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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Sensors and Their Applications for Connected Health and Environment

January 2018 (has links)
abstract: Connected health is an emerging field of science and medicine that enables the collection and integration of personal biometrics and environment, contributing to more precise and accurate assessment of the person’s state. It has been proven to help to establish wellbeing as well as prevent, diagnose, and determine the prognosis of chronic diseases. The development of sensing devices for connected health is challenging because devices used in the field of medicine need to meet not only selectivity and sensitivity of detection, but also robustness and performance under hash usage conditions, typically by non-experts in analysis. In this work, the properties and fabrication process of sensors built for sensing devices capable of detection of a biomarker as well as pollutant levels in the environment are discussed. These sensing devices have been developed and perfected with the aim of overcoming the aforementioned challenges and contributing to the evolving connected health field. In the first part of this work, a wireless, solid-state, portable, and continuous ammonia (NH3) gas sensing device is introduced. This device determines the concentration of NH3 contained in a biological sample within five seconds and can wirelessly transmit data to other Bluetooth enabled devices. In this second part of the work, the use of a thermal-based flow meter to assess exhalation rate is evaluated. For this purpose, a mobile device named here mobile indirect calorimeter (MIC) was designed and used to measure resting metabolic rate (RMR) from subjects, which relies on the measure of O2 consumption rate (VO2) and CO2 generation rate (VCO2), and compared to a practical reference method in hospital. In the third part of the work, the sensing selectivity, stability and sensitivity of an aged molecularly imprinted polymer (MIP) selective to the adsorption of hydrocarbons were studied. The optimized material was integrated in tuning fork sensors to detect environmental hydrocarbons, and demonstrated the needed stability for field testing. Finally, the hydrocarbon sensing device was used in conjunction with a MIC to explore potential connections between hydrocarbon exposure level and resting metabolic rate of individuals. Both the hydrocarbon sensing device and the metabolic rate device were under field testing. The correlation between the hydrocarbons and the resting metabolic rate were investigated. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2018
2

Setup for Micro Photo- and Electro-Luminescence of Optoelectronic Device Structures

Sun, Yuxuan January 2015 (has links)
Photoluminescence (PL) is an optical emission induced by photon absorption in a material where electrons are excited from the ground state to excited states, then relax to the lowest excited states and recombine radiatively. The PL emission provides vital information on bandgap energy, material purity and crystal quality. In this project, a PL characterization system, also capable of electroluminescence (EL) measurements, was designed and assem- bled to measure optoelectronic device structures with the capabilities of recording PL or EL spectra as well as micrometer-resolved PL or EL maps on device structures or active components. In order to realize the system with the above functions, an optical setup and a monochro- mator were used to achieve micrometer-range resolution and reasonable signal-to-noise ra- tio. A hardware control platform needed to be designed and assembled to control the precise movement of the sample stage and monochromator as well as for acquiring the signal. A PC-based control software were developed for fully automatic measurements . Furthermore, adequate alignment and calibration methods had to be developed to tune the optical path, monochromator and control program. The setup employs the basic ideas of confocal microscopy, with the parallel laser input focused on the sample surface with a spot diameter of 0.78 μm. A Czerny Turner diffraction grating based monochromator is used to measure PL emissions. A 532 nm laser diode and an InGaAs or Si detector are applied in the system for spectral range of detection of at least 850- 1600 nm, i.e. covering the important data and tele communication bands. The project builds on a platform containing EasyDrivers, an Anduino Uno micro-controller and a Labview based operation software, together working with an amplifier circuit for stepper motors actuation and signal acquisition. Finally, different quantum well samples were measured, showing that the wavelength accuracy and resolution as well as the program flexibility meet the specifications of the setup.
3

Assessment of Normal force testing to measure adhesion at organic-inorganic interfaces in organic optoelectronic devices

Das Gupta, Hrishikesh 11 1900 (has links)
Organic photovoltaic (OPV) devices are emerging as a reliable source of energy due to their combination of unique features. Though desired for their flexibility, low cost, light weight, large area fabrication compatibility and eco-friendly nature, these devices face numerous challenges in achieving high performance and stability. The organic-electrode interface specifically plays a key role in controlling device stability. Recent studies have revealed that the stability is heavily affected by the adhesion of the organic-electrode interface. Measurement of adhesion at these interfaces, however, is a challenging task. In this study, Normal Force Adhesion testing was assessed to determine its suitability for organic devices. In this approach, force is applied perpendicular to the substrate, over the entire surface area of one device (9 mm2) until delamination occurs. In addition to the extracted force-distance curves, images of the interfaces before and after each experiment and a real-time, in-situ video taken from a lateral perspective were examined. All three of these critical pieces of information are necessary to obtain a complete picture of the success of a Normal test. A statistical assessment has been made of the testing apparatus, using many samples (> 50) of one metal - organic combination, Al-Alq3 - an archetypal combination for organic electronics. In addition, five other metal-organic combinations widely used in organic electronic devices, have been chosen to assess the Normal force approach. Due to the ease of testing a large number of samples, Normal force testing does appear to be a viable approach to examining interfacial adhesion, though care must be taken in the experimental design to avoid common experimental failures. Based on the results, a few recommendations have been made to improve the utility of the adhesion testing system for rapid quality testing of organic devices. / Thesis / Master of Applied Science (MASc)
4

Studies of characteristics of frequency modulation liquid-crystal optoelectronic devices

Chen, Zheng-hsiung 21 July 2008 (has links)
We study the characteristics of the dual frequency liquid-crystal (LC) optoelectronic devices in this literary. We fabricate the LC lens with the dual frequency liquid crystal in our experiment. In this study, we first prepare a parabolic polymer structure on the glass substrate to form a polymeric lens glass, then, fill the dual-frequency LC into the empty cell which consists of one ITO glass and the polymeric lens glass to fabricate a frequency modulation LC lens. Additionally, a hybrid surface alignment is also used for our LC lens. For the dual-frequency LC, a hybrid surface alignment is necessary to obtain a frequency modulation LC lens. Because of the polymeric lens, the electric fields are inhomogeneous distributions in the LC lens when a voltage is applied to the electrodes. In this situation, an inhomogeneous electric field is applied to the cell to create GRIN lens-like distribution of the gradient refractive index. Thus, the focusing effects occur when the light passes through the LC lens. Moreover, by changing the amplitude and frequency of the applied voltage, the focal length of the LC lens can be changed. We mainly discuss the optical property and the response time of the LC lens based on the voltage modulation and the frequency modulation. The experimental results reveal that the frequency modulation has more advantages, such as widen range of controlled focal length and faster response time, comparing with the voltage modulation.
5

Conception d'un circuit intégré en SiC appliqué aux convertisseur de moyenne puissance / Design of an integrated circuit in SiC applied to medium power converter

Mogniotte, Jean-François 07 January 2014 (has links)
L’émergence d’interrupteurs de puissance en SiC permet d’envisager des convertisseurs de puissance capables de fonctionner au sein des environnements sévères tels que la haute tension (> 10 kV ) et la haute température (> 300 °C). Aucune solution de commande spécifique à ces environnements n’existe pour le moment. Le développement de fonctions élémentaires en SiC (comparateur, oscillateur) est une étape préliminaire à la réalisation d’un premier démonstrateur. Plusieurs laboratoires ont développé des fonctions basées sur des transistors bipolaires, MOSFETs ou JFETs. Cependant les recherches ont principalement portées sur la conception de fonctions logiques et non sur l’intégration de drivers de puissance. Le laboratoire AMPERE (INSA de Lyon) et le Centre National de Microélectronique de Barcelone (Espagne) ont conçu un MESFET latéral double grille en SiC. Ce composant élémentaire sera à la base des différentes fonctions intégrées envisagées. L’objectif de ces recherches est la réalisation d’un convertisseur élévateur de tension "boost" monolithique et de sa commande en SiC. La démarche scientifique a consisté à définir dans un premier temps un modèle de simulation SPICE du MESFET SiC à partir de caractérisations électriques statique et dynamique. En se basant sur ce modèle, des circuits analogiques tels que des amplificateurs, oscillateurs, paires différentielles, trigger de Schmitt ont été conçus pour élaborer le circuit de commande (driver). La conception de ces fonctions s’avère complexe puisqu’il n’existe pas de MESFETs de type P et une polarisation négative de -15 V est nécessaire au blocage des MESFETs SiC. Une structure constituée d’un pont redresseur, d’un boost régulé avec sa commande basée sur ces différentes fonctions a été réalisée et simulée sous SPICE. L’ensemble de cette structure a été fabriqué au CNM de Barcelone sur un même substrat SiC semi-isolant. L’intégration des éléments passifs n’a pas été envisagée de façon monolithique (mais pourrait être considérée pour les inductances et capacités dans la mesure où les valeurs des composants intégrés sont compatibles avec les processus de réalisation). Le convertisseur a été dimensionné pour délivrer une de puissance de 2.2 W pour une surface de 0.27 cm2, soit 8.14 W/cm2. Les caractérisations électriques des différents composants latéraux (résistances, diodes, transistors) valident la conception, le dimensionnement et le procédé de fabrication de ces structures élémentaires, mais aussi de la majorité des fonctions analogiques. Les résultats obtenus permettent d’envisager la réalisation d’un driver monolithique de composants Grand Gap. La perspective des travaux porte désormais sur la réalisation complète du démonstrateur et sur l’étude de son comportement en environnement sévère notamment en haute température (> 300 °C). Des analyses des mécanismes de dégradation et de fiabilité des convertisseurs intégrés devront alors être envisagées. / The new SiC power switches is able to consider power converters, which could operate in harsh environments as in High Voltage (> 10kV) and High Temperature (> 300 °C). Currently, they are no specific solutions for controlling these devices in harsh environments. The development of elementary functions in SiC is a preliminary step toward the realization of a first demonstrator for these fields of applications. AMPERE laboratory (France) and the National Center of Microelectronic of Barcelona (Spain) have elaborated an elementary electrical compound, which is a lateral dual gate MESFET in Silicon Carbide (SiC). The purpose of this research is to conceive a monolithic power converter and its driver in SiC. The scientific approach has consisted of defining in a first time a SPICE model of the elementary MESFET from electric characterizations (fitting). Analog functions as : comparator, ring oscillator, Schmitt’s trigger . . . have been designed thanks to this SPICE’s model. A device based on a bridge rectifier, a regulated "boost" and its driver has been established and simulated with the SPICE Simulator. The converter has been sized for supplying 2.2 W for an area of 0.27 cm2. This device has been fabricated at CNM of Barcelona on semi-insulating SiC substrate. The electrical characterizations of the lateral compounds (resistors, diodes, MESFETs) checked the design, the "sizing" and the manufacturing process of these elementary devices and analog functions. The experimental results is able to considerer a monolithic driver in Wide Band Gap. The prospects of this research is now to realize a fully integrated power converter in SiC and study its behavior in harsh environments (especially in high temperature > 300 °C). Analysis of degradation mechanisms and reliability of the power converters would be so considerer in the future.

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