INVESTIGATION OF THE STATIC AND DYNAMIC BEHAVIOR OF A MICRO MIRROR

Abstract

This dissertation presents the modeling, design, fabrication, and experimental testing of a polyimide based micro mirror for applications in MEMS logic devices based on its static behavior and in MEMS resonators using mixed frequency excitation. First, a universal MEMS logic device that can perform all the logic operations, such as INVERTER, AND, NAND, NOR, and OR gates using one physical structure, within an operating range of 0-10 volts. It can also perform XOR and XNOR with one access inverter using the same structure with different electrical interconnects. We discuss the fabrication, simulations and experimental results demonstrating these logic operations on a polyimide micro mirror. The device is capable of performing the switching operation with a frequency of 1 kHz, a switching time of 8.2 μs, and an electrical lifetime of 8000 cycles. Second, this study presents an experimental and theoretical investigation of a micro mirror under a mixed frequency signal composed of two harmonic AC sources. The experimental and theoretical dynamics are explored via frequency sweeps in the desired neighborhoods. One frequency is fixed while the other frequency is swept through a wide 5 range to study the dynamic responses of the micro mirror. These responses are studied under different frequencies and different input voltages. The results show interesting dynamics, where the system exhibits primary resonance, and combination resonances of additive and subtractive type. The mixed excitation is demonstrated as a way to increase the bandwidth of the resonator near primary resonance, which can be promising for resonant sensing applications in the effort to increase the signal-noise ratio over extended frequency range. It can be promising for energy harvesting as well; since it provides the system with resonances of very high amplitudes at very low frequencies regardless of what is the natural frequency of the system, however this still needs further investigation.