Design and simulation of microelectromechanical transducer using uncoupled finite element models

Due to the increased complexity demands and precision requirements of microelectromechanical systems (MEMS), there is a need for reliable and accurate simulation methods to model physical behavior involved. In particular, the design of improved MEMS transducers can be facilitated by simulating the interaction between the electrostatic and structural domains associated with these devices. In this work, several computational mechanics issues involving electrostatic and structural coupling for MEMS are presented and discussed, including the trade-off between cost and accuracy. Several uncoupled finite element (FE) models are presented and simulated to optimize the design and fabrication of a combdrive based electrostatic microactuator. The benefits and limitations of these uncoupled FE models are then discussed. The asymmetric structural response of the combdrive actuator is further analyzed and a simplified closed-form analytical model is presented for a basis of comparison for the FE results. Based on differences between FE and analytically calculated values, the contribution of fringing electrostatic fields to the mechanical forces produced in the combdrive are discussed.