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Approved for public release, distribution is unlimited / 100 m/s). Low voltage electrical contact was not maintained for some experimental shots and non-parallel rails were the suspected cause. In this thesis, we used a non-contact capacitive sensor to determine rail spacing to within 2/kAcm10mael, so that the rails will be parallel within small tolerances. Several rails were used in these experiments: 75-25 copper-tungsten, chromium-plated 75-25 Cu-W, and chromium-plated pure copper rails. Improving the control of rail spacing and parallelity did not ensure low-voltage electrical contact for our configurations. The largest damage was observed for chromium-plated copper rails and the least damage occurred for chromium-plated 75-25 Cu-W rails. / Lieutenant, United States Navy

Orientador: Paulo Roberto Bueno / Coorientador: Flávio Cesar Bedatty Fernandes / Banca: Hideko Yamanaka / Banca: Marina Ribeiro Batistuti / Resumo: Desde a primeira descrição de biossensor reportada por Clark e Lyons em 1962, houve um extenso trabalho no desenvolvimento e aprimoramento de novas técnicas de biossensoriamento para detecção de biomarcadores com relevância médica. Destaca-se nesse processo o estudo de superfície de eletrodos, pois esse influencia diretamente em aspectos como; sensibilidade, estabilidade e qualidade do sinal. Portanto, este projeto consiste em avaliar comparativamente três superfícies de eletrodos baseadas em nanoestruturas contendo nanopartículas de azul da Prússia, funcionando com sonda redox do sistema, e materiais carbonáceos (como óxido de grafeno e nanotubos de carbono) para aplicação em biossensores. Foram avaliados aspectos como composição, características capacitivas redox e estabilidade de sinal. A técnica de análise utilizada é a espectroscopia de capacitância eletroquímica (ECE) que apresenta vantagens como não usar amplificadores de sinal (sondas redox) em solução, configuração esta, importante para métodos de diagnóstico point-of-care. Das superfícies analisadas, a composta por nanopartículas de azul da Prússia e óxido de grafeno (PBNP+GO) apresentou os melhores parâmetros de estabilidade e compatibilidade com os aspectos teóricos da técnica de ECE, sendo então selecionada para realização de testes de biossensoriamento que, através da funcionalização da superfície com anticorpos Anti-IL-6, detectaram seletivamente a presença do biomarcador IL-6. / Abstract: Since the first description of biosensor reported by Clark and Lyons in 1962, numerous works related to the development and enhancement of novel medical biosensing techniques have been published. In that context, it must be highlighted the study of electrode surfaces as it has direct influence in aspects like; sensitivity, stability and signal quality. Therefore, this project aims to evaluate three electrode surfaces based on nanostructures with Prussian blue nanoparticles, as redox probe, and carbonaceous materials (like graphene oxide and carbon nanotubes) and their application in biosensors. It was evaluated aspects like composition, redox capacitive characteristics and signal stability. The electrochemical capacitance spectroscopy technique (ECE) was used as it offers several advantages like no need of signal amplifiers (redox probes) in solution and, then, making this technique more adequate for point-of-care diagnosis. Among the analysed surfaces, the one composed by Prussian blue nanoparticles and graphene oxide (PBNP+GO) was identified as the best surface in terms of stability and compatibility to the theoretical aspects of ECE. Therefore, that structure was selected to further biosensing essays, by functionalizing the surface with Anti-IL-6 antibodies, that indicated the selective detection of the IL-6 biomarker. / Mestre

The purpose of this research is to develop MEMS based acoustic emission sensors for structural health monitoring. Acoustic emission (AE) is a well-established nondestructive testing technique that is typically used to monitor for fatigue cracks in structures, leaks in pressurized systems, damages in composite materials or impacts. This technology can offer a precise evaluation of structural conditions and allow identification of imminent failures or minor failures that can be addressed by planned maintenances routines. AE causes a burst of ultrasonic energy that is measured as high frequency surface vibrations (30 kHz to 1 MHz) generated by transient elastic waves that are typically emitted from growing cracks at the interior of the structure. The AE sensor marketplace is currently dominated by bulky and expensive piezoelectric transducers that are wired to massive multichannel data acquisition systems. These systems are complex to operate with the need of signal conditioning units and near proximity pre-amplifiers for each sensor that demands a fairly complicated wiring requirements. Furthermore, due to the high prices of conventional AE sensors and associated instrumentation, and the current requirements in sensor volumes for smart transportation infrastructure, it is undeniable that new AE technology is required for affordable structural health monitoring. The new AE technology must deliver comparable performance at one or two orders of magnitude lower cost, size and weight. MEMS acoustic emission (AE) sensors technology has the potential to resolve several of these traditional sensor’s shortcomings with the advantage of possible integration of on-chip preamplifier while allowing substantially cost reduction due to the batch processing nature of MEMS technology. This study will focus on filling some of the major existing gaps between current developments in MEMS acoustic emission sensors and commercial piezoelectric sensors, such as sensor size, signal-to-noise ratio (SNR), cost and the possibility to conform to sharply curved surfaces. Basically, it is proposed to develop a new class of micro-machined AE sensors or sensor arrays through strategic design of capacitive and piezoelectric MEMS sensors, which will focus on optimizing the following performance aspects: Creating geometric designs to manipulate the sensor resonant frequency and to optimize Q factor under atmospheric pressure and ambient environment. Developing a strategic selection of materials according to its acoustic impedance as insulator, structure and backing material. Developing strategies to improve the signal to noise ratio SNR with and without integrated amplification/signal processing. Performing a comparison between MEMS and commercial piezoelectric sensors.

Doctor of Philosophy(PhD) / Complex (dusty) plasmas are a subject of growing interest. They areionized gases containing charged dust particles. In capacitively-coupled RF discharges, dust growth can occur naturally and two methods can be used to grow dust particles: chemically active plasmas or sputtering. The growth of dust particles in argon discharges by RF sputtering and the effect of dust particles on theplasma have been investigated from the plasma ignition to the afterglow. It was shown that plasma and discharge parameters are greatly affected by the dust particles. Furthermore, plasma instabilities can be triggered by the presence of the dust particles. These instabilities can be due to dust particle growth or they can be instabilities of a well established dust cloud filling the interelectrode space. When the discharge is switched off, the dust particles act like a sink for the charge carrier and consequently affect the plasma losses. It was shown that the dust particles do keep residual chargeswhich values are greatly affected by the diffusion of the charge carriers and especially the transition from ambipolar to free diffusion.

Les plasmas complexes (poussiéreux) sont un sujet d'intérêt croissant. Ce sont des gaz ionisés contenant des poudres chargées. Dans les décharges RF capacitives, deux méthodes peuvent être utilisées pour produire les poussières: les plasmas chimiquement actifs ou la pulvérisation. La croissance de poudres dans une décharge d'argon par pulvérisation ainsi que ses effets sur le plasma ont été étudiés depuis l'allumage de la décharge jusqu'à la phase post-décharge. Il a été montré que les paramètres du plasma et de la décharge sont grandement affectés par la présences de poudres. De plus, des instabilités du plasma peuvent être induites par la présence des poussières. Ces instabilités peuvent être dues à la croissance des poudres ou elles peuvent être des instabilités auto-excitées d'un nuage dense de poudres remplissant l'espace inter-électrode. Quand on éteint la décharge, les poudres agissent comme un piège pour les porteurs de charge et par conséquent modifient les mécanismes d'extinction du plasma. Il a aussi été montré que les poudres gardent une charge électrique résiduelle qui dépend fortement du processus de diffusion du plasma et notamment de la transition de la diffusion ambipolaire vers la diffusion libre.

The work presented in this thesis detail the measurement of the thermal expansion coefficient of three magnetic spin materials. Thermal expansion coefficient values were measured by capacitive dilatometry in several key low (T < 250 K) temperature regions specific to each material. This thesis is separated into several key parts. The first part establishes the theory behind observing phase transitions through the thermal expansion coefficient. Beginning with the classical definitions of the specific heat, compressibility and thermal expansion coefficient, the three properties are related using a property known as the Grüneisen parameter. To first order, the parameter allows phase transitions to be observed by the thermal expansion coefficient. The second part introduces capacitive dilatometry; a technique used to measure the thermal expansion coefficient. Three capacitive dilatometer devices are presented in this section. The silver compact dilatometer, the fused quartz dilatometer and the copper dilatometer. Each device discusses merits and weaknesses to their designs. Particular focus is made on the fused quartz dilatometer which was built during the duration of this thesis. The third part presents research on three magnetic spin materials; LiHoF4, Tb2Ti2O7 and Ba3NbFe3Si2O14. These materials are studied individually focusing on specific aspects. LiHoF4, a candidate material for the transverse field Ising model, provides insight to quantum phase transitions. Thermal expansion coefficient and magnetostriction along the c-axis for T ≈ 1.3-1.8 K and transverse field Ht ≈ 0-4 T were measured extracting critical points for a Ht-T phase diagram. Existing thermal expansion coefficient measurements had evidence of possible re-entrant behaviour. With a high density of low transverse field critical points it was established that LiHoF4 showed no evidence of re-entrant behaviour. The highly debated material Tb2Ti2O7 has a rich, controversial low temperature behaviour. Originally believed to be a spin liquid, specific heat results propose a scenario involving a sample composition dependent ordered state. Still under considerably attention, thermal expansion coefficient measurements were performed for T < 1 K. The results are interpreted to either fit into the proposed scenario or provide evidence for an alternate scenario. The material Ba3NbFe3Si2O14 exhibits a magnetoelectric multiferroic phase below TN ≈ 27 K; a phase where magnetic and electric order simultaneously exist. The formation of this phase is believed to have a similar structural shift observed in hexagonal perovskite multiferroic materials. The ferroelectric ordering in those materials are brought about through a centrosymmetric to non-centrosymmetric structural shift. The thermal expansion and thermal expansion coefficient coefficient along the a and c axis are measured for T > TN searching for a displacive structural phase transition.

Body-channel communication (BCC) is based on the principle of electrical field data transmission attributable to capacitive coupling through the human body. It is gaining importance now a day in the scenario of human centric communication because it truly offers a natural means of interaction with the human body. Traditionally, near field communication (NFC) considers as a magnetic field coupling based on radio frequency identification (RFID) technology. The RFID technology also limits the definition of NFC and thus reduces the scope of a wide range of applications. In recent years BCC, after its first origin in 1995, regain importance with its valuable application in biomedical systems. Primarily, KAIST and Philips research groups demonstrate BCC in the context of biomedical remote patient health monitoring system. BCC transceiver mainly consists of two parts: one is digital baseband and the other is an analog front end (AFE). In this thesis, an analog front end receiver has presented to support the overall BCC. The receiver (Rx) architecture consists of cascaded preamplifier and Schmitt trigger. When the signals are coming from the human body, they are attenuated around 60 dB and gives weak signals in the range of mV. A high gain preamplifier stage needs to amplify these weak signals and make them as strong signals. The preamplifier single stage needs to cascade for the gain requirement. The single stage preamplifier, which is designed with ST65 nm technology, has an open loop gain of 24.01 dB and close loop gain of 19.43 dB. A flipped voltage follower (FVF) topology is used for designing this preamplifier to support the low supply voltage of 1 V because the topology supports low voltage, low noise and also low power consumption. The input-referred noise is 8.69 nV/sqrt(Hz) and the SNR at the input are 73.26 dB. The Schmitt trigger (comparator with hysteresis) is a bistable positive feedback circuit. It builds around two stage OTA with lead frequency compensation. The DC gain for this OTA is 26.94 dB with 1 V supply voltage. The corner analyzes and eye diagram as a performance matrix for the overall receiver are also included in this thesis work.

This thesis presents research of two novel magnetic materials, LiHoF4 and Tb2Ti2O7. Experiments were performed at low temperatures and in an applied magnetic field to study thermal expansion and magnetostriction using a capacitive dilatometer designed during this project. This thesis presents 3 distinct topics. This manuscript begins with a thermodynamic description of thermal expansion and magnetostriction. The design of a capacitive dilatometer suitable for use at ultra-low temperatures and in high magnetic fields is presented. The thermal expansion of oxygen free high conductivity copper is used as a test of the absolute accuracy of the dilatometer. The first material studied using this dilatometer was LiHoF4. Pure LiHoF4 is a dipolar coupled Ising ferromagnet and in an applied transverse magnetic field is a good representation of the transverse field Ising model. An ongoing discrepancy between theoretical and experimental work motivates further study of this textbook material. Presented here are thermal expansion and magnetostriction measurements of LiHoF4 in an applied transverse field. We find good agreement with existing experimental work. This suggests that there is some aspect of LiHoF4 or the effect of quantum mechanical fluctuations at finite temperatures which is not well understood. The second material studied is the spin liquid Tb2Ti2O7. Despite theoretical predictions that Tb2Ti2O7 will order at finite temperature, a large body of experimental evidence demonstrates that spins within Tb2Ti2O7 remain dynamic to the lowest temperatures studied. In addition Tb2Ti2O7 also exhibits anomalous thermal expansion below 20K, giant magnetostriction, and orders in an applied magnetic field. Thermal expansion and magnetostriction measurements of Tb2Ti2O7 are presented in applied longitudinal and transverse fields. Zero-field thermal expansion measurements do not repeat the previously observed anomalous thermal expansion. A large feature is observed in thermal expansion at 100mK, in rough agreement with existing experimental work. Longitudinal and transverse magnetic fields were applied to Tb2Ti2O7. Longitudinal magnetostriction measurements show qualitatively di erent behavior than previous observations. These measurements were taken along di erent crystal axes so direct comparison cannot be made. Thermal expansion measurements in an applied transverse field show evolution with the strength of the applied field. This evolution may relate to an ordering transition, however difficulties in repeatability in a transverse field require that these results be repeated in an improved setup.

The change in global environment had bought about changes in economic structure, small to medium size LCD-display industry is now facing unprecedented challenges. In order to survive from global competition, it is a must for corporate to establish unique competitive advantages and technology innovation, is an integral part. Because quality and resolution of TFT-LCD is superior to STN-LCD, even price had gradually become more competitive, many electronic products have started designing in TFT-LCD displays. As a result, market share of STN-LCD is declining year by year. In recent years, some manufacturers are using technology innovation as the means to improve their own competitiveness. Utilization of the matured technology of STN to further development of other applications and emerging markets is the key task for many display manufacturers. Manufacturers from around the globe are aggressively seeking new development opportunities, hoping to achieve and obtain a more important position in the market. Since the introduction of iPhone, not only capacitive touch panel and multi-touch technology have become the focus for all manufacturers, but also flat touch screen design has also become the theme pursued by all assembly plants. The most attractive feature of iPhone is its beautiful trendy look, its simplicity and smart friendly user interface. The projected capacitive touch panel used on iPhone, not only includes advantages of traditional capacitive touch sensors, but also offer the function of multi-touch, which is an important and representative machine interface development trend. This study uses mainly case study method and we have selected E company, which is one of the top three of the STN-LCD industry, to carry out the research. By summarizing existing literature, analyzing touch panel industry & strategies, and in-depth interview with key personnel from the display and related industry, I hope to conclude E company¡¦s business model in both theoretical and practical dimensions; then use it as the reference for future business development for other small to medium size LCD-display manufacturers. The result shows that, E company¡¦s business model is to continuously strengthen level of integration and expand display applications. With the introduction of capacitive touch panel, E company integrates its own STN-LCD & outsourced TFT-LCD with self designed capacitive touch panel in order to achieve better competitiveness and expand display business into more applications.