Thesis (M.S.)--Rochester Institute of Technology, 2005. / Typescript. Includes bibliographical references (leaves 91-96).

Thesis (doctoral)--Helsinki University of Technology, 2006. / Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2008. / Includes bibliographical references.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2005 / Having simple structure and high sensitivity, micro accelerometer is a type of popular transducer used to measure the acceleration in a great variety of conditions. The bridge-type micro accelerometer is a typical micro accelerometer and has many types. As one of research project of Kentron in South Africa, the thesis presented here analyzes the bridge-type capacitive nticro accelerometer (BTCMA) and the bridge-type micro accelerometer with two piezoelectric thin films read-out (BTPMA). In this thesis, the similar structures are used on BTCMA and BTPMA For proving the fundamental mode of the structure can measure acceleration and utilizing the structural and electric characteristic to avoid the effect of higher modes, the program CoventorWare for nticro-electric-mechanical system (MEMS) design and analysis is used here to analyze the modes of these two structures, The two group piezoelectric thin films of BTPMA can be connected in serial or parallel configurations. Integrating piezoelectric effect method, strength method and energy method, the analytical analysis of these two configurations has been done with particular emphasis on the elastic characteristics of the thin films. The analytical formulas of transducer, sensitivity, resonance frequency, noise, quality factor, ntinimum detectable signal and maximum detectable range are obtained. According to the comparison results between these two configurations, the charge output in parallel configuration is a little more than that in serial configuration and the sensitivity in serial configuration is much higher than that in parallel configuration. Finally, a calculation of certain practical nticro accelerometer size is used to prove the above conclusions. On the base of capacitance theory, strength method and energy method, the analytical analysis of the BTCMA has been done in this thesis.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2005. / Due to an increasing in industrial micromation need in recent years, the use of micro accelerometers has been highly increased. Consecutively, this has promoted research activities in this field; capacitive accelerometers also have got high concern at large. As a research project of the Kentron in South Africa, this thesis deals with a theoretical model for a one-dimensional micro capacitive accelerometer with U-shape cantilever beam. The properties of the small angle tilted-plate capacitor have been analyzed; the capacitance equation and electrostatic force equation of this kind capacitor have been derived. The sensing element of this accelerometer consists of an inertial mass connected with two cantilever beams. The vibration modes analysis to the sensing element was accomplished by using CoventorWare2004's MemMech module, the result indicates that the main vibration mode can cause the capacitance change observably and the effect of the other modes to the capacitance can be ignored, which satisfied the purpose of the design. In the process of deriving the linearizing acceleration equation, the angle of the inertial mass caused by the deformation of the U-shape cantilever beam was taken into account as well as the electrostatic force between the two electrodes, thus the more precise acceleration linear equation was obtained. The sensitivity equation was derived through the acceleration linear equation, the relationship between the main parameters of the system and the sensitivity has been analyzed. The differential structure of this micro capacitive accelerometer was also analyzed; the linearizing acceleration equation and sensitivity equation of this kind structure were derived, it has been proven that the sensitivity of this structure is twice than the normal structure approximately. The maximum detectable signal was obtained in terms of the fracture strength of the cantilever beam and the maximum displacement of the inertial mass. The minimum detectable signal was obtained in terms of the thermal noise analysis. In the process of the dynamic analysis, the forced vibration produced by the sinusoidal periodic force and sinusoidal periodic moment was analyzed and the transient capacitance equation was derived, this proved the system has good dynamic character in theory. The system was simulated and analyzed by using CoventorWare2004's Saber module. The initial capacitance analysis indicates the relationship between the voltage and the initial capacitance, the result is close to the analytic model. The resonance frequencies analysis indicates that the main dimensions of the sensing element can determine the resonance frequencies and each vibration mode's sequence, the initial dimensions of the sensing element was proved reasonable by analyzing. Sensitivity analysis and Monte Carlo analysis indicate the effect of the sensing element's normal manufacturing tolerance to the system's frequency is small. Impact of plate curvature analysis indicates the effect of the inertial mass's deformation caused by the surface stress to the capacitance is small. Transient analysis obtained the system's transient displacement curve of six directions and transient capacitance curve in normal terms; this proved the system has good dynamic character in the simulating environment.

No description available.

Advanced Methods, Materials, and Devices for Microfluidics Celesta E. White 217 Pages Directed by Dr. Clifford L. Henderson Microfluidics is a rapidly growing research area that has the potential to influence a variety of industries from clinical diagnostics to drug discovery. Unlike the microelectronics industry, where the current emphasis is on reducing the size of transistors, the field of microfluidics is focusing on making more complex systems of channels with more sophisticated fluid-handling capabilities, rather than reducing the size of the channels. While lab-on-a-chip devices have shown commercial success in a variety of biological applications such as electrophoretic separations and DNA sequencing, there has not been a significant amount of progress made in other potential impact areas for microfluidics such as clinical diagnostics, portable sensors, and microchemical reactors. These applications can benefit greatly from miniaturization, but advancement in these and many other areas has been limited by the inability or extreme difficulty in fabricating devices with complex fluidic networks interfaced with a variety of active and passive electrical and mechanical components. Several techniques exist for the fabrication of microfluidic devices, but these methods have significant limitations, and alternative fabrication approaches are currently desperately needed. One such method that shows promise for its ability to integrate the desired high levels of functionality utilizes thermally sacrificial materials as place holders. An encapsulating overcoat material provides structural stability and becomes the microchannel walls when the sacrificial material is removed from the channel through thermal decomposition. Disadvantages of this method, however, include numerous processing steps required for sacrificial layer patterning and elevated temperatures needed for the decomposition of initial sacrificial materials. These limitations keep this method from becoming an economical alternative for microfluidic device fabrication. The materials needed for this method to reach its full potential as a valid fabrication technology for m-TAS are not currently available, and it was a major focus of this work to develop and characterize new sacrificial materials, particularly photosensitive polycarbonate systems. In addition to the development of new sacrificial polymers, the framework for a working microfluidic device was developed to show that this concept will indeed provide significant advancements in the development of future generations of microfluidic systems. Finally, novel fabrication methods for microfluidics through combined imprinting and photopatterning of photosensitive sacrificial materials was demonstrated.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: This thesis deals with the mathematical optimization of the detecting chamber of a thermal convective microfluidic gyroscope and the comparison of several different optimization strategies. An analytical model is developed for the gyroscope and some design considerations are discussed. Sequential approximate optimization strategies are explained and compared to each other by implementing test problems fromthe literature. The optimization problem is formulated from the analytical model and implemented using the different optimization strategies. Results are presented and compared to find the most effective optimization strategy. A sequential approximate optimization algorithm is implemented in MATLAB and tested using the gyroscope design problem and common test problems from the literature. Results and iteration history are compared with an existing FORTRAN implementation. / AFRIKAANSE OPSOMMING: Hierdie tesis handel oor die wiskundige optimering van die deteksiekamer van n termies-konvektiewe mikrovloeier giroskoop en die vergelyking van verskeie optimeringsstrategieë. ’n Analitiese model is opgestel vir die giroskoop en verskeie ontwerpsoorwegings word bespreek. Sekwensiëel benaderde optimeringsstrategieë word bespreek en met mekaar vergelyk, deur dit op toetsprobleme uit die literatuur toe te pas. Die optimeringsprobleem is geformuleer uit die analitiese model en geimplementeer deur gebruik te maak van verskeie optimeringsstrategieë. Resultate word getoon en vergelyk, omdie mees effektiewe optimeringsstrategie te vind. ’n Algoritme vir sekwensiëel benaderde optimeringsprobleme is inMATLAB geimplementeer. Die giroskoop probleem, asook probleme uit die literatuur, is gebruik om resultate en iterasie geskiedenis te vergelyk met ’n bestaande FORTRAN implementasie.

This work addresses the advanced probabilistic modeling of the stochastic nature of microgrinding in the machining of high-aspect ratio, ceramic micro-features. The heightened sensitivity of such high-fidelity workpieces to excessive grit cutting force drives a need for improved stochastic modeling. Statistical propagation is used to generate a comprehensive analytic probabilistic model for static wheel topography. Numerical simulation and measurement of microgrinding wheels show the model accurately predicts the stochastic nature of the topography when exact wheel specifications are known. Investigation into the statistical scale affects associated microgrinding wheels shows that the decreasing number of abrasives in the wheel increases the relative statistical variability in the wheel topography although variability in the wheel concentration number dominates the source of variance. An in situ microgrinding wheel measurement technique is developed to aid in the calibration of the process model to improve on the inaccuracy caused by wheel specification error. A probabilistic model is generated for straight traverse and infeed microgrinding dynamic wheel topography. Infeed microgrinding was shown to provide a method of measuring individual grit cutting forces with constant undeformed chip thickness within the grind zone. Measurements of the dynamic wheel topography in infeed microgrinding verified the accuracy of the probabilistic model.

Neste trabalho é proposto um dispositivo MEMS do tipo micro-transdutor acústico capacitivo, CMUT (sigla em inglês - Capacitive Micromachined Ultrasonic Transducer). Em vez de usar piezoeletricidade, o CMUT tem um array de capacitores, onde cada capacitor possui um eletrodo inferior fixo, uma cavidade e o eletrodo superior composto de uma placa flexível. Quando submetida a uma tensão CC adequada, a placa se deflete se aproximando do eletrodo inferior devido à força eletrostática. Assim a placa fica tensionada podendo vibrar quando excitada por uma tensão CA. Neste caso o CMUT opera como emissor de ondas acústicas. A placa também pode ser excitada por uma onda acústica agindo em sua superfície. Neste caso o dispositivo opera como sensor. Uma das contribuições desse trabalho é o processo de fabricação simplificado com o uso do fotorresiste SU-8 como parte da estrutura do dispositivo. Sua facilidade de processamento e suas propriedades físicas lhe conferem estabilidade e rigidez adequadas para tal fim. Foram realizadas modelagens e simulações analíticas e computacionais do comportamento da placa. Os resultados auxiliaram no melhor entendimento do comportamento do dispositivo sob tensão mecânica devido a uma carga ou uma tensão de polarização. Esses resultados também auxiliaram na definição de parâmetros iniciais do processo de fabricação. Durante o processo de fabricação, foram realizados diversos testes a fim de se encontrar o processo mais adequado à infraestrutura disponível. No processo escolhido, a base do dispositivo é fabricada num substrato de vidro com eletrodos inferiores de alumínio depositados por evaporação. Os pilares são fabricados em SU-8, depositado por spin coatting. A placa é colada posteriormente utilizando-se fotorresiste AZ. O AZ é depositado sobre um pedaço de folha de cobre ou alumínio. As duas partes são colocadas em contato e para promover a colagem é aplicada pressão durante a cura. As amostras foram caracterizadas eletricamente utilizando-se um medidor de impedância RCL. Foram levantadas curvas de impedância, capacitância e ângulo de fase em função da frequência (1 kHz a 1 MHz). Além do sinal CA utilizado pelo instrumento durante a medição foi aplicado um nível CC que variou conforme as dimensões dos protótipos. Também foram levantadas curvas de impedância, capacitância e angulo de fase em função de uma carga mecânica aplicada. Para valores de polarização mais elevados, foram montados circuitos específicos. Estes circuitos são capazes de polarizar o CMUT, aplicar um sinal CA para medição e proteger demais componentes e instrumentos dos aparatos de medição. O dispositivo respondeu bem a aplicação de carga mecânica, excitação por sinal CA e excitação com onda mecânica. Os resultados mostraram que o dispositivo apresenta bom potencial para ser aplicado na análise de fluidos. / This work presents a new process to fabricate an acoustic micro transducer to be used as a microsensor or a microactuator. The acoustic transducers are based on the electrostatic effect and consist on arrays of microfabricated capacitors. Such devices are commonly referred as CMUT, Capacitive Micromachined Ultrasonic Transducer. The bottom electrode (evaporated aluminum) of each capacitor is fixed on the surface of glass substrate, while the top electrode is a thin plate structure of copper or aluminum suspended on a cavity surrounded by posts. Since the top electrode is flexible, it bends toward the bottom electrode when a DC bias is applied. In this way, the top electrode can be forced to vibrate using an AC signal to be used as an acoustic wave emitter. Conversely, an ultrasound receiver is achieved as the measured capacitance changes when the DC biased top electrode moves following an external acoustic wave pressure. An innovation of this work is the use of the photoresist SU-8 to fabricate the post structures surrounding the cavities of the capacitive micro transducers. Its relatively simple processing steps and adequate mechanical properties make the SU-8 a convenient choice as an inexpensive structural material. The bottom part of the device is prepared on a glass substrate using an aluminum layer evaporated and etched to form the bottom electrodes. Then, SU-8 is spin coated, baked and etched adequately to form the posts surrounding the cavities. The top part is prepared by simply spinning an AZ-type photoresist on aluminum or copper plate. Finally, both halves are bonded under pressure on a hot plate. Several modeling and simulation analyses were performed in order to estimate the working performance of the micro transducers. The results of simulations helped to define the initial parameters and materials for the fabrication process. Samples submitted to a DC bias were initially characterized using an RCL meter in order to infer impedance, capacitance and phase angle behavior as a function of frequency (from 1 kHz to 1 MHz). Protection circuits were used in order to test CMUTs with high DC bias. These circuits allow to apply high DC bias, and an AC signal while other measuring equipments are protected. The device responded to application of mechanical loading, excitation by an AC signal and excitation by mechanical wave as well. The results showed that the device has good potential to be applied to the analysis of fluids.