Analysis And Optimization Design Of Micro-Electromechanical Systems With Electrostatic Comb

The composition of micro-electromechanical systems (MEMS) relates to many scientific fields such as: micro-electronics, micro-mechanics, micro-dynamics, micro-thermotics, micro-fluidics, material, physics, chemistry and biology. They forms many cross coupled energy domains, which bring difficulty to the modeling, simulation and optimization of MEMS. Electrostatic force is the main method to drive the mechanic action because of its simple principles. Comb-finger structure is widely used in MEMS apparatus such as micro resonators, micromachined silicon accelerometer, micromachined gyroscope, micro mirrors, micro grippers and micro stages. The simulation analysis and optimization design of the coupled electrical fields for comb-finger structure MEMS are quite important.The three main points of this paper are as following:1. electrostatic-structure coupled problem in electrostatic comb-finger drives was solved with reduced order macro modeling technique in which reduced order modeling (ROM) was used to present the static and dynamic characteristics of micro resonators. This paper analyzed the relationship between the parameters of the static comb-finger drives and the electrostatic force and the displace. The static electrical field of the electrostatic comb-finger drives was simulated and analyzed and the edge effect was also discussed deeply. Besides, six modes of the dynamic characteristics of the micro resonators were analyzed and their frequency and harmonic amplitude were calculated. The simulation result showed that the ROM could solve coupled fields rapidly and exactly.2. The influence of each subsystem to the comb-finger micromachined gyroscope was discussed from the system aspect. The configuration characteristic, electronic circuit, processing technique and air-damping of the comb-finger micromachined gyroscope which related to its sensitivity were detailedly analyzed. And the unified multidisciplinary design optimization (MDO) model for micromachined gyroscope was founded. The genetic algorithm (GA) and differential evolution algorithm(DE) were proved feasible in MEMS optimization by combining the global optimimazation of GA and DE with the the system level optimization of the gyroscope. The optimization results of GA and DE were compared. The differential evolution algorithm improved the performance of the system markedly.3. The influence of each subsystem to the comb-finger micromachined silicon accelerometer was discussed from the system aspect. Optimization model of each subsystem is respectively built based on the analysis of the design factors of the comb-finger micromachined silicon accelerometer. The differential evolution algorithm and multi-objective genetic algorithm (MOGA) were used for optimization and were proved feasible in the optimization of systems coupled with multi-sub systems. The optimization results solved by transforming multi-objective to single objective and the results solved with multi-objective were compared. These results improve the performance of system.