the induced change in capacity. It could be found that single droplets in the considered volume range of 5 nL < V(drop) < 100 nL lead to a linear change of the capacity up to ΔQ < 30 fC. The sensitivity of the focused capacitor geometry was evaluated to be S(i) = 0.3 fC/nL. The simulation results are validated by experiments which exhibit good agreement.

  19. Compliment Graphene Oxide Coating on Silk Fiber Surface via Electrostatic Force for Capacitive Humidity Sensor Applications

    Science.gov (United States)

    Han, Kook In; Kim, Seungdu; Lee, In Gyu; Kim, Jong Pil; Kim, Jung-Ha; Hong, Suck Won; Cho, Byung Jin; Hwang, Wan Sik

    2017-01-01

    Cylindrical silk fiber (SF) was coated with Graphene oxide (GO) for capacitive humidity sensor applications. Negatively charged GO in the solution was attracted to the positively charged SF surface via electrostatic force without any help from adhesive intermediates. The magnitude of the positively charged SF surface was controlled through the static electricity charges created on the SF surface. The GO coating ability on the SF improved as the SF’s positive charge increased. The GO-coated SFs at various conditions were characterized using an optical microscope, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and LCR meter. Unlike the intact SF, the GO-coated SF showed clear response-recovery behavior and well-behaved repeatability when it was exposed to 20% relative humidity (RH) and 90% RH alternatively in a capacitive mode. This approach allows humidity sensors to take advantage of GO’s excellent sensing properties and SF’s flexibility, expediting the production of flexible, low power consumption devices at relatively low costs. PMID:28218728

  20. Glucose Sensing

    CERN Document Server

    Geddes, Chris D

    2006-01-01

    Topics in Fluorescence Spectroscopy, Glucose Sensing is the eleventh volume in the popular series Topics in Fluorescence Spectroscopy, edited by Drs. Chris D. Geddes and Joseph R. Lakowicz. This volume incorporates authoritative analytical fluorescence-based glucose sensing reviews specialized enough to be attractive to professional researchers, yet also appealing to the wider audience of scientists in related disciplines of fluorescence. Glucose Sensing is an essential reference for any lab working in the analytical fluorescence glucose sensing field. All academics, bench scientists, and industry professionals wishing to take advantage of the latest and greatest in the continuously emerging field of glucose sensing, and diabetes care & management, will find this volume an invaluable resource. Topics in Fluorescence Spectroscopy Volume 11, Glucose Sensing Chapters include: Implantable Sensors for Interstitial Fluid Smart Tattoo Glucose Sensors Optical Enzyme-based Glucose Biosensors Plasmonic Glucose Sens...

  1. Development of capacitance-based and impedance-based wireless sensors and sensor nodes for structural health monitoring applications

    Science.gov (United States)

    Mascarenas, David D. L.; Flynn, Eric B.; Todd, Michael D.; Overly, Timothy G.; Farinholt, Kevin M.; Park, Gyuhae; Farrar, Charles R.

    2010-06-01

    A field demonstration of a new and hybrid wireless sensing network paradigm for structural health monitoring (SHM) is presented. In this paradigm, both power and data interrogation commands are conveyed via a mobile agent that is sent to each sensor node to perform individual interrogations, which can alleviate several limitations of traditional sensing networks. This paper will discuss such prototype systems, which will be used to interrogate capacitive-based and impedance-based sensors for SHM applications. The capacitive-based wireless sensor node is specifically built to collect peak displacement measurements. In addition, a wireless sensor node for collecting electromechanical impedance data has also been developed. Both sensor nodes are specifically designed to accept various power sources and to be wirelessly triggered on an as-needed basis so that they can be used for the hybrid sensing network approach. The capabilities of these miniaturized and portable devices are demonstrated in the laboratory and the field, which was performed at the Alamosa Canyon Bridge in southern New Mexico.

  2. Negative capacitance for ultra-low power computing

    Science.gov (United States)

    Khan, Asif Islam

    Owing to the fundamental physics of the Boltzmann distribution, the ever-increasing power dissipation in nanoscale transistors threatens an end to the almost-four-decade-old cadence of continued performance improvement in complementary metal-oxide-semiconductor (CMOS) technology. It is now agreed that the introduction of new physics into the operation of field-effect transistors---in other words, "reinventing the transistor'"--- is required to avert such a bottleneck. In this dissertation, we present the experimental demonstration of a novel physical phenomenon, called the negative capacitance effect in ferroelectric oxides, which could dramatically reduce power dissipation in nanoscale transistors. It was theoretically proposed in 2008 that by introducing a ferroelectric negative capacitance material into the gate oxide of a metal-oxide-semiconductor field-effect transistor (MOSFET), the subthreshold slope could be reduced below the fundamental Boltzmann limit of 60 mV/dec, which, in turn, could arbitrarily lower the power supply voltage and the power dissipation. The research presented in this dissertation establishes the theoretical concept of ferroelectric negative capacitance as an experimentally verified fact. The main results presented in this dissertation are threefold. To start, we present the first direct measurement of negative capacitance in isolated, single crystalline, epitaxially grown thin film capacitors of ferroelectric Pb(Zr0.2Ti0.8)O3. By constructing a simple resistor-ferroelectric capacitor series circuit, we show that, during ferroelectric switching, the ferroelectric voltage decreases, while the stored charge in it increases, which directly shows a negative slope in the charge-voltage characteristics of a ferroelectric capacitor. Such a situation is completely opposite to what would be observed in a regular resistor-positive capacitor series circuit. This measurement could serve as a canonical test for negative capacitance in any novel

  3. ZnO(CdS)/CIS/Mo solar cells characterized by modulation capacitance voltage measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sinh, N.D.; Scheer, R.; Kliefoth, K.; Fuessel, W.; Fuhs, W. [Hahn-Meitner-Inst., Berlin (Germany)

    1997-12-31

    From Modulation Capacitance Voltage (MCV) measurements the authors determined a voltage V{sub s} of several hundred mV at the depletion region in CuInS{sub 2} under PV generator and short circuit working conditions. In this solar cell type electron transport through shallow gap states in the CdS interlayer enhances interface recombination which increases the dark current. The CuInSe{sub 2} solar cells show a different behavior. In darkness, electron emission into the depletion region over a barrier of more than 500 mV was measured, and voltage losses while working as PV generator remain nearly constant below 60 mV. The authors interpret these results by a blocking CuInS{sub 2}/Mo contact and a band spike at the CdS/CuInSe{sub 2} junction.

  4. Capacitance-Based Frequency Adjustment of Micro Piezoelectric Vibration Generator

    Directory of Open Access Journals (Sweden)

    Xinhua Mao

    2014-01-01

    Full Text Available Micro piezoelectric vibration generator has a wide application in the field of microelectronics. Its natural frequency is unchanged after being manufactured. However, resonance cannot occur when the natural frequencies of a piezoelectric generator and the source of vibration frequency are not consistent. Output voltage of the piezoelectric generator will sharply decline. It cannot normally supply power for electronic devices. In order to make the natural frequency of the generator approach the frequency of vibration source, the capacitance FM technology is adopted in this paper. Different capacitance FM schemes are designed by different locations of the adjustment layer. The corresponding capacitance FM models have been established. Characteristic and effect of the capacitance FM have been simulated by the FM model. Experimental results show that the natural frequency of the generator could vary from 46.5 Hz to 42.4 Hz when the bypass capacitance value increases from 0 nF to 30 nF. The natural frequency of a piezoelectric vibration generator could be continuously adjusted by this method.

  5. Capacitance and compressibility of heterostructures with strong electronic correlations

    Science.gov (United States)

    Steffen, Kevin; Frésard, Raymond; Kopp, Thilo

    2017-01-01

    Strong electronic correlations related to a repulsive local interaction suppress the electronic compressibility in a single-band model, and the capacitance of a corresponding metallic film is directly related to its electronic compressibility. Both statements may be altered significantly when two extensions to the system are implemented which we investigate here: (i) we introduce an attractive nearest-neighbor interaction V as antagonist to the repulsive onsite repulsion U , and (ii) we consider nanostructured multilayers (heterostructures) assembled from two-dimensional layers of these systems. We determine the respective total compressibility κ and capacitance C of the heterostructures within a strong coupling evaluation, which builds on a Kotliar-Ruckenstein slave-boson technique. Whereas the capacitance C (n ) for electronic densities n close to half-filling is suppressed, illustrated by a correlation induced dip in C (n ) , it may be appreciably enhanced close to a van Hove singularity. Moreover, we show that the capacitance may be a nonmonotonic function of U close to half-filling for both attractive and repulsive V . The compressibility κ can differ from C substantially, as κ is very sensitive to internal electrostatic energies which in turn depend on the specific setup of the heterostructure. In particular, we show that a capacitor with a polar dielectric has a smaller electronic compressibility and is more stable against phase separation than a standard nonpolar capacitor with the same capacitance.

  6. Recent advances in understanding the capacitive storage in microporous carbons

    Energy Technology Data Exchange (ETDEWEB)

    Daffos, B.; Taberna, P.L. [Universite de Toulouse, CIRIMAT, UMR-CNRS 5085, Toulouse (France); Gogotsi, Y. [Department of Materials Science and Engineering, A.J. Drexel Nanotechnology Institute, Drexel University, Philadelphia, PA (United States); Simon, P.

    2010-10-15

    This paper presents a review of our recent work on capacitance of carbide-derived carbons (CDCs). Specific capacitance as high as 14 {mu}F cm{sup -2} or 160 F g{sup -1} was achieved using CDCs with tailored subnanometer pore size, which is significantly higher than 6 {mu}F cm{sup -2} or 100 F g{sup -1} for conventional activated carbons. Such high capacitance was obtained in several types of organic electrolytes with or without solvent. A maximum is obtained for the carbons with the mean pore size close to the bare ion size, ruling out the traditional point of view that mesoporosity is highly required for maximum capacitance. Surprisingly, carbons with subnanometer porosity exhibit high capacitance retention, since only a 10% loss is measured when 6 A g{sup -1} discharge is drawn. These findings show the importance of fitting the ion size with the mean pore size. The double layer theory falls short to explain such charge storage mechanisms at the nanometer scale; thus atomistic modelling is required to find out an alternative charge storage model. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  7. Characterization of Highly Efficient CdTe Thin Film Solar Cells by the Capacitance-Voltage Profiling Technique

    Science.gov (United States)

    Okamoto, Tamotsu; Yamada, Akira; Konagai, Makoto

    2000-05-01

    The electrical properties of highly efficient CdTe thin film solar cells prepared by close-spaced sublimation (CSS) were investigated by capacitance-voltage (C-V) measurement. According to the dependence of the cell performance on the substrate temperature in the CSS process, the open-circuit voltage (Voc) increased with increasing the substrate temperature below 630°C@. The carrier concentration profiles revealed that the net acceptor concentration exponentially increased from the CdS/CdTe interface to the rear and that the acceptor concentration increased with increasing substrate temperature. This result suggests that Voc is improved as a result of the increase in the acceptor concentration.

  8. Calculation of Dielectric Response in Molecular Solids for High Capacitance Organic Dielectrics

    Science.gov (United States)

    Heitzer, Henry Matthew

    The dielectric response of a material is critically important in numerous scientific processes spanning the fields of biology, chemistry, materials science, and physics. While important across these fundamental disciplines, it remains difficult to determine theoretically the dielectric environment of a system. With recent advances in nanotechnology, biochemistry, and molecular electronics, it has become necessary to determine the dielectric response in molecular systems that are difficult to measure experimentally, such as nanoscale interfaces, highly disordered biological environments, or molecular materials that are difficult to synthesize. In these scenarios it is highly advantageous to determine the dielectric response through efficient and accurate calculations. A good example of where a theoretical prediction of dielectric response is critical is in the development of high capacitance molecular dielectrics. Molecular dielectrics offer the promise of cheap, flexible, and mass producible electronic devices when used in conjunction with organic semiconducting materials to form Organic Field Effect Transistors (OFETs). To date, molecular dielectrics suffer from poor dielectric properties resulting in low capacitances. A low capacitance dielectric material requires a much larger power source to operate the device in OFETs, leading to modest device performance. Development of better performing dielectric materials has been hindered due to the time it takes to synthesize and fabricate new molecular materials. An accurate and efficient theoretical technique could drastically decrease this time by screening potential dielectric materials and providing design rules for future molecular dielectrics. Here in, the methodology used to calculate dielectric properties of molecular materials is described. The validity of the technique is demonstrated on model systems, capturing the frequency dependence of the dielectric response and achieving quantitative accuracy compared

  9. Performance of human body communication-based wearable ECG with capacitive coupling electrodes.

    Science.gov (United States)

    Sakuma, Jun; Anzai, Daisuke; Wang, Jianqing

    2016-09-01

    Wearable electrocardiogram (ECG) is attracting much attention in daily healthcare applications, and human body communication (HBC) technology provides an evident advantage in making the sensing electrodes of ECG also working for transmission through the human body. In view of actual usage in daily life, however, non-contact electrodes to the human body are desirable. In this Letter, the authors discussed the ECG circuit structure in the HBC-based wearable ECG for removing the common mode noise when employing non-contact capacitive coupling electrodes. Through the comparison of experimental results, they have shown that the authors' proposed circuit structure with the third electrode directly connected to signal ground can provide an effect on common mode noise reduction similar to the usual drive-right-leg circuit, and a sufficiently good acquisition performance of ECG signals.

  10. Charging the quantum capacitance of graphene with a single biological ion channel.

    Science.gov (United States)

    Wang, Yung Yu; Pham, Ted D; Zand, Katayoun; Li, Jinfeng; Burke, Peter J

    2014-05-27

    The interaction of cell and organelle membranes (lipid bilayers) with nanoelectronics can enable new technologies to sense and measure electrophysiology in qualitatively new ways. To date, a variety of sensing devices have been demonstrated to measure membrane currents through macroscopic numbers of ion channels. However, nanoelectronic based sensing of single ion channel currents has been a challenge. Here, we report graphene-based field-effect transistors combined with supported lipid bilayers as a platform for measuring, for the first time, individual ion channel activity. We show that the supported lipid bilayers uniformly coat the single layer graphene surface, acting as a biomimetic barrier that insulates (both electrically and chemically) the graphene from the electrolyte environment. Upon introduction of pore-forming membrane proteins such as alamethicin and gramicidin A, current pulses are observed through the lipid bilayers from the graphene to the electrolyte, which charge the quantum capacitance of the graphene. This approach combines nanotechnology with electrophysiology to demonstrate qualitatively new ways of measuring ion channel currents.

  11. Estimation of Transformer Winding Capacitances through Frequency Response Analysis - An Experimental Investigation

    Science.gov (United States)

    Shah, Krupa; Ragavan, K.

    2013-10-01

    This article focuses on developing a non-invasive method for determining capacitances using frequency response data. The proposed methodology involves acquiring driving-point impedance of the winding under consideration over wide frequency range. With certain terminal conditions and using the terminal impedance measured at specific frequencies, input and shunt capacitances are determined. For the purpose of estimating series capacitance of the winding, an algorithm is proposed. To demonstrate the capability of the method, initially model coils that have provisions for connecting external capacitances are considered. Then, it is found that the estimated values of capacitances are nearly same as those of connected capacitances. The method is, then, extended to transformer winding, and a capacitive ladder network is constructed. To assess the accuracy of estimation, capacitive voltage distribution is utilized. That is, the voltage distribution in the winding is compared with that of synthesized circuit. A good agreement between those data reveals that the estimated capacitance values are accurate.

  12. Simulating Capacitances to Silicon Quantum Dots: Breakdown of the Parallel Plate Capacitor Model

    Science.gov (United States)

    Thorbeck, Ted; Fujiwara, Akira; Zimmerman, Neil M.

    2012-09-01

    Many electrical applications of quantum dots rely on capacitively coupled gates; therefore, to make reliable devices we need those gate capacitances to be predictable and reproducible. We demonstrate in silicon nanowire quantum dots that gate capacitances are reproducible to within 10% for nominally identical devices. We demonstrate the experimentally that gate capacitances scale with device dimensions. We also demonstrate that a capacitance simulator can be used to predict measured gate capacitances to within 20%. A simple parallel plate capacitor model can be used to predict how the capacitances change with device dimensions; however, the parallel plate capacitor model fails for the smallest devices because the capacitances are dominated by fringing fields. We show how the capacitances due to fringing fields can be quickly estimated.

  13. Fabrication and characterization of gridded Pt/SiO{sub 2}/Si MOS structure for hydrogen and hydrogen sulphide sensing

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vinod, E-mail: vkchaudhary.rs.ece@iitbhu.ac.in [Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, Uttar Pradesh (India); Sunny [Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, Uttar Pradesh (India); Rawal, Ishpal [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Mishra, V.N.; Dwivedi, R.; Das, R.R. [Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, Uttar Pradesh (India)

    2014-08-01

    A gridded gate Pt/SiO{sub 2}/Si MOS capacitor has been fabricated for detection of Hydrogen (H{sub 2}) and Hydrogen Sulphide (H{sub 2}S) gases. The MOS device was fabricated on P-type Si <100> (1–6 Ω cm) wafer with thermal oxide layer of thickness about 100 Å, whereas, Platinum (Pt) gate of ∼350 Å was deposited by thermal evaporation technique. The C–V (capacitance vs voltage) and G–V (conductance vs voltage) measurements have been performed for the evaluation of gas sensing behavior of fabricated MOS capacitor structure in H{sub 2} (250–4000 ppm) and H{sub 2}S (1000–6000 ppm) gases at both room and 120 °C temperatures, in a closed chamber in air atmosphere. It has been observed that the value of capacitance decreases with increase in gas concentration. The fabricated MOS capacitor sensor has shown better sensitivity towards H{sub 2} (88.6%) at room temperature (∼25 °C) as compared to (∼45%) at 120 °C. Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) studies have revealed the porous nature of the deposited metal film. The side wall diffusion, spillover of Hydrogen into oxide layer, increase in fixed oxide charge density, increase in surface area caused by gridded structure, the formation of dipole layer and change in interface state density on gas exposure, may be the mechanisms of gas sensing for improved sensitivity of the fabricated MOS device. - Highlights: • Pt gate gridded MOS structure (Pt/SiO{sub 2}/Si) has been fabricated first time. • The fabricated MOS sensor was first time tested for hydrogen and hydrogen sulphide gases. • The sensitivity of the gridded structure is found greater than conventional structures.

  14. Impact of the Capacitance of the Dielectric on the Contact Resistance of Organic Thin-Film Transistors

    Science.gov (United States)

    Zojer, K.; Zojer, E.; Fernandez, A. F.; Gruber, M.

    2015-10-01

    As the operation of organic thin-film transistors relies exclusively on injected charge carriers, the gate-induced field assumes a dual role: It is responsible for charge-carrier accumulation and, provided that an injection barrier at the contact-semiconductor interface is present, aids charge-carrier injection across this barrier. Besides the gate-source bias, the thickness of the insulator and its dielectric constant influence the gate field. Here, we explore the impact of the capacitance of the gate dielectric on the performance of organic thin-film transistors utilizing drift-diffusion-based simulations comprising a self-consistent consideration of injection. Upon varying the capacitance of the insulating layer, we observe a conceptually different behavior for top-contact and bottom-contact architectures. Top-contact devices possess a nearly constant contact voltage in the linear regime leading to an apparent mobility lowering. In strong contrast, bottom-contact architectures possess non-Ohmic contact resistances in the linear regime due to a contact voltage whose value depends strongly on both the gate-source bias and the capacitance. Counterintuitively, this is accompanied by a mobility being apparently unaffected by the substantial contact resistance. Additionally, threshold-voltage shifts appear due to gate-limited injection. The latter is particularly dominant in bottom-contact architectures, where the threshold voltages steeply increase with the thickness of the insulating layer.

  15. Modelling of capacitance and threshold voltage for ultrathin normally-off AlGaN /GaN MOSHEMT

    Science.gov (United States)

    Swain, R.; Jena, K.; Lenka, T. R.

    2017-01-01

    A compact quantitative model based on oxide semiconductor interface density of states (DOS) is proposed for Al0.25Ga0.75N/GaN metal oxide semiconductor high electron mobility transistor (MOSHEMT). Mathematical expressions for surface potential, sheet charge concentration, gate capacitance and threshold voltage have been derived. The gate capacitance behaviour is studied in terms of capacitance-voltage (CV) characteristics. Similarly, the predicted threshold voltage ( V T) is analysed by varying barrier thickness and oxide thickness. The positive V T obtained for a very thin 3 nm AlGaN barrier layer enables the enhancement mode operation of the MOSHEMT. These devices, along with depletion mode devices, are basic constituents of cascode configuration in power electronic circuits. The expressions developed are used in conventional long-channel HEMT drain current equation and evaluated to obtain different DC characteristics. The obtained results are compared with experimental data taken from literature which show good agreement and hence endorse the proposed model.

  16. Remote Sensing.

    Science.gov (United States)

    Williams, Richard S., Jr.; Southworth, C. Scott

    1983-01-01

    The Landsat Program became the major event of 1982 in geological remote sensing with the successful launch of Landsat 4. Other 1982 remote sensing accomplishments, research, publications, (including a set of Landsat worldwide reference system index maps), and conferences are highlighted. (JN)

  17. Noise and mismatch optimization for capacitive MEMS readout

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Chong; Wu Qisong; Yin Tao; Yang Haigang, E-mail: yanghg@mail.ie.ac.c [Institute of Electronics, Chinese Academy of Sciences, Beijing 100190 (China)

    2009-11-15

    This paper presents a high precision CMOS readout circuit for a capacitive MEMS gyroscope. A continuous time topology is employed as well as the chopper noise cancelling technique. A detailed analysis of the noise and mismatch of the capacitive readout circuit is given. The analysis and measurement results have shown that thermal noise dominates in the proposed circuit, and several approaches should be used for both noise and mismatch optimization. The circuit chip operates under a single 5 V supply, and has a measured capacitance resolution of 0.2 aF/sq rootHz. With such a readout circuit, the gyroscope can accurately measure the angular rate with a sensitivity of 15.3 mV/{sup 0}/s. (semiconductor integrated circuits)

  18. Noise and mismatch optimization for capacitive MEMS readout

    Institute of Scientific and Technical Information of China (English)

    Zhang Chong; Wu Qisong; Yin Tao; Yang Haigang

    2009-01-01

    This paper presents a high precision CMOS readout circuit for a capacitive MEMS gyroscope. A continuous time topology is employed as well as the chopper noise cancelling technique. A detailed analysis of the noise and mismatch of the capacitive readout circuit is given. The analysis and measurement results have shown that thermal noise dominates in the proposed circuit, and several approaches should be used for both noise and mismatch optimization. The circuit chip operates under a single 5 V supply, and has a measured capacitance resolution of 0.2 aF/√Hz. With such a readout circuit, the gyroscope can accurately measure the angular rate with a sensitivity of 15.3 mV/°/s.

  19. CMOS capacitive biosensors for highly sensitive biosensing applications.

    Science.gov (United States)

    Chang, An-Yu; Lu, Michael S-C

    2013-01-01

    Magnetic microbeads are widely used in biotechnology and biomedical research for manipulation and detection of cells and biomolecules. Most lab-on-chip systems capable of performing manipulation and detection require external instruments to perform one of the functions, leading to increased size and cost. This work aims at developing an integrated platform to perform these two functions by implementing electromagnetic microcoils and capacitive biosensors on a CMOS (complementary metal oxide semiconductor) chip. Compared to most magnetic-type sensors, our detection method requires no externally applied magnetic fields and the associated fabrication is less complicated. In our experiment, microbeads coated with streptavidin were driven to the sensors located in the center of microcoils with functionalized anti-streptavidin antibody. Detection of a single microbead was successfully demonstrated using a capacitance-to-frequency readout. The average capacitance changes for the experimental and control groups were -5.3 fF and -0.2 fF, respectively.

  20. Extracting Impurity Locations using Scanning Capacitance Microscopy Measurements

    Directory of Open Access Journals (Sweden)

    AGHAEI, S.

    2016-08-01

    Full Text Available In this article we investigate the possibility to use scanning capacitance microscopy (SCM for the 2-D and 3-D "atomistic" dopant profiling of semiconductor materials. For this purpose, we first analyze the effects of random dopant fluctuations (RDF on SCM measurements with nanoscale probes and show that the discrete and random locations of dopant impurities significantly affect the differential capacitance measured in SCM experiments if the dimension of the probe is below 50 nm. Then, we present an algorithm to compute the x, y, and z coordinates of the ionized impurities in the semiconductor material using a set of SCM measurements. The algorithm is based on evaluating the doping sensitivity functions of the differential capacitance and uses a gradient-based iterative method to compute the locations of dopants. Finally, we discuss a standard simulation case and show that we are able to successfully retrieve the locations of the ionized impurities using the proposed algorithm.

  1. Quantum Capacitance Modifies Interionic Interactions in Semiconducting Nanopores

    CERN Document Server

    Lee, Alpha A; Goriely, Alain

    2016-01-01

    Nanopores made with low dimensional semiconducting materials, such as carbon nanotubes and graphene slit pores, are used in supercapacitors. In theories and simulations of their operation, it is often assumed that such pores screen ion-ion interactions like metallic pores, i.e. that screening leads to an exponential decay of the interaction potential with ion separation. By introducing a quantum capacitance that accounts for the density of states in the material, we show that ion-ion interactions in carbon nanotubes and graphene slit pores actually decay algebraically with ion separation. This result suggests a new avenue of capacitance optimization based on tuning the electronic structure of a pore: a marked enhancement in capacitance might be achieved by developing nanopores made with metallic materials or bulk semimetallic materials.

  2. Extraction method for parasitic capacitances and inductances of HEMT models

    Science.gov (United States)

    Zhang, HengShuang; Ma, PeiJun; Lu, Yang; Zhao, BoChao; Zheng, JiaXin; Ma, XiaoHua; Hao, Yue

    2017-03-01

    A new method to extract parasitic capacitances and inductances for high electron-mobility transistors (HEMTs) is proposed in this paper. Compared with the conventional extraction method, the depletion layer is modeled as a physically significant capacitance model and the extrinsic values obtained are much closer to the actual results. In order to simulate the high frequency behaviour with higher precision, series parasitic inductances are introduced into the cold pinch-off model which is used to extract capacitances at low frequency and the reactive elements can be determined simultaneously over the measured frequency range. The values obtained by this method can be used to establish a 16-elements small-signal equivalent circuit model under different bias conditions. The results show good agreements between the simulated and measured scattering parameters up to 30 GHz.

  3. On Machine Capacitance Dimensional and Surface Profile Measurement System

    Science.gov (United States)

    Resnick, Ralph

    1993-01-01

    A program was awarded under the Air Force Machine Tool Sensor Improvements Program Research and Development Announcement to develop and demonstrate the use of a Capacitance Sensor System including Capacitive Non-Contact Analog Probe and a Capacitive Array Dimensional Measurement System to check the dimensions of complex shapes and contours on a machine tool or in an automated inspection cell. The manufacturing of complex shapes and contours and the subsequent verification of those manufactured shapes is fundamental and widespread throughout industry. The critical profile of a gear tooth; the overall shape of a graphite EDM electrode; the contour of a turbine blade in a jet engine; and countless other components in varied applications possess complex shapes that require detailed and complex inspection procedures. Current inspection methods for complex shapes and contours are expensive, time-consuming, and labor intensive.

  4. Intrinsic Low Hysteresis Touch Mode Capacitive Pressure Sensor

    DEFF Research Database (Denmark)

    Fragiacomo, Giulio; Pedersen, Thomas; Hansen, Ole

    2011-01-01

    Hysteresis has always been one of the main concerns when fabricating touch mode capacitive pressure sensors (TMCPS). This phenomenon can be fought at two different levels: during fabrication or after fabrication with the aid of a dedicated signal conditioning circuit. We will describe a microfabr......Hysteresis has always been one of the main concerns when fabricating touch mode capacitive pressure sensors (TMCPS). This phenomenon can be fought at two different levels: during fabrication or after fabrication with the aid of a dedicated signal conditioning circuit. We will describe...... a microfabrication step that can be introduced in order to reduce drastically the hysteresis of this type of sensors without compromising their sensitivity. Medium-high range (0 to 10 bar absolute pressure) TMCPS with a capacitive signal span of over 100pF and less than 1 % hysteresis in the entire pressure range...

  5. Development of 3D carbon nanotube interdigitated finger electrodes on polymer substrate for flexible capacitive sensor application.

    Science.gov (United States)

    Hu, Chih-Fan; Wang, Jhih-Yu; Liu, Yu-Chia; Tsai, Ming-Han; Fang, Weileun

    2013-11-08

    This study reports a novel approach to the implementation of 3D carbon nanotube (CNT) interdigitated finger electrodes on flexible polymer, and the detection of strain, bending curvature, tactile force and proximity distance are demonstrated. The merits of the presented CNT-based flexible sensor are as follows: (1) the silicon substrate is patterned to enable the formation of 3D vertically aligned CNTs on the substrate surface; (2) polymer molding on the silicon substrate with 3D CNTs is further employed to transfer the 3D CNTs to the flexible polymer substrate; (3) the CNT-polymer composite (~70 μm in height) is employed to form interdigitated finger electrodes to increase the sensing area and initial capacitance; (4) other structures such as electrical routings, resistors and mechanical supporters are also available using the CNT-polymer composite. The preliminary fabrication results demonstrate a flexible capacitive sensor with 50 μm high CNT interdigitated electrodes on a poly-dimethylsiloxane substrate. The tests show that the typical capacitance change is several dozens of fF and the gauge factor is in the range of 3.44-4.88 for strain and bending curvature measurement; the sensitivity of the tactile sensor is 1.11% N(-1); a proximity distance near 2 mm away from the sensor can be detected.

  6. Penicillamine prevents ram sperm agglutination in media that support capacitation.

    Science.gov (United States)

    Leahy, T; Rickard, J P; Aitken, R J; de Graaf, S P

    2016-02-01

    Ram spermatozoa are difficult to capacitate in vitro. Here we describe a further complication, the unreported phenomenon of head-to-head agglutination of ram spermatozoa following dilution in the capacitation medium Tyrodes plus albumin, lactate and pyruvate (TALP). Sperm agglutination is immediate, specific and persistent and is not associated with a loss of motility. Agglutination impedes in vitro sperm handling and analysis. So the objectives of this study were to investigate the cause of sperm agglutination and potential agents which may reduce agglutination. The percentage of non-agglutinated, motile spermatozoa increased when bicarbonate was omitted from complete TALP suggesting that bicarbonate ions stimulate the agglutination process. d-penicillamine (PEN), a nucleophilic thiol, was highly effective at reducing agglutination. The inclusion of 250 μM PEN in TALP reduced the incidence of motile, agglutinated spermatozoa from 76.7 ± 2.7% to 2.8 ± 1.4%. It was then assessed if PEN (1 mM) could be included in existing ram sperm capacitation protocols (TALP +1 mM dibutyryl cAMP, caffeine and theophylline) to produce spermatozoa that were simultaneously capacitated and non-agglutinated. This protocol resulted in a sperm population which displayed high levels of tyrosine phosphorylated proteins and lipid disordered membranes (merocyanine-540) while remaining motile, viable, acrosome-intact and non-agglutinated. In summary, PEN (1 mM) can be included in ram sperm capacitation protocols to reduce sperm agglutination and allow for the in vitro assessment of ram sperm capacitation.

  7. SEMICONDUCTOR DEVICES Multi-bias capacitance voltage characteristic of AlGaN/GaN HEMT

    Science.gov (United States)

    Yan, Pu; Liang, Wang; Tingting, Yuan; Sihua, Ouyang; Lei, Pang; Guoguo, Liu; Weijun, Luo; Xinyu, Liu

    2010-10-01

    The method of multi-bias capacitance voltage measurement is presented. The physical meaning of gate—source and gate—drain capacitances in AlGaN/GaN HEMT and the variations in them with different bias conditions are discussed. A capacitance model is proposed to reflect the behaviors of the gate—source and gate—drain capacitances, which shows a good agreement with the measured capacitances, and the power performance obtains good results compared with the measured data from the capacitance model.

  8. Flexible Capacitive Electrodes for Minimizing Motion Artifacts in Ambulatory Electrocardiograms

    Directory of Open Access Journals (Sweden)

    Jeong Su Lee

    2014-08-01

    Full Text Available This study proposes the use of flexible capacitive electrodes for reducing motion artifacts in a wearable electrocardiogram (ECG device. The capacitive electrodes have conductive foam on their surface, a shield, an optimal input bias resistor, and guarding feedback. The electrodes are integrated in a chest belt, and the acquired signals are transmitted wirelessly for ambulatory heart rate monitoring. We experimentally validated the electrode performance with subjects standing and walking on a treadmill at speeds of up to 7 km/h. The results confirmed the highly accurate heart rate detection capacity of the developed system and its feasibility for daily-life ECG monitoring.

  9. Analysis of Capacitive Parasitism in PWM Inverter-Fed Motor

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effects of parasitic capacitance in induction motor system are unnoticed when it is fed from the AC line. but they are obvious when supplied directly from a PWM inverter. Consequently. many parasitic problems occur, such as motor-to-earth leakage current, bearing current, incoming line current distortion and uneven distribution of electrical stresses along the winding. On the ba sis of the uniform transmission line principle, a complete equivalent circuit of the PWM inverter-fed motor system is presented, based on which all the capacitive parasitic problems mentioned above are analyzed and simulated by means of PSPICE. All the results are consistent with the existing ones.

  10. An Effective Hybrid Optimization Algorithm for Capacitated Vehicle Routing Problem

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Capacitated vehicle routing problem (CVRP) is an important combinatorial optimization problem. However, it is quite difficult to achieve an optimal solution with the traditional optimization methods owing to the high computational complexity. A hybrid algorithm was developed to solve the problem, in which an artificial immune clonal algorithm (AICA) makes use of the global search ability to search the optimal results and simulated annealing (SA) algorithm employs certain probability to avoid becoming trapped in a local optimum. The results obtained from the computational study show that the proposed algorithm is a feasible and effective method for capacitated vehicle routing problem.

  11. Comprehensive measurements of GaAs pixel detectors capacitance

    CERN Document Server

    Caria, M; D'Auria, S; Lai, A; Randaccio, P; Cadeddu, S

    2002-01-01

    We have studied GaAs pixel detectors on semi-insulating wafers with Schottky contacts. We performed comprehensive measurements on the inter-pixel and capacitance to back plane. Being semi-insulating, the behaviour is totally different with respect to other common semiconductors, such as high resistivity silicon. Non-homogeneities are also an issue, due to both the contacts and the crystal bulk. In order to detect them and their influence on capacitance, we undertook systematic measurements with different configurations of the measuring electrodes.

  12. Nickel Oxide/Carbon Nanotubes Nanocomposite for Electrochemical Capacitance

    Institute of Scientific and Technical Information of China (English)

    Kui LIANG; Kayhyeok AN; Younghee LEE

    2005-01-01

    A nanocomposite of nickel oxide/carbon nanotubes was prepared through a simple chemical precipitation followed by thermal annealing. The electrochemical capacitance of this electrode material was studied. When the mass fraction of CNTs (carbon nanotubes) in NiO/CNT composites increases, the electrical resistivity of nanocomposites decreases and becomes similar to that of pure CNTs when it reaches 30%. The specific surface area of composites increases with increasing CNT mass fraction and the specific capacitance reaches 160 F/g under 10 mA/g discharge current density at CNT mass fraction of 10%.

  13. Quantum capacitance in monolayers of silicene and related buckled materials

    Science.gov (United States)

    Nawaz, S.; Tahir, M.

    2016-02-01

    Silicene and related buckled materials are distinct from both the conventional two dimensional electron gas and the famous graphene due to strong spin orbit coupling and the buckled structure. These materials have potential to overcome limitations encountered for graphene, in particular the zero band gap and weak spin orbit coupling. We present a theoretical realization of quantum capacitance which has advantages over the scattering problems of traditional transport measurements. We derive and discuss quantum capacitance as a function of the Fermi energy and temperature taking into account electron-hole puddles through a Gaussian broadening distribution. Our predicted results are very exciting and pave the way for future spintronic and valleytronic devices.

  14. [Impact of sperm capacitation on various populations of human spermatozoa].

    Science.gov (United States)

    Villanueva Díaz, C; Suárez Juárez, M; Díaz, M A; Ayala Ruiz, A

    1989-02-01

    With the purpose of evaluating the impact of spermatic capacitation on different spermatozooa populations, 49 samples of semen, before and after in vitro spermatic capacitation with Ham F-10 medium, were studied; motility of cells was evaluated according to WHO criteria. There was diminution of percentage of immobile cells, 27.8 to 20.0, as well as increase in population of cells with more mobility, 28.6% to 39.1%. Both difference were statistically significant (p = less than 0.05 and p = less than 0.005, respectively). These data suggest that spermatic capacitacion activates "in cascade" all groups of gametes.

  15. Stray capacitances in the watt balance operation: electrostatic forces

    DEFF Research Database (Denmark)

    Quagliotti, Danilo; Mana, G.

    2014-01-01

    In a watt balance, stray capacitances exist between the coil and the magnet. Since the electric current flowing in the coil creates a difference in electric potentials between the coil and magnet, their electrostatic interactions must be taken into account. This paper reports the results of a fin......In a watt balance, stray capacitances exist between the coil and the magnet. Since the electric current flowing in the coil creates a difference in electric potentials between the coil and magnet, their electrostatic interactions must be taken into account. This paper reports the results...

  16. Properties of the Mo-CuInSe2 interface

    Science.gov (United States)

    Russell, P. E.; Jamjoum, O.; Ahrenkiel, R. K.; Kazmerski, L. L.; Mickelsen, R. A.; Chen, W. S.

    1982-06-01

    Mo has been suggested and used as an ohmic back contact for CdS/p-CuInSe2 solar cells. The Mo-p-CuInSe2 interface has been studied for both polycrystalline and single-crystal CuInSe2, using electron beam induced current and capacitance-voltage techniques. The interface is found to form a Schottky barrier, thereby limiting the attainable voltage of a solar cell with Mo back contact. Au is the only known ohmic contact to p-CuInSe2.

  17. Home Automation System Using Capacitive Touchscreen

    Directory of Open Access Journals (Sweden)

    Yash Inaniya

    2014-06-01

    Full Text Available Technology has been constantly evolving and with the advent of touchscreen in human life , devices are much easier and simple to operate. This work is mainly focused on building home automation system which is more user friendly and thus can be operated by anyone. Earlier home automation systems were completely mechanically operated and thus required a lot of maintenance and were costly also. Now that human and computer interaction has been developed into a more wide and sophisticated field , designing and operating of intelligence system has been more user friendly than ever. Home automation is a system that helps a user to operate switching various appliances and lighting devices from a single input. The touchscreen used as input is much simpler to operate. Touchscreen has been widely accepted as the most comfortable input to be provided to the user. Not only they are easy to operate but they also give a sense of personal involvement which the user always appreciate. The materials used in this system are easily available in the local market so that the touch screen sytem is cost effective .

  18. Interfaces habladas

    Directory of Open Access Journals (Sweden)

    María Teresa Soto Sanfiel

    2012-04-01

    Full Text Available Este artículo describe y piensa al fenómeno de las Interfaces habladas (IH desde variados puntos de vista y niveles de análisis. El texto se ha concebido con los objetivos específicos de: 1.- procurar una visión panorámica de aspectos de la producción y consumo comunicativo de las IH; 2.- ofrecer recomendaciones para su creación y uso eficaz, y 3.- llamar la atención sobre su proliferación e inspirar su estudio desde la comunicación. A pesar de la creciente presencia de las IF en nues-tras vidas cotidianas, hay ausencia de textos que las caractericen y analicen por sus aspectos comunicativos. El trabajo es pertinente porque el fenómeno significa un cambio respecto a estadios comunica-tivos precedentes con consecuencias en las concepciones intelectuales y emocionales de los usuarios. La proliferación de IH nos abre a nue-vas realidades comunicativas: hablamos con máquinas.

  19. RF-MEMS capacitive switches with high reliability

    Science.gov (United States)

    Goldsmith, Charles L.; Auciello, Orlando H.; Carlisle, John A.; Sampath, Suresh; Sumant, Anirudha V.; Carpick, Robert W.; Hwang, James; Mancini, Derrick C.; Gudeman, Chris

    2013-09-03

    A reliable long life RF-MEMS capacitive switch is provided with a dielectric layer comprising a "fast discharge diamond dielectric layer" and enabling rapid switch recovery, dielectric layer charging and discharging that is efficient and effective to enable RF-MEMS switch operation to greater than or equal to 100 billion cycles.

  20. Capacitive sensor probe to assess frying oil degradation

    Directory of Open Access Journals (Sweden)

    Alfadhl Yahya Khaled

    2015-09-01

    Full Text Available The repeated usage of frying oil has been proven hazardous due to the degradation process by chemical reactions that lead to changes in the quality of the oil. Currently, the degree of frying oil degradation is indicated by the percentage of its total polar compounds (TPC. In this study, a capacitive sensor was designed to assess frying oil degradation at several heating time intervals by measuring changes on its electrical capacitance. The sensor was designed using interdigitated electrode structure. A total of 30 samples of 130 ml palm oil were heated at 180 °C up to 30 h. For each one hour interval, one sample was moved out from the laboratory oven. The electrical capacitance, total polar compound (TPC and viscosity of the samples were measured for analysis. Preliminary results demonstrated significant correlation between oil electrical capacitance with TPC and viscosity with R2 ranged from 0.83 to 0.90. The designed sensor has good potential for simple and inexpensive way of determining frying oil quality.

  1. Dynamic Adsorption/Desorption Process Model of Capacitive Deionization

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Limpt, van B.; Wal, van der A.

    2009-01-01

    In capacitive deionization (CDI), an electrical potential difference is applied across oppositely placed electrodes, resulting in the adsorption of ions from aqueous solution and a partially ion-depleted product stream. CDI is a dynamic process which operates in a sequential mode; i.e., after a cert

  2. Stray capacitances in the watt balance operation: electrostatic forces

    CERN Document Server

    Quagliotti, Danilo

    2014-01-01

    In a watt balance, stray capacitances exist between the coil and the magnet. Since the electric current flowing in the coil originates a difference between the coil and magnet electric-potentials, their electrostatic interactions must be taken into account. This paper reports the results of a finite element analysis of the forces acting on the coil.

  3. Capacitive technology for energy extraction from chemical potential differences

    NARCIS (Netherlands)

    Bastos Sales, B.

    2013-01-01

    This thesis introduces the principle of Capacitive energy extraction based on Donnan Potential (CDP) to exploit salinity gradients. It also shows the fundamental characterization and improvements of CDP. An alternative application of this technology aimed at thermal gradients was tested.  

  4. A Multifunction Low-Power Preamplifier for MEMS Capacitive Microphones

    DEFF Research Database (Denmark)

    Jawed, Syed Arsalan; Nielsen, Jannik Hammel; Gottardi, Massimo;

    2009-01-01

    A multi-function two-stage chopper-stabilized preamplifier (PAMP) for MEMS capacitive microphones (MCM) is presented. The PAMP integrates digitally controllable gain, high-pass filtering and offset control, adding flexibility to the front-end readout of MCMs. The first stage of the PAMP consists...

  5. Multilevel inverter based class D audio amplifier for capacitive transducers

    DEFF Research Database (Denmark)

    Nielsen, Dennis; Knott, Arnold; Andersen, Michael A. E.

    2014-01-01

    The reduced semiconductor voltage stress makes the multilevel inverters especially interesting, when driving capacitive transducers for audio applications. A ± 300 V flying capacitor class D audio amplifier driving a 100 nF load in the midrange region of 0.1-3.5 kHz with Total Harmonic Distortion...

  6. Energy consumption and constant current operation in membrane capacitive deionization

    NARCIS (Netherlands)

    Zhao, R.; Biesheuvel, P.M.; Wal, van der A.F.

    2012-01-01

    Membrane capacitive deionization (MCDI) is a water desalination technology based on applying a cell voltage between two oppositely placed porous electrodes sandwiching a spacer channel that transports the water to be desalinated. In the salt removal step, ions are adsorbed at the carbon–water interf

  7. Waterproof, Ultrahigh Areal-Capacitance, Wearable Supercapacitor Fabrics.

    Science.gov (United States)

    Yang, Yu; Huang, Qiyao; Niu, Liyong; Wang, Dongrui; Yan, Casey; She, Yiyi; Zheng, Zijian

    2017-02-24

    High-performance supercapacitors (SCs) are promising energy storage devices to meet the pressing demand for future wearable applications. Because the surface area of a human body is limited to 2 m(2) , the key challenge in this field is how to realize a high areal capacitance for SCs, while achieving rapid charging, good capacitive retention, flexibility, and waterproofing. To address this challenge, low-cost materials are used including multiwall carbon nanotube (MWCNT), reduced graphene oxide (RGO), and metallic textiles to fabricate composite fabric electrodes, in which MWCNT and RGO are alternatively vacuum-filtrated directly onto Ni-coated cotton fabrics. The composite fabric electrodes display typical electrical double layer capacitor behavior, and reach an ultrahigh areal capacitance up to 6.2 F cm(-2) at a high areal current density of 20 mA cm(-2) . All-solid-state fabric-type SC devices made with the composite fabric electrodes and water-repellent treatment can reach record-breaking performance of 2.7 F cm(-2) at 20 mA cm(-2) at the first charge-discharge cycle, 3.2 F cm(-2) after 10 000 charge-discharge cycles, zero capacitive decay after 10 000 bending tests, and 10 h continuous underwater operation. The SC devices are easy to assemble into tandem structures and integrate into garments by simple sewing.

  8. A Micro Dynamically Tuned Gyroscope with Adjustable Static Capacitance

    Directory of Open Access Journals (Sweden)

    Lun Kong

    2013-02-01

    Full Text Available This paper presents a novel micro dynamically tuned gyroscope (MDTG with adjustable static capacitance. First, the principle of MDTG is theoretically analyzed. Next, some simulations under the optimized structure parameters are given as a reference for the mask design of the rotor wafer and electrode plates. As two key components, the process flows of the rotor wafer and electrode plates are described in detail. All the scanning electron microscopy (SEM photos show that the fabrication process is effective and optimized. Then, an assembly model is designed for the static capacitance adjustable MDTG, whose static capacitance can be changed by rotating the lower electrode plate support and substituting gasket rings of different thicknesses. Thus, the scale factor is easily changeable. Afterwards, the digitalized closed-loop measurement circuit is simulated. The discrete correction and decoupling modules are designed to make the closed-loop stable and cross-coupling effect small. The dual axis closed-loop system bandwidths can reach more than 60 Hz and the dual axis scale factors are completely symmetrical. All the simulation results demonstrate the proposed fabrication of the MDTG can meet the application requirements. Finally, the paper presents the test results of static and dynamic capacitance values which are consistent with the simulation values.

  9. High bandwidth on-chip capacitive tuning of microtoroid resonators

    CERN Document Server

    Baker, Christopher G; McAuslan, David L; Sheridan, Eoin; Bowen, Warwick P

    2016-01-01

    We report on the design, fabrication and characterization of silica microtoroid based cavity opto-electromechanical systems (COEMS). Electrodes patterned onto the microtoroid resonators allow for rapid capacitive tuning of the optical whispering gallery mode resonances while maintaining their ultrahigh quality factor, enabling applications such as efficient radio to optical frequency conversion, optical routing and switching applications.

  10. Performance analysis of a digital capacitance measuring circuit.

    Science.gov (United States)

    Xu, Lijun; Sun, Shijie; Cao, Zhang; Yang, Wuqiang

    2015-05-01

    This paper presents the design and study of a digital capacitance measuring circuit with theoretical analysis, numerical simulation, and experimental evaluation. The static and dynamic performances of the capacitance measuring circuit are first defined, including signal-to-noise ratio (SNR), standard deviation, accuracy, linearity, sensitivity, and response time, within a given measurement range. Then numerical simulation is carried out to analyze the SNR and standard deviation of the circuit, followed by experiments to validate the overall performance of the circuit. The simulation results show that when the standard deviation of noise is 0.08 mV and the measured capacitance decreases from 6 pF to 3 fF, the SNR decreases from 90 dB to 22 dB and the standard deviation is between 0.17 fF and 0.24 fF. The experimental results show that when the measured capacitance decreases from 6 pF to 40 fF and the data sampled in a single period are used for demodulation, the SNR decreases from 88 dB to 40 dB and the standard deviation is between 0.18 fF and 0.25 fF. The maximum absolute error and relative error are 5.12 fF and 1.26%, respectively. The SNR and standard deviation can be further improved if the data sampled in more than one period are used for demodulation by the circuit.

  11. Water Desalination Using Capacitive Deionization with Microporous Carbon Electrodes

    NARCIS (Netherlands)

    Porada, S.; Weinstein, L.; Dash, R.; Wal, van der A.F.; Bryjak, M.; Gogotsi, Y.; Biesheuvel, P.M.

    2012-01-01

    Capacitive deionization (CDI) is a water desalination technology in which salt ions are removed from brackish water by flowing through a spacer channel with porous electrodes on each side. Upon applying a voltage difference between the two electrodes, cations move to and are accumulated in electrost

  12. Micro coriolis mass flow sensor with integrated capacitive readout

    NARCIS (Netherlands)

    Haneveld, J.; Lammerink, T.S.J.; Boer, de M.J.; Wiegerink, R.J.

    2009-01-01

    We have realized a micromachined micro Coriolis mass flow sensor with integrated capacitive readout to detect the extremely small Coriolis vibration of the sensor tube. A special comb-like detection electrode design eliminates the need for multiple metal layers and sacrificial layer etching methods.

  13. An organic integrated capacitive DC-DC up-converter

    NARCIS (Netherlands)

    Marien, H.; Steyaert, M.; Steudel, S.; Vicca, P.; Smout, S.; Gelinck, G.H.; Heremans, P.L.

    2010-01-01

    In this paper a fully integrated organic DC-DC upconverter is presented in a pentacene p-type only technology. This 3-stage Dickson converter reaches a voltage conversion factor of 3 for a purely capacitive load and 2.5 for a 10 μA load current. The maximal output voltage goes up to 75 V and the Dic

  14. Optimization of salt adsorption rate in membrane capacitive deionization

    NARCIS (Netherlands)

    Zhao, R.; Satpradit, O.A.; Rijnaarts, H.; Biesheuvel, P.M.; Wal, van der A.

    2013-01-01

    Membrane capacitive deionization (MCDI) is a water desalination technique based on applying a cell voltage between two oppositely placed porous electrodes sandwiching a spacer channel that transports the water to be desalinated. In MCDI, ion-exchange membranes are positioned in front of each porous

  15. Production of pulsed electric fields using capacitively coupled electrodes

    Science.gov (United States)

    Kendall, B. R. F.; Schwab, F. A. S.

    1980-01-01

    It is shown that pulsed electric fields can be produced over extended volumes by taking advantage of the internal capacitances in a stacked array of electrodes. The design, construction, and performance of practical arrays are discussed. The prototype arrays involved fields of 100-1000 V/cm extending over several centimeters. Scaling to larger physical dimensions is straightforward.

  16. An Approximation Algorithm for the Capacitated Arc Routing Problem

    DEFF Research Database (Denmark)

    Wøhlk, Sanne

    2008-01-01

    In this paper we consider approximation of the Capacitated Arc Routing Problem, which is the problem of servicing a set of edges in a graph using a fleet of capacity constrained vehicles. We present a 7/2 - 3/W-approximation algorithm for the problem and prove that this algorithm outperforms...

  17. Simple and economical capacitive displacement system for UHV operation.

    Science.gov (United States)

    Chow, R; Tiller, W A

    1979-12-01

    A parallel plate capacitor was assembled as a displacement transducer for operation in an UHV environment. The capacitive displacement system was linear over a 2.5 mum range with a resolution of 0.051 mum. Components in the electric circuit were common laboratory instruments.

  18. Carbon nanotube yarns as strong flexible conductive capacitive electrodes

    NARCIS (Netherlands)

    Liu, F.; Wagterveld, R.M.; Gebben, B.; Otto, M.J.; Biesheuvel, P.M.; Hamelers, H.V.M.

    2015-01-01

    Carbon nanotube (CNT) yarn, consisting of 23 µm diameter CNT filaments, can be used as capacitive electrodes that are long, flexible, conductive and strong, for applications in energy and electrochemical water treatment. We measure the charge storage capacity as function of salt concentration, and u

  19. Parasitic capacitance characteristics of deep submicrometre grooved gate MOSFETs

    Science.gov (United States)

    Sreelal, S.; Lau, C. K.; Samudra, G. S.

    2002-03-01

    Grooved gate metal-oxide-semiconductor field-effect transistors (MOSFETs) are known to alleviate many of the short channel and hot carrier effects that arise when MOSFET devices are scaled down to very short channel lengths. However, they exhibit much higher parasitic capacitance with stronger bias dependence when compared to conventional planar devices. In this paper, we present a model for gate-to-drain and gate-to-source capacitance characteristics of a deep submicrometre grooved gate MOSFET. Both the intrinsic and extrinsic parts of the capacitance are modelled separately. In particular, the model presents a novel but simple way to account for the accumulation layer formation in the source/drain region of MOSFETs due to the application of the gate voltage. The results are compared with those obtained from a two-dimensional device simulator. The close match between the modelled and simulated data establishes the validity of the model. The model is then used to account for the superiority of capacitance characteristics of planar device structures and to arrive at optimization guidelines for grooved gate devices to match these characteristics.

  20. Nanocoax Arrays for Sensing Devices

    Science.gov (United States)

    Rizal, Binod

    We have adapted a nanocoax array architecture for high sensitivity, all-electronic, chemical and biological sensing. Arrays of nanocoaxes with various dielectric annuli were developed using polymer replicas of Si nanopillars made via soft lithography. These arrays were implemented in the development of two different kinds of chemical detectors. First, arrays of nanocoaxes constructed with different porosity dielectric annuli were employed to make capacitive detectors for gaseous molecules and to investigate the role of dielectric porosity in the sensitivity of the device. Second, arrays of nanocoaxes with partially hollowed annuli were used to fabricate three-dimensional electrochemical biosensors within which we studied the role of nanoscale gap between electrodes on device sensitivity. In addition, we have employed a molecular imprint technique to develop a non-conducting molecularly imprinted polymer thin film of thickness comparable to size of biomolecules as an "artificial antibody" architecture for the detection of biomolecules.

  1. Influence of interface traps inside the conduction band on the capacitance–voltage characteristics of InGaAs metal–oxide–semiconductor capacitors

    Science.gov (United States)

    Taoka, Noriyuki; Yokoyama, Masafumi; Kim, Sang Hyeon; Suzuki, Rena; Iida, Ryo; Takenaka, Mitsuru; Takagi, Shinichi

    2016-11-01

    We investigated the influences of the AC response with interface/bulk-oxide traps near the conduction band (CB) and a low effective density of states (DOS) on the accumulation capacitance C acc of an n-type InGaAs metal–oxide–semiconductor (MOS) capacitor. We found that the capacitance associated with the interface traps inside the CB significantly increases C acc compared to the C acc value constrained by a low DOS. These results indicate that accurate characterization inside the CB and considering the capacitance due to the interface traps inside the CB in the MOS capacitance–voltage curves are indispensable for accurate characterization of InGaAs MOS interface properties.

  2. Deep-Hole Inner Diameter Measuring System Based on Non-contact Capacitance Sensor

    Institute of Scientific and Technical Information of China (English)

    于永新; 张恒; 王宗超; 常以哲

    2010-01-01

    A precise aperture measuring system of small deep holes with capacitance sensors is presented. Based on the working principle of non-contact capacitance sensors, influence of the edge effect of gauge head is studied, and one capacitance sensor for measuring the aperture of the small blind holes or through holes is introduced. The system is composed of one positioning device, one aperture measuring capacitance sensor, one measuring circuit, and software. This system employs visual CCD and two-dimensional mic...

  3. Capacitive wearable tactile sensor based on smart textile substrate with carbon black /silicone rubber composite dielectric

    Science.gov (United States)

    Guo, Xiaohui; Huang, Ying; Cai, Xia; Liu, Caixia; Liu, Ping

    2016-04-01

    To achieve the wearable comfort of electronic skin (e-skin), a capacitive sensor printed on a flexible textile substrate with a carbon black (CB)/silicone rubber (SR) composite dielectric was demonstrated in this paper. Organo-silicone conductive silver adhesive serves as a flexible electrodes/shielding layer. The structure design, sensing mechanism and the influence of the conductive filler content and temperature variations on the sensor performance were investigated. The proposed device can effectively enhance the flexibility and comfort of wearing the device asthe sensing element has achieved a sensitivity of 0.02536%/KPa, a hysteresis error of 5.6%, and a dynamic response time of ~89 ms at the range of 0-700 KPa. The drift induced by temperature variations has been calibrated by presenting the temperature compensation model. The research on the time-space distribution of plantar pressure information and the experiment of the manipulator soft-grasping were implemented with the introduced device, and the experimental results indicate that the capacitive flexible textile tactile sensor has good stability and tactile perception capacity. This study provides a good candidate for wearable artificial skin.

  4. Atomically thin Co3O4 nanosheet-coated stainless steel mesh with enhanced capacitive Na+ storage for high-performance sodium-ion batteries

    Science.gov (United States)

    Dou, Yuhai; Wang, Yunxiao; Tian, Dongliang; Xu, Jiantie; Zhang, Zhijia; Liu, Qiannan; Ruan, Boyang; Ma, Jianmin; Sun, Ziqi; Xue Dou, Shi

    2017-03-01

    Capacitive storage (e.g., double layer capacitance and pseudocapacitance) with Na+ stored mainly at the surface or interface of the active materials rather than inserted into the bulk crystal is an effective approach to achieve high rate capability and long cycle life in sodium-ion batteries (SIBs). Herein, atomically thin Co3O4 nanosheets are successfully synthesized and grown directly on the stainless steel mesh as an anode material for SIBs. This anode delivers a high average capacity of 509.2 mAh g-1 for the initial 20 cycles (excluding the first cycle) at 50 mA g-1, presents excellent rate capability with an average capacity of 427.0 mAh g-1 at 500 mA g-1, and exhibits high cycling stability, which significantly outperforms the electrode prepared from conventional Co3O4 nanostructures, the electrode prepared by conventional casting method, and previously reported Co3O4 electrodes. The superior electrochemical performance is mainly attributable to the atomic thickness of the Co3O4 nanosheets and the direct growth method in electrode processing, which lead to remarkably enhanced surface redox pseudocapacitance and interfacial double layer capacitance. This Na+ capacitive storage mechanism provides a promising strategy for the development of electrode materials with high energy and power densities and ultralong cycle life for SIBs.

  5. Redox additives of Na2MoO4 and KI: Synergistic effect and the improved capacitive performances for carbon-based supercapacitors

    Science.gov (United States)

    Xu, Dong; Hu, Wei; Sun, Xiao Na; Cui, Peng; Chen, Xiang Ying

    2017-02-01

    A dual system of redox additive by incorporating Na2MoO4 and KI into H2SO4 solution has been developed to highly elevate the capacitance of supercapacitors primarily owing to the synergistic effect between them at the superposed redox voltage. Furthermore, the synergistic effect therein is attributed to the formation of complex substance of (MoxIyO4x)n-Cz, which can promote redox reaction of Mon+ and In- at the interface of carbon electrode and electrolyte. On the other hand, many crucial factors mainly including the molar ratio, concentration of redox additive and voltage window strongly determine the final capacitive behaviors. For example, when adding Na2MoO4 and KI into H2SO4 with the same concentration of 0.1 mol L-1, the resultant capacitance has remarkably increased by 17.4 times, compared with the one without any redox additive, at 3 A g-1 in a two-electrode system. What's more, the homologous energy density can reach up to 65.3 Wh kg-1 at the suitable voltage window (0-1 V). Hence, the present synergism of various kinds of redox additives is intriguing and easily extended to other systems, which could highly elevate the capacitive performances of supercapacitors.

  6. A branch-and-cut-and-price algorithm for the mixed capacitated general routing problem

    DEFF Research Database (Denmark)

    Bach, Lukas; Wøhlk, Sanne; Lysgaard, Jens

    2016-01-01

    In this paper, we consider the Mixed Capacitated General Routing Problem which is a combination of the Capacitated Vehicle Routing Problem and the Capacitated Arc Routing Problem. The problem is also known as the Node, Edge, and Arc Routing Problem. We propose a Branch-and-Cut-and-Price algorithm...

  7. Comparison of C-V measurement methods for RF-MEMS capacitive switches

    NARCIS (Netherlands)

    Wang, J; Salm, Cora; Schmitz, Jurriaan

    2013-01-01

    The applicability of several capacitance-voltage measurement methods is investigated for the on-wafer characterization of RF-MEMS capacitive switches. These devices combine few-picofarad capacitance with a high quality factor. The standard quasistatic and high-frequency measurements are employed, as

  8. Fabrication and Evaluation of a Graphene Oxide-Based Capacitive Humidity Sensor

    Directory of Open Access Journals (Sweden)

    Jinfeng Feng

    2016-03-01

    Full Text Available In this study, a CMOS compatible capacitive humidity sensor structure was designed and fabricated on a 200 mm CMOS BEOL Line. A top Al interconnect layer was used as an electrode with a comb/serpent structure, and graphene oxide (GO was used as sensing material. XRD analysis was done which shows that GO sensing material has a strong and sharp (002 peak at about 10.278°, whereas graphite has (002 peak at about 26°. Device level CV and IV curves were measured in mini-environments at different relative humidity (RH level, and saturated salt solutions were used to build these mini-environments. To evaluate the potential value of GO material in humidity sensor applications, a prototype humidity sensor was designed and fabricated by integrating the sensor with a dedicated readout ASIC and display/calibration module. Measurements in different mini-environments show that the GO-based humidity sensor has higher sensitivity, faster recovery time and good linearity performance. Compared with a standard humidity sensor, the measured RH data of our prototype humidity sensor can match well that of the standard product.

  9. A batch fabricated capacitive pressure sensor with an integrated Guyton capsule for interstitial fluid pressure measurement

    Science.gov (United States)

    Maleki, Teimour; Fogle, Benjamin; Ziaie, Babak

    2011-05-01

    In this paper, we present the design, fabrication and test of a batch fabricated capacitive pressure sensor with an integrated Guyton capsule for interstitial fluid pressure measurement. The sensor is composed of 12 µm thick single crystalline silicon membrane and a 3 µm gap, hermetically sealed through silicon-glass anodic bonding. A novel batch scale method for creating electrical feed-throughs inside the sealed capacitor chamber is developed. The Guyton capsule consists of an array of 10 µm diameter access holes etched onto a silicon back-plate separated from the silicon sensing membrane by a gap of 5 µm. The presence of the Guyton capsule (i.e. plates with access holes plus the gap separating them from the sensing membrane) allows for the ingress of interstitial fluid inside the 5 µm gap following the implantation, thus, providing an accurate measurement of interstitial fluid pressure. The fabricated sensor is 3 × 2 × 0.42 mm3 in dimensions and has a maximum sensitivity of 10 fF mmHg-1.

  10. Fabrication and Evaluation of a Graphene Oxide-Based Capacitive Humidity Sensor.

    Science.gov (United States)

    Feng, Jinfeng; Kang, Xiaoxu; Zuo, Qingyun; Yuan, Chao; Wang, Weijun; Zhao, Yuhang; Zhu, Limin; Lu, Hanwei; Chen, Juying

    2016-03-01

    In this study, a CMOS compatible capacitive humidity sensor structure was designed and fabricated on a 200 mm CMOS BEOL Line. A top Al interconnect layer was used as an electrode with a comb/serpent structure, and graphene oxide (GO) was used as sensing material. XRD analysis was done which shows that GO sensing material has a strong and sharp (002) peak at about 10.278°, whereas graphite has (002) peak at about 26°. Device level CV and IV curves were measured in mini-environments at different relative humidity (RH) level, and saturated salt solutions were used to build these mini-environments. To evaluate the potential value of GO material in humidity sensor applications, a prototype humidity sensor was designed and fabricated by integrating the sensor with a dedicated readout ASIC and display/calibration module. Measurements in different mini-environments show that the GO-based humidity sensor has higher sensitivity, faster recovery time and good linearity performance. Compared with a standard humidity sensor, the measured RH data of our prototype humidity sensor can match well that of the standard product.

  11. Use of a Precision Mercury Manometer with Capacitance Sensing of the Menisci

    Science.gov (United States)

    Jäger, J.

    1994-01-01

    A commercially available dual-cistern mercury manometer, modified in some details, has been in use for many years as the main standard instrument of the PTB for the pressure range up to 200 kPa (absolute and gauge). With this instrument the PTB participated in an international intercomparison of pressure standards in the barometric range, organized under the auspices of the Comité Consultatif pour la Masse et les grandeurs apparentées (CCM). An error analysis for absolute pressure measurements with the manometer is presented together with a discussion of experimental data and some technical details.

  12. Radio frequency and capacitive sensors for dielectric characterization of low-conductivity media

    Science.gov (United States)

    Sheldon, Robert T.

    Low-conductivity media are found in a vast number of applications, for example as electrical insulation or as the matrix polymer in high strength-to-weight ratio structural composites. In some applications, these materials are subjected to extreme environmental, thermal, and mechanical conditions that can affect the material's desired performance. In a more general sense, a medium may be comprised of one or more layers with unknown material properties that may affect the desired performance of the entire structure. It is often, therefore, of great import to be able to characterize the material properties of these media for the purpose of estimating their future performance in a certain application. Low-conductivity media, or dielectrics, are poor electrical conductors and permit electromagnetic waves and static electric fields to pass through with minimal attenuation. The amount of electrical energy that may be stored (and lost) in these fields depends directly upon the material property, permittivity, which is generally complex, frequency-dependent and has a measurable effect on sensors designed to characterize dielectric media. In this work, two different types of dielectric sensors: radio frequency resonant antennas and lower-frequency (environmental aging mechanisms. One embodiment involves the application of coplanar concentric interdigital electrode sensors for the purpose of investigating polymer-matrix degradation in glass-fiber composites due to isothermal aging. Samples of bismaleimide-matrix glass-fiber composites were aged at several high temperatures to induce thermal degradation and capacitive sensors were used to measure the sensor capacitance and dissipation factor, parameters that are directly proportional to the real and imaginary components of complex permittivity, respectively. It was shown that real permittivity and dissipation factor decreased with increasing aging temperature, a trend that was common to both interdigital sensor measurements

  13. A 2.5 mW 370 mV/pF high linearity stray-immune symmetrical readout circuit for capacitive sensors

    Institute of Scientific and Technical Information of China (English)

    Zhou Kaimin; Wang Ziqiang; Zhang Chun; Wang Zhihua

    2012-01-01

    A stray-insensitive symmetrical capacitance-to-voltage converter for capacitive sensors is presented.By introducing a reference branch,a symmetrical readout circuit is realized.The linear input range is increased,and the systematic offsets of two input op-amps are cancelled.The common-mode noise and even-order distortion are also rejected.A chopper stabilization technique is adopted to further reduce the offset and flicker noise of the op-amps,and a Verilog-A-based varaetor is used to model the real variable sensing capacitor.Simulation results show that the output voltage of this proposed readout circuit responds correctly,while the under-test capacitance changes with a frequency of 1 kHz.A metal-insulator-metal capacitor array is designed on chip for measurement,and the measurement results show that this circuit achieves sensitivity of 370 mV/pF,linearity error below 1% and power consumption as low as 2.5 mW.This symmetrical readout circuit can respond to an FPGA controlled sensing capacitor array changed every 1 ms.

  14. Healable capacitive touch screen sensors based on transparent composite electrodes comprising silver nanowires and a furan/maleimide diels-alder cycloaddition polymer.

    Science.gov (United States)

    Li, Junpeng; Liang, Jiajie; Li, Lu; Ren, Fengbo; Hu, Wei; Li, Juan; Qi, Shuhua; Pei, Qibing

    2014-12-23

    A healable transparent capacitive touch screen sensor has been fabricated based on a healable silver nanowire-polymer composite electrode. The composite electrode features a layer of silver nanowire percolation network embedded into the surface layer of a polymer substrate comprising an ultrathin soldering polymer layer to confine the nanowires to the surface of a healable Diels-Alder cycloaddition copolymer and to attain low contact resistance between the nanowires. The composite electrode has a figure-of-merit sheet resistance of 18 Ω/sq with 80% transmittance at 550 nm. A surface crack cut on the conductive surface with 18 Ω is healed by heating at 100 °C, and the sheet resistance recovers to 21 Ω in 6 min. A healable touch screen sensor with an array of 8×8 capacitive sensing points is prepared by stacking two composite films patterned with 8 rows and 8 columns of coupling electrodes at 90° angle. After deliberate damage, the coupling electrodes recover touch sensing function upon heating at 80 °C for 30 s. A capacitive touch screen based on Arduino is demonstrated capable of performing quick recovery from malfunction caused by a razor blade cutting. After four cycles of cutting and healing, the sensor array remains functional.

  15. A 2.5 mW 370 mV/pF high linearity stray-immune symmetrical readout circuit for capacitive sensors

    Science.gov (United States)

    Kaimin, Zhou; Ziqiang, Wang; Chun, Zhang; Zhihua, Wang

    2012-06-01

    A stray-insensitive symmetrical capacitance-to-voltage converter for capacitive sensors is presented. By introducing a reference branch, a symmetrical readout circuit is realized. The linear input range is increased, and the systematic offsets of two input op-amps are cancelled. The common-mode noise and even-order distortion are also rejected. A chopper stabilization technique is adopted to further reduce the offset and flicker noise of the op-amps, and a Verilog-A-based varactor is used to model the real variable sensing capacitor. Simulation results show that the output voltage of this proposed readout circuit responds correctly, while the under-test capacitance changes with a frequency of 1 kHz. A metal-insulator-metal capacitor array is designed on chip for measurement, and the measurement results show that this circuit achieves sensitivity of 370 mV/pF, linearity error below 1% and power consumption as low as 2.5 mW. This symmetrical readout circuit can respond to an FPGA controlled sensing capacitor array changed every 1 ms.

  16. Optical Waveguide Sensing and Imaging

    CERN Document Server

    Bock, Wojtek J; Tanev, Stoyan

    2008-01-01

    The book explores various aspects of existing and emerging fiber and waveguide optics sensing and imaging technologies including recent advances in nanobiophotonics. The focus is both on fundamental and applied research as well as on applications in civil engineering, biomedical sciences, environment, security and defence. The main goal of the multi-disciplinarry team of Editors was to provide an useful reference of state-of-the-art overviews covering a variety of complementary topics on the interface of engineering and biomedical sciences.

  17. Intelligent sensing, instrumentation and measurements

    CERN Document Server

    Mukhopadhyay, Subhas Chandra

    2013-01-01

      “Intelligent Sensing, Instrumentation and Measurements” addresses issues towards the development of sensor nodes for wireless Sensor Networks. The fundamentals of sensors, interfacing, power supplies, configuration of sensor node, and GUI development are covered. The book will be useful for engineers and researchers in the field ,especially for higher undergraduate and postgraduate students as well as practitioners working on the development of Wireless Sensor Networks or Smart Sensors.

  18. Online monitoring of oil film using electrical capacitance tomography and level set method

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Q., E-mail: xueqian@tju.edu.cn; Ma, M. [College of Aeronautical Automation, Civil Aviation University of China, Tianjin 300300 (China); Sun, B. Y.; Cui, Z. Q.; Wang, H. X. [School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China)

    2015-08-15

    In the application of oil-air lubrication system, electrical capacitance tomography (ECT) provides a promising way for monitoring oil film in the pipelines by reconstructing cross sectional oil distributions in real time. While in the case of small diameter pipe and thin oil film, the thickness of the oil film is hard to be observed visually since the interface of oil and air is not obvious in the reconstructed images. And the existence of artifacts in the reconstructions has seriously influenced the effectiveness of image segmentation techniques such as level set method. Besides, level set method is also unavailable for online monitoring due to its low computation speed. To address these problems, a modified level set method is developed: a distance regularized level set evolution formulation is extended to image two-phase flow online using an ECT system, a narrowband image filter is defined to eliminate the influence of artifacts, and considering the continuity of the oil distribution variation, the detected oil-air interface of a former image can be used as the initial contour for the detection of the subsequent frame; thus, the propagation from the initial contour to the boundary can be greatly accelerated, making it possible for real time tracking. To testify the feasibility of the proposed method, an oil-air lubrication facility with 4 mm inner diameter pipe is measured in normal operation using an 8-electrode ECT system. Both simulation and experiment results indicate that the modified level set method is capable of visualizing the oil-air interface accurately online.

  19. Online monitoring of oil film using electrical capacitance tomography and level set method

    Science.gov (United States)

    Xue, Q.; Sun, B. Y.; Cui, Z. Q.; Ma, M.; Wang, H. X.

    2015-08-01

    In the application of oil-air lubrication system, electrical capacitance tomography (ECT) provides a promising way for monitoring oil film in the pipelines by reconstructing cross sectional oil distributions in real time. While in the case of small diameter pipe and thin oil film, the thickness of the oil film is hard to be observed visually since the interface of oil and air is not obvious in the reconstructed images. And the existence of artifacts in the reconstructions has seriously influenced the effectiveness of image segmentation techniques such as level set method. Besides, level set method is also unavailable for online monitoring due to its low computation speed. To address these problems, a modified level set method is developed: a distance regularized level set evolution formulation is extended to image two-phase flow online using an ECT system, a narrowband image filter is defined to eliminate the influence of artifacts, and considering the continuity of the oil distribution variation, the detected oil-air interface of a former image can be used as the initial contour for the detection of the subsequent frame; thus, the propagation from the initial contour to the boundary can be greatly accelerated, making it possible for real time tracking. To testify the feasibility of the proposed method, an oil-air lubrication facility with 4 mm inner diameter pipe is measured in normal operation using an 8-electrode ECT system. Both simulation and experiment results indicate that the modified level set method is capable of visualizing the oil-air interface accurately online.

  20. Concentration Fluctuations and Capacitive Response in Dense Ionic Solutions

    CERN Document Server

    Uralcan, Betul; Debenedetti, Pablo G; Limmer, David T

    2016-01-01

    We use molecular dynamics simulations in a constant potential ensemble to study the effects of solution composition on the electrochemical response of a double layer capacitor. We find that the capacitance first increases with ion concentration following its expected ideal solution behavior but decreases upon approaching a pure ionic liquid. The non-monotonic behavior of the capacitance as a function of ion concentration results from the competition between the independent motion of solvated ions in the dilute regime and solvation fluctuations in the concentrated regime. When charge fluctuations induced by correlated ion-solvent fluctuations are large relative to those induced by the pure ionic liquid, such non-monotonic behavior is expected to be generic.

  1. Capacitated Vehicle Routing with Non-Uniform Speeds

    CERN Document Server

    Gortz, Inge Li; Nagarajan, Viswanath; Ravi, R

    2010-01-01

    The capacitated vehicle routing problem (CVRP) involves distributing (identical) items from a depot to a set of demand locations, using a single capacitated vehicle. We study a generalization of this problem to the setting of multiple vehicles having non-uniform speeds (that we call Heterogenous CVRP), and present a constant-factor approximation algorithm. The technical heart of our result lies in achieving a constant approximation to the following TSP variant (called Heterogenous TSP). Given a metric denoting distances between vertices, a depot r containing k vehicles with possibly different speeds, the goal is to find a tour for each vehicle (starting and ending at r), so that every vertex is covered in some tour and the maximum completion time is minimized. This problem is precisely Heterogenous CVRP when vehicles are uncapacitated. The presence of non-uniform speeds introduces difficulties for employing standard tour-splitting techniques. In order to get a better understanding of this technique in our con...

  2. Microbial desalination cell with capacitive adsorption for ion migration control.

    Science.gov (United States)

    Forrestal, Casey; Xu, Pei; Jenkins, Peter E; Ren, Zhiyong

    2012-09-01

    A new microbial desalination cell with capacitive adsorption capability (cMDC) was developed to solve the ion migration problem facing current MDC systems. Traditional MDCs remove salts by transferring ions to the anode and cathode chambers, which may prohibit wastewater beneficial reuse due to increased salinity. The cMDC uses adsorptive activated carbon cloth (ACC) as the electrodes and utilizes the formed capacitive double layers for electrochemical ion adsorption. The cMDC removed an average of 69.4% of the salt from the desalination chamber through electrode adsorption during one batch cycle, and it did not add salts to the anode or cathode chamber. It was estimated that 61-82.2mg of total dissolved solids (TDS) was adsorbed to 1g of ACC electrode. The cMDC provides a new approach for salt management, organic removal, and energy production. Further studies will be conducted to optimize reactor configuration and achieve in situ electrode regeneration.

  3. Leakage Currents and Capacitances of Thick CZT Detectors

    CERN Document Server

    Garson, Alfred; Jung, Ira V; Dowkontt, Paul; Bose, Richard; Simburger, Garry; Krawczynski, Henric

    2009-01-01

    The quality of Cadmium Zinc Telluride (CZT) detectors is steadily improving. For state of the art detectors, readout noise is thus becoming an increasingly important factor for the overall energy resolution. In this contribution, we present measurements and calculations of the dark currents and capacitances of 0.5 cm-thick CZT detectors contacted with a monolithic cathode and 8x8 anode pixels on a surface of 2 cm x 2 cm. Using the NCI ASIC from Brookhaven National Laboratory as an example, we estimate the readout noise caused by the dark currents and capacitances. Furthermore, we discuss possible additional readout noise caused by pixel-pixel and pixel-cathode noise coupling.

  4. Parameter optimization of temperature field in RF-capacitive hyperthermia

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To realize a certain target temperature distribution in tumor tissues and avoid over-heating in normal tissues in radio frequency (RF)-capacitive hyperthermia, an objective function and some weight coefficients are introduced. Then using the 2-D finite element method, the electromagnetic and bio-heat transfer equations are solved, and using the genetic algorithm the heating configurations are recursively modified to minimize the objective function. Finally an optimum solution of the expected heating field distribution in hyperthermia is achieved. And with a human heterogeneous tissue model extracted from X-ray CT images, satisfactory optimization results are obtained in the simulations on a biplate RF-capacitive hyperthermia device. This optimization technique for controlling the body temperature field has shown scientific importance and practical values in the research of hyperthermia.

  5. OPTIMIZATION OF CAPACITATED VEHICLE ROUTING PROBLEM USING PSO

    Directory of Open Access Journals (Sweden)

    S.R.VENKATESAN

    2011-10-01

    Full Text Available This paper presents solution techniques for Capacitated Vehicle Routing Problem (CVRP using metaheuristics. Capacitated Vehicle Routing Problem is divided into set of customers called cluster, and find optimum travel distance of vehicle route. The CVRP is a combinatorial optimization problem; particle swarm optimization(PSO technique is adapted in this paper to solve this problem. The main problem is divided into subprograms/clusters and each subprogram is treated as travelling salesman problem and solved by usingparticle swarm optimization techniques (PSO. This paper presents a sweep, Clark and wright algorithm to form the clusters. This model is then solved by using a particle swarm optimization (PSO method to find optimum travel distance of vehicle route. Our analysis suggests that the proposed model enables users to establish route to serve all given customers with minimum distance of vehicles and maximum capacity.

  6. Composition change and capacitance properties of ruthenium oxide thin film

    Institute of Scientific and Technical Information of China (English)

    刘泓; 甘卫平; 刘仲武; 郑峰

    2015-01-01

    RuO2·nH2O film was deposited on tantalum foils by electrodeposition and heat treatment using RuCl3·3H2O as precursor. Surface morphology, composition change and cyclic voltammetry from precursor to amorphous and crystalline RuO2·nH2O films were studied by X-ray diffractometer, Fourier transformation infrared spectrometer, differential thermal analyzer, scanning electron microscope and electrochemical analyzer, respectively. The results show that the precursor was transformed gradually from amorphous to crystalline phase with temperature. When heat treated at 300 °C for 2 h, RuO2·nH2O electrode surface gains mass of 2.5 mg/cm2 with specific capacitance of 782 F/g. Besides, it is found that the specific capacitance of the film decreased by roughly 20%with voltage scan rate increasing from 5 to 250 mV/s.

  7. Capacitance of a passive iron electrode in acidic solutions

    Energy Technology Data Exchange (ETDEWEB)

    Grilikhes, M.S.; Berezin, M.Yu.; Gorlin, A.V.; Sapelova, E.V.; Sokolov, M.A.; Sukhotin, A.M.

    1985-12-01

    In the present work the authors measured the capacitance of the electrical double layer on passive Armco iron in acidic solutions with the simultaneous recording of the potentiodynamic curves. The measurements were carried out on an apparatus which is based on the double-pulse variant of the galvanostatic method with a pulse lifetime of 2 microseconds, in which the influence of the faradic processes on the capacitance curves is negligibly small in the case of electrochemical systems with small exchange currents. The experiments were carried out at room temperature in 0.5 M sulfuric acid (pH 0.25) and 0.5 M tartaric acid H/sub 2/C/sub 4/H/sub 4/O/sub 6/ (pH 1.6).

  8. Capacitance Variation of Electrolyte-Gated Bilayer Graphene Based Transistors

    Directory of Open Access Journals (Sweden)

    Hediyeh Karimi

    2013-01-01

    Full Text Available Quantum capacitance of electrolyte-gated bilayer graphene field-effect transistors is investigated in this paper. Bilayer graphene has received huge attention due to the fact that an energy gap could be opened by chemical doping or by applying external perpendicular electric field. So, this extraordinary property can be exploited to use bilayer graphene as a channel in electrolyte-gated field-effect transistors. The quantum capacitance of bi-layer graphene with an equivalent circuit is presented, and also based on the analytical model a numerical solution is reported. We begin by modeling the DOS, followed by carrier concentration as a function V in degenerate and nondegenerate regimes. To further confirm this viewpoint, the presented analytical model is compared with experimental data, and acceptable agreement is reported.

  9. Capacitated Vehicle Routing with Non-Uniform Speeds

    DEFF Research Database (Denmark)

    Gørtz, Inge Li; Molinaro, Marco; Nagarajan, Viswanath

    2011-01-01

    The capacitated vehicle routing problem (CVRP) [21] involves distributing (identical) items from a depot to a set of demand locations in the shortest possible time, using a single capacitated vehicle. We study a generalization of this problem to the setting of multiple vehicles having non-uniform...... vehicles having speeds {λ i } i = 1 k , the goal is to find a tour for each vehicle (starting and ending at r), so that every vertex is covered in some tour and the maximum completion time is minimized. This problem is precisely Heterogenous CVRP when vehicles are uncapacitated. The presence of non-uniform...... the introduction of a new approximate MST construction called Level-Prim, which is related to Light Approximate Shortest-path Trees [18]. The last component of our algorithm involves partitioning the Level-Prim tree and matching the resulting parts to vehicles. This decomposition is more subtle than usual since...

  10. A High-Stability Capacitance Sensor System and Its Evaluation

    Science.gov (United States)

    2008-12-01

    15:45 from IEEE Xplore . Restrictions apply. Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of...45 from IEEE Xplore . Restrictions apply. AVRAMOV-ZAMUROVIC AND LEE: HIGH-STABILITY CAPACITANCE SENSOR SYSTEM AND ITS EVALUATION 957 Fig. 4...Authorized licensed use limited to: US Naval Academy. Downloaded on May 13, 2009 at 15:45 from IEEE Xplore . Restrictions apply. 958 IEEE TRANSACTIONS

  11. Simulation of New Switched Capacitance Power Converter for Srm

    Directory of Open Access Journals (Sweden)

    S. M. Mohamed Saleem

    2014-06-01

    Full Text Available In this paper, design and simulation of switched capacitance power converter are proposed for 6/4 switched reluctance motor (SRM drive. The operating principle and design consideration of the proposed converter is explained. The proposed converter performance is better in reduction of torque ripple and constant speed can be achieved quickly with reduced power loss when compared with asymmetric converter. The proposed system is simulated by using MATLAB Simulink and their results are clearly presented.

  12. Enhanced Capacitive Characteristics of Activated Carbon by Secondary Activation

    Institute of Scientific and Technical Information of China (English)

    YANG Hui; LU Tian-hong; Yoshio Masaki

    2004-01-01

    The effect of the improvement of commercial activated carbon(AC) on its specific capacitance and high rate capability of double layer(dl) charging/discharging process has been studied. The improvement of AC was carried out via a secondary activation under steam in the presence of catalyst NiCl2, and the suitable condition was found to be a heat treatment at about 875 ℃ for 1 h. Under those conditions, the discharge specific capacitance of the improved AC increases up to 53.67 F/g, showing an increase of about 25% as compared with that of as-received AC. The good rectangular-shaped voltammograms and A.C. impedance spectra prove that the high rate capability of the capacitor made of the improved AC is enhanced significantly. The capacitance resistance(RC) time constant of the capacitor containing the improved AC is 1.74 s, which is much lower than that of the one containing as-received AC(an RC value of 4. 73 s). It is noted that both kinds of AC samples show a similar specific surface area and pore size distribution, but some changes have taken place in the carbon surface groups, especially a decrease in the concentration of surface carbonyl groups after the improvement, which have been verified by means of X-photoelectron spectroscopy. Accordingly, it is suggested that the decrease in the concentration of surface carbonyl groups for the improved AC is beneficial to the organic electrolyte ion penetrating into the pores, thus leading to the increase in both the specific capacitance and high rate capability of the supercapacitor.

  13. Computation of Capacitance for MEMS Comb-Drive Structures

    Institute of Scientific and Technical Information of China (English)

    LI Ming-hui; GAO Shi-qiao; LIU Hai-peng; LIANG Xin-jian

    2009-01-01

    According to the characteristics of comb-drive structures,the electrical potential field is analyzed;the model based on corner capacitor is presented and solved with the capacitance characteristic formula of nonlinear capacitor.Compared with the results of finite element method simulation,the model based on corner capacitor is more accurate than the models based on infinite parallel plate capacitor and parallel plate capacitor with edge effects,

  14. Capacitive technology for energy extraction from chemical potential differences

    OpenAIRE

    Bastos Sales, B.

    2013-01-01

    This thesis introduces the principle of Capacitive energy extraction based on Donnan Potential (CDP) to exploit salinity gradients. It also shows the fundamental characterization and improvements of CDP. An alternative application of this technology aimed at thermal gradients was tested.   Chapter 2 introduces the principle and initial tests. The entropy increase of mixing two solutions of different salt concentrations can be harnessed to generate electrical energy. Worldwide, the potent...

  15. Managing periodic review inventory systems with capacitated replenishments

    OpenAIRE

    B. RAA; Dubois, T.; Dullaert, W

    2011-01-01

    This paper studies periodic review inventory systems in which replenishments are capacitated. This capacity restriction implies that the order-up-to level may not always be reached at each replenishment, such that additional safety stock is needed to achieve the same service level as in the uncapacitated case usually assumed in the existing literature. To determine the required level of safety stock, and hence the order-up-to level, an iterative procedure is proposed which can be adjusted to ...

  16. Modification of carbon fabrics by radio-frequency capacitive discharge at low pressure to regulate mechanical properties of carbon fiber reinforced plastics based on it

    Science.gov (United States)

    Garifullin, A. R.; Krasina, I. V.; Skidchenko, E. A.; Shaekhov, M. F.; Tikhonova, N. V.

    2017-01-01

    To increase the values of mechanical properties of carbon fiber (CF) composite materials used in sports equipment production the method of radio-frequency capacitive (RFC) low-pressure plasma treatment in air was proposed. Previously it was found that this type of modification allows to effectively regulate the surface properties of fibers of different nature. This treatment method differs from the traditional ones by efficiency and environmental friendliness as it does not require the use of aggressive, environmentally hazardous chemicals. In this paper it was established that RFC low-pressure air plasma treatment of carbon fabrics enhances the interlaminar shear strength (ILSS) of carbon fiber reinforced plastic (CFRP). As a result of experimental studies of CF by Fourier Transform Infrared (FTIR) spectroscopy method it was proved that after radio-frequency capacitive plasma treatment at low pressure in air the oxygen-containing functional groups is grafted on the surface. These groups improve adhesion at the interface “matrix-fiber”.

  17. DNA Nucleotides Detection via capacitance properties of Graphene

    Science.gov (United States)

    Khadempar, Nahid; Berahman, Masoud; Yazdanpanah, Arash

    2016-05-01

    In the present paper a new method is suggested to detect the DNA nucleotides on a first-principles calculation of the electronic features of DNA bases which chemisorbed to a graphene sheet placed between two gold electrodes in a contact-channel-contact system. The capacitance properties of graphene in the channel are surveyed using non-equilibrium Green's function coupled with the Density Functional Theory. Thus, the capacitance properties of graphene are theoretically investigated in a biological environment, and, using a novel method, the effect of the chemisorbed DNA nucleotides on electrical charges on the surface of graphene is deciphered. Several parameters in this method are also extracted including Electrostatic energy, Induced density, induced electrostatic potential, Electron difference potential and Electron difference density. The qualitative and quantitative differences among these parameters can be used to identify DNA nucleotides. Some of the advantages of this approach include its ease and high accuracy. What distinguishes the current research is that it is the first experiment to investigate the capacitance properties of gaphene changes in the biological environment and the effect of chemisorbed DNA nucleotides on the surface of graphene on the charge.

  18. Capacitance-modulated transistor detects odorant binding protein chiral interactions

    Science.gov (United States)

    Mulla, Mohammad Yusuf; Tuccori, Elena; Magliulo, Maria; Lattanzi, Gianluca; Palazzo, Gerardo; Persaud, Krishna; Torsi, Luisa

    2015-01-01

    Peripheral events in olfaction involve odorant binding proteins (OBPs) whose role in the recognition of different volatile chemicals is yet unclear. Here we report on the sensitive and quantitative measurement of the weak interactions associated with neutral enantiomers differentially binding to OBPs immobilized through a self-assembled monolayer to the gate of an organic bio-electronic transistor. The transduction is remarkably sensitive as the transistor output current is governed by the small capacitance of the protein layer undergoing minute changes as the ligand-protein complex is formed. Accurate determination of the free-energy balances and of the capacitance changes associated with the binding process allows derivation of the free-energy components as well as of the occurrence of conformational events associated with OBP ligand binding. Capacitance-modulated transistors open a new pathway for the study of ultra-weak molecular interactions in surface-bound protein-ligand complexes through an approach that combines bio-chemical and electronic thermodynamic parameters.

  19. Ring VCO Design with Variable Capacitance XNOR Delay Cell

    Science.gov (United States)

    Kumar, Manoj; Arya, Sandeep; Pandey, Sujata

    2015-12-01

    This paper presents the new designs of voltage controlled oscillator (VCO) with three transistors XNOR gate as variable capacitive load. Design of three, five and seven stage VCO have been reported using single ended ring topology. CMOS inverter based delay cell is modified with addition of XNOR capacitive load. Output frequency has been controlled by applied voltage to variable capacitive load. Control voltage of VCO has been varied from 1.3 to 2.1 V. Three stage VCO provides output frequency variation in the range of 3.52-3.34 GHz with power consumption variation from 0.81 to 1.76 mW. Five stage VCO shows frequency variation from 2.06 to 1.98 GHz with power consumption varying from 1.35 to 2.94 mW. Moreover, frequency of seven stage VCO varies from 1.47 to 1.41 GHz with varying power from 1.89 to 4.12 mW. Power consumption and output frequency of proposed VCO circuits have been compared with earlier reported circuits and present approach shows considerable improvements.

  20. Capacitive-coupled Series Spoof Surface Plasmon Polaritons

    Science.gov (United States)

    Yin, Jia Yuan; Ren, Jian; Zhang, Hao Chi; Zhang, Qian; Cui, Tie Jun

    2016-04-01

    A novel method to realize stopband within the operating frequency of spoof surface plasmon polaritons (SPPs) is presented. The stopband is introduced by a new kind of capacitive-coupled series spoof SPPs. Two conventional H-shaped unit cells are proposed to construct a new unit cell, and every two new unit cells are separated by a gap with certain distance, which is designed to implement capacitive coupling. The original surface impedance matching is disturbed by the capacitive coupling, leading to the stopband during the transmission of SPPs. The proposed method is verified by both numerical simulations and experiments, and the simulated and measured results have good agreements. It is shown that the proposed structure exhibits a stopband in 9-9.5 GHz while the band-pass feature maintains in 5-9 GHz and 9.5-11 GHz. In the passband, the reflection coefficient is less than -10 dB, and the transmission loss is around 3 dB in the stopband, the reflection coefficient is -2 dB, and the transmission coefficient is less than -30 dB. The compact size, easy fabrication and good band-pass and band-stop features make the proposed structure a promising plasmonic device in SPP communication systems.

  1. Capacitive properties of polypyrrole/activated carbon composite

    Directory of Open Access Journals (Sweden)

    Porjazoska-Kujundziski Aleksandra

    2014-01-01

    Full Text Available Electrochemical synthesis of polypyrrole (PPy and polypyrrole / activated carbon (PPy / AC - composite films, with a thickness between 0.5 and 15 μm were performed in a three electrode cell containing 0.1 mol dm-3 Py, 0.5 mol dm-3 NaClO4 dissolved in ACN, and dispersed particles of AC (30 g dm-3. Electrochemical characterization of PPy and PPy / AC composites was performed using cyclic voltammetry (CV and electrochemical impedance spectroscopy (EIS techniques. The linear dependences of the capacitance (qC, redox capacitance (qred, and limiting capacitance (CL of PPy and PPy / AC - composite films on their thickness (L, obtained by electrochemical and impedance analysis, indicate a nearly homogeneous distribution of the incorporated AC particles in the composite films (correlation coefficient between 0.991 and 0.998. The significant enhancement of qC, qred, and CL, was observed for composite films (for ∼40 ± 5% in respect to that of the “pure” PPy. The decreased values of a volume resistivity in the reduced state of the composite film, ρ = 1.3 ⋅ 106 Ω cm (for L = 7.5 μm, for two orders of magnitude, compared to that of PPy - film with the same thickness, ρ ∼ 108 Ω cm, was also noticed.

  2. Can a Pressure Standard be Based on Capacitance Measurements?

    Science.gov (United States)

    Moldover, Michael R

    1998-01-01

    We consider the feasibility of basing a pressure standard on measurements of the dielectric constant ϵ and the thermodynamic temperature T of helium near 0 °C. The pressure p of the helium would be calculated from fundamental constants, quantum mechanics, and statistical mechanics. At present, the relative standard uncertainty of the pressure ur(p) would exceed 20 × 10(-6), the relative uncertainty of the value of the molar polarizability of helium Aϵ calculated ab initio. If the relativistic corrections to Aϵ were calculated as accurately as the classical value is now known, a capacitance-based pressure standard might attain ur(p) < 6 × 10(-6) for pressures near 1 MPa, a result of considerable interest for pressure metrology. One obtains p by eliminating the density from the virial expansions for p and ϵ - 1. If ϵ - 1 were measured with a very stable, 0.5 pF toroidal cross capacitor, the small capacitance and the small values of ϵ - 1 would require state-of-the-art capacitance measurements to achieve a useful pressure standard.

  3. Investigation on the Sensitivity Distribution in Electrical Capacitance Tomography System

    Directory of Open Access Journals (Sweden)

    Pan Jiang

    2013-07-01

    Full Text Available The gas-solid-liquid three-phase flow is a very complicated flow pattern in pipeline transportation. By using electrical capacitance tomography (ETC it can acquire the permittivity distribution of the multi-phase. The sensitivity distribution in ETC may affect the analysis of the permittivity distribution of the multi-phase. However, very limited work has been done in this issue. In order to investigate the sensitivity distribution in ETC, this paper employs the finite element method (FEM to establish the principle and components of ECT. The FEM model of the sensitivity distribution as a function of the inter-electrode capacitance was discussed. Simulation tests were carried out to calculate the charge on the electrode pairs to access the potential distribution of the ETC. The analysis results show that the dielectric have great influence on the capacitance value and small distance between the electrode pair and the sensitivity field will produce high sensitivity value. Hence, the findings of this work can provide reference for the design of ECT in practice.

  4. Tactile sensor integrated dielectric elastomer actuator for simultaneous actuation and sensing

    Science.gov (United States)

    Kadooka, Kevin; Imamura, Hiroya; Taya, Minoru

    2016-04-01

    Dielectric elastomers (DE) are a subgroup of electroactive polymers which may be used as soft transducers. Such soft transducers exhibit high energy density and silent operation, which makes them desirable for life-like robotic systems such as a robotic hand. A robotic hand must be able to sense the object being manipulated, in terms of normal and shear force being applied, and note when contact has been achieved or lost. To this end, a dielectric elastomer actuator (DEA) with integrated tactile sensing has been developed to provide simultaneous actuation and sensing. The tactile sensing dielectric elastomer actuator consists of a unimorph-type structure, where the active portion is a laminate of alternating DE and electrode material which expands under applied voltage, and the sensing portion is a stiffer sensing dielectric elastomer which has no electrical connection to the active portion. Under applied voltage, the deformation of the active portion expands but is constrained on one side by the sensing portion, resulting in bending actuation. The sensing portion is a DE with electrodes patterned to form 2x2 capacitive sensing arrays. Dome-shaped bumps positioned over the sensing arrays redistribute tactile forces onto the sensor segments, so that measurement of the capacitance change across the array allows for reconstruction of magnitude and direction of the incoming force.

  5. Ion-step method for surface potential sensing of silicon nanowires

    NARCIS (Netherlands)

    Chen, Songyue; Nieuwkasteele, van Jan W.; Berg, van den Albert; Eijkel, Jan C.T.

    2016-01-01

    This paper presents a novel stimulus-response method for surface potential sensing of silicon nanowire (Si NW) field-effect transistors. When an "ion-step" from low to high ionic strength is given as a stimulus to the gate oxide surface, an increase of double layer capacitance is therefore expected.

  6. Pulse mode actuation-readout system based on MEMS resonator for liquid sensing

    DEFF Research Database (Denmark)

    Tang, Meng; Cagliani, Alberto; Davis, Zachary James;

    2014-01-01

    A MEMS (Micro-Electro-Mechanical Systems) bulk disk resonator is applied for mass sensing under its dynamic mode. The classical readout circuitry involves sophisticated feedback loop and feedthrough compensation. We propose a simple straightforward non-loop pulse mode actuation and capacitive...

  7. Performance Analysis and Test of Noise in Differential Capacitance to Voltage Conversion Circuit%差分电容电压转换电路噪声性能分析及测试

    Institute of Scientific and Technical Information of China (English)

    张霞; 胡世昌; 朱辉杰

    2011-01-01

    本文对电容检测式加速度计系统中广泛采用的差分电容电压转换电路建立了电容电压转换电路的等效噪声模型,并对双运放集成电路芯片所构成的差分电容电压转换电路的本底噪声以及仪表放大器输出端的噪声进行了测试,将电容电压转换电路本底噪声中的差模噪声分量和共模噪声分量进行了分离.测试结果表明影响加速度计系统噪声性能的差模噪声分量占电容电压转换电路本底噪声的50%.%This paper presents an equivalent noise model of differential capacitance to voltage conversion circuit which is widely used in capacitive sensing accelerometers. The noise floors of the capacitance to voltage conversion circuit realized by dual amplifiers (two in a package) and the instrumentation amplifier are measured. The common-mode noise and the difference-mode noise in the noise floor of the capacitance to voltage conversion circuit can be calculated. The test results show that the difference-mode noise, which would affect the resolution of the capacitive sensing accelerometer system, constitutes nearly half the noise floor of the capacitance to voltage conversion circuit.

  8. Sensing at the nanoscale

    Science.gov (United States)

    Demming, Anna; Hierold, Christofer

    2013-11-01

    label-free detection of DNA at concentrations as low as 1-10 fM, a sensitivity comparable to the best signal amplification-assisted electrochemical sensors reported [12]. In another study actin-conjugated gold and silver nanorods are used to detect ATP, a common indicator of cell viability [13]. They show how aggregation induced by ATP-induced polymerization of the G-actin gives rise to a measurable change in the plasmon resonance absorbance of the nanorods. A review of the use of fluorescent silica nanoparticles for biomedical applications is provided by researchers at Dublin City University in Ireland [14]. The first scanning tunnelling microscope in the early 1980s and subsequent scanning probe developments brought the world of nanoscale structures into view in a manner that gorged the imaginations of scientists and the public. New ways of probing structures at this scale revealed a wealth of curious properties that triggered a surge of research activity in nanotechnology, now a multibillion dollar industry. One good turn deserves another and in fact nanostructures provide the perfect tools for the type of sensing and imaging applications that brought such widespread research interest to nanotechnology. This special issue highlights just how broad and innovative the range of sensing nanotechnologies has grown. References [1] Zappa D, Comini E and Sberveglieri G 2013 Thermally-oxidized zinc oxide nanowires chemical sensors Nanotechnology 24 444008 [2] Kemmler J A, Pokhrel S, Mädler L, Weimar U and Barsan N 2013 Flame spray pyrolysis for sensing at the nanoscale Nanotechnology 24 442001 [3] Bache M et al 2013 Nanomechanical recognition of prognostic biomarker suPAR with DVD-ROM optical technology Nanotechnology 24 444011 [4] Hu C-F, Wang J-Y, Liu Y-C, Tsai M-H and Fang W 2013 Development of 3D carbon nanotubes interdigitated finger electrodes on polymer substrate for flexible capacitive sensor application Nanotechnology 24 444006 [5] Neumann C, Volk C, Engels S and

  9. Theoretical study of quantum capacitance and associated delay in armchair-edge graphene nanoribbons

    Science.gov (United States)

    Hassan, Asif; Hossain, Md. Faruque; Rana, Md. Sohel; Kouzani, Abbas Z.

    2015-09-01

    This work presents a comprehensive investigation of the quantum capacitance and the associated effects on the carrier transit delay in armchair-edge graphene nanoribbons (A-GNRs) based on semi-analytical method. We emphasize on the realistic analysis of bandgap with taking edge effects into account by means of modified tight binding (TB) model. The results show that the edge effects have significant influence in defining the bandgap which is a necessary input in the accurate analyses of capacitance. The quantum capacitance is discussed in both nondegenerate (low gate voltage) and degenerate (high gate voltage) regimes. We observe that the classical capacitance limits the total gate (external) capacitance in the degenerate regime, whereas, quantum capacitance limits the external gate capacitance in the nondegenerate regime. The influence of gate capacitances on the gate delay is studied extensively to demonstrate the optimization of switching time. Moreover, the high-field behavior of a GNR is studied in the degenerate and nondegenerate regimes. We find that a smaller intrinsic capacitance appears in the channel due to high velocity carrier, which limits the quantum capacitance and thus limit the gate delay. Such detail analysis of GNRs considering a realistic model would be useful for the optimized design of GNR-based nanoelectronic devices.

  10. A simple efficient model of parasitic capacitances of deep-submicron LDD MOSFETs

    Science.gov (United States)

    Prégaldiny, Fabien; Lallement, Christophe; Mathiot, Daniel

    2002-12-01

    Estimation of parasitic capacitances in a MOSFET device is very important, notably in mixed circuit simulation. For deep-submicron LDD MOSFETs, the extrinsic capacitance (overlap plus fringing capacitances) is a growing fraction of the total gate capacitance. A correct estimation of the extrinsic capacitance requires an accurate modeling of each of its constituents. However the major existing models do not correctly predict the overlap capacitance and the inner fringing capacitance (which is often ignored). In this paper a new approach to model the overlap Cov and fringing Cif+ Cof capacitances in the zero-current regime is presented. The bias dependence of the extrinsic capacitance is investigated and a detailed study of the influence of the LDD doping dose is also undertaken. Then, an efficient, simple and continuous model describing the evolution of overlap and fringing capacitances in all operating regimes of a n-channel LDD MOSFET is developed. Finally this model is incorporated in an existing compact-model for circuit simulation. It is shown that this new model leads to excellent results in comparison with full 2D numerical device simulation.

  11. Subwavelength resonant nanostructured films for sensing

    Energy Technology Data Exchange (ETDEWEB)

    Alvine, Kyle J.; Bernacki, Bruce E.; Suter, Jonathan D.; Bennett, Wendy D.; Edwards, Daniel L.; Mendoza, Albert

    2013-05-29

    We present a novel subwavelength nanostructure architecture that may be utilized for optical standoff sensing applications. The subwavelength structures are fabricated via a combination of nanoimprint lithography and metal sputtering to create metallic nanostructured films encased within a transparent media. The structures are based on the open ring resonator (ORR) architecture and have their analog in resonant LC circuits, which display a resonance frequency that is inversely proportional to the square root of the product of the inductance and capacitance. Therefore, any perturbation of the nanostructured films due to chemical or environmental effects can alter the inductive or capacitive behavior of the subwavelength features, which can shift the resonant frequency and provide an indication of the external stimulus. This shift in resonance can be interrogated remotely either actively using either laser illumination or passively using hyperspectral or multispectral sensing. These structures may be designed to be either anisotropic or isotropic, which can also provide polarization-sensitive interrogation. Due to the nanometer-scale of the structures, they can be tailored to be optically responsive in the visible or near infrared spectrum with a highly reflective resonant peak that is dependent solely on structural dimensions and material characteristics. We present experimental measurements of the optical response of these structures as a function of wavelength, polarization, and incident angle demonstrating the resonant effect in the near infrared region. Numerical modeling data showing the effect of different fabrication parameters such as structure parameters are also discussed.

  12. Interface Simulation Distances

    Directory of Open Access Journals (Sweden)

    Pavol Černý

    2012-10-01

    Full Text Available The classical (boolean notion of refinement for behavioral interfaces of system components is the alternating refinement preorder. In this paper, we define a distance for interfaces, called interface simulation distance. It makes the alternating refinement preorder quantitative by, intuitively, tolerating errors (while counting them in the alternating simulation game. We show that the interface simulation distance satisfies the triangle inequality, that the distance between two interfaces does not increase under parallel composition with a third interface, and that the distance between two interfaces can be bounded from above and below by distances between abstractions of the two interfaces. We illustrate the framework, and the properties of the distances under composition of interfaces, with two case studies.

  13. After Rigid Interfaces

    DEFF Research Database (Denmark)

    Troiano, Giovanni Maria

    Deformable and shape-changing interfaces are rapidly emerging in the field of human-computer interaction (HCI). Deformable interfaces provide users with newer input possibilities such as bending, squeezing, or stretching, which were impossible to achieve with rigid interfaces. Shape-changing inte......Deformable and shape-changing interfaces are rapidly emerging in the field of human-computer interaction (HCI). Deformable interfaces provide users with newer input possibilities such as bending, squeezing, or stretching, which were impossible to achieve with rigid interfaces. Shape...

  14. Integrated sensing and actuation of muscle-like actuators

    Science.gov (United States)

    Gisby, T. A.; Xie, S.; Calius, E. P.; Anderson, I. A.

    2009-03-01

    The excellent overall performance and compliant nature of Dielectric Elastomer Actuators (DEAs) make them ideal candidates for artificial muscles. Natural muscle however is much more than just an actuator, it provides position feedback to the brain that is essential for the body to maintain balance and correct posture. If DEAs are to truly earn the moniker of "artificial muscles" they need to be able to reproduce, if not improve on, this functionality. Self-sensing DEAs are the ideal solution to this problem. This paper presents a system by which the capacitance of a DEA can be sensed while it is being actuated and used for feedback control. This system has been strongly influenced by the desire for portability i.e. designed for use in a battery operated microcontroller based system. It is capable of controlling multiple independent DEAs using a single high voltage power supply. These features are important developments for artificial muscle devices where accuracy and low mass are important e.g. a prosthetic hand or force-feedback surgical tools. A numerical model of the electrical behaviour of the DEA that incorporates arbitrary leakage currents and the impact of arbitrary variable capacitance has been created to model a DEA system. A robust capacitive self-sensing method that uses a slew-rate controlled Pulse Width Modulation (PWM) signal and compensates for the effects of leakage current and variable capacitance is presented. The numerical model is then used to compare the performance of this new method with an earlier method previously published by the authors.

  15. Modelling of capacitance and threshold voltage for ultrathin normally-off AlGaN/GaN MOSHEMT

    Indian Academy of Sciences (India)

    R SWAIN; K JENA; T R LENKA

    2017-01-01

    A compact quantitative model based on oxide semiconductor interface density of states (DOS) is proposed for Al$_{0.25}$Ga$_{0.75}$N/GaN metal oxide semiconductor high electron mobility transistor (MOSHEMT). Mathematical expressions for surface potential, sheet charge concentration, gate capacitance and threshold voltage have been derived. The gate capacitance behaviour is studied in terms of capacitance–voltage (CV) characteristics. Similarly, the predicted threshold voltage ($V_T$) is analysed by varying barrier thickness and oxide thickness. The positive $V_T$ obtained for a very thin 3 nm AlGaN barrier layer enables the enhancement mode operation of the MOSHEMT. These devices, along with depletion mode devices, are basic constituents of cascode configuration in power electronic circuits. The expressions developed are used in conventional long-channel HEMT drain current equation and evaluated to obtain different DC characteristics. The obtained results are compared withexperimental data taken from literature which show good agreement and hence endorse the proposed model.

  16. Temperature-dependent electrochemical capacitive performance of the α-Fe2O3 hollow nanoshuttles as supercapacitor electrodes.

    Science.gov (United States)

    Zheng, Xin; Yan, Xiaoqin; Sun, Yihui; Yu, Yinsheng; Zhang, Guangjie; Shen, Yanwei; Liang, Qijie; Liao, Qingliang; Zhang, Yue

    2016-03-15

    The design and optimization of supercapacitors electrodes nanostructures are critically important since the properties of supercapacitors can be dramatically enhanced by tunable ion transport channels. Herein, we demonstrate high-performance supercapacitor electrodes materials based on α-Fe2O3 by rationally designing the electrode microstructure. The large solid-liquid reaction interfaces induced by hollow nanoshuttle-like structures not only provide more active sites for faradic reactions but also facilitate the diffusion of the electrolyte into electrodes. These result in the optimized electrodes with high capacitance of 249 F g(-1) at a discharging current density of 0.5 A g(-1) as well as good cycle stability. In addition, the relationship between charge storage and the operating temperature has been researched. The specific capacitance has no significant change when the working temperature increased from 20 °C to 60 °C (e.g. 203 F g(-1) and 234 F g(-1) at 20 °C and 60 °C, respectively), manifesting the electrodes can work stably in a wide temperature range. These findings here elucidate the α-Fe2O3 hollow nanoshuttles can be applied as a promising supercapacitor electrode material for the efficient energy storage at various potential temperatures.

  17. Interface design in the process industries

    Science.gov (United States)

    Beaverstock, M. C.; Stassen, H. G.; Williamson, R. A.

    1977-01-01

    Every operator runs his plant in accord with his own mental model of the process. In this sense, one characteristic of an ideal man-machine interface is that it be in harmony with that model. With this theme in mind, the paper first reviews the functions of the process operator and compares them with human operators involved in control situations previously studied outside the industrial environment (pilots, air traffic controllers, helmsmen, etc.). A brief history of the operator interface in the process industry and the traditional methodology employed in its design is then presented. Finally, a much more fundamental approach utilizing a model definition of the human operator's behavior is presented.

  18. Large area graphene ion sensitive field effect transistors with tantalum pentoxide sensing layers for pH measurement at the Nernstian limit

    Energy Technology Data Exchange (ETDEWEB)

    Fakih, Ibrahim, E-mail: ibrahim.fakih@mail.mcgill.ca; Sabri, Shadi; Szkopek, Thomas, E-mail: thomas.szkopek@mcgill.ca [Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec H3A 2A7 (Canada); Mahvash, Farzaneh [Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec H3A 2A7 (Canada); Département de Chimie et Biochimie, Universite du Québec à Montréal, Montreal, Quebec H3C 3P8 (Canada); Nannini, Matthieu [McGill Nanotools Microfab, McGill University, Montreal, Quebec H3A 2A7 (Canada); Siaj, Mohamed [Département de Chimie et Biochimie, Universite du Québec à Montréal, Montreal, Quebec H3C 3P8 (Canada)

    2014-08-25

    We have fabricated and characterized large area graphene ion sensitive field effect transistors (ISFETs) with tantalum pentoxide sensing layers and demonstrated pH sensitivities approaching the Nernstian limit. Low temperature atomic layer deposition was used to deposit tantalum pentoxide atop large area graphene ISFETs. The charge neutrality point of graphene, inferred from quantum capacitance or channel conductance, was used to monitor surface potential in the presence of an electrolyte with varying pH. Bare graphene ISFETs exhibit negligible response, while graphene ISFETs with tantalum pentoxide sensing layers show increased sensitivity reaching up to 55 mV/pH over pH 3 through pH 8. Applying the Bergveld model, which accounts for site binding and a Guoy-Chapman-Stern picture of the surface-electrolyte interface, the increased pH sensitivity can be attributed to an increased buffer capacity reaching up to 10{sup 14} sites/cm{sup 2}. ISFET response was found to be stable to better than 0.05 pH units over the course of two weeks.

  19. The Semen pH Affects Sperm Motility and Capacitation.

    Science.gov (United States)

    Zhou, Ji; Chen, Li; Li, Jie; Li, Hongjun; Hong, Zhiwei; Xie, Min; Chen, Shengrong; Yao, Bing

    2015-01-01

    As the chemical environment of semen can have a profound effect on sperm quality, we examined the effect of pH on the motility, viability and capacitation of human sperm. The sperm in this study was collected from healthy males to avoid interference from other factors. The spermatozoa cultured in sperm nutrition solution at pH 5.2, 6.2, 7.2 and 8.2 were analyzed for sperm total motility, progressive motility (PR), hypo-osmotic swelling (HOS) rate, and sperm penetration. Our results showed that these parameters were similar in pH 7.2 and 8.2 sperm nutrition solutions, but decreased in pH 5.2 and 6.2 solutions. The HOS rate exhibited positive correlation with the sperm total motility and PR. In addition, the sperm Na(+)/K(+)-ATPase activity at different pHs was measured, and the enzyme activity was significantly lower in pH 5.2 and 6.2 media, comparing with that in pH 8.2 and pH 7.2 solutions. Using flow cytometry (FCM) and laser confocal scanning microscopy (LCSM) analysis, the intracellular Ca2(+ )concentrations of sperm cultured in sperm capacitation solution at pH 5.2, 6.2, 7.2 and 8.2 were determined. Compared with that at pH 7.2, the mean fluorescence intensity of sperm in pH 5.2 and 6.2 media decreased significantly, while that of pH 8.2 group showed no difference. Our results suggested that the declined Na(+)/K(+)-ATPase activity at acidic pHs result in decreased sperm movement and capacitation, which could be one of the mechanisms of male infertility.

  20. Capacitive micromachined ultrasonic transducer arrays as tunable acoustic metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Lani, Shane W., E-mail: shane.w.lani@gmail.com, E-mail: karim.sabra@me.gatech.edu, E-mail: levent.degertekin@me.gatech.edu; Sabra, Karim G. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801Ferst Drive, Georgia 30332-0405 (United States); Wasequr Rashid, M.; Hasler, Jennifer [School of Electrical and Computer Engineering, Georgia Institute of Technology, Van Leer Electrical Engineering Building, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250 (United States); Levent Degertekin, F. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801Ferst Drive, Georgia 30332-0405 (United States); School of Electrical and Computer Engineering, Georgia Institute of Technology, Van Leer Electrical Engineering Building, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250 (United States)

    2014-02-03

    Capacitive Micromachined Ultrasonic Transducers (CMUTs) operating in immersion support dispersive evanescent waves due to the subwavelength periodic structure of electrostatically actuated membranes in the array. Evanescent wave characteristics also depend on the membrane resonance which is modified by the externally applied bias voltage, offering a mechanism to tune the CMUT array as an acoustic metamaterial. The dispersion and tunability characteristics are examined using a computationally efficient, mutual radiation impedance based approach to model a finite-size array and realistic parameters of variation. The simulations are verified, and tunability is demonstrated by experiments on a linear CMUT array operating in 2-12 MHz range.

  1. Dynamic actuation methods for capacitive MEMS shunt switches

    Science.gov (United States)

    Khater, M. E.; Vummidi, K.; Abdel-Rahman, E. M.; Nayfeh, A. H.; Raman, S.

    2011-03-01

    We develop dynamic actuation methods for capacitive MEMS shunt switches. We show that the dynamic actuation voltage is significantly less than the static actuation voltage and demonstrate 60% reduction in the actuation voltage. We also show that this reduction in the actuation voltage depends on the specific dynamic switching technique adopted. For a given operating condition, the minimum realizable switching time is that obtained using static switching. However, we developed a dynamic switching method that yields comparable switching time to that minimum. We also found that squeeze-film damping is the dominant damping mechanism for a shunt switch with a relatively slender bridge (aspect ratio of 11:1).

  2. Low-Frequency Relaxation Oscillations in Capacitive Discharge Processes

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhu-Wen; M.A.LIEBERMAN; Sungjin KIM; JI Shi-Yin; DENG Ming-Sen; SUN Guang-Yu

    2008-01-01

    Low-frequency (2.72-3.70 Hz) relaxation oscillations at 100m Tort at higher absorbed power were observed from time-varying optical emission of the main discharge chamber and the periphery.We interpret the low frequency oscillations using an electromagnetic model of the slot impedance with parallel connection variational peripheral capacitance,coupled to a circuit analysis of the system including the matching network.The model results are in general agreement with the experimental observations,and indicate a variety of bchaviours dependent on the matching conditions.

  3. Leakage Currents and Capacitances of Thick CZT Detectors

    OpenAIRE

    Garson III, Alfred; Li, Qiang; Jung, Ira V.; Dowkontt, Paul; Bose, Richard; Simburger, Garry; Krawczynski, Henric

    2009-01-01

    The quality of Cadmium Zinc Telluride (CZT) detectors is steadily improving. For state of the art detectors, readout noise is thus becoming an increasingly important factor for the overall energy resolution. In this contribution, we present measurements and calculations of the dark currents and capacitances of 0.5 cm-thick CZT detectors contacted with a monolithic cathode and 8x8 anode pixels on a surface of 2 cm x 2 cm. Using the NCI ASIC from Brookhaven National Laboratory as an example, we...

  4. Rapid Prototyping of Tangibles with a Capacitive Mouse

    DEFF Research Database (Denmark)

    Ramos, Juan David Hincapie; Esbensen, Morten; Kogutowska, Magdalena

    2011-01-01

    This paper presents the Toki toolkit: a do-it-yourself guide and API to support the rapid prototyping of tangibles. The toolkit provides support for two common requirements for tangibles: capture of touch input by an user and commu- nication of such input to a computer. At the core of the toolkit...... lays the capacitive surface and communication capa- bilities of a Microsoft TouchMouse, both of which are ap- propriated to fulfill the mentined requirements. Unlike ex- isting approaches for rapid prototyping of tangibles like the Arduino boards, using the Toki toolkit does not require de- velopers...

  5. Correlated Coulomb drag in capacitively coupled quantum-dot structures

    DEFF Research Database (Denmark)

    Kaasbjerg, Kristen; Jauho, Antti-Pekka

    2016-01-01

    We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs) -- a biasdriven dot coupled to an unbiased dot where transport is due to Coulomb mediated energy transfer drag. To this end, we introduce a master-equation approach which accounts for higher-order tunneling (cotunneling....... Interestingly, the direction of the drag current is not determined by the drive current, but by an interplay between the energy-dependent lead couplings. Studying the drag mechanism in a graphene-based CQD heterostructure, we show that the predictions of our theory are consistent with recent experiments...

  6. Experimental Analysis of Bisbenzocyclobutene Bonded Capacitive Micromachined Ultrasonic Transducers

    OpenAIRE

    2016-01-01

    Experimental measurement results of a 1.75 mm × 1.75 mm footprint area Capacitive Micromachined Ultrasonic Transducer (CMUT) planar array fabricated using a bisbenzocyclobutene (BCB)-based adhesive wafer bonding technique has been presented. The array consists of 40 × 40 square diaphragm CMUT cells with a cavity thickness of 900 nm and supported by 10 µm wide dielectric spacers patterned on a thin layer of BCB. A 150 µm wide one µm thick gold strip has been used as the contact pad for gold wi...

  7. New Multipole Method for 3-D Capacitance Extraction

    Institute of Scientific and Technical Information of China (English)

    Zhao-Zhi Yang; Ze-Yi Wang

    2004-01-01

    This paper describes an effcient improvement of the multipole accelerated boundary element method for 3-D capacitance extraction.The overall relations between the positions of 2-D boundary elements are considered instead of only the relations between the center-points of the elements,and a new method of cube partitioning is introduced.Numerical results are presented to demonstrate that the method is accurate and has nearly linear computational growth as O(n),where n is the number of panels/boundary elements.The proposed method is more accurate and much faster than Fastcap.

  8. Design of capacitance sensor system for void fraction measurement

    Institute of Scientific and Technical Information of China (English)

    LIU Yi-ping; NIU Gang; WANG Jing

    2005-01-01

    Simulation and optimization were applied to a capacitive sensor system based on electrical tomography technology.Sensors, consisting of Morgantown Energy Technology Center (METC) axial synchro driving guard electrodes and two sets of detecting electrodes, make it possible to obtain simultaneously two groups of signals of the void fraction in oil-gas two-phase flow.The computational and experimental results showed that available sensors, charactered by high resolution and fast real-time response can be used for real-time liquid-gas two-phase flow pattern determination.

  9. Contrast distortion induced by modulation voltage in scanning capacitance microscopy

    Science.gov (United States)

    Chang, M. N.; Hu, C. W.; Chou, T. H.; Lee, Y. J.

    2012-08-01

    With a dark-mode scanning capacitance microscopy (SCM), we directly observed the influence of SCM modulation voltage (MV) on image contrasts. For electrical junctions, an extensive modulated area induced by MV may lead to noticeable changes in the SCM signal phase and intensity, resulting in a narrowed junction image and a broadened carrier concentration profile. This contrast distortion in SCM images may occur even if the peak-to-peak MV is down to 0.3 V. In addition, MV may shift the measured electrical junction depth. The balance of SCM signals components explain these MV-induced contrast distortions.

  10. FPGA Based Low Power ROM Design Using Capacitance Scaling

    DEFF Research Database (Denmark)

    Bansal, Meenakshi; Bansal, Neha; Saini, Rishita

    2015-01-01

    An ideal capacitor will not dissipate any power, but a real capacitor wil l have some power dissipation. In this work, we are going to design capacitance scaling based low power ROM design. In order to test the compatibility of this ROM design with latest i7 Processor, we are operating this ROM w...... in I/O Power, saving of 0.2% occur in Leakage Power, there will be a saving of 11.54% occur in Total Power. This design is implemented on Virtex-5 FPGA using Xilinx ISE and Verilog....

  11. Capacitively Loaded Loop-Based Antennas with Reconfigurable Radiation Patterns

    Directory of Open Access Journals (Sweden)

    Saber Dakhli

    2015-01-01

    Full Text Available A class of metamaterial-inspired antennas having reconfigurable radiation patterns is proposed. They consist of a driven monopole antenna with one- and two-capacitively loaded loop (CLL, near field resonant parasitic elements. Two configurations are studied by considering the state of these CLL elements as being either open or closed configurations. Simulation results explain the design features and demonstrate that the structure can change its beam direction simply by controlling the switched states. Two prototypes with one- and two-CLL elements were fabricated and tested. The measured impedance mismatch and radiation pattern results are presented and compared to the corresponding simulated values.

  12. Development of a MEMS dual-axis differential capacitance floating element shear stress sensor

    Energy Technology Data Exchange (ETDEWEB)

    Barnard, Casey [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Griffin, Benjamin [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    A single-axis MEMS wall shear stress sensor with differential capacitive transduction method is produced. Using a synchronous modulation and demodulation interface circuit, the system is capable of making real time measurements of both mean and fluctuating wall shear stress. A sensitivity of 3.44 mV/Pa is achieved, with linearity in response demonstrated up to testing limit of 2 Pa. Minimum detectable signals of 340 μPa at 100 Hz and 120 μPa at 1 kHz are indicated, with a resonance of 3.5 kHz. Multiple full scale wind tunnel tests are performed, producing spectral measurements of turbulent boundary layers in wind speeds ranging up to 0.5 Ma (18 Pa of mean wall shear stress). The compact packaging allows for minimally invasive installation, and has proven relatively robust over multiple testing events. Temperature sensitivity, likely due to poor CTE matching of packaged materials, is an ongoing concern being addressed. These successes are being directly leveraged into a development plan for a dual-axis wall shear stress sensor, capable of producing true vector estimates at the wall.

  13. Noise-driven interfaces and their macroscopic representation

    Science.gov (United States)

    Dentz, Marco; Neuweiler, Insa; Méheust, Yves; Tartakovsky, Daniel M.

    2016-11-01

    We study the macroscopic representation of noise-driven interfaces in stochastic interface growth models in (1 +1 ) dimensions. The interface is characterized macroscopically by saturation, which represents the fluctuating sharp interface by a smoothly varying phase field with values between 0 and 1. We determine the one-point interface height statistics for the Edwards-Wilkinson (EW) and Kadar-Paris-Zhang (KPZ) models in order to determine explicit deterministic equations for the phase saturation for each of them. While we obtain exact results for the EW model, we develop a Gaussian closure approximation for the KPZ model. We identify an interface compression term, which is related to mass transfer perpendicular to the growth direction, and a diffusion term that tends to increase the interface width. The interface compression rate depends on the mesoscopic mass transfer process along the interface and in this sense provides a relation between meso- and macroscopic interface dynamics. These results shed light on the relation between mesoscale and macroscale interface models, and provide a systematic framework for the upscaling of stochastic interface dynamics.

  14. Analytical comparison of circular diaphragm based simple, single and double touch mode - MEMS capacitive pressure sensor

    Science.gov (United States)

    Jindal, Sumit Kumar; Raghuwanshi, Sanjeev Kumar

    2016-03-01

    In this paper a comparative study is done between normal capacitive pressure sensor, a touch mode capacitive pressure sensor and a double touch mode capacitive pressure sensor. The diaphragm in use is of circular shape. The theory and underlying equations has been described for the said devices and then simulations have been done for different performance parameters to understand the advantage of one over the other.

  15. Interface localization near criticality

    CERN Document Server

    Delfino, Gesualdo

    2016-01-01

    The theory of interface localization in near-critical planar systems at phase coexistence is formulated from first principles. We show that mutual delocalization of two interfaces, amounting to interfacial wetting, occurs when the bulk correlation length critical exponent $\

  16. Capacitance of the double electrical layer on the copper-group metals in molten alkali metal halides

    Science.gov (United States)

    Kirillova, E. V.; Stepanov, V. P.

    2016-08-01

    The electrochemical impedance is measured to study the capacitance of the double electrical layer of metallic Au, Ag, and Cu as a function of potential and temperature in nine molten salts, namely, the chlorides, bromides, and iodides of sodium, potassium, and cesium. The C- E curve of a gold electrode has an additional minimum in the anodic branch. This minimum for silver is less pronounced and is only observed at low ac signal frequencies in cesium halides. The additional minimum is not detected for copper in any salt under study. This phenomenon is explained on the assumption that the adsorption of halide anions on a positively charged electrode surface has a predominantly chemical rather than an electrostatic character. The specific adsorption in this case is accompanied by charge transfer through the interface and the formation of an adsorbent-adsorbate covalent bond.

  17. Identification of Capacitive MEMS Accelerometer Structure Parameters for Human Body Dynamics Measurements

    Directory of Open Access Journals (Sweden)

    Vincas Benevicius

    2013-08-01

    Full Text Available Due to their small size, low weight, low cost and low energy consumption, MEMS accelerometers have achieved great commercial success in recent decades. The aim of this research work is to identify a MEMS accelerometer structure for human body dynamics measurements. Photogrammetry was used in order to measure possible maximum accelerations of human body parts and the bandwidth of the digital acceleration signal. As the primary structure the capacitive accelerometer configuration is chosen in such a way that sensing part measures on all three axes as it is 3D accelerometer and sensitivity on each axis is equal. Hill climbing optimization was used to find the structure parameters. Proof-mass displacements were simulated for all the acceleration range that was given by the optimization problem constraints. The final model was constructed in Comsol Multiphysics. Eigenfrequencies were calculated and model’s response was found, when vibration stand displacement data was fed into the model as the base excitation law. Model output comparison with experimental data was conducted for all excitation frequencies used during the experiments.

  18. Electrical Capacitance Tomography Measurement of the Migration of Ice Frontal Surface in Freezing Soil

    Science.gov (United States)

    Liu, J.; Suo, X. M.; Zhou, S. S.; Meng, S. Q.; Chen, S. S.; Mu, H. P.

    2016-12-01

    The tracking of the migration of ice frontal surface is crucial for the understanding of the underlying physical mechanisms in freezing soil. Owing to the distinct advantages, including non-invasive sensing, high safety, low cost and high data acquisition speed, the electrical capacitance tomography (ECT) is considered to be a promising visualization measurement method. In this paper, the ECT method is used to visualize the migration of ice frontal surface in freezing soil. With the main motivation of the improvement of imaging quality, a loss function with multiple regularizers that incorporate the prior formation related to the imaging objects is proposed to cast the ECT image reconstruction task into an optimization problem. An iteration scheme that integrates the superiority of the split Bregman iteration (SBI) method is developed for searching for the optimal solution of the proposed loss function. An unclosed electrodes sensor is designed for satisfying the requirements of practical measurements. An experimental system of one dimensional freezing in frozen soil is constructed, and the ice frontal surface migration in the freezing process of the wet soil sample containing five percent of moisture is measured. The visualization measurement results validate the feasibility and effectiveness of the ECT visualization method

  19. Relevance of GaAs(001) surface electronic structure for high frequency dispersion on n-type accumulation capacitance

    Science.gov (United States)

    Pi, T. W.; Chen, W. S.; Lin, Y. H.; Cheng, Y. T.; Wei, G. J.; Lin, K. Y.; Cheng, C.-P.; Kwo, J.; Hong, M.

    2017-01-01

    This study investigates the origin of long-puzzled high frequency dispersion on the accumulation region of capacitance-voltage characteristics in an n-type GaAs-based metal-oxide-semiconductor. Probed adatoms with a high Pauling electronegativity, Ag and Au, unexpectedly donate charge to the contacted As/Ga atoms of as-grown α2 GaAs(001)-2 × 4 surfaces. The GaAs surface atoms behave as charge acceptors, and if not properly passivated, they would trap those electrons accumulated at the oxide and semiconductor interface under a positive bias. The exemplified core-level spectra of the Al2O3/n-GaAs(001)-2 × 4 and the Al2O3/n-GaAs(001)-4 × 6 interfaces exhibit remnant of pristine surface As emission, thereby causing high frequency dispersion in the accumulation region. For the p-type GaAs, electrons under a negatively biased condition are expelled from the interface, thereby avoiding becoming trapped.

  20. Digital methods and remote sensing in archaeology archaeology in the age of sensing

    CERN Document Server

    Campana, Stefano

    2016-01-01

    This volume debuts the new scope of Remote Sensing, which was first defined as the analysis of data collected by sensors that were not in physical contact with the objects under investigation (using cameras, scanners, and radar systems operating from spaceborne or airborne platforms). A wider characterization is now possible: Remote Sensing can be any non-destructive approach to viewing the buried and nominally invisible evidence of past activity. Spaceborne and airborne sensors, now supplemented by laser scanning, are united using ground-based geophysical instruments and undersea remote sensing, as well as other non-invasive techniques such as surface collection or field-walking survey. Now, any method that enables observation of evidence on or beneath the surface of the earth, without impact on the surviving stratigraphy, is legitimately within the realm of Remote Sensing. The new interfaces and senses engaged in Remote Sensing appear throughout the book. On a philosophical level, this is about the landscap...

  1. Microcomputer interfacing and applications

    CERN Document Server

    Mustafa, M A

    1990-01-01

    This is the applications guide to interfacing microcomputers. It offers practical non-mathematical solutions to interfacing problems in many applications including data acquisition and control. Emphasis is given to the definition of the objectives of the interface, then comparing possible solutions and producing the best interface for every situation. Dr Mustafa A Mustafa is a senior designer of control equipment and has written many technical articles and papers on the subject of computers and their application to control engineering.

  2. H2 S Sensors: Fumarate-Based fcu-MOF Thin Film Grown on a Capacitive Interdigitated Electrode.

    Science.gov (United States)

    Yassine, Omar; Shekhah, Osama; Assen, Ayalew H; Belmabkhout, Youssef; Salama, Khaled N; Eddaoudi, Mohamed

    2016-12-19

    Herein we report the fabrication of an advanced sensor for the detection of hydrogen sulfide (H2 S) at room temperature, using thin films of rare-earth metal (RE)-based metal-organic framework (MOF) with underlying fcu topology. This unique MOF-based sensor is made via the in situ growth of fumarate-based fcu-MOF (fum-fcu-MOF) thin film on a capacitive interdigitated electrode. The sensor showed a remarkable detection sensitivity for H2 S at concentrations down to 100 ppb, with the lower detection limit around 5 ppb. The fum-fcu-MOF sensor exhibits a highly desirable detection selectivity towards H2 S vs. CH4 , NO2 , H2 , and C7 H8 as well as an outstanding H2 S sensing stability as compared to other reported MOFs.

  3. Bovine serum albumin detection and quantitation based on capacitance measurements of liquid crystals

    Science.gov (United States)

    Lin, Chi-Hao; Lee, Mon-Juan; Lee, Wei

    2016-08-01

    Liquid crystal (LC)-based biosensing is generally limited by the lack of accurate quantitative strategies. This study exploits the unique electric capacitance properties of LCs to establish quantitative assay methods for bovine serum albumin (BSA) biomolecules. By measuring the voltage-dependent electric capacitance of LCs under an alternating-current field with increasing amplitude, positive correlations were derived between the BSA concentration and the electric capacitance parameters of LCs. This study demonstrates that quantitative analysis can be achieved in LC-based biosensing through electric capacitance measurements extensively employed in LCD research and development.

  4. Complex Interfaces Under Change

    DEFF Research Database (Denmark)

    Rosbjerg, Dan

    and mechanical processes that develop within this structure. Water-related processes at the interfaces between the compartments are complex, depending both on the interface itself, and on the characteristics of the interfaced compartments. Various aspects of global change directly or indirectly impact...

  5. Water at Interfaces

    DEFF Research Database (Denmark)

    Björneholm, Olle; Hansen, Martin Hangaard; Hodgson, Andrew

    2016-01-01

    The interfaces of neat water and aqueous solutions play a prominent role in many technological processes and in the environment. Examples of aqueous interfaces are ultrathin water films that cover most hydrophilic surfaces under ambient relative humidities, the liquid/solid interface which drives...

  6. Capacitated arc routing problem and its extensions in waste collection

    Energy Technology Data Exchange (ETDEWEB)

    Fadzli, Mohammad; Najwa, Nurul [Institut Matematik Kejuruteraan, Universiti Malaysia Perlis, Kampus Pauh Putra, 02600 Arau, Perlis (Malaysia); Luis, Martino [Othman Yeop Abdullah Graduate School of Business, Universiti Utara Malaysia, 06010 Sintok, Kedah (Malaysia)

    2015-05-15

    Capacitated arc routing problem (CARP) is the youngest generation of graph theory that focuses on solving the edge/arc routing for optimality. Since many years, operational research devoted to CARP counterpart, known as vehicle routing problem (VRP), which does not fit to several real cases such like waste collection problem and road maintenance. In this paper, we highlighted several extensions of capacitated arc routing problem (CARP) that represents the real-life problem of vehicle operation in waste collection. By purpose, CARP is designed to find a set of routes for vehicles that satisfies all pre-setting constraints in such that all vehicles must start and end at a depot, service a set of demands on edges (or arcs) exactly once without exceeding the capacity, thus the total fleet cost is minimized. We also addressed the differentiation between CARP and VRP in waste collection. Several issues have been discussed including stochastic demands and time window problems in order to show the complexity and importance of CARP in the related industry. A mathematical model of CARP and its new version is presented by considering several factors such like delivery cost, lateness penalty and delivery time.

  7. A novel capacitance sensor for fireside corrosion measurement

    Science.gov (United States)

    Ban, Heng; Li, Zuoping

    2009-11-01

    Fireside corrosion in coal-fired power plants is a leading mechanism for boiler tube failures. Online monitoring of fireside corrosion can provide timely data to plant operators for mitigation implementation. This paper presents a novel sensor concept for measuring metal loss based on electrical capacitance. Laboratory-scale experiments demonstrated the feasibility of design, fabrication, and operation of the sensor. The fabrication of the prototype sensor involved sputtering deposition of a thin metal coating with varying thickness on a ceramic substrate. Corrosion metal loss resulted in a proportional decrease in electrical capacitance of the sensor. Laboratory experiments using a muffle furnace with an oxidation environment demonstrated that low carbon steel coatings on ceramic substrate survived cyclic temperatures over 500 °C. Measured corrosion rates of sputtered coating in air had an Arrhenius exponential dependence on temperature, with metal thickness loss ranging from 2.0 nm/h at 200 °C to 2.0 μm/h at 400 °C. Uncertainty analysis indicated that the overall measurement uncertainty was within 4%. The experimental system showed high signal-to-noise ratio, and the sensor could measure submicrometer metal thickness changes. The laboratory experiments demonstrated that the sensor concept and measurement system are capable of short term, online monitoring of metal loss, indicating the potential for the sensor to be used for fireside corrosion monitoring and other metal loss measurement.

  8. Evidence for nonlinear capacitance in biomembrane channel system.

    Science.gov (United States)

    Ghosh, S; Bera, A K; Das, S

    1999-10-01

    The electrophysiological properties of voltage-dependent anion channels from mitochondrial membrane have been studied in a bilayer membrane system. It was observed that the probability of opening of the membrane channel depends on externally applied voltage and the plot is a bell-shaped curve symmetric around probability axis. A scheme of conformational energy levels under varying externally applied voltage was formulated. Assuming that the probability follows Boltzmann distribution, we arrive at an expression of change in energy containing a separate term identical to the energy of a capacitor. This fact indicates the possibility of existence of an added capacitance due to the channel protein. Further it was shown that the aforesaid channel capacitor could be a function of voltage leading to nonlinearity. We have offered a general method of calculating nonlinear capacitance from the experimental data on opening probability of a membrane channel. In case of voltage-dependent anion channel the voltage dependence of the capacitor has a power 0.786. The results have been interpreted in view of the structural organization of the channel protein in the membrane. Our hypothesis is that the phenomenon of capacitor behaviour is a general one for membrane channels.

  9. Capacitated arc routing problem and its extensions in waste collection

    Science.gov (United States)

    Fadzli, Mohammad; Najwa, Nurul; Luis, Martino

    2015-05-01

    Capacitated arc routing problem (CARP) is the youngest generation of graph theory that focuses on solving the edge/arc routing for optimality. Since many years, operational research devoted to CARP counterpart, known as vehicle routing problem (VRP), which does not fit to several real cases such like waste collection problem and road maintenance. In this paper, we highlighted several extensions of capacitated arc routing problem (CARP) that represents the real-life problem of vehicle operation in waste collection. By purpose, CARP is designed to find a set of routes for vehicles that satisfies all pre-setting constraints in such that all vehicles must start and end at a depot, service a set of demands on edges (or arcs) exactly once without exceeding the capacity, thus the total fleet cost is minimized. We also addressed the differentiation between CARP and VRP in waste collection. Several issues have been discussed including stochastic demands and time window problems in order to show the complexity and importance of CARP in the related industry. A mathematical model of CARP and its new version is presented by considering several factors such like delivery cost, lateness penalty and delivery time.

  10. High capacitance of coarse-grained carbide derived carbon electrodes

    Science.gov (United States)

    Dyatkin, Boris; Gogotsi, Oleksiy; Malinovskiy, Bohdan; Zozulya, Yuliya; Simon, Patrice; Gogotsi, Yury

    2016-02-01

    We report exceptional electrochemical properties of supercapacitor electrodes composed of large, granular carbide-derived carbon (CDC) particles. Using a titanium carbide (TiC) precursor, we synthesized 70-250 μm sized particles with high surface area and a narrow pore size distribution. Electrochemical cycling of these coarse-grained powders defied conventional wisdom that a small particle size is strictly required for supercapacitor electrodes and allowed high charge storage densities, rapid transport, and good rate handling ability. The material showcased capacitance above 100 F g-1 at sweep rates as high as 250 mV s-1 in organic electrolyte. 250-1000 micron thick dense CDC films with up to 80 mg cm-2 loading showed superior areal capacitances. The material significantly outperformed its activated carbon counterpart in organic electrolytes and ionic liquids. Furthermore, large internal/external surface ratio of coarse-grained carbons allowed the resulting electrodes to maintain high electrochemical stability up to 3.1 V in ionic liquid electrolyte. In addition to presenting novel insights into the electrosorption process, these coarse-grained carbons offer a pathway to low-cost, high-performance implementation of supercapacitors in automotive and grid-storage applications.

  11. Effect of displacement on resistance and capacitance of polyaniline film

    Institute of Scientific and Technical Information of China (English)

    Khasan Sanginovich Karimov; Muhammad Tariq Saeed; Fazal Ahmad Khalid; Syed Abdul Moiz

    2011-01-01

    This paper investigates the properties of displacement sensors based on polyaniline(PANI)films. About 1 wt% of PANI micropowder is mixed and stirred in a solution of 90 wt% water and 10 wt% alcohol at room temperature. The films of PANI are deposited from solution by drop-casting on Ag electrodes, which are preliminary deposited on glass substrates. The thicknesses of the PANI films are in the range of 20 jun-80 p.m. A displacement sensor with polyaniline film as an active material is designed and fabricated. The investigations showed that, on average, the AC resistance of the sensor decreases by 2 times and the capacitance accordingly increases by 1.6 times as the displacement changes in the range of 0 mm-0.5 mm. The polyaniline is the only active material of the displacement sensor. The resistance and capacitance of the PANI changes under the pressure of spring and elastic rubber, and this pressure is created by the downward movement of the micrometer.

  12. Interfacing with the WEB

    CERN Document Server

    Dönszelmann, M

    1995-01-01

    Interfacing to the Web or programming interfaces for the Web is used to provide dynamic information for Web users. Using the Web as a transport system of information poses three constraints: namespace, statelessness and performance. To build interfaces on either server or client side of the Web one has to meet these constraints. Several examples, currently in use in High Energy Physics Experiments are described. They range from an interface to show where buildings are located to an interface showing active values of the On-line System of the DELPHI (CERN)..

  13. Quantization of interface currents

    Energy Technology Data Exchange (ETDEWEB)

    Kotani, Motoko [AIMR, Tohoku University, Sendai (Japan); Schulz-Baldes, Hermann [Department Mathematik, Universität Erlangen-Nürnberg, Erlangen (Germany); Villegas-Blas, Carlos [Instituto de Matematicas, Cuernavaca, UNAM, Cuernavaca (Mexico)

    2014-12-15

    At the interface of two two-dimensional quantum systems, there may exist interface currents similar to edge currents in quantum Hall systems. It is proved that these interface currents are macroscopically quantized by an integer that is given by the difference of the Chern numbers of the two systems. It is also argued that at the interface between two time-reversal invariant systems with half-integer spin, one of which is trivial and the other non-trivial, there are dissipationless spin-polarized interface currents.

  14. Entanglement and topological interfaces

    CERN Document Server

    Brehm, Enrico M; Jaud, Daniel; Schmidt-Colinet, Cornelius

    2015-01-01

    In this paper we consider entanglement entropies in two-dimensional conformal field theories in the presence of topological interfaces. Tracing over one side of the interface, the leading term of the entropy remains unchanged. The interface however adds a subleading contribution, which can be interpreted as a relative (Kullback-Leibler) entropy with respect to the situation with no defect inserted. Reinterpreting boundaries as topological interfaces of a chiral half of the full theory, we rederive the left/right entanglement entropy in analogy with the interface case. We discuss WZW models and toroidal bosonic theories as examples.

  15. Remote shock sensing and notification system

    Energy Technology Data Exchange (ETDEWEB)

    Muralidharan, Govindarajan [Knoxville, TN; Britton, Charles L [Alcoa, TN; Pearce, James [Lenoir City, TN; Jagadish, Usha [Knoxville, TN; Sikka, Vinod K [Oak Ridge, TN

    2010-11-02

    A low-power shock sensing system includes at least one shock sensor physically coupled to a chemical storage tank to be monitored for impacts, and an RF transmitter which is in a low-power idle state in the absence of a triggering signal. The system includes interface circuitry including or activated by the shock sensor, wherein an output of the interface circuitry is coupled to an input of the RF transmitter. The interface circuitry triggers the RF transmitter with the triggering signal to transmit an alarm message to at least one remote location when the sensor senses a shock greater than a predetermined threshold. In one embodiment the shock sensor is a shock switch which provides an open and a closed state, the open state being a low power idle state.

  16. Ion-gap sensing for engine control

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-09-01

    This article reports that in addition to detecting misfire to conform with California onboard diagnostic (OBD II) regulations, Delco Electronics and Mecel AB engineers are looking at ion-gap sensing to control knock, A/F ratio, and other possible engine control parameters. The combustion of fuel in an engine cylinder produces ions. Detection of those ions by the spark plug (ion-gap sensing), and use of the resulting ion currents, has been employed in engine management systems since 1988. Saab introduced the first application, for cam-phase sensing. The main driving force for ion-gap sensing is OBD II requirements for 100% misfire detection at all speeds and loads. The technique has been expanded in subsequent applications to include misfire, knock, and pre-ignition detection and control, and more recently in combustion-ion detection using a capacitance-type, ion-current measurement method. Use of the ion current`s wave shape to control knock allows elimination of the separate piezoelectric type (PZT) sensor. Future applications could provide additional engine-control features including air/fuel ratio measurement and control.

  17. Infrastructure sensing.

    Science.gov (United States)

    Soga, Kenichi; Schooling, Jennifer

    2016-08-01

    Design, construction, maintenance and upgrading of civil engineering infrastructure requires fresh thinking to minimize use of materials, energy and labour. This can only be achieved by understanding the performance of the infrastructure, both during its construction and throughout its design life, through innovative monitoring. Advances in sensor systems offer intriguing possibilities to radically alter methods of condition assessment and monitoring of infrastructure. In this paper, it is hypothesized that the future of infrastructure relies on smarter information; the rich information obtained from embedded sensors within infrastructure will act as a catalyst for new design, construction, operation and maintenance processes for integrated infrastructure systems linked directly with user behaviour patterns. Some examples of emerging sensor technologies for infrastructure sensing are given. They include distributed fibre-optics sensors, computer vision, wireless sensor networks, low-power micro-electromechanical systems, energy harvesting and citizens as sensors.

  18. Sensing temperature.

    Science.gov (United States)

    Sengupta, Piali; Garrity, Paul

    2013-04-22

    Temperature is an omnipresent physical variable reflecting the rotational, vibrational and translational motion of matter, what Richard Feynman called the "jiggling" of atoms. Temperature varies across space and time, and this variation has dramatic effects on the physiology of living cells. It changes the rate and nature of chemical reactions, and it alters the configuration of the atoms that make up nucleic acids, proteins, lipids and other biomolecules, significantly affecting their activity. While life may have started in a "warm little pond", as Charles Darwin mused, the organisms that surround us today have only made it this far by devising sophisticated systems for sensing and responding to variations in temperature, and by using these systems in ways that allow them to persist and thrive in the face of thermal fluctuation.

  19. Nyquist AD Converters, Sensor Interfaces, and Robustness Advances in Analog Circuit Design, 2012

    CERN Document Server

    Baschirotto, Andrea; Steyaert, Michiel

    2013-01-01

    This book is based on the presentations during the 21st workshop on Advances in Analog Circuit Design.  Expert designers provide readers with information about a variety of topics at the frontier of analog circuit design, including Nyquist analog-to-digital converters, capacitive sensor interfaces, reliability, variability, and connectivity.  This book serves as a valuable reference to the state-of-the-art, for anyone involved in analog circuit research and development.  Provides a state-of-the-art reference in analog circuit design, written by experts from industry and academia; Presents material in a tutorial-based format; Includes coverage of Nyquist A/D converters, capacitive sensor interfaces, reliability, variability, and connectivity.

  20. Ionizing radiation effects on electrical and reliability characteristics of sputtered Ta2O5/Si interface

    Science.gov (United States)

    Rao, Ashwath; Verma, Ankita; Singh, B. R.

    2015-06-01

    This paper describes the effect of ionizing radiation on the interface properties of Al/Ta2O5/Si metal oxide semiconductor (MOS) capacitors using capacitance-voltage (C-V) and current-voltage (I-V) characteristics. The devices were irradiated with X-rays at different doses ranging from 100 rad to 1 Mrad. The leakage behavior, which is an important parameter for memory applications of Al/Ta2O5/Si MOS capacitors, along with interface properties such as effective oxide charges and interface trap density with and without irradiation has been investigated. Lower accumulation capacitance and shift in flat band voltage toward negative value were observed in annealed devices after exposure to radiation. The increase in interfacial oxide layer thickness after irradiation was confirmed by Rutherford Back Scattering measurement. The effect of post-deposition annealing on the electrical behavior of Ta2O5 MOS capacitors was also investigated. Improved electrical and interface properties were obtained for samples deposited in N2 ambient. The density of interface trap states (Dit) at Ta2O5/Si interface sputtered in pure argon ambient was higher compared to samples reactively sputtered in nitrogen-containing plasma. Our results show that reactive sputtering in nitrogen-containing plasma is a promising approach to improve the radiation hardness of Ta2O5/Si MOS devices.

  1. Cellular nanotechnology: making biological interfaces smarter.

    Science.gov (United States)

    Mendes, Paula M

    2013-12-21

    Recently, there has been an outburst of research on engineered cell-material interfaces driven by nanotechnology and its tools and techniques. This tutorial review begins by providing a brief introduction to nanostructured materials, followed by an overview of the wealth of nanoscale fabrication and analysis tools available for their development. This background serves as the basis for a discussion of early breakthroughs and recent key developments in the endeavour to develop nanostructured materials as smart interfaces for fundamental cellular studies, tissue engineering and regenerative medicine. The review covers three major aspects of nanostructured interfaces - nanotopographical control, dynamic behaviour and intracellular manipulation and sensing - where efforts are continuously being made to further understand cell function and provide new ways to control cell behaviour. A critical reflection of the current status and future challenges are discussed as a conclusion to the review.

  2. Novel graphene-like electrodes for capacitive deionization.

    Science.gov (United States)

    Li, Haibo; Zou, Linda; Pan, Likun; Sun, Zhuo

    2010-11-15

    Capacitive deionization (CDI) is a novel technology that has been developed for removal of charged ionic species from salty water, such as salt ions. The basic concept of CDI, as well as electrosorption, is to force charged ions toward oppositely polarized electrodes through imposing a direct electric field to form a strong electrical double layer and hold the ions. Once the electric field disappears, the ions are instantly released back to the bulk solution. CDI is an alternative low-energy consumption desalination technology. Graphene-like nanoflakes (GNFs) with relatively high specific surface area have been prepared and used as electrodes for capacitive deionization. The GNFs were synthesized by a modified Hummers' method using hydrazine for reduction. They were characterized by atomic force microscopy, N2 adsorption at 77 K and electrochemical workstation. It was found that the ratio of nitric acid and sulfuric acid plays a vital role in determining the specific surface area of GNFs. Its electrosorption performance was much better than commercial activated carbon (AC), suggesting a great potential in capacitive deionisation application. Further, the electrosorptive performance of GNFs electrodes with different bias potentials, flow rates and ionic strengths were measured and the electrosorption isotherm and kinetics were investigated. The results showed that GNFs prepared by this process had the specific surface area of 222.01 m²/g. The specific electrosorptive capacity of the GNFs was 23.18 µmol/g for sodium ions (Na+) when the initial concentration was at 25 mg/L, which was higher than that of previously reported data using graphene and AC under the same experimental condition. In addition, the equilibrium electrosorption capacity was determined as 73.47 µmol/g at 2.0 V by fitting data through the Langmuir isotherm, and the rate constant was found to be 1.01 min⁻¹ by fitting data through pseudo first-order adsorption. The results suggested that the

  3. Variation of carrier concentration and interface trap density in 8MeV electron irradiated c-Si solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, Sathyanarayana, E-mail: asharao76@gmail.com; Rao, Asha, E-mail: asharao76@gmail.com [Department of Physics, Mangalore Institute of Technology and Engineering, Moodabidri, Mangalore-574225 (India); Krishnan, Sheeja [Department of Physics, Sri Devi Institute of Technology, Kenjar, Mangalore-574142 (India); Sanjeev, Ganesh [Microtron Centre, Department of Physics, Mangalore University, Mangalagangothri-574199 (India); Suresh, E. P. [Solar Panel Division, ISRO Satellite Centre, Bangalore-560017 (India)

    2014-04-24

    The capacitance and conductance measurements were carried out for c-Si solar cells, irradiated with 8 MeV electrons with doses ranging from 5kGy – 100kGy in order to investigate the anomalous degradation of the cells in the radiation harsh environments. Capacitance – Voltage measurements indicate that there is a slight reduction in the carrier concentration upon electron irradiation due to the creation of radiation induced defects. The conductance measurement results reveal that the interface state densities and the trap time constant increases with electron dose due to displacement damages in c-Si solar cells.

  4. Minimization of the transformer inter-winding parasitic capacitance for modular stacking power supply applications

    DEFF Research Database (Denmark)

    Nguyen-Duy, Khiem; Ouyang, Ziwei; Knott, Arnold;

    2014-01-01

    In an isolated power supply, the inter-winding parasitic capacitance plays a vital role in the mitigation of common mode noise currents created by fast voltage transient responses. The lower the transformer inter-winding capacitance, the more immune the power supply is to fast voltage transient r...

  5. A capacitive level shifter for high voltage (2.5kV)

    DEFF Research Database (Denmark)

    Andersen, Thomas; Andersen, Michael A. E.; Thomsen, Ole Cornelius;

    2012-01-01

    with focus on low power consumption as well as low capacitive load between the floating half-bridge node and ground (output capacitance). The operation of the level-shifter is tested and verified by measurements on a prototype half-bridge gate driver. Results conclude stabile operation at 2.44kV, 50k...

  6. A branch-and-cut-and-price algorithm for the cumulative capacitated vehicle routing problem

    DEFF Research Database (Denmark)

    Wøhlk, Sanne; Lysgaard, Jens

    2014-01-01

    The paper considers the Cumulative Capacitated Vehicle Routing Problem (CCVRP), which is a variation of the well-known Capacitated Vehicle Routing Problem (CVRP). In this problem, the traditional objective of minimizing total distance or time traveled by the vehicles is replaced by minimizing...

  7. An iterated tabu search heuristic for the Single Source Capacitated Facility Location Problem

    DEFF Research Database (Denmark)

    Ho, Sin C.

    2015-01-01

    This paper discusses the Single Source Capacitated Facility Location Problem (SSCFLP) where the problem consists in determining a subset of capacitated facilities to be opened in order to satisfy the customers’ demands such that total costs are minimized. The paper presents an iterated tabu search...

  8. Polycrystalline VO{sub 2} film characterization by quantum capacitance measurement

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zhe; Knighton, Talbot, E-mail: talbot.knighton@wayne.edu; Tarquini, Vinicio; Huang, Jian [Department of Physics and Astronomy, Wayne State University, Detroit, Michigan 48201 (United States); Torres, David; Wang, Tongyu; Sepúlveda, Nelson [Electrical and Computer Engineering Department, Michigan State University, East Lansing, Michigan 48824 (United States)

    2015-09-07

    Capacitance measurement is performed using a home-built bridge on quasi two-dimensional vanadium dioxide films grown on silicon-dioxide/p-doped silicon substrates. Correlated effects appearing in the quantum capacitance are obtained as a function of temperature at low frequencies. The thermodynamic density of states reveals the opening band gap in the insulating monoclinic phase.

  9. Faster Time Response by the Use of Wire Electrodes in Capacitive Salinity Gradient Energy Systems

    NARCIS (Netherlands)

    Burheim, O.S.; Liu, F.; Sales, B.B.; Schaetzle, O.; Buisman, C.J.N.; Hamelers, H.V.M.

    2012-01-01

    Capacitive energy extraction based on Donnan potential (CDP) and capacitive energy extraction based on double layer expansion (CDLE) are novel electroctrochemical processes to convert the potential free energy of mixing sea and river water into electric work. This is done by the use of supercapacito

  10. The polarizability and the capacitance change of a bounded object in a parallel plate capacitor

    Science.gov (United States)

    Kristensson, Gerhard

    2012-09-01

    A method for solving the change in capacitance (or charge) if an object is introduced in a parallel plate capacitor is developed. The integral representation of the potential is exploited in a systematic way to solve the potential everywhere inside the capacitor. In particular, the change in capacitance is extracted. The method shows similarities with the null field approach for solving dynamic problems.

  11. Capacitance-voltage characteristics of GaAs ion-implanted structures

    Directory of Open Access Journals (Sweden)

    Privalov E. N.

    2008-08-01

    Full Text Available A noniterative numerical method is proposed to calculate the barrier capacitance of GaAs ion-implanted structures as a function of the Schottky barrier bias. The features of the low- and high-frequency capacitance-voltage characteristics of these structures which are due to the presence of deep traps are elucidated.

  12. Circuit modeling on polyaniline functionalized nanowire-templated micro-interdigital capacitors for pH sensing

    DEFF Research Database (Denmark)

    Antohe, V.A.; Radu, A.; Mátéfi-Tempfli, Stefan

    2011-01-01

    This study presents an improved alternative current (ac) circuit modeling of a highly sensitive capacitive pH-sensing element based on polyaniline (PANI) functionalized nanowire-templated micro-interdigited electrodes (NWs μIDEs). While electrical resonance measurements deal with a total equivalent...

  13. Electron heating in low pressure capacitive discharges revisited

    Science.gov (United States)

    Kawamura, E.; Lieberman, M. A.; Lichtenberg, A. J.

    2014-12-01

    The electrons in capacitively coupled plasmas (CCPs) absorb energy via ohmic heating due to electron-neutral collisions and stochastic heating due to momentum transfer from high voltage moving sheaths. We use Particle-in-Cell (PIC) simulations to explore these heating mechanisms and to compare the PIC results with available theories on ohmic and stochastic heating. The PIC results for ohmic heating show good agreement with the ohmic heating calculation of Lafleur et al. [Phys. Plasmas 20, 124503 (2013)]. The PIC results for stochastic heating in low pressure CCPs with collisionless sheaths show good agreement with the stochastic heating model of Kaganovich et al. [IEEE Trans. Plasma Sci. 34, 696 (2006)], which revises the hard wall asymptotic model of Lieberman [IEEE Trans. Plasma Sci. 16, 638 (1988)] by taking current continuity and bulk oscillation into account.

  14. A novel heuristic algorithm for capacitated vehicle routing problem

    Science.gov (United States)

    Kır, Sena; Yazgan, Harun Reşit; Tüncel, Emre

    2017-02-01

    The vehicle routing problem with the capacity constraints was considered in this paper. It is quite difficult to achieve an optimal solution with traditional optimization methods by reason of the high computational complexity for large-scale problems. Consequently, new heuristic or metaheuristic approaches have been developed to solve this problem. In this paper, we constructed a new heuristic algorithm based on the tabu search and adaptive large neighborhood search (ALNS) with several specifically designed operators and features to solve the capacitated vehicle routing problem (CVRP). The effectiveness of the proposed algorithm was illustrated on the benchmark problems. The algorithm provides a better performance on large-scaled instances and gained advantage in terms of CPU time. In addition, we solved a real-life CVRP using the proposed algorithm and found the encouraging results by comparison with the current situation that the company is in.

  15. Enhanced capacitive deionization of graphene/mesoporous carbon composites

    Science.gov (United States)

    Zhang, Dengsong; Wen, Xiaoru; Shi, Liyi; Yan, Tingting; Zhang, Jianping

    2012-08-01

    Capacitive deionization (CDI) with low-energy consumption and no secondary waste is emerging as a novel desalination technology. Graphene/mesoporous carbon (GE/MC) composites have been prepared via a direct triblock-copolymer-templating method and used as CDI electrodes for the first time. The influences of GE content on the textural properties and electrochemical performance were studied. The transmission electron microscopy and nitrogen adsorption-desorption analysis indicate that mesoporous structures are well retained and the composites display improved specific surface area and pore size distribution, as well as pore volume. Well dispersed GE nanosheets are deduced to be beneficial for enhanced electrical conductivity. The electrochemical performance of electrodes in an NaCl aqueous solution was characterized by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy measurements. The composite electrodes perform better on the capacitance values, conductive behaviour, rate performance and cyclic stability. The desalination capacity of the electrodes was evaluated by a batch mode electrosorptive experiment and the amount of adsorbed ions can reach 731 μg g-1 for the GE/MC composite electrode with a GE content of 5 wt%, which is much higher than that of MC alone (590 μg g-1). The enhanced CDI performance of the composite electrodes can be attributed to the better conductive behaviour and higher specific surface area.Capacitive deionization (CDI) with low-energy consumption and no secondary waste is emerging as a novel desalination technology. Graphene/mesoporous carbon (GE/MC) composites have been prepared via a direct triblock-copolymer-templating method and used as CDI electrodes for the first time. The influences of GE content on the textural properties and electrochemical performance were studied. The transmission electron microscopy and nitrogen adsorption-desorption analysis indicate that mesoporous structures are

  16. Advances in Modern Capacitive ECG Systems for Continuous Cardiovascular Monitoring

    Directory of Open Access Journals (Sweden)

    A. Schommartz

    2011-01-01

    Full Text Available The technique of capacitive electrocardiography (cECG is very promising in a flexible manner. Already integrated into several everyday objects, the single lead cECG system has shown that easy-to-use measurements of electrocardiograms are possible without difficult preparation of the patients. Multi-channel cECG systems enable the extraction of ECG signals even in the presence of coupled interferences, due to the additional redundant information. Thus, this paper presents challenges for electronic hardware design to build on developments in recent years, going from the one-lead cECG system to multi-channel systems in order to provide robust measurements - e.g. even while driving an automobile.

  17. Interaction phenomena in graphene seen through quantum capacitance.

    Science.gov (United States)

    Yu, G L; Jalil, R; Belle, Branson; Mayorov, Alexander S; Blake, Peter; Schedin, Frederick; Morozov, Sergey V; Ponomarenko, Leonid A; Chiappini, F; Wiedmann, S; Zeitler, Uli; Katsnelson, Mikhail I; Geim, A K; Novoselov, Kostya S; Elias, Daniel C

    2013-02-26

    Capacitance measurements provide a powerful means of probing the density of states. The technique has proved particularly successful in studying 2D electron systems, revealing a number of interesting many-body effects. Here, we use large-area high-quality graphene capacitors to study behavior of the density of states in this material in zero and high magnetic fields. Clear renormalization of the linear spectrum due to electron-electron interactions is observed in zero field. Quantizing fields lead to splitting of the spin- and valley-degenerate Landau levels into quartets separated by interaction-enhanced energy gaps. These many-body states exhibit negative compressibility but the compressibility returns to positive in ultrahigh B. The reentrant behavior is attributed to a competition between field-enhanced interactions and nascent fractional states.

  18. Improved Circuits with Capacitive Feedback for Readout Resistive Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Óscar Oballe-Peinado

    2016-01-01

    Full Text Available One of the most suitable ways of distributing a resistive sensor array for reading is an array with M rows and N columns. This allows reduced wiring and a certain degree of parallelism in the implementation, although it also introduces crosstalk effects. Several types of circuits can carry out the analogue-digital conversion of this type of sensors. This article focuses on the use of operational amplifiers with capacitive feedback and FPGAs for this task. Specifically, modifications of a previously reported circuit are proposed to reduce the errors due to the non-idealities of the amplifiers and the I/O drivers of the FPGA. Moreover, calibration algorithms are derived from the analysis of the proposed circuitry to reduce the crosstalk error and improve the accuracy. Finally, the performances of the proposals is evaluated experimentally on an array of resistors and for different ranges.

  19. A novel design of micromachined capacitive Lamb wave transducers

    Science.gov (United States)

    Ge, Lifeng

    2006-11-01

    A new design for micromachined capacitive Lamb wave transducers (mCLWT) has been developed. The design is based on a theoretical TDK model previously developed for groove ultrasonic transducers. By the investigation of the dynamic behavior of a rectangular high aspect ratio diaphragm of the mCLWTs, the second order bending mode of the diaphragm is exploited to excite and detect Lamb wave. The new exiting mechanism can minimize the energy of the acoustic radiation at the normal direction of the diaphragm so as to provide more energy coupled into the Lamb wave in the silicon substrate. Also, the natural frequencies and mode shapes of such a mCLWT can be determined accurately from its geometry and materials used, so the TDK model provides guidance for the optimal design of mCLWTs.

  20. Capacitively coupled hybrid pixel assemblies for the CLIC vertex detector

    CERN Document Server

    AUTHOR|(SzGeCERN)734627; Benoit, Mathieu; Dannheim, Dominik; Dette, Karola; Hynds, Daniel; Kulis, Szymon; Peric, Ivan; Petric, Marko; Redford, Sophie; Sicking, Eva; Valerio, Pierpaolo

    2016-01-01

    The vertex detector at the proposed CLIC multi-TeV linear e+e- collider must have minimal material content and high spatial resolution, combined with accurate time-stamping to cope with the expected high rate of beam-induced backgrounds. One of the options being considered is the use of active sensors implemented in a commercial high-voltage CMOS process, capacitively coupled to hybrid pixel ASICs. A prototype of such an assembly, using two custom designed chips (CCPDv3 as active sensor glued to a CLICpix readout chip), has been characterised both in the lab and in beam tests at the CERN SPS using 120 GeV/c positively charged hadrons. Results of these characterisation studies are presented both for single and dual amplification stages in the active sensor. Pixel cross-coupling results are also presented, showing the sensitivity to placement precision and planarity of the glue layer.