This thesis deals with the fabrication of MEMS air quality sensors for automotive applications. The goal of this project is to design, fabricate and test an integrated sensor that measures three important air quality components inside the automotive cabin, which are temperature, relative humidity and carbon monoxide (CO) concentration. The sensors are fabricated on silicon substrate covered with thermal oxide and LPCVD nitride. Various deposition and etching techniques were utilized to fabricate these sensors including E-beam evaporation, thermal oxide growth, PECVD, LPCVD, RIE, KOH and HF etching. The temperature and humidity sensor use nickel as the sensitive material while the CO sensor was designed to use SnO2 although it was not fabricated to completion. A chamber was created where the temperature and humidity are controlled and the sensors were tested. Curves of sensor resistance vs. temperature and sensor resistance vs. humidity were created and the two sensor’s sensitivity was calculated.

This thesis deals with the fabrication of MEMS air quality sensors for automotive applications. The goal of this project is to design, fabricate and test an integrated sensor that measures three important air quality components inside the automotive cabin, which are temperature, relative humidity and carbon monoxide (CO) concentration. The sensors are fabricated on silicon substrate covered with thermal oxide and LPCVD nitride. Various deposition and etching techniques were utilized to fabricate these sensors including E-beam evaporation, thermal oxide growth, PECVD, LPCVD, RIE, KOH and HF etching. The temperature and humidity sensor use nickel as the sensitive material while the CO sensor was designed to use SnO2 although it was not fabricated to completion. A chamber was created where the temperature and humidity are controlled and the sensors were tested. Curves of sensor resistance vs. temperature and sensor resistance vs. humidity were created and the two sensor’s sensitivity was calculated.

This thesis is focused on the design and realisation of inertial navigation unit INS. The unit is capable to measure, store and send data to a PC in real-time for a later offline processing. The first part of the thesis introduces the reader with the basic principles of accelerometers, gyroscopes and MEMS sensors. An introduction to coordinate systems and measuring errors is also included. The second and third part of the thesis deals with the analysis of the solution and the implementation of the INS unit. The fourth part of the document is dedicated to the software for the INS unit. This thesis concludes with explanation how the gathered data are processed.

A proposta deste trabalho é contribuir com a construção de uma plataforma de veículo autônomo para viabilizar as pesquisas na área pelo Departamento de Engenharia de Transportes da USP. Até o momento o departamento dispõe de uma plataforma que, a partir de sua posição conhecida, consegue navegar autonomamente até um ponto de destino utilizando apenas uma solução GNSS, no caso, GPS. Para ampliar a mobilidade da plataforma, está sendo sugerida aqui, a adição de sensores inerciais ao veículo, para que ele consiga obter uma solução de posição mesmo em áreas sem cobertura GNSS. Um Sistema de Navegação Inercial não depende de infraestrutura externa, exceto para inicializar suas variáveis, o que neste caso pode ser feito com auxílio de um receptor GPS. Sensores inerciais de alto desempenho são caros, tem alta complexidade mecânica e em geral são de grande porte. A alternativa é o uso de sensores do tipo MEMS que são pequenos, fáceis de serem manipulados e apresentam baixo consumo de energia. A contrapartida é que a solução é mais susceptível a ruído do que seus pares que custam na faixa de centena de milhões de dólares. / The proposal of this paper is to build an autonomous vehicle platform to enable the researches in this area by the Transport Engineering Department of the USP. Until now the Department has a platform that, once its initial position is known, it can navigate autonomously to a destination point using only the GNSS, in this case, GPS. To expand the mobility resources of the platform, it is being suggested here the addition of inertial sensors to the vehicle, enabling it to acquire a position solution even in areas where there is no coverage of the GNSS. An Inertial Navigation System does not depend on an external infra-structure, with the exception on the initial setup, where the GPS can be used to provide this kind of initialization. High performance inertial sensors are expensive, have high mechanical complexity and in general are big. The alternative is the usage of MEMS sensors, which are small, easy to handle and has low power consumption. In the opposite side this solution is more susceptible to noises in comparison to those High performance sensors that cost hundreds of thousands of dollars.

A proposta deste trabalho é contribuir com a construção de uma plataforma de veículo autônomo para viabilizar as pesquisas na área pelo Departamento de Engenharia de Transportes da USP. Até o momento o departamento dispõe de uma plataforma que, a partir de sua posição conhecida, consegue navegar autonomamente até um ponto de destino utilizando apenas uma solução GNSS, no caso, GPS. Para ampliar a mobilidade da plataforma, está sendo sugerida aqui, a adição de sensores inerciais ao veículo, para que ele consiga obter uma solução de posição mesmo em áreas sem cobertura GNSS. Um Sistema de Navegação Inercial não depende de infraestrutura externa, exceto para inicializar suas variáveis, o que neste caso pode ser feito com auxílio de um receptor GPS. Sensores inerciais de alto desempenho são caros, tem alta complexidade mecânica e em geral são de grande porte. A alternativa é o uso de sensores do tipo MEMS que são pequenos, fáceis de serem manipulados e apresentam baixo consumo de energia. A contrapartida é que a solução é mais susceptível a ruído do que seus pares que custam na faixa de centena de milhões de dólares. / The proposal of this paper is to build an autonomous vehicle platform to enable the researches in this area by the Transport Engineering Department of the USP. Until now the Department has a platform that, once its initial position is known, it can navigate autonomously to a destination point using only the GNSS, in this case, GPS. To expand the mobility resources of the platform, it is being suggested here the addition of inertial sensors to the vehicle, enabling it to acquire a position solution even in areas where there is no coverage of the GNSS. An Inertial Navigation System does not depend on an external infra-structure, with the exception on the initial setup, where the GPS can be used to provide this kind of initialization. High performance inertial sensors are expensive, have high mechanical complexity and in general are big. The alternative is the usage of MEMS sensors, which are small, easy to handle and has low power consumption. In the opposite side this solution is more susceptible to noises in comparison to those High performance sensors that cost hundreds of thousands of dollars.

This thesis is focused on the design and realisation of inertial navigation unit INS. The unit is capable to measure, store and send data to a PC in real-time for a later offline processing. The first part of the thesis introduces the reader with the basic principles of accelerometers, gyroscopes and MEMS sensors. An introduction to coordinate systems and measuring errors is also included. The second and third part of the thesis deals with the analysis of the solution and the implementation of the INS unit. The fourth part of the document is dedicated to the software for the INS unit. This thesis concludes with explanation how the gathered data are processed.

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abstract: Energy harvesting from ambient is important to configuring Wireless Sensor Networks (WSN) for environmental data collecting. In this work, highly flexible thermoelectric generators (TEGs) have been studied and fabricated to supply power to the wireless sensor notes used for data collecting in hot spring environment. The fabricated flexible TEGs can be easily deployed on the uneven surface of heated rocks at the rim of hot springs. By employing the temperature gradient between the hot rock surface and the air, these TEGs can generate power to extend the battery lifetime of the sensor notes and therefore reduce multiple batteries changes where the environment is usually harsh in hot springs. Also, they show great promise for self-powered wireless sensor notes. Traditional thermoelectric material bismuth telluride (Bi2Te3) and advanced MEMS (Microelectromechanical systems) thin film techniques were used for the fabrication. Test results show that when a flexible TEG array with an area of 3.4cm2 was placed on the hot plate surface of 80°C in the air under room temperature, it had an open circuit voltage output of 17.6mV and a short circuit current output of 0.53mA. The generated power was approximately 7mW/m2. On the other hand, high pressure, temperatures that can reach boiling, and the pH of different hot springs ranging from <2 to >9 make hot spring ecosystem a unique environment that is difficult to study. WSN allows many scientific studies in harsh environments that are not feasible with traditional instrumentation. However, wireless pH sensing for long time in situ data collection is still challenging for two reasons. First, the existing commercial-off-the-shelf pH meters are frequent calibration dependent; second, biofouling causes significant measurement error and drift. In this work, 2-dimentional graphene pH sensors were studied and calibration free graphene pH sensor prototypes were fabricated. Test result shows the resistance of the fabricated device changes linearly with the pH values (in the range of 3-11) in the surrounding liquid environment. Field tests show graphene layer greatly prevented the microbial fouling. Therefore, graphene pH sensors are promising candidates that can be effectively used for wireless pH sensing in exploration of hot spring ecosystems. / Dissertation/Thesis / Doctoral Dissertation Exploration Systems Design 2018

A sensor node 'AccuMicroMotion' is proposed that has the ability to detect motion in 6 degrees of freedom for the application of physiological activity monitoring. It is expected to be light weight, low power, small and cheap. The sensor node may collect and transmit 3 axes of acceleration and 3 axes of angular rotation signals from MEMS transducers wirelessly to a nearby base station while attached to or implanted in human body. This dissertation proposes a wireless electronic system-on-a-single-chip to implement the sensor in a traditional CMOS process. The system is low power and may operate 50 hours from a single coin cell battery. A CMOS readout circuit, an analog to digital converter and a wireless transmitter is designed to implement the proposed system. In the architecture of the 'AccuMicroMotion' system, the readout circuit uses chopper stabilization technique and can resolve DC to 1 KHz and 200 nV signals from MEMS transducers. The base band signal is digitized using a 10-bit successive approximation register analog to digital converter. Digitized outputs from up to nine transducers can be combined in a parallel to serial converter for transmission by a 900 MHz RF transmitter that operates in amplitude shift keying modulation technique. The transmitter delivers a 2.2 mW power to a 50 Ù antenna. The system consumes an average current of 4.8 mA from a 3V supply when 6 sensors are in operation and provides an overall 60 dB dynamic range. Furthermore, in this dissertation, a methodology is developed that applies accelerated electrical stress on MOS devices to extract BSIM3 models and RF parameters through measurements to perform comprehensive study, analysis and modeling of several analog and RF circuits under hot carrier and breakdown degradation.

Le contrôle des écoulements vise à modifier le comportement naturel d’un écoulement fluidique. Dans le domaine des transports, contrôler les phénomènes fluidiques tels que le décollement peut permettre d’économiser du carburant, d’améliorer les performances des véhicules ou encore d’assurer davantage la sécurité des passagers. Dans ce contexte, des capteurs avec de fines résolutions temporelle et spatiale sont requis afin de connaître l’écoulement à contrôler et adapter en temps réel le contrôle. Dans ce travail, l’objectif a été de développer des micro-capteurs de frottement et de pression pour les mesures en écoulements turbulents et le contrôle de décollement. Tout d’abord un micro-capteur calorimétrique a été conçu et réalisé par des techniques de microfabrication pour mesurer simultanément le frottement pariétal et la direction de l’écoulement. Le micro-capteur a ensuite été intégré en paroi d’une soufflerie afin de réaliser son étalonnage statique et dynamique et d’étudier sa sensibilité à la direction de l’écoulement. Troisièmement, le micro-capteur calorimétrique a été utilisé pour caractériser des écoulements décollés. Plusieurs micro-capteurs avec électronique miniaturisée ont été intégrés avec succès dans une maquette de volet et des essais de contrôle actif ont été réalisés. Enfin, la quatrième partie concerne le développement d’un micro-capteur de pression et d’un micro-capteur multi-paramètres réunissant les deux technologies. L’ensemble de ces micro-capteurs ont été caractérisés avec succès et montrent des résultats prometteurs pour caractériser les écoulements turbulents et permettre la mise en place de contrôle d’écoulement en boucle fermée. / Flow control aims at artificially changing the natural behaviour of a flow. In transport industries, controlling fluidic phenomena such as boundary layer separation allows saving fuel and power, improving vehicles performances or insuring passenger’s safety. In this context, sensors with accurate spatial and temporal resolution are required. Such devices enable to estimate the flow to control and allow real-time adaptation of the control. In this work, the objective is to develop wall shear stress and pressure micro-sensors for turbulent flows measurements and flow separation control.Firstly, a calorimetric micro-sensor was designed and realized using micromachining techniques for measuring simultaneously the wall shear stress amplitude and the flow direction. Secondly, the micro-sensor was flush-mounted at the wall of a wind tunnel for static and dynamic calibrations. Thirdly, it was used to characterized separated flows. Several configurations were studied: separation on airfoil profile, separation and reattachment downstream a 2D square rib and the separation on a flap model. Several micro-sensors with embedded electronics were successfully integrated on a flap model and active flow control experiments were performed. Finally, the fourth part of the document concerns the development of a pressure micro-sensor and the development of a multi-parameter micro-sensor combining both technologies.All these micro-sensors have been successfully realized and characterized and demonstrate promising results for measuring turbulent flows and implementing closed loop reactive flow control