Surface micromachining of micro-electro-mechanical systems (MEMS), like all other fabrication processes, has inherent variation that leads to uncertain material and dimensional parameters. To obtain accurate and reliable predictions of mechanism behavior, the effects of these variations need to be analyzed. This thesis expands already existing tolerance and uncertainty analysis methods to apply to micro compliant mechanisms. For simple compliant members, explicit equations can be used in uncertainty analysis. However, for a nonlinear implicit system of equations, the direct linearization method may be used to obtain sensitivities of output parameters to small changes in known variables. This is done by including static equilibrium equations and pseudo-rigid-body model relationships with the kinematic vector loop equations. Examples are used to show a comparison of this method to other deterministic and probabilistic methods and finite element analysis.

In order to support UCLA’s development of the 3 cm Miniature Xenon Ion (MiXI) thruster, Cal Poly has a 3 cm thruster under development. This version, called MiXI Cal Poly Version 1 (MiXI-CPv1), is complete and has been utilized in vacuum chamber thermal validation testing. Testing on this version was used to check the validity of heat transfer simulations modeled in SolidWorks. Investigations of the 3 cm ion thruster configuration were intended to discover the driving factors affecting the thermal behavior of the discharge chamber and surrounding design space. Numerical simulations indicate that the heating of the samarium cobalt permanent magnets can be mitigated through the implementation of two proposed modifications. The first modification is to implement a 2% thoriated tungsten filament cathode. This design exhibited maximum permanent magnet temperatures of 325°C, twenty-five degrees below the maximum upper temperature of 350°C. Since some magnetic degaussing effects have been observed at temperatures above 300°C, the aforementioned solution can be combined with a thruster design modification to achieve a reduced permanent magnet temperature of 298°C. This modification would involve increase the anode wall thickness from approximately 0.7 mm to 2 mm below the permanent magnet ring, creating a stepped anode design. Additionally, less effective solutions were proposed and modeled and are presented for completeness.

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This dissertation presents an investigation of micromachined three-dimensional microelectrode arrays (3-D MEAs) targeted toward in-vitro and in-vivo biomedical applications. Current 3-D MEAs are predominantly silicon-based, fabricated in a planar fashion, and are assembled to achieve a true 3-D form: a technique that cannot be extended to micro-manufacturing. The integrated 3-D MEAs developed in this work are polymer-based and thus offer potential for large-scale, high volume manufacturing. Two different techniques are developed for microfabrication of these MEAs - laser micromachining of a conformally deposited polymer on a non-planar surface to create 3-D molds for metal electrodeposition; and metal transfer micromolding, where functional metal layers are transferred from one polymer to another during the process of micromolding thus eliminating the need for complex and non-repeatable 3-D lithography processes. In-vitro and in-vivo 3-D MEAs are microfabricated using these techniques and are packaged utilizing Printed Circuit Boards (PCB) or other low-cost manufacturing techniques. To demonstrate in-vitro applications, growth of 3-D co-cultures of neurons/astrocytes and tissue-slice electrophysiology with brain tissue of rat pups were implemented. To demonstrate in-vivo application, measurements of nerve conduction were implemented. Microelectrode impedance models, noise models and various process models were evaluated. The results confirmed biocompatibility of the polymers involved, acceptable impedance range and noise of the microelectrodes, and potential to improve upon an archaic clinical diagnostic application utilizing these 3-D MEAs.

Pulsos ultracurtos de laser vêm sendo usados tanto para estudar e desenvolver processos ópticos não lineares em materiais, quanto para o seu processamento visando as mais diversas aplicações tecnológicas. Neste trabalho, estas duas áreas (estudos de não linearidades e processamento de materiais) foram exploradas em distintas amostras vítreas. Primeiramente, investigamos o espectro das propriedades ópticas não lineares de terceira ordem de vidros oxifluoroboratos de chumbo (50BO 1,5 - (50-x)PbF2 - xPbO) em função da variação da composição. Os espectros não lineares foram determinados na região do visível e infravermelho próximo pela técnica de varredura-z, utilizando um sistema laser de Ti: safira (775 nm, 150 fs, 1 kHZ) juntamente com um amplificador óptico paramétrico (470 a 2000 nm). Os resultados revelaram que a formação de oxigênios não ligantes favorece a resposta óptica não linear do material; o vidro com x = 50 apresentou as maiores não linearidades de terceira ordem, com índice de refração não linear de aproximadamente 4,7 x \'10 POT.-19\' \'M POT.2\'/W para comprimentos de onda entre 470 a 1550 nm, e coeficiente de absorção de dois fótons da ordem de 1 cm/GW, na região de engrandecimento de ressonância. Estes resultados, associados com a análise do fator de mérito e medidas de limitação óptica, sugerem que esses vidros têm potencialidades para aplicações em limitadores de potência e chaves puramente ópticas. Com relação ao processamento de materiais, utilizamos a técnica de microestruturação com laser de femtossegundos para produzir microestruturas em vidros borato de chumbo e borosilicatos. Foi possível obter linhas na superfície destes materiais, cuja largura pode ser controlada no intervalo de 3 a 35 µm pela alteração das condições de focalização, energia e velocidade de varredura do feixe. Ainda, através da irradiação com pulsos de femtossegundos foi possível produzir nanopartículas de cobre, cujo tamanho está em torno de 15 nm, tanto no volume quanto na superfície de um vidro borosilicato. Observamos que existe uma combinação ótima entre a velocidade de varredura do laser e a temperatura de tratamento térmico que permite a formação dessas nanopartículas apenas nas regiões irradiadas. / Ultrashort laser pulses have been used to study and develop nonlinear optical processes in materials, as well as for their processing, aiming at several technological applications. In this work, both areas (study of optical nonlinearities and materials processing) were exploited for different glass materials. Initially, we have studied the third order nonlinear optical spectrum of lead oxifluoroborate glasses (50BO 1,5 - (50-x)PbF2 - xPbO) as a function of the composition. The optical nonlinearities were determined from the visible to the near infrared employing the Z-scan technique, using a Ti: sapphire laser system (775 nm, 150 fs, 1 kHZ) and an optical parametric amplifier (470 a 2000 nm) as excitation sources. The results revealed that the formation of non-bridging oxygens favors the nonlinear optical properties of the material; the glass with x = 50 presents the higher third order nonlinearities, exhibiting a nonlinear index of refraction of about 4,7 x \'10 POT.-19\' \'M POT.2\'/W at the range of 470 - 1550 nm, and a two-photon absorption coefficient of approximately 1 cm/GW at the resonant enhancement region. Figure of merit analysis and optical limiting measurements suggest that these glasses have potential for applications in optical limiting and all-optical switching. Regarding materials processing, we have used femtosecond laser micromachining to produce microstructures in lead borate and borosilicate glasses. We were able to produce lines with controlled widths, from 3 - 35 µm, on the surface of the glasses by changing the focus, speed and energy of the laser beam. Moreover, using femtosecond laser pulses we obtained copper nanoparticles on the surface as well as in the bulk of a borosilicate glass. We have observed that there is an optimal combination between scanning speed and annealing temperature to promote the formation of nanoparticles at the regions irradiated by the laser.