Modeling and Stability Analysis of Comb-Fingers in MEMS Electrostatic Actuators

This article presents a side electromechanical instability of slender comb-fingers in MEMS electrostatic devices. Two models are developed for predicting such side pull-in of comb-fingers; one is based in the lumped modeling technique and another is developed by FEM approach. In the slender finger array, the deflection of every finger and pull-in voltage can be calculated by the models. Results indicate every comb-finger bends with different amplitudes. In the finger array, few sided fingers are strongly deflected, the extreme sided fingers in particular, while other inner fingers show negligible deformations. We suggest these extreme sided fingers can dominate the side pull-in of the comb-fingers and should be considered with careful device design by employing the proposed models in this paper.