Dissertations / Theses on the topic 'Electrostatic sensors'
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Krabicka, Jan. "Flow measurement of pneumatically conveyed solids using intrusive electrostatic sensors." Thesis, University of Kent, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516206.
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Lloyd, Justin Michael. "Electrical Properties of Macro-Fiber Composite Actuators and Sensors." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/10013.
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Piezoceramic fiber composite (PFC) actuators and sensors offer many advantages over conventional monolithic piezoceramic devices. Conformable, durable and, when equipped with interdigitated electrodes (IDEs), more responsive than regular monolithic devices, PFCs promise to revolutionize the application of piezoelectric materials. Developed by the NASA-Langley Research Center, the Macro-Fiber Composite (MFC) actuator and sensor is the most sophisticated PFC device yet invented. With superior qualities among PFCs in performance, behavior repeatability and manufacturability, the MFC has spawned great interest in the commercial and academic community as a tool in multitudinous engineering applications.
While the MFC's characteristics render it a singularly useful device, limited characterization and modeling research on the MFC exists. Empirically designed and assembled, the MFC is poorly understood, especially in terms of its underlying operating principles, its dependence on design parameters and its electrical properties. The majority of published MFC studies focus on experimental quantification of MFC mechanical and actuation properties, and the research that attempts to model the MFC relies totally on finite element analysis. Published works widely assume that analytical models of the MFC are totally impossible.
Rectifying gaps in the current body of MFC research, this study presents the first accurate analytical model of the static electrical field properties of the MFC. Implementing the techniques of conformal mapping, a branch of complex analysis, the following chapters derive a closed-form, exact analytical solution describing the electrical potential field and electrical field of the MFC's dual-IDE structure. Based on the conformal mapping solution for the MFC's electrical field, the electrical field of the commercially available MFC is examined and analyzed, introducing an intuitive knowledge of the MFC's operation. Demonstrating the utility of this solution in modeling the MFC, this work also predicts the capacitance and induced strain properties of a continuum of potential MFC designs and offers final suggestions on improving the current commercial MFC design. After establishing the theoretical underpinnings of the analytical MFC model, this report derives the conformal mapping solutions for the MFC, discusses the computational application of the resulting equations and then presents the results of numerical analyses executed using the new analytical model.Master of Science
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Wilson, Lester W. "Piezoelectric sensors incorporating electrostatic focusing and automated cleaning for personal aerosol monitoring." Thesis, Glasgow Caledonian University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308328.
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Mendonça, Lucas Gonçalves Dias. "Desenvolvimento de um micro-transdutor acústico capacitivo." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-17102014-113303/.
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Neste trabalho é proposto um dispositivo MEMS do tipo micro-transdutor acústico capacitivo, CMUT (sigla em inglês - Capacitive Micromachined Ultrasonic Transducer). Em vez de usar piezoeletricidade, o CMUT tem um array de capacitores, onde cada capacitor possui um eletrodo inferior fixo, uma cavidade e o eletrodo superior composto de uma placa flexível. Quando submetida a uma tensão CC adequada, a placa se deflete se aproximando do eletrodo inferior devido à força eletrostática. Assim a placa fica tensionada podendo vibrar quando excitada por uma tensão CA. Neste caso o CMUT opera como emissor de ondas acústicas. A placa também pode ser excitada por uma onda acústica agindo em sua superfície. Neste caso o dispositivo opera como sensor. Uma das contribuições desse trabalho é o processo de fabricação simplificado com o uso do fotorresiste SU-8 como parte da estrutura do dispositivo. Sua facilidade de processamento e suas propriedades físicas lhe conferem estabilidade e rigidez adequadas para tal fim. Foram realizadas modelagens e simulações analíticas e computacionais do comportamento da placa. Os resultados auxiliaram no melhor entendimento do comportamento do dispositivo sob tensão mecânica devido a uma carga ou uma tensão de polarização. Esses resultados também auxiliaram na definição de parâmetros iniciais do processo de fabricação. Durante o processo de fabricação, foram realizados diversos testes a fim de se encontrar o processo mais adequado à infraestrutura disponível. No processo escolhido, a base do dispositivo é fabricada num substrato de vidro com eletrodos inferiores de alumínio depositados por evaporação. Os pilares são fabricados em SU-8, depositado por spin coatting. A placa é colada posteriormente utilizando-se fotorresiste AZ. O AZ é depositado sobre um pedaço de folha de cobre ou alumínio. As duas partes são colocadas em contato e para promover a colagem é aplicada pressão durante a cura. As amostras foram caracterizadas eletricamente utilizando-se um medidor de impedância RCL. Foram levantadas curvas de impedância, capacitância e ângulo de fase em função da frequência (1 kHz a 1 MHz). Além do sinal CA utilizado pelo instrumento durante a medição foi aplicado um nível CC que variou conforme as dimensões dos protótipos. Também foram levantadas curvas de impedância, capacitância e angulo de fase em função de uma carga mecânica aplicada. Para valores de polarização mais elevados, foram montados circuitos específicos. Estes circuitos são capazes de polarizar o CMUT, aplicar um sinal CA para medição e proteger demais componentes e instrumentos dos aparatos de medição. O dispositivo respondeu bem a aplicação de carga mecânica, excitação por sinal CA e excitação com onda mecânica. Os resultados mostraram que o dispositivo apresenta bom potencial para ser aplicado na análise de fluidos.This work presents a new process to fabricate an acoustic micro transducer to be used as a microsensor or a microactuator. The acoustic transducers are based on the electrostatic effect and consist on arrays of microfabricated capacitors. Such devices are commonly referred as CMUT, Capacitive Micromachined Ultrasonic Transducer. The bottom electrode (evaporated aluminum) of each capacitor is fixed on the surface of glass substrate, while the top electrode is a thin plate structure of copper or aluminum suspended on a cavity surrounded by posts. Since the top electrode is flexible, it bends toward the bottom electrode when a DC bias is applied. In this way, the top electrode can be forced to vibrate using an AC signal to be used as an acoustic wave emitter. Conversely, an ultrasound receiver is achieved as the measured capacitance changes when the DC biased top electrode moves following an external acoustic wave pressure. An innovation of this work is the use of the photoresist SU-8 to fabricate the post structures surrounding the cavities of the capacitive micro transducers. Its relatively simple processing steps and adequate mechanical properties make the SU-8 a convenient choice as an inexpensive structural material. The bottom part of the device is prepared on a glass substrate using an aluminum layer evaporated and etched to form the bottom electrodes. Then, SU-8 is spin coated, baked and etched adequately to form the posts surrounding the cavities. The top part is prepared by simply spinning an AZ-type photoresist on aluminum or copper plate. Finally, both halves are bonded under pressure on a hot plate. Several modeling and simulation analyses were performed in order to estimate the working performance of the micro transducers. The results of simulations helped to define the initial parameters and materials for the fabrication process. Samples submitted to a DC bias were initially characterized using an RCL meter in order to infer impedance, capacitance and phase angle behavior as a function of frequency (from 1 kHz to 1 MHz). Protection circuits were used in order to test CMUTs with high DC bias. These circuits allow to apply high DC bias, and an AC signal while other measuring equipments are protected. The device responded to application of mechanical loading, excitation by an AC signal and excitation by mechanical wave as well. The results showed that the device has good potential to be applied to the analysis of fluids.
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Liu, Wei. "Wearable lip-based electrostatic display feasibility study, modeling and system design /." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5971.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 6, 2008) Includes bibliographical references.
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Panzardi, Enza. "Measurement systems for industrial plants condition monitoring." Doctoral thesis, Università di Siena, 2019. http://hdl.handle.net/11365/1072401.
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Negli ultimi decenni, il mercato mondiale dell’energia ha dovuto far fronte ad una richiesta di produzione sempre crescente e ad un costante mutamento del settore industriale, sempre più attento all’impatto ambientale e all’innovazione tecnologica.
Oltre agli impianti per la produzione di energia da fonti rinnovabili, quelli a ciclo combinato o a cogenerazione basati su turbine a gas sono i più diffusi, in quanto garantiscono maggiore rendimento e minori emissioni, a parità di energia prodotta rispetto agli altri impianti a combustione disponibili nel settore. Inoltre, offrono una maggiore flessibilità operativa consentendo una migliore modulabilità del carico.
In questo contesto, una sempre maggiore spinta innovativa ha coinvolto gli operatori del settore nel mettere a punto nuove tecnologie di controllo e monitoraggio degli impianti per garantire una maggiore affidabilità e rimanere competitivi a lungo termine.
A tale scopo, sono diverse le tecniche che possono essere implementate per raccogliere informazioni sulle condizioni operative delle macchine, consentendo quindi un rilevamento e una manutenzione precoce dei guasti che posso avere un forte impatto sulla produttività e sulla riduzione complessiva dei costi.
Il mio lavoro di tesi si inserisce in questo contesto applicativo. L’obiettivo finale è stato quello di sviluppare delle tecniche di monitoraggio innovative e a basso costo basate sul principio di induzione elettrostatica per il rilevamento di detriti solidi, generati da guasti o malfunzionamenti, nel percorso dei gas di scarico di una turbomacchina.
In questo lavoro vengono presentati diversi sistemi innovativi di monitoraggio basati sull’utilizzo di sensori elettrostatici e amplificatori di carica, con prestazioni migliorate che possono essere impiegati anche in altre applicazioni che coinvolgono processi di combustione o in impianti industriali che impiegano tubazioni per il trasporto pneumatico.
Il sistema di rilevamento consiste in uno o più sensori elettrostatici montati all’interno del condotto di scarico della turbomacchina i quali rilevano le particelle con carica elettrostatica presenti nel flusso di gas. L’amplificatore di carica ha il compito di convertire il segnale di carica in un segnale di tensione adatto ad essere acquisito e processato da un sistema appositamente implementato.
La tecnica di misura implementata sfrutta le informazioni fornite dal modello fisico usato per descrivere il problema di misura e le caratteristiche geometriche del set-up scelto per i sensori per ricostruire la traiettoria, il livello di carica, la posizione e la velocità della particella carica rilevata.
Il sistema di misura realizzato è stato caratterizzato in un ampio intervallo di condizioni operative e studiato sia dal punto di vista teorico che sperimentale. In particolare, è stato sviluppato un sistema di misura basato su array circolari di tre sensori elettrostatici per il quale si riesce ad ottenere un errore relativo inferiore all’1% sulla stima dei parametri necessari alla ricostruzione della traiettoria, della velocità e della carica della particella in movimento rilevata.
Inoltre, dalla caratterizzazione teorica dell’accuratezza di misura del sistema emerge come quest’ultima sia indipendente dalla direzione assunta dalla particella in movimento rispetto alla disposizione dei sensori, garantendo un’accuratezza isotropica planare.
Inoltre, rimanendo nello stesso ambito applicativo, una parte di questo lavoro ha riguardato lo studio e la realizzazione di una sonda capacitiva triassiale. La particolarità del dispositivo proposto è quella di essere realizzato per essere depositato direttamente sul componente dell’impianto da monitorare e per questo definita: "on-component.
Un prototipo del sensore è stato realizzato con tecnologia serigrafica e il suo comportamento caratterizzato in frequenza, dimostrando caratteristiche comparabili alle comuni sonde triassiali ("bulk").
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Ciotirca, Lavinia-Elena. "System design of a low-power three-axis underdamped MEMS accelerometer with simultaneous electrostatic damping control." Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/17939/7/CIOTIRCA_L.pdf.
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Recently, consumer electronics industry has known a spectacular growth that would have not been possible without pushing the integration barrier further and further. Micro Electro Mechanical Systems (MEMS) inertial sensors (e.g. accelerometers, gyroscopes) provide high performance, low power, low die cost solutions and are, nowadays, embedded in most consumer applications. In addition, the sensors fusion has become a new trend and combo sensors are gaining growing popularity since the co-integration of a three-axis MEMS accelerometer and a three-axis MEMS gyroscope provides complete navigation information. The resulting device is an Inertial measurement unit (IMU) able to sense multiple Degrees of Freedom (DoF). Nevertheless, the performances of the accelerometers and the gyroscopes are conditioned by the MEMS cavity pressure: the accelerometer is usually a damped system functioning under an atmospheric pressure while the gyroscope is a highly resonant system. Thus, to conceive a combo sensor, aunique low cavity pressure is required. The integration of both transducers within the same low pressure cavity necessitates a method to control and reduce the ringing phenomena by increasing the damping factor of the MEMS accelerometer. Consequently, the aim of the thesis is the design of an analog front-end interface able to sense and control an underdamped three-axis MEMSaccelerometer. This work proposes a novel closed-loop accelerometer interface achieving low power consumption The design challenge consists in finding a trade-off between the sampling frequency, the settling time and the circuit complexity since the sensor excitation plates are multiplexed between the measurement and the damping phases. In this context, a patenteddamping sequence (simultaneous damping) has been conceived to improve the damping efficiency over the state of the art approach performances (successive damping). To investigate the feasibility of the novel electrostatic damping control architecture, several mathematical models have been developed and the settling time method is used to assess the damping efficiency. Moreover, a new method that uses the multirate signal processing theory and allows the system stability study has been developed. This very method is used to conclude on the loop stability for a certain sampling frequency and loop gain value. Next, a 0.18μm CMOS implementation of the entire accelerometer signal chain is designed and validated.
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Degefa, Tesfaye Hailu. ""Ion channel (mimetic) sensors" mechanism of charge propagation through thiol-, protein- and dendrimer-modified electrodes /." Doctoral thesis, [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=980218624.
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Zhao, Xin. "Study of Multimode Extrinsic Fabry-Perot Interferometric Fiber Optic Sensor on Biosensing." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/34534.
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The electrostatic self-assembly (ESA) method presents an effective application in the field of biosensing due to the uniform nanoscale structure. In previous research, a single mode fiber (SMF) sensor system had been investigated for the thin-film measurement due to the high fringe visibility. However, compared with a SMF sensor system, a multimode fiber (MMF) sensor system is lower-cost and has larger sensing area (the fiber core), providing the potential for higher sensing efficiency.
In this thesis, a multimode fiber-optic sensor has been developed based on extrinsic Fabry-Perot interferometry (EFPI) for the measurement of optical thickness in self-assembled thin film layers as well as for the immunosensing test. The sensor was fabricated by connecting a multimode fiber (MMF) and a silica wafer. A Fabry-Perot cavity was formed by the reflections from the two interfaces of the wafer. The negatively charged silica wafer could be used as the substrate for the thin film immobilization scheme. The sensor is incorporated into the white-light interferometric system. By monitoring the optical cavity length increment, the self-assembled thin film thickness was measured; the immunoreaction between immunoglobulin G (IgG) and anti-IgG was investigated.
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Leonard-Pugh, Eurion. "Acoustic anemometry on the surface of Mars." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:5179c757-3ec9-44a1-97ca-41b46b6d4873.
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There is a need for wind sensors with high accuracy and measurement frequency for deployment on the surface of Mars. The wind data obtained to date have been adversely affected by thermal contamination and calibration issues. Improved data would not only help to constrain and validate theoretical models, but also increase safety and longevity of lander operations. The mechanical and thermal wind sensing techniques used on previous missions, whilst sufficient for basic meteorology, are wholly inadequate for measuring fundamental phenomena such as dust and volatile transport. Two promising technologies, optical and acoustic anemometry, could permit precise and high-frequency measurement of three-dimensional wind speeds on the Martian surface. Ultrasonic acoustic anemometry, which relies on time-of-flight measurements, was ultimately chosen for its lower processing requirements and ability to measure the speed of sound; and therefore temperature. Capacitive transducers were selected for their low impedance and high sensitivity, to maximise signal transmission through the rarefied Martian atmosphere. These transducers, which consist of a metallised polymer film oscillating on top of a contoured metal backplane, were evaluated for their suitability as anemometers on the Martian surface. A theoretical framework was assembled to model transducer performance and determine which factors are the most important in determining received signal amplitude. A pair of transducers were designed and manufactured to allow for testing of a wide range of parameters including thickness of the oscillating membrane and diameter. Tests were carried out on the assembled transducers to investigate the dependence on these parameters, and their behaviour was generally found to fit the assembled theoretical framework well. Transducer performance was highly dependent on roughness depth of the backplanes, as expected. The frequency response of the transducers was dominated by the backplane roughness at atmospheric pressure but by film thickness at low pressures. Cross-correlation of the sent and received signals was confirmed as the most reliable signal detection method at low signal amplitudes. The transducers were tested under simulated Martian conditions (a low-pressure carbon dioxide atmosphere with airborne dust), and found to be capable of accurately and reliably measuring the incident wind speed. The cumulative deposition of airborne dust noticeably reduced received signal amplitude, but further testing is required to determine the effect of significant amounts of dust on transducer performance. The impact of the transducer heads impeding the incident fluid flow was found to be very significant in wind tunnel testing. Preliminary computational models were found to accurately predict these effects, but a more comprehensive modelling campaign and experimental validation would be required to ensure accurate instrument calibration.
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Kedia, Sunny. "Optical Communication Using Hybrid Micro Electro Mechanical Structures (MEMS) and Commercial Corner Cube Retroreflector (CCR)." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5969.
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This dissertation presents a free-space, long-range, passive optical communication system that uses electrostatically modulated microelectromechanical systems (MEMS) structures coupled with a glass total internal reflection (TIR)-type corner cube retroreflector (CCR) as a non-emitting data transmitter. A CCR consists of three mirrors orthogonal to each other, so that the incident beam is reflected back to the incident beam, source. The operational concept is to have a MEMS modulator fusion with TIR CCR, such that the modulators are working periodically to disrupt the evanescent waves at the air interface of one of the three back glass faces of a TIR CCR. The MEMS chip has two primary components: (1) an array of movable light scattering silicon structures with nano roughness and (2) a glass lid with a transparent conductive indium tin oxide (ITO) film. The MEMS structures are bonded to a glass lid using flip-chip bonding. Once bonded, the MEMS structures can be modulated either toward or away from the glass lid, thus disrupting evanescent energy delivered from a probing laser beam. The MEMS structure is precisely bonded to the TIR CCR with an accuracy of 10-30 arc-seconds using a Michelson interferometry feedback system. This is a novel step by which an existing passive commercial CCR can be converted into a modulating active CCR. This CCR-MEMS unit acts as the key element of the transmitter. To illustrate the concept of a low-power, unattended, sensor-monitoring system, we developed a sensor board containing temperature, humidity, and magnetic sensors along with a microprocessor and other electronics. The sensor board and CCR board are packed together and act as the transmitter unit. We developed a benchtop system and an improved portable receiver system. The receiver system contains the laser (as source), a collimating lens (to collect retroreflected signal), an optical, narrow band pass filter, and a detector. The detector signal was amplified and filtered and sent either to the oscilloscope, a lock-in-amplifier, or a laptop to display the sensor data. Using the receiver system, a sensor-CCR-based transmitter unit, and receiver with 635 nm as source, we achieved retroreflective communication over a distance of 300 m.
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Palierakis, Y. "Non-intrusive flow measurement of pneumatically conveyed solids; physical modelling and application of spatial windowing to improve microwave and electrostatic sensors : Conveyed solids velocity measurement systems based on transit time correlation and th." Thesis, University of Bradford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371496.
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Three sensor systems measuring particle velocity in gas-solids flows have been studied. These are the microwave Doppler flow sensor, the electrostatic sensor, and the microwave sensor for correlation measurement, all utilizing different principles of operation. The Doppler sensor is based on the Doppler frequency shift observed when microwaves are backscattered by moving targets. An analysis of the process of Doppler signal generation and a computer model based on this analysis have been presented. A novel feature of this work is the implementation of partial screening of the flow field which improves the shape of the Doppler spectrum and results in a mean Doppler frequency proportional to the flow velocity and independent of the flow profile. The electrostatic sensor is based on the principle of monitoring the charge induced on metallic surfaces by charged particles moving in their neighbourhood. A theoretical analysis of the spatial performance of the sensor along with a computer model and experimental verification are presented. Principally, ring type of sensors have been examined and the streched band electrostatic sensor is introduced (SBES). The advantage gained with the introduction of the stretched band electrostatic sensor is a uniform sensitivity across the plane of the sensor. The microwave correlation sensor follows the principles of previous ultrasonic and laser correlation flovrneters. That is, "a transmitted beam penetrates the flow field, suffers modulation, and is detected by receivers placed on the other side of the flow field. An analysis of the principles has been presented and a simplified computer model has been used for system design studies. The study presented here shows that a microwave correlation sensor is viable device for measuring solids velocity. Wherever possible direct comparisons of the properties and the performance of the three sensors are made in order to draw conclusions as to which sensor is best for a specific industrial application. Engineering, environmental and safety problems which might be encountered in the practical implementation of the sensors are discussed. In addition, areas of uncertainty where further work is required are summarized.
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Soora, Praveen K. "CMOS fingerprint sensor electrostatic modeling." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1805.
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Thesis (M.S.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains viii, 94 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 88-89).
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Cheng, Ruixue. "A study of electrostatic pulverised fuel meters." Thesis, Teesside University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262830.
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Chang, Huai-Ning. "Electrostatic Feedback for Mems Sensor : Development of in situ TEM instrumentation." Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11649.
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This thesis work is about further developing an existing capacitive MEMS sensor for in situ TEM nanoindentation developed by Nanofactory Instrument AB. Today, this sensor uses a parallel plate capacitor suspended by springs to measure the applied force. The forces are in the micro Newton range. One major issue using with this measurement technique is that the tip mounted on one of the sensor plates can move out of the TEM image when a force is applied. In order to improve the measurement technique electrostatic feedback has been investigated. The sensor’s electrostatic properties have been evaluated using Capacitance-Voltage measurements and a white light interferometer has been used to directly measure the displacement of the sensor with varying voltage. Investigation of the sensor is described with analytical models with detailed treatment of the capacitive response as function of electrostatic actuation. The model has been tested and refined by using experimental data. The model showed the existence of a serial capacitor in the sensor. Moreover, a feedback loop was tested, by using small beads as load and by manually adjusting the voltage. With the success of controlling the feedback loop manually, it is shown that the idea is feasible, but some modifications and improvements are needed to perform it more smoothly.
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Peyser, Alexander. "Theoretical Studies of Structure-Function Relationships in Kv Channels: Electrostatics of the Voltage Sensor." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/667.
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Voltage-gated ion channels mediate electrical excitability of cellular membranes. Re- duced models of the voltage sensor (VS) of Kv channels produce insight into the electrostatic physics underlying the response of the highly positively charged S4 transmembrane domain to changes in membrane potential and other electrostatic parameters. By calculating the partition function computed from the electrostatic energy over translational and/or rotational degrees of freedom, I compute expectations of charge displacement, energetics, probability distributions of translation & rotation and Maxwell stress for arrangements of S4 positively charged residues and S2 & S3 negatively charged counter-charges; these computations can then be compared with experimental results to elucidate the role of various putative atomic level features of the VS. A "paddle" model (Jiang et al., 2003) is rejected on electrostatic grounds, owing to unfavorable energetics, insufficient charge displacement and excessive Maxwell stress. On the other hand, a "sliding helix" model (Catterall, 1986) with three local counter-charges, a protein dielectric coefficient of 4 and a 2/3 interval of counter-charge positioning relative to the S4 alpha-helix period of positive residues is electrostatically reasonable, comparing well with Shaker (Seoh et al., 1996). Lack of counter-charges destabilizes the S4 in the membrane; counter-charge interval helps determine the number and shape of energy barriers and troughs over the range of motion of the S4; and the local dielectric coefficient of the protein (S2, S3 & S4) constrains the height of energy maxima relative to the energy troughs. These "sliding helix" models compare favorably with experimental results for single & double mutant charge experiments on Shaker by Seoh et al. (1996). Single S4 positive charge mutants are predicted quite well by this model; single S2 or S3 negative counter-charge mutants are predicted less well; and double mutants for both an S4 charge and an S2 or S3 counter-charge are characterized least well by these electrostatic models (which do not include gating load, unlike their biological analogs). Further computational and experimental investigation of S2 & S3 counter-charge structure for voltage-gated ion channels is warranted.
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Wolfram, Heiko, and Wolfram Dötzel. "Stability Analysis of a MEMS Acceleration Sensor." Universitätsbibliothek Chemnitz, 2007. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200700143.
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The electrostatic actuation with its several advantages is the main principle for micro-electro-mechanical systems (MEMS). One major drawback is the nonlinear behavior, which results into instability, known as the electrostatic pull-in effect. This effect might also push a closed-loop configuration into instability and thus makes a linear time-invariant control inapplicable to the system. The paper investigates the stability of an acceleration sensor in closed-loop operation with this setting. A simplified controller adjustment gives a first insight into this topic. Practical implementations saturate on the quantizer's full-scale value, which is also considered in the stability analysis. Numerical phase-plane analysis verifies the stability and shows further surprising results.
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Ratanatriwong, Puntarika. "Sensory Evaluation of electrostatically coated chips and powder physical property effects (size and food composition) on electrostatic coating improvement." The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1085776831.
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Bennett, Ashley L. "Electrostatic Networks and Mechanisms of ΔpH-Dependent Gating in the Human Voltage-Gated Proton Channel Hv1." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/6046.
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The structure of the voltage-gated proton (H+) channel Hv1 is homologous to the voltage sensor domain (VSD) of tetrameric voltage-gated Na+, K+ and Ca2+ channels (VGCs), but lacks a pore domain and instead forms a homodimer. Similar to other VSD proteins, Hv1 is gated by changes in membrane potential (V), but unlike VGCs, voltage-dependent gating in Hv1 is modulated by changes in the transmembrane pH gradient (DpH = pHo - pHi). In Hv1, pHo or pHi changes shift the open probability (POPEN)-V relation by ~40 mV per pH unit. To better understand the structural basis of pHo-dependent gating in Hv1, we constructed new resting- and activated-state Hv1 VSD homology models using physical constraints determined from experimental data measured under voltage clamp and conducted all-atom molecular dynamics (MD) simulations. Analyses of salt bridges and calculated pKas at conserved side chains suggests the existence of intracellular and extracellular electrostatic networks (ICEN and ECEN, respectively) that stabilize resting- or activated-state conformations of the Hv1 VSD. Structural analyses led to a novel hypothesis: two ECEN residues (E119 and D185) with coupled pKas coordinately interact with two S4 ‘gating charge’ Arg residues to modulate activated-state pHo sensitivity. Experimental data confirm that pH-dependent gating is compromised at acidic pHo in Hv1 E119A-D185A mutants, indicating that specific ECEN residue interactions are critical components of the ∆pH-dependent gating mechanism. E119 and D185 are known to participate in extracellular Zn2+ coordination, suggesting that H+ and Zn2+ utilize similar mechanisms to allosterically modulate the activated/resting state equilibrium in Hv1.
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Coombes, James Robert. "Development of electrostatic and piezoelectric sensor arrays for determining the velocity and concentration profiles and size distribution of pneumatically conveyed bulk solids." Thesis, University of Kent, 2016. https://kar.kent.ac.uk/59801/.
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One way countries around the world are increasing the proportion of renewable fuels for electricity generation is to convert coal fired power stations to co-fired (biomass/coal fired) or converting coal fired power stations to burn only biomass fuels. This however has led to measurement challenges monitoring the complex multi-phase flow of the pulverised fuels entering the furnace due to the complex shape of biomass particles. To meet these measurement challenges a novel electrostatic sensor array and piezoelectric sensor array have been developed. The electrostatic sensor array consists of an array of electrostatic electrode pairs that span the diameter of the pipe. Consequently the electrostatic sensor array is capable of determining the particle velocity and concentration profiles as well as detecting specific flow regimes such as roping. The piezoelectric impact sensor array consists of an array of piezoelectric individual impact sensors that span the diameter of the pipe. The piezoelectric sensor array is capable of determining the particle concentration and size distribution profiles. Experimentation has been carried out on laboratory scale pneumatic conveying systems using a variety of materials such as coal, biomass, coal/biomass blends and plastic shot. Experiments using the electrostatic sensor array have shown that it is indeed capable of determining the particle velocity and concentration profiles in both dilute developed and undeveloped flows. Analysis of the standard deviation of the velocity profiles as well as the correlation coefficient profiles have indicated that parts of the pipe cross section have a more stable flow compared to others. Data obtained through on-line and off-line experimentation using the piezoelectric sensor array has shown that through selective frequency filtering of the impact signal particle size can be determined assuming the particle velocity and the mechanical properties of the conveyed pulverised materials are known. By using a threshold voltage to determine when an impact has occurred on each element of the piezoelectric sensor array the particle concentration profile has been determined. The concentration profiles measured by the piezoelectric sensor array were verified using the electrostatic sensor array.
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Geisler, Matthias. "Récupération d’énergie mécanique pour vêtements connectés autonomes." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI090/document.
Full textAbstract:
La fonctionnalisation « intelligente » des vêtements et accessoires portés par la personne est un phénomène à croissance rapide. L’installation des smartphones dans le quotidien des personnes en une décennie à peine en témoigne. L’autonomie énergétique de ces systèmes est un enjeu important, tant en termes d’ergonomie que de ressources : l’usage de piles ou batteries électrochimiques à l’échelle de milliards d’objets connectés est difficilement envisageable. La récupération d’énergie se pose en alternative pour complémenter ou remplacer ces unités de stockages. Cette thèse explore plusieurs approches pour utiliser l’énergie mécanique de la personne afin d’alimenter un vêtement intelligent en énergie électrique.Après avoir identifié le besoin énergétique d’un vêtement connecté typique, et comparé les possibilités des récupérateurs d’énergie de la littérature, trois formats de récupérateurs d’énergie sont étudiés. Le premier est un générateur inertiel à induction résonant non linéaire, de la taille d’une pile AA et permettant l’exploitation des impacts des pas de la personne. L’étude porte essentiellement sur la modélisation et l’optimisation du système pour l’activité humaine. Le prototype associé présente une densité de puissance supérieure à 500µW/cm3 lors de la course à pied. Le second récupérateur étudié est aussi un générateur inertiel à induction. D’une forme « toroïdale », il exploite le balancier des membres de la personne, et est capable de produire des puissances supérieures au milliwatt lorsqu’il est fixé au niveau du pied ou du bras. Enfin, le troisième concept de récupérateur d’énergie proposé s’appuie sur la transduction électrostatique à capacité variable pour exploiter des déformations dans les vêtements. Le système associe la triboélectricité avec un circuit d’auto-polarisation passif, le doubleur de Bennet. Cette combinaison permet de polariser une capacité variable de façon importante, sans source de tension externe, et ainsi de maximiser l’énergie électrostatique générée. Le dispositif réalisé pour faire la preuve du concept produit ainsi plus de 150µJ par cycle. Cette architecture électrostatique ouvre d’intéressantes possibilités en matière d’ergonomie et d’intégration dans les vêtements. En effet, elle laisse entrevoir le développement de structures étirables et flexibles s’adaptant bien aux contraintes de cette application.La comparaison de ces trois approches est instructive quant aux perspectives de développement du domaine de la conversion de l’énergie mécanique de la personneThe functionalization of common objects in the human’s environment with electronics is a fast-growing trend, as demonstrated by the emblematic example of smartphones which became almost essential in the everyday life in less than a decade. One important stake of these systems is their power supply, in terms of ergonomics as well as resources: the use of electromechanical batteries to fuel billions of connected “things” is not the most attractive prospect. Energy harvesting techniques may provide an alternative or a complement to the use of these storage units. This thesis explores different structures of generators to efficiently convert the user’s mechanical energy to ensure the electrical self-sufficiency of smart wearables.Based on power requirement considerations for a typical “smart shirt” and comparing human energy harvesters from the literature, different structures are investigated. The first one is an inertial electromagnetic generator, the size of an AA-battery, designed to convert footsteps impacts. A thoroughly modelled and optimized device is able to generate power densities over 500µW/cm3 while attached on the arm during a run. The second considered energy harvester format is a “looped” inertial structure which is adapted to exploit the swing-type motions of the user’s limbs. This system is able to produce milliwatts-level powers from the motion of a small magnetic ball inside the device. Finally, a third generator concept that relies on electrostatic induction was developed, which uses variable capacitance structures to turn clothes deformations into electricity. The architecture of this energy harvester combines the triboelectric effect with a circuit of built-up self-polarization, Bennet’s doubler. It enables high levels of bias voltages without the need of an external source, and thus to maximize the energy generated per electrostatic cycle. A simple test device is shown to produce over 150µJ per cycle. This approach is promising in terms of integration in smart clothing, because it enables the development of flexible and stretchable devices well complying with the comfort requirements of worn systems.The comparison of those three energy harvesters provides an interesting basis for the future developments of energy harvesters converting one’s mechanical energy
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Grahmann, Jan. "Hochempfindliche resonante Gassensoren auf der Basis von einkristallinen Silizium-Plattenschwingern." Doctoral thesis, Universitätsbibliothek Chemnitz, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-201000101.
Full textAbstract:
Die vorliegende Arbeit beschäftigt sich mit der Modellerstellung und Technologie eines gravimetrischen Gassensors für organische Gase. Die Besonderheit liegt in dem verwendeten Resonatortyp. Es handelt sich um einen lateral elektrostatisch angeregten quadratischen Plattenresonator, der mit einer Rezeptorschicht versehen wird. Mit Hilfe von FEM-Berechnungen werden die Eigenfrequenzen und Eigenformen berechnet. Für die untersuchte Lamé- und Square-Mode wird die Sensorgüte unter Berücksichtigung des "Squeeze-Film-Damping" sowie der viskoelastischen Rezeptorschichteigenschaften bestimmt. Die Sensormoden werden durch ein Feder-Masse-Modell mit einem Freiheitsgrad modelliert und durch ein elektrisches Ersatzschaltbild repräsentiert. Die berechneten Nachweisgrenzen für Oktan und Toluol bei 6-facher Rauschgrenze liegen im zweistelligen ppb-Bereich. Für die technologische Umsetzung werden SOI-Wafer verwendet. Die ≤ 100 nm betragenden Spaltbreiten zwischen Elektroden und Resonator werden durch das RIE-Ätzen von Siliziumgräben mit senkrechten Seitenwänden, der Abscheidung von SiO2 als Opferschicht und dem Füllen der Gräben mit hochdotiertem Polysilizium hergestellt. Die Kontaktierung der Resonatoren erfolgt über einen leitenden Stamm, der aufgrund von selbstjustierenden Prozessen die Resonatorplatte zentriert einspanntThe following work is concerned with the modelling and fabrication technology of a gravimetric sensor for volatile organic compounds (VOC). Novelty is the combination of a lateral electrostatic driven square plate resonator with a gas sensitive detection layer. The eigenfrequencies and -modes are calculated with FEM simulations. Especially suited for gas sensors are the Lamé- and Square eigenmodes which are studied more closely. The quality factor is determined considering "squeeze film damping" and the viscoelastic properties of the gas sensitive detection layer. To present the sensor oscillation modes a spring mass model with one degree of freedom is determined and extended by an equivalent circuit diagram. The calculated limits of detections for octane and toluene are in the binary ppb-range, working with six times the limit of frequency noise. SOI-wafers are the base material for the sensor process flow. Electrode gaps ≤100 nm, essential for the electrostatic drive, are fabricated by RIE-etching vertical trenches into the device layer down to the buried oxide and by depositing a silicon dioxide as sacrifical layer and by refilling the trenches with highly doped polysilicon. The electrical contact of the resonator plate is ensured through an electrical conducting polysilicon stem. The developed process flow enables a self alignment ot the stem, clamping the plate centered
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SALCEDO, Javier. "DESIGN AND CHARACTERIZATION OF NOVELDEVICES FOR NEW GENERATION OF ELECTROSTATICDISCHARGE (ESD) PROTECTION STRUCTURES." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2812.
Full textAbstract:
The technology evolution and complexity of new circuit applications involve emerging reliability problems and even more sensitivity of integrated circuits (ICs) to electrostatic discharge (ESD)-induced damage. Regardless of the aggressive evolution in downscaling and subsequent improvement in applications' performance, ICs still should comply with minimum standards of ESD robustness in order to be commercially viable. Although the topic of ESD has received attention industry-wide, the design of robust protection structures and circuits remains challenging because ESD failure mechanisms continue to become more acute and design windows less flexible. The sensitivity of smaller devices, along with a limited understanding of the ESD phenomena and the resulting empirical approach to solving the problem have yielded time consuming, costly and unpredictable design procedures. As turnaround design cycles in new technologies continue to decrease, the traditional trial-and-error design strategy is no longer acceptable, and better analysis capabilities and a systematic design approach are essential to accomplish the increasingly difficult task of adequate ESD protection-circuit design. This dissertation presents a comprehensive design methodology for implementing custom on-chip ESD protection structures in different commercial technologies. First, the ESD topic in the semiconductor industry is revised, as well as ESD standards and commonly used schemes to provide ESD protection in ICs. The general ESD protection approaches are illustrated and discussed using different types of protection components and the concept of the ESD design window. The problem of implementing and assessing ESD protection structures is addressed next, starting from the general discussion of two design methods. The first ESD design method follows an experimental approach, in which design requirements are obtained via fabrication, testing and failure analysis. The second method consists of the technology computer aided design (TCAD)-assisted ESD protection design. This method incorporates numerical simulations in different stages of the ESD design process, and thus results in a more predictable and systematic ESD development strategy. Physical models considered in the device simulation are discussed and subsequently utilized in different ESD designs along this study. The implementation of new custom ESD protection devices and a further integration strategy based on the concept of the high-holding, low-voltage-trigger, silicon controlled rectifier (SCR) (HH-LVTSCR) is demonstrated for implementing ESD solutions in commercial low-voltage digital and mixed-signal applications developed using complementary metal oxide semiconductor (CMOS) and bipolar CMOS (BiCMOS) technologies. This ESD protection concept proposed in this study is also successfully incorporated for implementing a tailored ESD protection solution for an emerging CMOS-based embedded MicroElectroMechanical (MEMS) sensor system-on-a-chip (SoC) technology. Circuit applications that are required to operate at relatively large input/output (I/O) voltage, above/below the VDD/VSS core circuit power supply, introduce further complications in the development and integration of ESD protection solutions. In these applications, the I/O operating voltage can extend over one order of magnitude larger than the safe operating voltage established in advanced technologies, while the IC is also required to comply with stringent ESD robustness requirements. A practical TCAD methodology based on a process- and device- simulation is demonstrated for assessment of the device physics, and subsequent design and implementation of custom P1N1-P2N2 and coupled P1N1-P2N2//N2P3-N3P1 silicon controlled rectifier (SCR)-type devices for ESD protection in different circuit applications, including those applications operating at I/O voltage considerably above/below the VDD/VSS. Results from the TCAD simulations are compared with measurements and used for developing technology- and circuit-adapted protection structures, capable of blocking large voltages and providing versatile dual-polarity symmetric/asymmetric S-type current-voltage characteristics for high ESD protection. The design guidelines introduced in this dissertation are used to optimize and extend the ESD protection capability in existing CMOS/BiCMOS technologies, by implementing smaller and more robust single- or dual-polarity ESD protection structures within the flexibility provided in the specific fabrication process. The ESD design methodologies and characteristics of the developed protection devices are demonstrated via ESD measurements obtained from fabricated stand-alone devices and on-chip ESD protections. The superior ESD protection performance of the devices developed in this study is also successfully verified in IC applications where the standard ESD protection approaches are not suitable to meet the stringent area constraint and performance requirement.Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Tremblay, Gérard. "Cartographie électro-optique de tension : application au test des circuits imprimés." Grenoble INPG, 1988. http://www.theses.fr/1988INPG0134.
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Cette these developpe un outil mathematique de modelisation electrostatique permettant de determiner la reponse du capteur de mesure de tension a une repartition bidimensionnelle quelconque de potentiel electrique. Ces considerations theoriques ont ete verifiees grace a un capteur de tension experimental
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Rabenimanana, Toky Harrison. "Modélisation, fabrication et caractérisation expérimentale de réseaux MEMS faiblement couplés pour la détection de masse." Thesis, Bourgogne Franche-Comté, 2020. http://www.theses.fr/2020UBFCD062.
Full textAbstract:
Une étude sur les détecteurs de masse utilisant la localisation d’Anderson est menée dans le cadre de cette thèse. Différents moyens permettant d’améliorer leurs performances sont proposés et démontrés à travers deux dispositifs MEMS. Les deux dispositifs utilisent le même système composé de deux cantilevers couplés mécaniquement, mais les vibrations sont générées de deux manières différentes: le premier dispositif est actionné par une force électrostatique attractive tandis que le second est actionné par une force électrostatique répulsive. Afin de se débarrasser du déséquilibre créé par les défauts de fabrication, on utilise l’assouplissement électrostatique en réglant la tension continue de l’actionnement. Pour le premier dispositif, une approche utilisant un système asymétrique avec deux cantilevers de longueurs différentes est proposée. On réduit alors la rigidité effective de la poutre courte pour équilibrer le système. Avec le second type d’actionnement, le faible assouplissement électrostatique nous oblige à utiliser deux micropoutres de même longueur. Mais le système est toujours équilibré de la même manière. Grâce à la fonctionnalisation des non-linéarités électrostatiques, le premier dispositif montre une meilleure sensibilité, qui est de 67% supérieure à la sensibilité maximale atteignable en régime linéaire. Quant au second dispositif, il montre l’absence de non-linéarités électrostatiques, ce qui permet d’augmenter sa gamme dynamique linéaire jusqu’à 70% de la distance qui sépare les poutres des électrodes inférieures. Cela devrait améliorer non seulement la résolution en masse du détecteur, mais aussi la précision des mesures. Tous ces concepts sont d’abord étudiés théoriquement avec le modèle analytique basé sur la théorie d’Euler-Bernoulli. Ils sont ensuite démontrés expérimentalement après que les détecteurs aient été fabriqués suivant le processus MUMPSA study on mass microsensors using Anderson localization is conducted in this thesis. Different ways allowing to enhance their performances are proposed and demonstrated through two MEMS devices. Both devices use the same system composed of two mechanically coupled cantilevers, but the vibrations are generated in two different ways: the first device is actuated with an attractive electrostatic force while the second device is actuated with a repulsive electrostatic force. In order to get rid of initial imbalance due to manufacturing defects, the electrostatic softening effect is used by tuning the DC voltage of the actuation. For the first device, a concept with an asymmetric system including two cantilevers of different lengths is proposed. We thus reduce the effective stiffness of the short cantilever to balance the system. With the second type of actuation, the weak electrostatic softening effect forces us to use two microbeams of the same length. But the system is still balanced with the same approach. Thanks to the functionalization of electrostatic nonlinearities, the first device shows an enhanced sensitivity, which is 67% higher than the maximum sensitivity reachable in the linear regime. Concerning the second device, it shows the absence of electrostatic nonlinearities, which allows to increase the linear dynamic range by up to 70% of the gap. It should improve not only the mass resolution of the sensor, but also the accuracy of the mass sensing. All of these concepts are first theoretically investigated with the developed analytical model based on the Euler-Bernoulli beam theory. They are then experimentally demonstrated after the sensors are manufactured with the MUMPS
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Mayberry, Curtis Lee. "Interface circuits for readout and control of a micro-hemispherical resonating gyroscope." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53116.
Full textAbstract:
Gyroscopes are inertial sensors that measure the rate or angle of rotation. One of the most promising technologies for reaching a high-performance MEMS gyroscope has been development of the micro-hemispherical shell resonator. (μHSR) This thesis presents the electronic control and read-out interface that has been developed to turn the μHSR into a fully functional micro-hemispherical resonating gyroscope (μHRG) capable of measuring the rate of rotation. First, the μHSR was characterized, which both enabled the design of the interface and led to new insights into the linearity and feed-through characteristics of the μHSR. Then a detailed analysis of the rate mode interface including calculations and simulations was performed. This interface was then implemented on custom printed circuit boards for both the analog front-end and analog back-end, along with a custom on-board vacuum chamber and chassis to house the μHSR and interface electronics. Finally the performance of the rate mode gyroscope interface was characterized, showing a linear scale factor of 8.57 mv/deg/s, an angle random walk (ARW) of 34 deg/sqrt(hr) and a bias instability of 330 deg/hr.
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Peterson, Shawn. "Manufacturing technology for consistent high quality production of electrostatic sensors and circuits." 1991. http://catalog.hathitrust.org/api/volumes/oclc/24049315.html.
Full textAbstract:
Thesis (M.S.)--University of Wisconsin--Madison, 1991.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 110-112).
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Khater, Mahmoud Elsayed. "Use of Instabilities in Electrostatic Micro-Electro-Mechanical Systems for Actuation and Sensing." Thesis, 2011. http://hdl.handle.net/10012/6398.
Full textAbstract:
This thesis develops methods to exploit static and dynamic instabilities in electrostatic MEMS to develop new MEMS devices, namely dynamically actuated micro switches and binary micro gas sensors. Models are developed for the devices under consideration where the structures are treated as elastic continua. The electrostatic force is treated as a nonlinear function of displacement derived under the assumption of parallel-plate theorem. The Galerkin method is used to discretize the distributed-parameter models, thus reducing the governing partial differential equations into sets of nonlinear ordinary-differential equations.
The shooting method is used to numerically solve those equations to obtain the frequency-response curves of those devices and the Floquet theory is used to investigate their stability.
To develop the dynamically actuated micro switches, we investigate the response of microswitches to a combination of DC and AC excitations. We find that dynamically actuated micro switches can realize significant energy savings, up to 60 %, over comparable switches traditionally actuated by pure DC voltage. We devise two dynamic actuation methods: a fixed-frequency method and a shifted-frequency method. While the fixed-frequency method is simpler to implement, the shifted-frequency method can minimize the switching time to the same order as that realized using traditional DC actuation. We also introduce a parameter identification technique to estimate the switch geometrical and material properties, namely thickness, modulus of elasticity, and residual stress.
We also develop a new detection technique for micro mass sensors that does not require any readout electronics. We use this method to develop static and dynamic binary mass sensors. The sensors are composed of a cantilever beam connected to a rigid plate at its free end and electrostatically coupled to an electrode underneath it.
Two versions of micro mass sensors are presented: static binary mass sensor and dynamic binary mass sensor.
Sensitivity analysis shows that the sensitivity of our static mass sensor represents an upper bound for the sensitivity of comparable statically detected inertial mass sensors. It also shows that the dynamic binary mass sensors is three orders of magnitude more sensitive than the static binary mass sensor. We equip our mass sensor with a polymer detector, doped Polyaniline, to realize a formaldehyde vapor sensor and demonstrate its functionality experimentally. We find that while the static binary gas sensor is simpler to realize than the dynamic binary gas sensor, it is more susceptible to external disturbances.
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Chen, Chien-Yu, and 陳建宇. "Dependence of anti-electrostatic ability of capacitive touch sensor." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/99834114010962149323.
Full textAbstract:
博士國立交通大學
平面顯示技術碩士學位學程
103
This paper discusses the current touch panel process development. In order to avoid the touch panel scratches in the manufacturing process, it would attached a protect film on the touch panel at each process stop. However, the protective film can reduce the chance of scratching, but the differences in personnel practices, or the temperature and humidity of working environment made the touch panel suffered ESD issue. The main way to prevent the touch panel of ESD damage is releasing and shielding. We used the commonly touch sensor pattern, and this pattern is at the basis of the case from the lower the resistance and the change the capacitance to design different touch sensor unit. Then we made a small touch panel in each condition and used an electrostatic discharge simulator to test antistatic ability of each samples. Finally, the results show in the experiment, whether resistance is reduced in the X direction, the Y direction, or change the setting of capacitance can improve the antistatic ability of the touch panel.
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Seleim, Abdulrahman Saad. "Design and Implementation of a Controller for an Electrostatic MEMS Actuator and Sensor." Thesis, 2010. http://hdl.handle.net/10012/5243.
Full textAbstract:
An analog controller has been analyzed and built for an electrostatic micro-cantilever
beam. The closed loop MEMS device can be used as both actuator and sensor. As an
actuator it will have the advantage of large stable travel range up to 90% of the gap. As a
sensor the beam is to be driven into chaotic motion which is very sensitive changes in the
system parameters.
Two versions of the controller have been analyzed and implemented, one for the actuator
and one for the sensor. For the actuator, preliminary experiments show good matching
with the model. As for the sensor, the dynamic behavior have been studied and the best
operating regions have been determined.
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Cheng, Ting-Hsun, and 鄭莛薰. "The study of anti-electrostatic discharge ability for the sensor of OGS touch panel." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/90460256463163742344.
Full textAbstract:
碩士國立交通大學
平面顯示技術碩士學位學程
104
With the upgrading of touch panel technology and population of consumer using electronic products in recent years, the upgrading becomes an important index in the photovoltaic industry. OGS capacitive touch panel becomes a mainstream in this domain. Touch panel is easy to be damaged by ESD without protective element. It affects the yield rate and be an important factor in overall manufacturing process. The main purpose of this study is to explore effective solutions in order to solve the ESD(electrostatic discharge) issue of OGS touch panel within manufacturing and assembling process. it could reduce the losses caused by static electricity and enhance yield rate with lower cost. Our study is also to integrate anti-ESD protection of OGS touch sensor by designing OGS sensor without protective elements, and proposed add a layer of insulating material of low dielectric constant and available layout area plus improving effective prevention of OGS touch sensor structure. My research proposes robust anti-ESD design of OGS touch sensor. It's proved that our anti-ESD design has improved about three times than old deigns by experiments. My study has contributed much to reduce ESD of OGS touch sensor structure and be a follow-up product design reference.
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Alhasan, Ammar. "Comparison Of Casimir , Elastic, Electrostatic Forces For A Micro-Cantilever." Master's thesis, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6049.
Full textAbstract:
Casimir force is a cause of stiction (adhesion) between metal surfaces in Micro-Electro Mechanical Systems (MEMS). Casimir Force depends strongly on the separation of the two surfaces and the contact area. This thesis reviews the theory and prior experimental demonstrations of the Casimir force. Then the Casimir attractive force is calculated for a particular MEMS cantilever device, in which the metal cantilever tip is required to repeatedly touch and release from a metal tip pad on the substrate surface in response to a periodic driving electrostatic force. The elastic force due to the bending of the cantilever support arms is also a consideration in the device operation. The three forces are calculated analytically and compared as a function of cantilever tip height. Calculation of the electrostatic force uses coefficients of capacitance and electrostatic induction determined numerically by the finite element method, including the effect of permittivity for the structural oxide. A condition on the tip area to allow electrostatic release of the tip from the surface against Casimir sticking and elastic restoring forces is established.M.S.
Masters
Physics
Sciences
Physics
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Wu, Chen Hao, and 吳振豪. "Preparation of Fluorescent Electrospun Nanofibers Sensor via Electrostatic Force: Synthesis, Characterization and Metal Ions Detection." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/35144738040838427726.
Full textAbstract:
碩士國立中正大學
化學工程研究所
104
Detecting and recycling metal ions play an important role in environmental protection. Combination of fluorescent sensing molecules and electrospinning (ES) technique to fabricate nanofibers provides high sensitivity for metal ions due to the high surface-to-volume ratio of nanofibers. Two common methods are used to fabricate the ES nanofibers containing fluorescent sensing molecules: covalent conjugation or physical doping. However, synthesis of the fluorescent sensing monomer for covalent conjugation has several drawbacks, such as tedious synthetic procedure, difficult purification and low overall yield. Moreover, physical doping of fluorescent sensing molecules into nanofibers may cause the sensing molecules releasing from nanofibers in medium. Therefore, in this study, electrostatic interaction is introduced to immobilize the fluorescent sensing molecules on the ES nanofibers in order to solve the above problems. First, we synthesized a quaternized monomer (MAQAC12) which contains loosen ion pair. Then we prepared a series of copolymers using free radical polymerization, which containing MAQAC12 at different molar ratios, thermo-responsive N-isopropyl acrylamide (NIPAAm), and chemical cross-linking N-methylol acrylamide (NMA). We also fabricated nonwoven nanofibers via electrospinning, and immersed the crosslinked fibers into 8-Hydroxyquinoline-5-sulfonic acid (HQS) solution to immobilize HQS through electrostatic interaction between quaternary amine of MAQAC12 and negative sulfonate group of HQS. 1H-NMR, GPC, UV, TGA, DSC and UV-vis were used to charaterize the effect of the different MAQAC12 content on their molecular weight, and thermal properties. Generally, the molecular weight decreased as the amount of MAQAC12 increased due to the high steric strain of MAQAC12. And it also caused the reduction of Td. FTIR was used to confirm the occurrence of crosslinking reaction of NMA moieties. FE-SEM was used to investigate the morphology of ES nanofibers in pristine fibers and fibers soaked into water for 10 minutes, 20 minutes and 30 minutes. XPS was utilized to quantify elements compositions of nanofibers in the presence and absence of HQS. For metal ions detection, several factors that have significant influence on the sensitivity of the ES nanofibers were evaluated, including molar ratios of MAQAC12, the types and concentration of metal ions, environmental temperature and pH. We demonstrated that the sensitivity increased with increasing the molar ratios of MAQAC12, due to more HQS immobilized. Among the tested metal ions, the nanofibers showed obvious increase of fluorescent towards Al3+、Zn2+and Cd2+. The ES nanofibers also exhibited good sensitivity for detection at an extremely dilute concentration of the above metal ions (10-8M). The on/off sensitivity of ES nanofibers towards meral ions was observed due to the low critical solution temperature (LCST) characteristic of PNIPAAm. In addition, as a result of intra/inter-molecular photoinduced proton transfer, the sensitivity of HQS for metal ions is decreased in protic solution (pH 3).
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Botero-Cadavid, Juan F. "Fiber-optic sensor for detection of hydrogen peroxide in PEM fuel cells." Thesis, 2014. http://hdl.handle.net/1828/5271.
Full textAbstract:
This dissertation presents chemical sensors that are based on an emerging optical fiber sensing technology for the determination of the presence and concentration of hydrogen peroxide (H2O2) at low concentrations. The motivation to determine hydrogen peroxide lies on the fact that this chemical species is generated as a by-product of the operation of hydrogen-based polymer electrolyte membrane fuel cells (PEMFCs), and the presence and formation of this peroxide has been associated with the chemical degradation that results in low durability of PEMFCs. Currently, there are no techniques that allow the hydrogen peroxide to be determined in situ in PEMFCs in a reliable manner, since the only report of this type of measurement was performed using electrochemical techniques, which can be affected by the environmental conditions and that can alter the proper
operation of the PEMFCs.
The sensors presented in this dissertation are designed to detect the presence and quantify hydrogen peroxide in solution at the conditions at which PEMFCs operate. Since they are made using fused silica optical fibers and are based on a spectroscopic technique to perform the detection of H2O2 , they are not affected by the electromagnetic fields or the harsh chemical environment inside PEMFCs. In addition, they are able to still detect the presence of H2O2 at the operating temperatures.
The construction of the sensing film on the tip of an optical fiber and its small size (125 µm diameter), make the sensors here developed an ideal solution for being deployed in situ in PEMFCs, ensuring that they would be minimally invasive and that the operation of the fuel cell would not be compromised by the presence of the sensor.
The sensors developed in this dissertation not only present design characteristics that are applicable to PEMFCs, they are also suitable for applications in other fields such as environmental, defense, and biological processes.Graduate
0548
0756
0791
jfbotero@gmail.com
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Ward, Andrew. "A Study of Mechanisms Governing Single Walled Carbon Nanotube Thin Film Electric Biosensors." Thesis, 2013. http://hdl.handle.net/10012/8125.
Full textAbstract:
The successful fabrication and characterization of two chemiresistive platforms for biomolecule detection was demonstrated by this work. The Si/Silica based single walled nanotube thin film (SWNTTF) platform was developed to understand the effect of device geometry on pH and M13 bacteriophage sensing capabilities as well as the underlying mechanisms governing SWNTTF chemiresistive biosensors. The dominant mechanism of sensing switched from direct chemical doping to electrostatic gating when the target analyte changed from H+/OH- ions in pH testing to whole viruses. The experimental limit of detection for M13 for this platform was 0.5pM and an increased sensitivity as well as variability was observed in devices with smaller channel widths. Preliminary device calibration was completed in order to correlate a resistance response to a bulk M13 concentration. The polyethylene terephthalate (PET) based SWNTTF platform was developed to demonstrate the commercial potential of SWNTTF chemiresistive biosensors by detecting relevant concentrations of brain natriuretic peptide (BNP) on economically viable substrates. The pH response of these chemiresistors confirmed that chemical doping was the cause for resistance change in the SWNTTFs. The preliminary results demonstrated successful BNP detection at 50pg/mL using both aptamers and antibodies as recognition elements. Using SWNTTFs as the transducing element of chemiresistors allowed for further understanding of electrical mechanisms of sensing as well as achieving sensitive, real-time and reproducible electrical virus and biomolecule detection. Although these platforms do not achieve ultrasensitive limits of detection, they demonstrate the commercial potential of platforms using SWNTTFs as the transducing element of electrical biomolecule sensors.
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Grahmann, Jan. "Hochempfindliche resonante Gassensoren auf der Basis von einkristallinen Silizium-Plattenschwingern." Doctoral thesis, 2007. https://monarch.qucosa.de/id/qucosa%3A19264.
Full textAbstract:
Die vorliegende Arbeit beschäftigt sich mit der Modellerstellung und
Technologie eines gravimetrischen Gassensors für organische Gase. Die
Besonderheit liegt in dem verwendeten Resonatortyp. Es handelt sich um einen
lateral elektrostatisch angeregten quadratischen Plattenresonator, der mit
einer Rezeptorschicht versehen wird. Mit Hilfe von FEM-Berechnungen werden die
Eigenfrequenzen und Eigenformen berechnet. Für die untersuchte Lamé- und
Square-Mode wird die Sensorgüte unter Berücksichtigung des
"Squeeze-Film-Damping" sowie der viskoelastischen Rezeptorschichteigenschaften
bestimmt. Die Sensormoden werden durch ein Feder-Masse-Modell mit einem
Freiheitsgrad modelliert und durch ein elektrisches Ersatzschaltbild
repräsentiert. Die berechneten Nachweisgrenzen für Oktan und Toluol bei
6-facher Rauschgrenze liegen im zweistelligen ppb-Bereich. Für die
technologische Umsetzung werden SOI-Wafer verwendet. Die ≤ 100 nm betragenden
Spaltbreiten zwischen Elektroden und Resonator werden durch das RIE-Ätzen von
Siliziumgräben mit senkrechten Seitenwänden, der Abscheidung von SiO2 als
Opferschicht und dem Füllen der Gräben mit hochdotiertem Polysilizium
hergestellt. Die Kontaktierung der Resonatoren erfolgt über einen leitenden
Stamm, der aufgrund von selbstjustierenden Prozessen die Resonatorplatte
zentriert einspannt.The following work is concerned with the modelling and fabrication technology of a gravimetric sensor for volatile organic compounds (VOC). Novelty is the combination of a lateral electrostatic driven square plate resonator with a gas sensitive detection layer. The eigenfrequencies and -modes are calculated with FEM simulations. Especially suited for gas sensors are the Lamé- and Square eigenmodes which are studied more closely. The quality factor is determined considering "squeeze film damping" and the viscoelastic properties of the gas sensitive detection layer. To present the sensor oscillation modes a spring mass model with one degree of freedom is determined and extended by an equivalent circuit diagram. The calculated limits of detections for octane and toluene are in the binary ppb-range, working with six times the limit of frequency noise. SOI-wafers are the base material for the sensor process flow. Electrode gaps ≤100 nm, essential for the electrostatic drive, are fabricated by RIE-etching vertical trenches into the device layer down to the buried oxide and by depositing a silicon dioxide as sacrifical layer and by refilling the trenches with highly doped polysilicon. The electrical contact of the resonator plate is ensured through an electrical conducting polysilicon stem. The developed process flow enables a self alignment ot the stem, clamping the plate centered.