Dissertations / Theses on the topic 'Microsensors'
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1
McCarthy, Jeffrey J. "Potentiometric microsensors and telemetry." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39268.
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The use of ion-selective field-effect transistors (ISFETs) as potentiometric microsensors was investigated. In the first stage, an instrument was designed and built to operate an array of ISFETs. A microcomputer was used for instrument control and acquisition of data.The second phase of research focussed on the development of a pH sensitive radiotelemetric device that could eventually be used for the noninvasive monitoring of gastric pH. The first attempt used an ISFET as a variable resistor in a simple telemetry circuit. The drift in the pH dependent signal from this device was significant. The use of a differential sensor was studied as a possible way to minimize the effect of signal drift. This system measured the differential output of a pH ISFET and a pH insensitive ISFET. The pH insensitivity was due to an alkanethiol monolayer at the ISFET$ vert$solution interface.
It was shown that ISFETs are well suited for use as sensors in telemetry devices. The union of these previously independent research areas has been achieved.
2
Kerness, Nicole. "CMOS-based calorimetric chemical microsensors /." [S.l.] : [s.n.], 2002. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=14839.
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Pathak, Shrey. "Piezoelectric microsensors for semiochemical communication." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/57210/.
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Chemical communication plays vital role in the mediating the behaviour of an organism living in the “odour space”. The mechanisms by which odours are generated and detected by the organism has evolved over thousands of years and thus the potential advantages of translating this system into a fully functional communication system has opened new avenues in the area of multi-disciplinary research. This formed the basis of the Biosynthetic Infochemical Communications project – iCHEM whose central aim was to develop a new class of communication technology based on the biosynthesis pathways of the moth, S. littoralis. This novel infochemical communication system would consist of a “chemoemitter” unit which would generate a precise mix of infochemicals which after travelling through the odour space would be detected by a complementary tuned detector – the “chemoreceiver” unit comprising of a ligand specific detection element and an associated biophysical model functioning similar to the antennal lobe neuron of the moth. This combined novel system will have the capability of communicating by the help of chemicals only, in the vapour or liquid phase. For the work presented in this thesis, the novel concept of infochemical communication has been examined in the vapour and liquid phase by employing piezoelectric microsensors. This has been achieved and demonstrated throughout the thesis by employing chemo-specific acoustic wave microsensors. For vapour phase assessment, quartz crystal microbalance, were coated with different organic polymer coatings and incorporated in a prototype infochemical communication system detecting encoded volatiles. For liquid phase assessment, shear horizontal surface acoustic wave (SH-SAW) microsensors were specifically designed and immobilised within Sf9 insect cells. This GPCR based whole cell biosensing system was then employed to detect ligand specific activations thus acting as a precursor to the development of a fully functionalised OR based signalling system, thus contributing to the growing field of communication and labelling technology.
4
Lin, Jenn-Yu Gary. "Sensor compatible digitizing techniques for integrated microsensors." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/22215.
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Weltin, Andreas [Verfasser], and Gerald A. [Akademischer Betreuer] Urban. "Multiparametric, flexible microsensors for in vivo application." Freiburg : Universität, 2015. http://d-nb.info/1119327407/34.
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McCulloch, Scott. "Fibre optic microsensors for intracellular chemical measurements." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248617.
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SAUSER, FRANK EDWARD. "PACKAGING OF PRESSURE MICROSENSORS FOR CLINICAL APPLICATIONS." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1109368416.
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Srinivas, T. A. S. "A free-standing microthermopile infrared detector." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259660.
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Lazaro, Orlando. "CMOS inductively coupled power receiver for wireless microsensors." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51874.
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This research investigates how to draw energy from a distant emanating and alternating (i.e., AC) magnetic source and deliver it to a battery (i.e., DC). The objective is to develop, design, simulate, build, test, and evaluate a CMOS charger integrated circuit (IC) that wirelessly charges the battery of a microsystem. A fundamental challenge here is that a tiny receiver coil only produces mV's of AC voltage, which is difficult to convert into DC form. Although LC-boosted diode-bridge rectifiers in the literature today extract energy from similar AC sources, they can do so only when AC voltages are higher than what miniaturized coils can produce, unless tuned off-chip capacitors are available, which counters the aim of integration. Therefore, rather than rectify the AC voltage, this research proposes to rectify the current that the AC voltage induces in the coil. This way, the system can still draw power from voltages that fall below the inherent threshold limit of diode-bridge rectifiers. Still, output power is low because, with these low currents, small coils can only extract a diminutive fraction of the magnetic energy available, which is why investing battery energy is also part of this research. Ultimately, the significance of increasing the power that miniaturized platforms can output is higher integration and functionality of micro-devices, like wireless microsensors and biomedical implants.
10
Cho, SeongHwan 1974. "Energy efficient RF communication systems for wireless microsensors." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/29240.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 131-137).
Emerging distributed wireless microsensor networks will enable the reliable and fault tolerant monitoring of the environment. Microsensors are required to operate for years from a small energy source while maintaining a reliable communication link to the base station. In order to reduce the energy consumption of the sensor network, two aspects of the system design hierarchy are explored: design of the communication protocol and implementation of the RF transmitter. In the first part of the thesis, energy efficient communication protocols for a coordinated static sensor network are proposed. A detailed communication energy model, obtained from measurements, is introduced that incorporates the non-ideal behavior of the physical layer electronics. This includes the frequency errors and start-up energy costs of the radio, which dominate energy consumption for short packet, low duty cycle communication. Using this model, various communication protocols are proposed from an energy perspective, such as MAC protocols, bandwidth allocation methods and modulation schemes. In the second part of the thesis, design methodologies for an energy efficient transmitter are presented for a low power, fast start-up and high data rate radio.
(cont.) The transmitter is based on a [Epsilon]-[Delta] fractional-N synthesizer that exploits trade-offs between the analog and digital components to reduce the power consumption. The transmitter employs closed loop direct VCO modulation for high data rate FSK modulation and a variable loop bandwidth technique to achieve fast start-up time. A prototype transmitter that demonstrates these techniques is implemented using 0.25[mu]m CMOS. The test chip achieves 20[mu]s is start-up time with an effective data rate of 2.5Mbps while consuming 22mW.
by SeongHwan Cho.
Ph.D.
11
Leonte, Irina Ionela. "High frequency acousto-electric microsensors for liquid analysis." Thesis, University of Warwick, 2008. http://wrap.warwick.ac.uk/3681/.
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Liquid sensors are required for a multitude of applications in the food and beverage sectors, in the pharmaceutical industry or environmental monitoring. The focus of this work is on the development of high frequency shear horizontal surface acoustic wave (SH-SAW) sensors for liquid media identification and characterisation. Among the various types of surface acoustic wave modes propagating in solids, the SH-SAWs were found to be the most suitable for operation in liquids. Dual delay line and resonator sensor configurations were designed and fabricated on lithium tantalate (LiTa03) substrates; the design and the subsequent fabrication procedures of the sensors are described in detail. Furthermore, the electrical characterization of the sensors was carried out with a network analyser, and a comparative analysis was performed between sensors with different configurations. The interdigital transducers, used as the interface between the electrical and acoustic domains, presented good reflection coefficients and had near perfect matched impedances and return loss figures up to 45 dB. The insertion loss of the sensors varied with the surface conditions while it was improved by using total or partial metallization of the surface or employing grating structures on the propagation path. The SH-SAW devices were exposed to basic taste solutions and all the sensor configurations tested were able to discriminate them well. Measurements were done in both standard wired set-ups and a semi-wireless set-up, thus proving the sensor's capability for remote operation. Further investigations regarding the electronic tongue applicability of the SH-SAW sensors were conducted on a two port resonator device. The resonator was tested with six basic taste solutions, with taste solutions with varying concentrations, with binary mixtures of taste solutions and proved successful in identifying all test samples. A multivariate analysis was performed on the resonator data, and confirmed that the sensor's responses are influenced by the physical properties of the tested solutions. The multiple linear models derived are statistically significant and can explain high percentage of the data variability, offering a simplified alternative to the complex analytical models of the SH-SAW sensors. Also, a voltage modulated sensor system was proposed for smart assaying of biomaterials and its operation principle is described. The preliminary tests carried out showed a significant voltage effect on carbon nanoparticles. The voltage modulated system is proposed as an analytical microsystem for the screening of bacterial cells. All sensors in this project had no bio-chemical selective layer making them nonspecific, yet they create robust, durable and low-cost systems.
12
Ding, Xiaoyi. "Mechanical properties of silicon films and capacitive microsensors." Case Western Reserve University School of Graduate Studies / OhioLINK, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=case1054842799.
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Garcia, Castro Fatima. "Deformation microsensors on flexible substrate for health applications." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S100.
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Ce travail de recherche porte sur la fabrication de microcapteurs de déformation sur substrat souple. Les dispositifs sont élaborés et optimisés dans l’objectif de détecter de faibles déformations en temps réel et peuvent trouver des applications en santé en particulier via l’acquisition de faibles signaux électrophysiologiques pouvant être détectés par une déformation, par exemple à la surface de la peau. Le travail comprend le développement technologique des capteurs réalisés sur des substrats souples de très faible épaisseur (Kapton de 25 µm d’épaisseur), à partir de silicium microcristallin déposé par PECVD ou par ICPCVD. Pour chaque type de dépôt, les études de contraintes mécaniques et de stress sont exposées, en particulier via la détermination du facteur de jauge. La caractérisation dynamique des capteurs est réalisée via le développement d’un banc de test spécifique pour les mesures reproductibles de déformation. Les résultats permettent de déterminer des géométries optimisées, capables de suivre en temps réel des déformations complexes allant jusqu’aux signaux de type ECG. Des matrices de capteurs sont également réalisées et testéesThis work focuses on the processing of mechanical sensors on flexible substrates. The devices are designed and optimized with the objective of detecting small deformations in real time. They can be applied for health signal acquisition, in particular small electrophysiological signals that can be detected by deformation, for example on the surface of the skin. The work includes the technological development of sensors made of microcrystalline silicon deposited by PECVD or ICPCVD on very thin flexible substrates (Kapton 25 µm thick). For each type of deposition, mechanical stress studies are presented, in particular through the determination of the gauge factor. The dynamic characterization of the sensors is carried out through the development of a specific test bench for reproducible real-time deformation measurements. The results make it possible to determine optimized geometries, capable of monitoring complex deformations in real time, up to ECG-type signals. Sensor matrices are also produced and tested
14
Menolfi, Christian Ivo. "Low noise CMOS chopper instrumentation amplifiers for thermoelectric microsensors /." Zürich, 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13583.
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Aydemir, Akin. "Deep-trench Rie Optimization For High Performance Mems Microsensors." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608719/index.pdf.
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This thesis presents the optimization of deep reactive ion etching process (DRIE) to achieve high precision 3-dimensional integrated micro electro mechanical systems
(MEMS) sensors with high aspect ratio structures. Two optimization processes have been performed to achieve 20 μ
m depth for 1 &
#956
m opening for a dissolved wafer process (DWP) and to achieve 100 &
#956
m depth for 1 &
#956
m opening for silicon-on-glass (SOG) process. A number of parameters affecting the etch rate and profile angle are investigated, including the step times, etch step pressure, platen power, and electrode temperature. Silicon etch samples are prepared and processed in METU-MET facilities to understand and optimize the DRIE process parameters that can be used for the production of MEMS gyroscopes and accelerometers. The etch samples for DWP are masked using a photoresist, Shipley S1813. After the optimization process, vertical trench profiles are achieved with minimum critical dimension loss for trench depths up to 20 &
#956
m. Since the selectivity of the resist is not sufficient for 100 &
#956
m deep trench etch process, silicon dioxide (SiO2) is used as the mask for this process. At the end of the optimization processes, more than 100 &
#956
m depth for 1 &
#956
m opening with almost vertical sidewalls are achieved. In summary, this study provides an extensive understanding of the DRIE process for successful implementations of integrated MEMS sensors.
16
Siegesmund, Øyvind. "Development and electrochemical characterization of ultra-microsensors using nanotechnology." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-6851.
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Scalera, Jonathan E. "Image Chipping with a Common Architecture for Microsensors (CAuS)." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/34172.
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Recent interest has emerged in microsensor platforms that are capable of supporting reconnaissance,
surveillance and target acquisition operations. These devices typically consist of one or more
sensors, signal conditioning and processing subsystems, a radio link and a power source. Sensors
employed can range from acoustic, to seismic, to magnetic, to visible/infrared imagers.
A notable shortcoming of these systems is the fact that they are battery powered. The use of a finite power source places an upper limit on the lifespan of such a system. Thus, a major thrust in the development and usage of these microsensor platforms lies in the conservation of their limited energy resources. In attempt to reduce power consumption and hence extend the system's lifespan, communication bandwidths are often limited. In order to reduce the required bandwidth, much of the signal processing necessary to achieve a desired functionality must be performed within the microsensor platform itself.
This thesis effort provides this crucial bandwidth reduction by implementing in hardware an algorithm
developed by the University of Maryland, which limits transmissions to the best view
Regions-of-Interest (ROI) data, on the CAuS platform by BAE Systems. The hardware implementation
was verified with a Matlab script that compared its results with those of the original
algorithm. It was shown that these implementations were consistent for all of the data sets tested.
Moreover, a subjective analysis, in which the detected ROIs were visually inspected, was performed
to corroborate the former quantitative results.
Master of Science
18
Zorlu, Özge. "Orthogonal fluxgate type magnetic microsensors with wide linear operation range." Konstanz Hartung-Gorre, 2008. http://d-nb.info/988140535/04.
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Walmet, Eric Robert. "In-situ monitoring of PMMA solution polymerization with dielectric microsensors." Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/10036.
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Schmidt, Martin Arnold. "Microsensors for the measurement of shear forces in turbulent boundary layers." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14781.
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Lin, Qian. "A Plastic-Based Thick-Film Li-Ion Microbattery for Autonomous Microsensors." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1175.pdf.
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Wu, Zhizhen. "Flexible Microsensors based on polysilicon thin film for Monitoring Traumatic Brain Injury (TBI)." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1512045589967871.
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Fink, Klaus Michael. "Investigations of environmental degradation of materials by measurement of electrolyte parameters using microsensors and microelectrodes." Case Western Reserve University School of Graduate Studies / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=case1058210033.
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Wang, Lin. "Design, analysis and testing of humidity microsensors produced in mitel 1.5[mu]m CMOS technology." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0015/MQ47841.pdf.
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Flamm, Hubert [Verfasser], and Gerald A. [Akademischer Betreuer] Urban. "Electrochemical microsensors for superoxide monitoring in cell culture = Elektrochemische Mikrosensoren fuer Superoxid-Monitoring in Zellkultur." Freiburg : Universität, 2014. http://d-nb.info/1123482217/34.
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Mehta, Anjum. "MICROMACHINED ELECTROCHEMICAL SENSORS FOR HYDROGEN PEROXIDE AND CHLORINE DETECTION." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3464.
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Hydrogen peroxide and chlorine detection is critical for many biological and environmental applications. Hydrogen peroxide plays important roles in a variety of fields including plant physiology, medical, environmental and biochemical applications. Its role in plant defense and signal transduction, diseases such as Parkinson's and Alzhemier's, industrial processes such as disinfection and wastewater treatment and biochemical enzymatic reactions is critical. Given the gamut of areas that hydrogen peroxide is a key component of; its detection assumes great importance. Similarly chlorine has long been used as a disinfectant for making drinking water safe, but excessive chlorination is an environmental and health hazard in itself. In this work, micromachining techniques have been used to design, fabricate and test electrochemical sensors and microneedle structure that can be integrated for detection of hydrogen peroxide and free chlorine. A novel nanomaterial has been integrated with the hydrogen peroxide microsensor, which greatly increases the sensor lifetime and robustness. Miniaturization, low detection limits, high sensitivity and selectivity, as well as ease of fabrication are some of the other advantages of this work.M.S.M.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
27
Ferrara, Lisa Anne. "The Development of an In Vivo Spinal Fusion Monitor Using Microelectromechanical(MEMS) Technology to Create Implantable Microsensors." Cleveland State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=csu1234531155.
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LI, CHUNYAN. "A SPIRALLY-ROLLED FLEXIBLE POLYMER TUBE INTEGRATED WITH MICROSENSORS AND MICROFLUIDIC DEVICES FOR MULTIFUNCTIONAL SMART MICROCATHETERS." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1196111658.
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Kumar, Abhishek. "Development, characterization and experimental validation of metallophthalocyanines based microsensors devoted to monocyclic aromatic hydrocarbon monitoring in air." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22635/document.
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Résumé indisponibleThis PhD work is dedicated to investigate potentialities of phthalocyanines materials to realize a Quartz Crystal Microbalance (QCM) sensor for Benzene, Toluene and Xylenes (BTX) detection in air. The goal is to develop a sensor-microsystem capable of measuring BTX concentrations quantitatively below the environmental guidelines with sufficient accuracy. To achieve these objectives, our strategies mainly focused on experimental works encompassing sensors realization, sensing material characterizations, development of gas-testing facility and sensor testing for different target gases. One of the main aims is to identify most appropriate phthalocyanine material for sensor development. After comparative sensing studies, tert-butyl-copper phthalocyanine based QCM device is found as most sensitive and detail metrological characteristics are further investigated. Results show repeatable, reversible and high magnitude of response, low response and recovery times, sub-ppm range detection limit, high resolutions and combined selectivity of BTX gases among common atmospheric pollutants. Special focus is given to understand the gas/material interactions which are achieved by (a) XRD and SEM characterizations of sensing layers, (b) formalization of a two-step adsorption model and (c) assessing extent of diffusion of target gas in sensing layer. At last, possible ageing of sensor and suitable storage conditions to prevent such effect are investigated
30
Scaglia, Philipp, and Martin Zimdahl. "Treatment effects of van Beek activator comparing two wear-time prescriptions assessed by microsensors: a randomized clinical trial." Thesis, Malmö universitet, Odontologiska fakulteten (OD), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-19730.
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Syfte: Syftet med den här studien var att undersöka följsamheten och reduktionen av det horisontella överbettet vid behandling med van Beek-aktivator genom att jämföra en rekommenderad användningstid av tolv och åtta timmar per dag. Material och metod: Tretton patienter (4 pojkar och 9 flickor) ingick i undersökningsmaterialet med en medelålder på 10,0 år (SD = 0,9). Alla patienter var diagnostiserade med en Angle Klass II-bettavvikelse och behandlades med van Beek-aktivator. Patienterna var randomiserade i två grupper med två olika användningstider (8 timmar och 12 timmar). Följsamheten mättes med hjälp av en mikrosensor (TheraMon®) inbyggd i aktivatorn och det horisontella och vertikala överbettet registrerades efter första, tredje och sjätte månaden. Efter att datan var insamlad gjordes statistisk analys för att påvisa ifall statistisk skillnad fanns mellan grupperna.Resultat: Medelreduceringen i horisontellt överbett i 8-timmarsgruppen var efter sex månader 3,4 mm jämfört med hos 12-timmarsgruppen som var 3,5 mm. Medelanvändningstiden var i 12-timmarsgruppen och 8-timmarsgruppen 8.2 timmar (SD=1,7) och 7,9 timmar (SD=2,6) per dag respektive. Den genomsnittliga användningstiden för samtliga patienter var 8,1 timmar.Slutsats: Rekommendation av åtta timmar var enklare att uppnå jämfört med tolv timmar. Van Beek-aktivatorn var effektiv för korrigering av Angle Klass II-bettavvikelser, ingen klinisk signifikant skillnad i behandlingseffekt observerades mellan de två grupperna.Aim: The aim of this study was to evaluate the compliance and overjet changes among patients treated with the van Beek activator comparing a twelve- and eight-hours daily wear-time prescription. Material and methods: The study sample consisted of thirteen patients (4 boys and 9 girls) with a mean age of 10.0 years (SD = 0.9). All patients had a Class II malocclusion and were treated with the van Beek activator. Patients were randomly assigned to two groups with a wear-time of twelve and eight hours respectively. Compliance was measured with the aid of a microsensor (TheraMon®) built into the activator and the overjet and overbite were recorded after the first, third and sixth month. Results: The mean decrease in overjet among the 8 hours group after six months was 3.4 mm compared to the 3.5 mm overjet reduction recorded in the 12 hours group. The mean wear-time in the 12 hours group and 8 hours group were 8.2 hours (SD = 1.7) and 7.9 hours (SD = 2.6) per day respectively. The overall mean daily wear-time of all patients in both groups was 8.1 hours. Conclusions: The eight-hours prescription was easier to achieve compared to the twelve-hours. The van Beek activator was effective in Class II correction, no clinically significant difference in treatment effect was observed between the two wear-time prescriptions.
31
Suzuki, Takeharu, and n/a. "Integrated, Intelligent Sensor Fabrication Strategies for Environmental Monitoring." Griffith University. School of Microelectronic Engineering, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040813.131206.
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The humidity, temperature, wind speed/direction micro sensors can be manufactured individually, resulting in three individual substrates. The integration of the three sensors into a single substrate is a vital challenge to achieve an integrated intelligent sensor so called a multiple sensor. This requires the integration of process flows and is a major challenge because adequate sensor performance must be maintained. Polyimide was selected as a humidity sensing material for its compatibility with conventional integrated circuit fabrication technology, negligible temperature dependence and good resistance against contamination. Nickel was selected for the temperature and wind speed/direction sensor because of its useful temperature coefficient and the advantage of its cost. Since the known wet etchant for nickel requires hard-baked photoresist, a method which does not attack the polyimide while removing the photoresist must be developed. The method developed for etching nickel employs hard-bake-free photoresist. Other challenge was ensuring good thermal isolation for the wind speed/direction sensor fabricated on a silicon nitride layer preformed on top of a silicon wafer. Since silicon acts as a good heat sink, the silicon under the sensor was etched entirely away until the silicon nitride layer was reached. This structure achieved good thermal isolation resulting in small power consumption. This low power feature is essential for sensors deployed in fields where power access or replacement of power sources is restricted. This structure was compared with the structure created by polyimide plateau on a silicon nitride layer coated on a silicon substrate as a function of power consumption. Based on the examination of thermal isolation, the multiple sensor utilizing a MEMS technique was fabricated with a single-sided mask aligner. The characteristics of humidity sensors fabricated with polyimide were examined in detail with respect to variations of electrode structures, improvement of sensitivity, effect of process temperature, temperature and frequency dependence, and stability. The humidity sensor constructed with O2 plasma treated polyimide resulted an improvement in sensitivity and hysteresis. The investigation using XPS, FTIR and AFM concluded the chemical modification of polyimide played an important role in this improvement. The design, fabrication and results of a series of humidity sensors are quantified. There is always no unique packaging solution for sensors because of the application-specific nature of the sensors. This intelligent environmental monitoring system was designed to accommodate both an environmental sensor and its signal conditioning electronics circuitry (SICONEC) into a single package. The environmental sensors need direct exposure to the environment while SICONEC needs a sealed encapsulation to avoid environmental damage. A new style of packaging addressing these requirements was demonstrated using a hot embossing machine. The hot embossing machine was used to embed an integrated circuit (IC) in a bare die condition into a polycarbonate (PC) sheet. In this case, the IC was flipped down against the PC, which protects the front side of the IC from the environmental damages. In a test phase, a die containing operational amplifiers was embossed into the PC. A humidity sensor and surface mount resisters were placed on the same surface of the PC to test the validity of this new technique. Interconnection between the embossed die and the humidity sensor was established using bonding wires. Copper tracks were also used to ensure all electrical connections for the die, the humidity sensor and the resistors. The results clarified the method developed. Details of process methods, issues and further potential improvement are reported.
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Suzuki, Takeharu. "Integrated, Intelligent Sensor Fabrication Strategies for Environmental Monitoring." Thesis, Griffith University, 2004. http://hdl.handle.net/10072/367295.
Full textAbstract:
The humidity, temperature, wind speed/direction micro sensors can be manufactured individually, resulting in three individual substrates. The integration of the three sensors into a single substrate is a vital challenge to achieve an integrated intelligent sensor so called a multiple sensor. This requires the integration of process flows and is a major challenge because adequate sensor performance must be maintained. Polyimide was selected as a humidity sensing material for its compatibility with conventional integrated circuit fabrication technology, negligible temperature dependence and good resistance against contamination. Nickel was selected for the temperature and wind speed/direction sensor because of its useful temperature coefficient and the advantage of its cost. Since the known wet etchant for nickel requires hard-baked photoresist, a method which does not attack the polyimide while removing the photoresist must be developed. The method developed for etching nickel employs hard-bake-free photoresist. Other challenge was ensuring good thermal isolation for the wind speed/direction sensor fabricated on a silicon nitride layer preformed on top of a silicon wafer. Since silicon acts as a good heat sink, the silicon under the sensor was etched entirely away until the silicon nitride layer was reached. This structure achieved good thermal isolation resulting in small power consumption. This low power feature is essential for sensors deployed in fields where power access or replacement of power sources is restricted. This structure was compared with the structure created by polyimide plateau on a silicon nitride layer coated on a silicon substrate as a function of power consumption. Based on the examination of thermal isolation, the multiple sensor utilizing a MEMS technique was fabricated with a single-sided mask aligner. The characteristics of humidity sensors fabricated with polyimide were examined in detail with respect to variations of electrode structures, improvement of sensitivity, effect of process temperature, temperature and frequency dependence, and stability. The humidity sensor constructed with O2 plasma treated polyimide resulted an improvement in sensitivity and hysteresis. The investigation using XPS, FTIR and AFMconcluded the chemical modification of polyimide played an important role in this improvement. The design, fabrication and results of a series of humidity sensors are quantified. There is always no unique packaging solution for sensors because of the application-specific nature of the sensors. This intelligent environmental monitoring system was designed to accommodate both an environmental sensor and its signal conditioning electronics circuitry (SICONEC) into a single package. The environmental sensors need direct exposure to the environment while SICONEC needs a sealed encapsulation to avoid environmental damage. A new style of packaging addressing these requirements was demonstrated using a hot embossing machine. The hot embossing machine was used to embed an integrated circuit (IC) in a bare die condition into a polycarbonate (PC) sheet. In this case, the IC was flipped down against the PC, which protects the front side of the IC from the environmental damages. In a test phase, a die containing operational amplifiers was embossed into the PC. A humidity sensor and surface mount resisters were placed on the same surface of the PC to test the validity of this new technique. Interconnection between the embossed die and the humidity sensor was established using bonding wires. Copper tracks were also used to ensure all electrical connections for the die, the humidity sensor and the resistors. The results clarified the method developed. Details of process methods, issues and further potential improvement are reported.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Microelectronic Engineering
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Karavai, Olga. "Mapping local corrosion parameters using SVET and SIET." Doctoral thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22052.
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Doutoramento em Ciência e Engenharia de MateriaisLocalized corrosion, i.e., corrosion confined to local regions, is difficult to predict and control. In general, it appears as a result of heterogeneities, either in the metal or in the corrosive environment. One of the phenomenological features of localised corrosion is the development of specific environments close to active sites. In practice, the micro-environment near the metallic surface is different from that of the bulk medium and varies with time and conditions of the system under study. Localized electrochemical techniques based on the use of microelectrodes are well suited for in situ sensing the distribution of potential, current and chemical species in active zones, pores or defects. Most of the published work dealing with microelectrodes in corrosion is mainly exploratory and their use in a regular basis is still rare in corrosion research. This work presents the development and application of microelectrodes as experimental tools capable to assess local electrochemical reactions on metallic substrates immersed in aggressive solutions. Traditional electrochemical techniques used in corrosion research give the average response of the global activity of the whole surface not discriminating local effects and local chemistry. Therefore they are unable per si to properly characterize localized phenomena and the corresponding corrosion, inhibitive mechanisms and, sometimes, even to select the best protection methods. It is important to know local parameters such as pH, micro-galvanic effects, concentration of oxidizing (like O2) and aggressive (like Cl-) species, and formation of surface films. The Scanning Vibrating Electrode Technique (SVET) was used for local measurements of ionic currents in solution. The technique detects the potential distribution in solution associated to ionic currents in solution. For the analysis of the chemical species involved in the corrosion process, electrochemical microsensors were used in SIET (Scanning Ion Selective Electrode Technique) mode. Microelectrodes sensitive to pH, dissolved oxygen and metal cations (namely, Mg2+, Zn2+ and Cu2+) were developed and characterized. Work was also done with microeloectrodes sensitive to Al3+, but with less success. Then, they were used for investigating the reactivity on defects and corrosion inhibition on coated aluminium and magnesium alloys, detecting the micro-distribution of chemical species in solution close to the corroding surface of Zn, Cu and a Zn- Fe galvanic couple specimens. ix Limitations and difficulties exist for the use of these techniques in corrosion research due to the inherent reactivity of corroding metals, with the formation of corrosion products and sharp changes of pH, O2 and ionic strength along the samples surface. In spite of the difficulties, the results presented here demonstrate that the SVET/SIET mapping gives useful information for the quantification of electrochemical processes at the micro-level. The data are of prime importance for the modelling and simulation of corrosion mechanisms, selection of new corrosion inhibitors and development of ‘‘smart” coatings that suppress the corrosion processes.
A corrosão localizada, i.e., corrosão confinada a locais específicos, é difícil de prever e controlar. Em geral, ocorre como resultado de heterogeneidades tanto no metal como no ambiente corrosivo. Uma das características da corrosão localizada é o desenvolvimento de ambientes específicos junto das zonas activas. Na prática, o micro-ambiente junto da superfície metálica é diferente do do seio da solução, variando com o tempo e com as condições do sistema em estudo. Técnicas electroquímicas localizadas baseadas na utilização de microeléctrodos são convientes para medir a distribuição de potencial, intensidade de corrente e espécies químicas em solução junto de zonas activas, poros ou defeitos. Muito do trabalho que existe publicado sobre microeléctrodos em corrosão refere-se a trabalho exploratório que permanece numa etapa preliminar. A aplicação de microeléctrodos em estudo de corrosão numa base rotineira é ainda rara. Este trabalho apresenta o desenvolvimento e aplicação de microeléctrodos como ferramentas experimentais capazes de aceder a reacções electroquímicas locais em substratos metálicos imersos em soluções agressivas. As técnicas electroquímicas tradicionais usadas no estudo de corrosão dão resposta média do processo global em toda a superfície da amostra sem distinguir efeitos locais e a química local. Não são, portanto, adequadas para a descrição detalhada dos mecanismos de corrosão localizada, de processos de inibição e, por vezes, para a selecção dos métodos de protecção mais adequados. É importante conhecer parâmetros locais, como pH, efeitos micro-galvânicos, concentração de espécies oxidantes (como O2) e agressivas (como Cl-), formação de filmes superficiais. Neste trabalho usou-se a técnica do eléctrodo vibrante de varrimento (SVET) para medições locais de corrente iónica em solução. A técnica detecta a distribuição de potencial em solução, associada à corrente iónica. Para a análise de espécies químicas envolvidas no processo corrosivo, foram usados microsensores electroquímicos no modo SIET (Técnica de Varrimento de Eléctrodo Selectivo de Iões). vii Foram desenvolvidos e caracterizados microeléctrodos sensíveis a pH, oxigénio dissolvido e catiões metálicos (nomeadamente, Mg2+, Zn2+ e Cu2+). Trabalhou-se também no desenvolvimento de microeléctrodos sensíveis a Al3+, embora com menos sucesso. Os microeléctrodos foram utilizados na investigação da corrosão e inibição em defeitos induzidos em revestimentos protectores aplicados sobre ligas de alumínio e de magnésio, e na detecção da micro-distribuição de espécies químicas em solução perto de eléctrodos de zinco, cobre e de um par galvânico Zn-Fe. Este trabalho revela também as limitações e dificuldades na aplicação destas técnicas ao estudo de corrosão devido à inerente reactividade do processo corrosivo, com formação de produtos de corrosão e grandes variações de pH, O2 e força iónica ao longo da superfície de amostra. Apesar das dificuldades, os resultados aqui apresentados demonstram que o mapeamento por SVET/SIET fornece informações muito úteis para a quantificação de processos electroquímicos à micro-escala. Os dados são de primordial importância para a modelação e simulação de mecanismos de corrosão, selecção de novos inibidores de corrosão e desenvolvimento de revestimentos anticorrosivos “inteligentes”.
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Spínola, Ana Lúcia Gerardi. "Biofilmes aeróbios para remoção de nitrogênio em células de fluxo, submetidos a diferentes velocidades superficiais e taxas de carregamento." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-04042010-170727/.
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O pós-tratamento de efluentes de reatores anaeróbios, tais como o Upflow Anaerobic Sludge Blanket (UASB), na maior parte de suas aplicações, faz-se necessário, já que esse tipo de tratamento biológico promove remoção de DBO na faixa de 60 a 75% e tem baixa eficiência na remoção de nitrogênio e fósforo. A remoção de nitrogênio geralmente é feita de forma convencional pela nitrificação, seguida da desnitrificação. Tanto a nitrificação, como a desnitrificação podem ser efetuadas em reatores com crescimento suspenso ou crescimento aderido, contudo é conhecido que sistemas baseados em biofilmes exercem influência direta na taxa da degradação de substrato e facilitam a retenção de bactérias nitrificantes em reatores. O principal objetivo deste trabalho é o de acompanhar o desenvolvimento de biofilmes aeróbios em reatores do tipo célula de fluxo para a nitrificação de substrato sintético simulando efluente de UASB, submetidos a diferentes velocidades superficiais (1, 4 e 8 m/h) e taxas de carregamento (0,25; 0,5 e 1,0 g N/\'M POT.2\' biofilme.dia). O desenvolvimento dos biofilmes nitrificantes foi acompanhado mediante perfis de microssensores e estimativa do número mais provável de bactérias nitrificantes (NMP). Nas células de fluxo operadas com taxa de carregamento mais baixa (0,25 g N/\'M POT.2\' biofilme.dia), foram obtidas as melhores eficiências de remoção de NTK, a qual representa valor menor que as taxas de carregamento empregadas na literatura para reatores de crescimento aderido usados na nitrificação. Considerando as células de fluxo com taxa de carregamento mais baixa, a célula que apresentou remoção de NTK próxima a 100% foi a de menor velocidade superficial de (1 m/h). Porém, esses sistemas apresentaram baixa eficiência para a nitrificação completa, obtendo maior produção de nitrito do que de nitrato; poderiam ser usados então na remoção de nitrogênio pela via curta. Os microssensores de OD foram eficientes para as análises de perfis de OD no interior dos biofilmes nitrificantes, mostrando grandes variações, à medida que o biofilme se desenvolvia, nas concentrações de OD do líquido circundante e do fundo do biofilme.The post-treatment of anaerobic reactor effluents, such as the Upflow Anaerobic Sludge Blanket (UASB), in most applications, is necessary, since this kind of biological treatment promotes BOD removal ranging from 60 to 75% and it has low efficiency in nitrogen and phosphorous removal. Nitrogen removal is usually carried out in a conventional way through nitrification, followed by denitrification. Nitrification, as well as denitrification, can be achieved in suspended growth reactors, or in adhered growth reactors, however it is known that systems based on biofilms exert direct influence in substrate degradation rates and ease the retention of nitrifying bacteria in reactors. The main objective of this work is to follow the development of aerobic biofilms in flow cell type reactors for the nitrification of synthetic substrate simulating an UASB effluent, submitted to different superficial velocities (1, 4 and 8 m/h) and loading rates (0.25; 0.5 and 1.0 g N/\'M POT.2\' biofilm.day). The development of nitrifying biofilms was followed by microsensors profiles and an estimative of the most probable number of nitrifying bacteria (MPN). The best NTK removal efficiencies were obtained in flow cells operated with a lower loading rate (0.25 g N/\'M POT.2\' biofilm.day), which represents a lower level than the levels applied in literature for adhered growth reactors used for nitrification. Considering the flow cells with a lower loading rate, the cell that presented NTK removal close to 100% was the one with the lowest superficial velocity (1 m/h). However, these systems present low efficiency for complete nitrification, obtaining higher nitrite than nitrate production; they could then be used in nitrogen removal by short way. The DO microsensors were efficient for analyses of DO profiles inside nitrifying biofilms, showing great variations, while the biofilm developed itself, in the DO concentrations in the contiguous liquid and at the bottom of the biofilm.
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Tsopela, Aliki Theodora. "Development of a lab-on-chip platform integrating electrochemical microsensors for the detection of water contaminants based on algal physiology monitoring." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30017/document.
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Le suivi de la qualité de l'eau a été d'une grande importance depuis ces dernières décennies afin de trouver des solutions de contrôler la contamination de l'eau, induite en grande partie par les activités agricoles et industrielles. Bien que les méthodes conventionnelles, comme la chromatographie, sont des outils très précis et sensibles, un intérêt grandissant a été placé sur des techniques prometteuses qui peuvent être utilisées sur site, sont bas coût, et offrent la possibilité d'effectuer des analyses rapides. Le travail présenté ici est dédié au développement de composant Laboratoire sur Puce pour l'analyse de la toxicité de l'eau. Il consiste en un système portable pour la détection sur site et offre la possibilité d'une double détection complémentaire : optique et électrochimique. Comme la partie dédiée au capteur électrochimique a préalablement été validée, cette étude est focalisée sur l'implémentation d'un biocapteur électrochimique basé sur l'utilisation d'une algue, pour la détection de polluants dans l'eau. Le principe basique de détection consiste au suivi de changements de l'activité métabolique d'algues induits par la présence d'herbicides. La réponse de l'algue est différente pour chaque concentration d'herbicide dans un échantillon examiné. Deux herbicides sélectionnés affectent l'activité photosynthétique de l'algue et par conséquent, induisent des modifications dans la quantité des espèces électroactives produites par l'algue : O2, H2O2 et H3O+/OH-. Avant le développement du composant final type Laboratoire sur Puce, les principes de détection aussi bien que les matériaux d'électrode qui vont être intégrés, ont été validés en utilisant un type de composant plus simple, qui a été réalisé grâce aux technologies de fabrication silicium et qui a été caractérisé par des procédures plus simples. Une puce sur silicium contenant un microsystème électrochimique intégrant trois électrodes a été mis en place. Une fois validés, les matériaux de détection et les configurations choisis précédemment ont été utilisés pour la fabrication des composants Laboratoire sur Puce. Les composants Laboratoire sur Puce ont été ensuite utilisés pour des tests biologiques afin de détecter les herbicides d'intérêt. Une attention spéciale a été placée sur le suivi de O2 comme indicateur de la présence d'herbicide, étant donné que cet élément est le plus représentatif de modifications de l'activité métabolique. Un effet d'inhibition sur la photosynthèse, dépendant de la concentration de l'herbicide a été démontré. La détection de l'herbicide a été réalisée avec une grande sensibilité et sur une gamme couvrant la limite de concentration maximale acceptable imposé par le gouvernement canadienWater quality assessment has attracted wide attention during the last decades in order to find ways to control contamination of water bodies induced, in a big part, by agricultural and industrial activities. Although conventional techniques, such as chromatography are highly accurate and sensitive tools, increasing interest has been placed lately to powerful alternative techniques that can be used on field, are cost-effective and offer the possibility of conducting rapid analysis. The present work was therefore dedicated to the development of a lab-on-chip device for water toxicity analysis. It consists in a portable system for on-site detection and aims at offering the possibility of conducting double complementary detection: optical and electrochemical. Since the optical sensor is already validated, this study focused on the implementation of the algal-based, electrochemical biosensor for detection water contaminants. The basic detection principle consists in monitoring disturbances in metabolic activities of algae induced by the presence of the herbicides. Algal response is different for each herbicide concentration in the examined sample. The two selected herbicides affect algal photosynthetic activity and consequently induce modifications in the quantity of electroactive species, O2, H2O2 and H3O+/OH- ions related to pH, produced by algae. Prior to the development of the final lab-on-chip device, the detection principle as well as the electrode materials that were going to be integrated were validated using a simpler device that was implemented using a silicon-based fabrication technology and was characterized using simpler procedures. A silicon chip containing the integrated three-electrode electrochemical microsystem was fabricated. The performance of the microsystem was evaluated through electrochemical characterization and calibration was performed. Once validated, the aforementioned materials and configurations were used for the fabrication of the lab-on-chip devices. The lab-on-chip devices were further used in bioassays to detect the herbicides of interest. Special emphasis was placed on O2 monitoring as indicator of the presence of herbicide, as it is the element the most representative of variations in metabolic activities. A concentration-dependent inhibition effect of the herbicide on photosynthesis was demonstrated. Herbicide detection was achieved with a greater sensitivity and a range covering the limit of maximum acceptable concentration imposed by Canadian government
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Sbartai, Amel. "Conception et développement de nouveaux microcapteurs chimiques pour la détection des métaux dans les eaux." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10226.
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Broadbent, Heather Allison. "Development of a CTD system for environmental measurements using novel PCB MEMS fabrication techniques." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001328.
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Bouhadda, Ismaïl. "Élaboration et réalisation de transistors à effet de champ à canal microfluidique intégré dédiés à la détection en milieu liquide." Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S131/document.
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Ce travail de recherche porte sur la réalisation de dispositifs électroniques spécifiques et originaux (Transistors à effet de champ à microcanaux) dédiés à la détection des espèces chimiques et biochimiques en milieu liquide. Ce dispositif s'appuie sur la technologie des transistors à grille suspendue (SGFET) déjà réalisés à l'IETR, en y apportant une amélioration majeure qui consiste en l'intégration au sein de la structure d'un canal microfluidique. Cette structure, nommée transistor à canal microfluidique intégré, doit permettre de conserver la forte sensibilité de détection du SGFET mais aussi de garantir le passage du liquide testé sous la grille. Cette architecture permet aussi d'augmenter sa robustesse et sa fiabilité tout en ne nécessitant que de très petits volumes de solutions. Des microcanaux avec un bon maintien mécanique ont été réalisés par micro-usinage de surface en utilisant différents matériaux comme couche sacrificielle. Ces canaux ont été intégré dans un FET et leurs accès microfluidiques ont été assurés en réalisant des ouvertures (inlet/outlet) par la face avant. Les tests électriques ont montré un bon fonctionnement de ces capteurs avec une grande sensibilité de mesure du pH mais le passage du liquide est alors majoritairement dû aux phénomènes de capillarité. Une amélioration sur l'architecture de la structure a été faite, en réalisant des ouvertures par la face arrière. Un bon fonctionnement avec une grande sensibilité de mesure de pH ont été présentés. Finalement, une structure hybride contenant une ouverture sur la face avant et une autre sur la face arrière, a été élaborée et les tests d'injection de la solution ont été un succèsThis work presents the achievement of specific and original electronic devices (Field effect transistor with microfluidic channel), dedicated to the detection of chemical and biochemical species in liquid. This device relies on the technologies of suspended gate transistor, developed in IETR, with a major improvement in the structure by adjunction of a microfluidic channel integrated in the structure. This structure named transistor with integrated microfluidic channel must enable to guarantee the flow of liquid under the gate, while keeping the high sensitivity of the SGFET. This architecture also allows increasing its robustness and reliability while requiring only a very small amount of chemicals solutions. Microchannels with good mechanical properties were fabricated by surface micromachining using different materials as a sacrificial layer. These channels have been integrated into a FET and microfluidic accesses (inlet / outlet) were provided by making openings via the front face. Electrical tests showed good functioning of these sensors with high sensitivity of pH measurement. However in this case, liquid flow is mainly achieved by capillarity. An improvement on the architecture of the structure was made with opening on the rear face. A good behaviour with high sensitivity of pH measurement was presented. Finally, a hybrid structure containing one opening access in the front face and one on the rear face was elaborated and the injection of the solution was successful
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Wither, Sandra, and Sofia Myllenberg. "Treatment effects and adherence of van Beek activator during the first year comparing two wear-time prescriptions assessed by microsensors: a randomized clinical trial." Thesis, Malmö universitet, Odontologiska fakulteten (OD), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-19676.
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Syfte: Syftet med denna studie var att utvärdera följsamheten och förändringen i det horisontella överbettet hos patienter som behandlas med en van Beek-aktivator, under det första behandlingsåret, genom att jämföra två rekommenderade användningstider; 8 timmar och 12 timmar. Material och metod: Totalt 20 patienter, 9 flickor och 11 pojkar, med en medelålder på 10,0 år, ingick i undersökningsmaterialet. Samtliga patienter diagnosticerades med en Angle Class II-bettavvikelse, och behandlades med en van Beek-aktivator. Patienterna delades slumpmässigt in i två grupper med olika rekommenderade användningstider; 8 timmar och 12 timmar. Följsamhetsnivån mättes med hjälp av TheraMon®, en mikrosensor, inbäddad i aktivatorn. Följsamheten, det horisontella och det vertikala överbettet registrerades efter 3, 6, 9 och 12 månader. Resultat: I båda grupperna observerades en minskning av både det horisontella och vertikala överbettet. Det fanns ingen signifikant skillnad mellan 8- och 12-timmarsgruppen för reduktion av överbetten. Följsamheten var däremot bättre i 8-timmarsgruppen under hela 12-månadersperioden.Slutsatser: En rekommenderad användningstid på 8 timmar per dag visade en högre nivå av följsamhet än 12 timmar, i den aktuella studien. Ingen klinisk signifikant skillnad i behandlingseffekt upptäcktes mellan 8-timmars och 12-timmars rekommenderad användningstid. Följsamhetsnivån är högre under de första 6 månaderna av en behandling och minskar sedan mellan 6-12 månader.Aim: The aim of this study was to evaluate the adherence and the changes in overjet among patients treated with the van Beek activator during the first year, comparing two wear-time prescriptions; 8 hours and 12 hours. Materials and methods: The study sample consisted of 20 patients, 9 girls and 11 boys, with a mean age of 10.0 years. All patients were diagnosed with a class II malocclusion and were treated with the van Beek activator. The patients were randomized into two groups with different wear-time prescriptions; 8 hours and 12 hours. The level of adherence was measured with the aid of TheraMon®, a microsensor embedded in the activator. The adherence, overjet and overbite were recorded after 3, 6, 9 and 12 months of treatment. Results: In both groups, a reduction of both overjet and overbite was observed. There was no significant difference between the 8- and 12-hour group for overjet and overbite reduction. The adherence, on the other hand, was better in the 8-hour group during the whole 12-month period. Conclusions: A wear-time prescription of 8 hours per day displayed a higher level of adherence than 12 hours in the present trial. No clinically significant differences in treatment effects were detected between an 8-hour and 12-hour wear-time prescription. The level of adherence is higher during the first 6 months of a treatment and is then reduced between 6-12 months.
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Gonzalez, Beatriz Cruz. "Construção de microssensores e sua aplicação para estudo de biofilme empregado no tratamento de água residuária." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-10072009-115724/.
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A presente pesquisa teve como objetivo a construção de microssensores amperométricos e potenciométricos para mensuração de oxigênio dissolvido (OD), gás sulfídrico (\'H IND.2\'S\'), íons amônio (\'NH IND.4\'POT.+\'), nitrato (\'NO IND.3\'POT.-\'), nitrito (\'NO IND.2\'POT.-\') e hidrogeniônicos (\'H POT.+\') em biofilmes aplicados a nitrificação de água residuária. Os biofilmes analisados por meio do uso dos microssensores construídos foram desenvolvidos sobre superfícies suportes de reatores de bancada do tipo célula de fluxo, as quais foram operadas sob diferentes condições operacionais em cinco experimentos distintos. Substrato sintético com concentrações de nitrogênio total Kjeldahl (NTK) de 40 ± 10 mg/L e demanda química de oxigênio (DQO) de 95 ± 5 mg/L foi utilizado para alimentação das células de fluxo no decorrer de todos os experimentos. Lodo aeróbio proveniente de reator de lodos ativados da Estação de Tratamento de Esgoto das Flores localizada em Rio Claro-SP foi usado como inóculo das células de fluxo. Análises físico-químicas de pH, alcalinidade, DQO, NTK, \'NO IND.3\'POT.-\', \'NO IND.2\'POT.-\' do afluente e do efluente das células de fluxo operadas foram realizadas para o monitoramento das condições de operação das mesmas. Concomitantemente às últimas, a obtenção de perfis de concentrações de oxigênio dissolvido, pH, íons nitrato e amônio foi realizada nos biofilmes formados sobre as superfícies inertes nas células. Os microssensores de OD se mostraram eficientes na mensuração de oxigênio dissolvido no interior de filmes biológicos que continham zonas aeróbias, anóxicas e anaeróbias. Os microeletrodos de pH e de íons amônio permitiram a verificação das variações de pH e das concentrações de \'NH IND.4\'POT.+\' (sentido meio líquido-biofilme) que se deram nas células de fluxo operadas. Os microssensores de íons nitrato construídos não apresentaram seletividade aos seus analitos (\'NO IND.3\'POT.-\') e foi constatado que os mesmos detectavam concentrações de íons nitrato e nitrito no meio, portanto esses passaram a ser denominados de microssensores para detecção de íons \'NO IND.X\'POT.-\'. A construção dos microeletrodos destinados a mensuração de íons nitrito não foi passível de realização visto que a membrana íon seletiva que seria aplicada nos mesmos não se encontrou disponível no mercado. Os microeletrodos de \'H IND.2\'S\' foram calibrados e, mediante as suas curvas de calibração verificou-se que os mesmos foram eficientes na medição da concentração do gás dissolvido em água, entretanto esses microssensores não foram empregados em biofilmes.The goal of the current research was the construction of amperometric and potentiometric microsensors to measure dissolved oxygen (DO), hydrogen sulfide (\'H IND.2\'S\'), nitrite, nitrate, ammonium and pH in biofilms applied at wastewater treatment. The biofilms that were analyzed with the constructed microsensors were grown at the surface of flat-plate reactors, which were operated in five distinct experiments under different operational conditions. The growth media that had total Kjeldahl nitrogen (TNK) of 40 ± 10 mg/L and carbon oxygen demand (COD) of 90 ± 5 mg/L was used as feed of the flatplate reactors during the experiments. The reactors were inoculated with sludge originating from activated sludge reactor located in Rio Claro (SP). Alkalinity, pH, COD, \'NO IND.3\'POT.-\', \'NO IND.2\'POT.-\' analyses of the affluent and effluent of the reactors were carried out for the accompaniment of the operational conditions of the flat-plate reactors. Concomitantly to the last ones, microprofiles of DO, pH, nitrate and ammonium were obtained in the biofilms. The DO microsensors constructed showed a good performance when they were applied to measure oxygen concentrations in the microenvironments in biofilms. Ammonium and pH microelectrodes allowed the verification of the variations of pH and ammonium concentrations in the direction from the bulk liquid to the biofilm that occurred at the flatplate reactors. The nitrate microsensor has not presented selectivity for its primary ions (\'NO IND.3\'POT.-\') and it was evidenced that the same one detected the concentration of nitrate and nitrite (\'NO IND.X\'POT.-\'). The nitrite microsensor could not be constructed since the membrane that would be used was not available in the market. The \'H IND.2\'S\' microelectrodes had shown efficiency in measuring aqueous solutions with different concentrations of dissolved \'H IND.2\'S\'; however these devices were not applied in biofilms.
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Ono, Alexandre Fernandes. "Estratégias de operação de reatores aeróbio/anóxico operados em batelada sequencial para remoção de nitrogênio de água residuária industrial." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-18092007-100009/.
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A pesquisa propôs avaliar o desempenho e o comportamento de reatores seqüenciais em batelada com biomassa suspensa e imobilizada, em escala de bancada, na remoção de compostos de nitrogênio. Tais sistemas foram testados como tratamento complementar de reatores sulfetogênico e metanogênico utilizados no tratamento de água residuária industrial com alta concentração de sulfato e amônia. Visou o desenvolvimento de uma estratégia de operação que viabilizasse o uso dos próprios constituintes da água residuária para a maximização da eficiência do tratamento. O estudo foi dividido em 3 etapas principais. Na etapa 1 (181 dias de operação), o reator com biomassa suspensa foi mantido com 4 fases alternadas aeróbio/anóxico e ciclo de 24 horas, e verificou-se a presença da desnitrificação endógena (eficiência de remoção de nitrogênio de 65 \'+ OU -\' 27%). Para a etapa 2 (127 dias de operação), o reator de biomassa suspensa foi submetido ao tempo de ciclo de 12 horas, com uma fase aeróbia (6 horas) e com posterior fase anóxica (6 horas). Nessa etapa adicionou-se efluentes dos reatores metanogênico e sulfetogênico, ricos em ácidos voláteis (ácido acético), com intuito de acelerar o processo desnitrificante. Os resultados obtidos foram baixos em termos de remoção de nitrogênio (42 \'+ OU -\' 21%). Para a etapa 3 (134 dias de operação), foram ensaiados vários meios suportes, através de técnica de microsensores de oxigênio dissolvido, a fim de verificar a formação de biofilme específico (nitrificante/desnitrificante) e optou-se pelo uso do carvão mineral no reator com biomassa imobilizada. Nesta última etapa, foi mantida a estratégia operacional adotada na etapa 2 (ciclo 12 horas), bem como a adição de parcela do afluente na fase anóxica. A remoção de nitrogênio, com períodos aeróbio e anóxico e ciclo de 12 horas, mostrou-se viável no reator com biomassa imobilizada (eficiência de remoção de nitrogênio de 72 \'+ OU -\' 13%). Ao final dos ensaios experimentais, realizaram-se modelagens cinéticas que permitiram a compreensão dos processos convencionais e não convencionais ocorridos nas várias etapas para remoção de nitrogênio, tais como desnitrificação em fase aeróbia e o processo ANAMMOX.The purpose of this research was to evaluate the performance and the behavior of sequential batch reactors with suspended and immobilized biomass, in benches scale, for the nitrogen composite removal. Such systems had been tested as sulphetogenic and methanogenic reactors complementary treatment, used in an industrial waste water treatment with high sulphate and ammonia concentrations. The research aimed for the development of an operation strategy that could make possible the use of the proper waste water constituent for the improvement of the treatment efficiency. The study was divided into 3 main stages. In stage 1 (181 days of operation), the reactor with suspended biomass was kept with 4 alternating phases aerobic/anoxic and a 24-hour cycle was used, and the endogenous denitrification was verified (nitrogen removal efficiency of 65 \'+ OU -\' 27%). For stage 2 (127 days of operation), the suspended biomass reactor was submitted to a cycle of 12 hours, with an aerobic phase (6 hours) and posterior anoxic phase (6 hours). In this stage effluent of the methanogenic and sulphetogenic reactors, rich in volatile acid (acetic acid), was added to accelerate the denitrify process. The achieved results had been low in terms of nitrogen removal(42 \'+ OU -\' 21%). For stage 3 (134 days of operation), some supports media was tested through dissolved oxygen microsensors technique, in order to check the specific biofilm formation (nitrificant/denitrificant) and the mineral coal was opted to be used in the immobilized biomass reactor. In this last stage it was adopted an operational strategy similar in stage 2 (12 hours cycle), as well as the addition of part of the affluent in the anoxic phase. The nitrogen removal, with aerobic and anoxic periods and 12 hours cycle, revealed feasible in the reactor with immobilized biomass (nitrogen removal efficiency of 72 \'+ OU -\' 13%). In the end of the experimental tests, kinetic modelings were done and had allowed the understanding of conventional and not conventional processes occurred in the stages for nitrogen removal, such as desnitrification in aerobic phase and ANAMMOX process.
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Gonzalez, Beatriz Cruz. "Geração de energia elétrica a partir de eletrodos imersos em sistema do tipo célula a biocombustível composta por reator anaeróbio e reator aeróbio operados em série alimentado com esgoto sanitário." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-02102013-153024/.
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A presente pesquisa teve como objetivo primordial a verificação da viabilidade técnica de empregar sistema do tipo célula a biocombustível para tratamento de esgoto sanitário com geração de energia elétrica. A célula a biocombustível, em escala de bancada, adotada foi constituída por reator anaeróbio seguido de reator aeróbio, visando à remoção de matéria orgânica carbonácea e à nitrificação Cada reator apresentou área de 0,6275 m2 e volume útil de 24,0 L. A célula a biocombustível foi alimentada com esgoto sanitário com tempo de detenção hidráulica médio de 8 horas (nos dois módulos). Em cada reator instalou-se um eletrodo imerso, de modo que os dois eletrodos foram unidos por fio condutor externo. Foi verificada a potencialidade do sistema em gerar energia elétrica a partir das reações químicas e bioquímicas que se deram junto aos eletrodos e nos biofilmes aderidos aos mesmos. A operação da célula a biocombustível foi dividida em cinco Fases, denominadas de I, II, III, IV e V, sendo que o fator principal que distinguiu essas Fases consistiu no material eletródico. Manta de fibra de carbono e placa de grafite foram adotadas como ânodo da célula (reator anaeróbio). Chapa de aço inoxidável (AISI 316) e malhas de aço inoxidável (AISI 316) foram usadas como cátodo do sistema (reator aeróbio). Para monitoramento do sistema foram realizadas análises físico-químicas do afluente, do efluente do reator anaeróbio e do efluente do reator aeróbio e para o acompanhamento da produção de energia elétrica utilizou-se potenciômetro acoplado a software específico. Microssensores de OD, pH e potencial redox foram empregados como ferramentas auxiliares para o acompanhamento do crescimento e desenvolvimento dos biofilmes aderidos aos eletrodos da célula a biocombustível. Como resultados concernentes ao tratamento do esgoto sanitário foram obtidas eficiências médias de remoção de DQO de (74,4±17,1)% e de nitrificação de (65,8±21,0)%, no decorrer das cinco Fases. O valor da maior densidade de potência média verificada foi de 107,0 mW.m-2, ocorrida quando o ânodo da célula a biocombustível consistiu em placa de grafite e o cátodo em malha de aço inoxidável (AISI 316) do tipo 20, na Fase V. A dosagem de cloreto férrico e a colocação de meio suporte de material plástico no sistema para limpeza automática do cátodo, realizadas na Fase em que se observou a maior densidade de potência média foram consideradas como positivas no aprimoramento da obtenção de energia elétrica. Por meio da combinação dos resultados relacionados à geração de energia elétrica e da aplicação dos microssensores constatou-se que o desenvolvimento de biofilmes espessos sobre os eletrodos da célula a biocombustível consiste em fator negativo da sua eficiência energética. Concluiu-se que a célula a biocombustível é tecnicamente viável para o tratamento de esgoto com geração de energia elétrica, contudo diante do conhecimento que se tem sobre essa tecnologia, a sua adoção em escala real ainda é economicamente inviável.This research aimed mainly to verify the technical feasibility of employing a system called biofuel cell for treating wastewater and generating electricity at the same time. The biofuel cell, in lab scale, adopted consisted of an anaerobic followed by an aerobic reactor, aiming the removal of carbonaceous organic matter and nitrification. Each reactor had an area of 0.6275 m2 and useful volume of 24.0 L. The biofuel cell was fed with sanitary wastewater with hydraulic retention time of eight hours (in both modules). In each reactor was installed an electrode immersed, and the two electrodes were connected by a wire conductor. The capability of the system to generate electricity from the chemical and biochemical reactions that occurred along the electrodes and in biofilms attached to them was verified. The biofuel cell operation was divided into five Phases, named I, II, III, IV and V, and the main factor that distinguished these Phases consisted of the electrode material. Carbon fiber felt and graphite plate were adopted as the anode of the cell (on anaerobic reactor). Stainless steel plates (AISI 316) and stainless steel meshes (AISI 316) were used as the cathode (on aerobic reactor). Monitoring system were carried out with physicochemical analyzes of the influent, anaerobic effluent and aerobic effluent and for monitoring the electricity production it was used a potentiometer coupled with a specific software. DO, pH and redox potential microsensors were employed as auxiliary tools for monitoring the growth and development of biofilms attached to the electrodes of the biofuel cell. The results concerning the treatment of wastewater were COD efficiencies removal of (74.4 ± 17.1)% and nitrification of (65.8 ± 21.0)%, throughout the five Phases. The amount of the higher power density observed was 107.0 mW.m-2 occurred when the anode of the biofuel cell consisted of graphite plate and cathode of stainless steel mesh (AISI 316) type 20, on Phase V . The dosage of ferric chloride and the placement of plastic midia on the aerobic module of the system for automatic cleaning of the cathode, conducted on Phase V, were considered positive for the improvement in obtaining electricity. By combining the results related to power generation and application of microsensors it was concluded that the development of thick biofilms on the electrodes of a biofuel cell is a negative factor in their energy efficiency. It was also concluded that the biofuel cell is technically feasible to treat sanitary wastewater and to generate electricity, but actually, based on the knowledge we have about this technology, its adoption in large scale is still not economically feasible.
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Didier, Pierre. "Développement d’un système à ondes acoustiques pour le suivi rhéologique de la polymérisation de protéines. Application à la maladie d’Alzheimer." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLN016/document.
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La mise au point de nouveaux systèmes biocompatibles de suivi des phénomènes de polymérisation de protéines est un enjeu majeur pour la compréhension des mécanismes moléculaires en vue d’une détection et d’un traitement précoce des pathologies dites conformationnelles telles que la maladie d’Alzheimer ou les maladies à prions. Dans ces pathologies, des protéines ou des fragments de celles-ci perdent leur structure, puis s’assemblent en fibres ordonnées au sein d’agrégats. Les mécanismes moléculaires du changement de conformation d'une protéine et sa polymérisation en fibres amyloïdes sont encore largement inconnus. La compréhension de ces mécanismes et le diagnostic sont étroitement liés à la disponibilité d’un concept analytique performant pour le suivi ex vivo de ces phénomènes.Pour répondre à cette problématique, un microsystème a été mis au point pour la détection et le suivi de polymérisation de la protéine tau et du peptide Aß, principaux biomarqueurs de la maladie d’Alzheimer. Le microcapteur est basé sur la propagation d’ondes acoustiques hautes fréquences qui permettent d’extraire les propriétés rhéologiques du milieu cible. En mesurant l’impédance complexe du biocapteur, un traitement du signal dédié permet l’extraction des paramètres viscoélastiques (module élastique et module visqueux). L’étude et le développement de ce microsystème impliquent un savoir-faire pluridisciplinaire en instrumentation : élaboration et conception et modélisation de biocapteurs, conditionnement des signaux et résolution des problèmes inverses associés.Tout d’abord, le capteur a été optimisé pour améliorer sa sensibilité et permettre le suivi de polymérisation. Un travail sur la faisabilité du système a montré la possibilité de discriminer des solutions de protéines de différentes concentrations. La finalité du système de détection étant la détection simultanée des différents biomarqueurs à l’origine de la maladie d’Alzheimer, un capteur multi-électrodes permettant la détection de ces différents analytes a été développéThe development of new biocompatible systems for monitoring protein polymerization processes is a key issue for understanding the molecular mechanisms of detection and for early treatment of so-called conformational diseases such as Alzheimer's disease or prion diseases. In these pathologies, proteins or fragments lose their structure and then assemble themselves into ordered fibers within aggregates. The molecular mechanisms of the conformational changes of a protein and its polymerization into amyloid fibers are still largely unknown. Understanding these mechanisms and diagnosis are closely related to the availability of an efficient analytical concept for the ex vivo monitoring of these phenomena.To address this problem, a microsystem has been developed for the detection and monitoring of polymerization of tau and Aß peptide, the main biomarkers of Alzheimer's disease. The microsensor is based on the propagation of acoustic high frequency waves that extract the rheological properties of the target environment. By measuring complex impedance of the biosensor, a dedicated signal processing allows the extraction of viscoelastic parameters (viscosity and elasticity). The study and development of this microsystem involve multidisciplinary expertise in instrumentation: development and design and modeling of biosensors, signal conditioning and solving associated inverse problems.First, the sensor has been optimized to improve its sensitivity and allow tracking of polymerization. Work on the feasibility of the system showed the ability to discriminate protein solutions of different concentrations. Since the purpose of the detection system is the simultaneous detection of different biomarkers responsible for Alzheimer's disease, a multi-electrode sensor for the detection of these different analytes has been developed. The optimization of the sensor, the microfabrication processes and chemical surface treatments are also developed in this work
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Oldenziel, Weite Hendrik. "Application of a glutamate microsensor to brain tissue construction, evaluation and application of a glutamate microsensor /." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2006. http://irs.ub.rug.nl/ppn/297660691.
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Byun, Albert Joonsoo. "Chemical Application of Silicon-Based Resonant Microsensor." Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16296.
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The detection of volatile organic compounds in liquid is of interest for applications in public health, workplace safety and environmental monitoring. Traditionally, water samples were taken and analyzed in the laboratory using classical laboratory instrumentation. Current trends target real-time measurements using e.g. chemical microsensors built with microfabrication technologies. Among these, mass-sensitive chemical sensors, based on cantilever beams or surface acoustic devices, have shown substantial promise in gas-phase applications. In a liquid environment, the resonant microstructures typically suffer from high damping, which negatively affects the sensor resolution. In this work, a novel disk-type resonator developed at Georgia Tech was investigated as chemical microsensor for liquid-phase applications. The micromachined resonator vibrates in a rotational in-plane mode shape, reducing damping in a liquid environment. As part of the present research, a measurement setup with a custom-made flow cell for liquid-phase chemical measurements and a coating system to locally deposit polymer sensitive films onto the resonators were developed. To improve the film adhesion on the resonator surface in liquid, physical and chemical binding techniques were developed and tested on wafer samples. Polymers such as poly(4-vinylpyrrolidone), poly(ethylene-co-propylene) and poly(styrene-co-butadiene) were deposited using the custom-designed coating system onto the disk-type resonators. Liquid-phase measurements using tetrachloroethylene as the chemical analyte were performed. The experimental results are discussed, sources of problems are identified and recommendations for future research are made.
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Tang, David 1977. "Rotor speed microsensor for the MIT Microengine." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8554.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.Includes bibliographical references (p. 123-127).
This thesis presents the design, fabrication, and testing of a temperature-based sensor for measuring rotor speeds in the MIT MEMS micro gas turbine engine. The MIT microengine is a gas combustion engine made by micromachining and bonding six silicon wafers. The sensor is a boron-doped polysilicon resistor with a serpentine geometry that is thermally isolated from the substrate. The sensor is designed to measure the rotor rpm by responding to the heat flux fluctuations on the wall above the compressor blade tips. This thesis investigates the feasibility of this approach. The sensor development process involved fabricating stand-alone devices (which have only the sensor and contact pads and not integrated with other microengine components) and testing them using a furnace and a shock tube. The furnace test characterized the stability with thermal cycling and annealing. The shock tube test characterized the dynamic response. The temperature coefficient of resistivity (TCR), 0.009/K , and the room temperature resistance, ~9 kohms, measured in the furnace characterization experiments were approximately 50% less and 300% more than the predicted values, respectively. These discrepancies may be due to the fabrication process conditions, such as ion implant dose, polysilicon deposition temperature, and anneal conditions. The time constant, 9-10 [mu] sec, measured from the shock tube experiments matched predicted values to within 20-40% depending on the model used to estimate the convective heat flux into the sensor. However, the sensor's amplitude response was less than predicted values by approximately 10 - 75% perhaps due to the simplicity of the models used to estimate the convective heat flux. The experimental results suggest that this concept is viable as a microengine rpm sensor. Some design changes are suggested which should improve sensor performance.
by David Tang.
S.M.
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Kim, Ho-Young 1971. "Microsensor development for the study of droplet spreading." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/40244.
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Wang, Ron-wen, and 王榮文. "Microsensors By CMOS Technology." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/40890740454120796200.
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碩士國立臺灣大學
電機工程學系
85
In this thesis, two integrated microsensors are designed and implemented. Thesis two sensors are CMOS infrared (IR) thermopile sensor and CMOS 2D vertical Hall sensor, both are integrated with on-chip readout circuits.The IR sensor is characterized by its ease of operation, requirement of no bias, wide spectral response and being fabricated by standard IC process.Though itis always not the optimal process for sensor, considerable sensor proformancestill can be obtained by using this industrial IC process and minimal post-process micromachining steps. On the other hand, the 2D vertical Hall sensor is outstanding for its ability to measure two-dimensional magnetic fieldsimultaneously, its ability to adjust sensitivity by maskless post-processmicromachining and active carrier confinement arrangement. The maximal absolutesensitivity value of the 2D Hall sensor is approximately 34 mV/T, which is higher than that reported by other researchers in 1996. Through empirical study of teh design, fabrication and measurement of these sensors, some experiences are gained. Therefore, in this thesis, some observations are also offered to hopefully help the interested researchers successfully implement their desired sensors.
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Silva, Cátia Samanta Ribeiro. "Polymeric microsensors using microtechnologies." Doctoral thesis, 2016. http://hdl.handle.net/1822/42537.
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Tese de Doutoramento - Programa Doutoral em Ciência e Engenharia de Polímeros e CompósitosThe work present here aims to combine advanced and specialized polymeric materials and microtechnologies with silicon based microtechnologies to develop an innovative concept for a thermal convective accelerometer with improved performance while also overcoming existing limitations. Thermal convective accelerometers have a transduction mechanism based in heat transfer by convection over a working fluid. The thermal accelerometer is a relatively recent technology and although research focused in improving many properties, parameters and processing techniques, thermal accelerometers still present some drawbacks regarding the power consumption caused by thermal losses through the fabrication material (typically silicon based) and limited third sensing dimension (planar silicon based microtechnologies). New developments towards the optimization of the existing thermal accelerometers may limit the power consumption and allow an easy integration of a Z-axis sensitive dimension. The methodology from the development of a concept to the actual fabrication and characterization requires a series of steps that need to be followed in a sequential way, namely: design and simulation analysis of the device concept (considering the electrical, thermal and fluidic domains), based on CAD and FEM techniques (using a FSI approach); development (project and simulation analysis) of tools based on CAD and CFD techniques; definition and optimization of a fabrication methodology (combination of polymeric and silicon based microtechnologies); and a full characterization of the fabricated device (sensitivity, bandwidth, dynamic range, and power). A three-axes thermal convective accelerometer was fully manufactured containing two main components: a polymeric based external structure fabricated my means of microinjection moulding technology that generates an isolated chamber from outside influences while supporting the second component, a polymeric flexible membrane that sustains and protects the metallic heating and sensing elements fabricated by microtechnologies. The proposed solution for the fabrication of a three-dimensional polymer based thermal accelerometer based in convection is innovative and the main contribution will be the use of polymeric materials not commonly used in microsystem technology and in electronic and instrumentation systems that are suitable to solve the main problems related to the current stateof- art of thermal accelerometers. Fabricated accelerometers were fully tested and characterized presenting a XY-axes sensitivity around 8 mV/g, a Z-axis sensitivity of 2.2 mV/g, and a 4 Hz bandwidth for a power of 45 mW. Thermal tests performed show that the heater can sustain up to 280 ºC without overheating the remaining structures and damaging the device. The developed technology has huge potential for functional highly complex threedimensional geometries at the micro-scale.
O trabalho aqui apresentado tem como intuito combinar materiais e microtecnologias poliméricas avançadas e especializadas com microtecnologias à base de silício para o desenvolvimento de um conceito inovador para um acelerómetro térmico convectivo com um desempenho melhorado superando também as limitações existentes. Os acelerómetros térmicos convectivos tem um mecanismo de transdução baseado na transferência de calor por convecção através de um fluído funcional. O acelerómetro térmico é uma tecnologia relativamente recente e embora os estudos científicos se tenham focado na otimização de diversas propriedades, parâmetros e técnicas de processamento, os acelerómetros térmicos ainda apresentam algumas desvantagens relativas ao consumo energético provocado pelas perdas térmicas através do material de fabrico (normalmente à base de silício) e também uma terceira dimensão sensível limitada (microtecnologias planares à base de silício). Novos desenvolvimentos no sentido da otimização dos existentes acelerómetros térmicos podem limitar o consumo energético e permitir uma integração mais fácil da dimensão sensível do eixo dos ZZ. A metodologia desde o desenvolvimento do conceito até à atual fabricação e caracterização requere uma série de etapas que necessitam de ser seguidas de uma forma sequencial, nomeadamente: projeto e análise por simulação do conceito do dispositivo (considerando os domínios elétrico, térmico, e fluídico), com base em técnicas CAD e FEM (através de uma abordagem FSI); desenvolvimento (projeto e análise por simulação) de ferramentas com base em técnicas CAD e CFD; definição e otimização de uma metodologia de fabrico (combinação de microtecnologias de polímeros com microtecnologias à base de silício); e uma caracterização completa do dispositivo fabricado (sensibilidade, largura de banda; gama dinâmica, e energia). Um acelerómetro térmico convectivo com três eixos foi inteiramente fabricado contendo dois componentes principais: uma estrutura externa à base de polímeros fabricada através da tecnologia de moldação por microinjeção gerando uma câmara isolada de influências externas que suporta o segundo componente, uma membrana polimérica flexível que sustem e protege os elementos metálicos de aquecimento e sensoriais fabricados por microtecnologias. A solução proposta para o fabrico de um acelerómetro térmico polimérico tri-dimensional baseado em convecção é inovativa e a principal contribuição consiste no uso de materiais poliméricos não comumente utilizados na tecnologia de microsistemas e na electrónica e instrumentação de sistemas que são adequados para solucionar os principais problemas relacionados com o atual estado da arte dos acelerómetros térmicos. Os acelerómetros fabricados foram testados e caracterizados apresentando uma sensibilidade de cerca de 8 mV/g para os eixos XY e 2.2 mV/g para o eixo ZZ, e uma largura de banda de 4 Hz para uma energia de 45 mW. Foram realizados testes térmicos demonstrando que a resistência de aquecimento consegue suportar até 280 ºC sem sobreaquecimento das restantes estruturas e sem danificar o dispositivo. A tecnologia desenvolvida apresenta um grande potencial para geometias tri-dimensionais altamente complexas e funcionais à escala micro.
Portuguese Fundação para a Ciência e a Tecnologia (FCT), for the financial support under the PhD scholarship SFRH/BD/78372/2011). The work was supported by FEDER through COMPETE and national funds through FCT in the framework of the project PTDC/EEA-ELC/099834/2008. The author would like to acknowledge the doctoral program in Science and Engineering of Polymers and Composites for supporting this work.
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Chen, Ya-Hui, and 陳雅惠. "The Study of Mutiple Pressure Microsensors." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/47147874835077983081.
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碩士逢甲大學
自動控制工程學系
89
Based on silicon micro-fabrication technology, the piezoresistive bridge-type pressure microsensors are designed. A chip includes sixteen microsensors in the designed membrane to form four Wheatstone-bridges. The pressure sensing theory of microsensors do follow piezoresistive effect, i.e. the resistivity variation is proportional to diaphragm deflection that is induced from applied pressure. The proposed microsensor can obtain more information from a micro-point measurement simultaneously. The physical dimension of the piezoresist-type sensors is about 6.5mm×6mm×0.7mm. The sensors integrated sensing elements and pre-processing circuits are fabricated by using MEMS techniques. The developed pressure sensors are following the procedures of simulation, design, fabrication, and test. The optimal design of microstructure and related sensing response analysis were simulated by the finite element method. The simulated sensor sensitivity is about 77.17μV/V/mmHg. Both responses of sensitivity and stress are related to the diagragm thickness and the length of the sensing resistors. The maximum pressure measurement range of the microsensors is designed up to 300mmHg, and the optimum stress response is achieved about 0.417MPa/mmHg. The three-dimensional microstructures are realized by anisotropic wet-etching technology. The piezoresistors are formed by offering N-type boron impurity diffusion whose sensitivity can be improved by controling process parameters. The resistance deviation of the silicon-based piezoresistive pressure microsensors with contact mesa is less than 3%. The sensor nonlinearity is less than 2% at temperature range from 25℃ to 55℃. The compound microsnesors developed in the research can supply more medical treatment information for auxiliary clinical research. They can also apply in various-type of force pressure measurement systems to improve equipment efficiency.