Pull-in Analysis of Scanners Actuated by Electrostatic Vertical Combdrives

This paper presents an analysis of pull-in due to in-plane twist in MEMS scanners actuated by vertical combdrives with general comb gap arrangements and cross-sections. The analysis is based on a 2-DOF actuator with a single voltage control. A closed-form pull-in deflection angle expression is obtained by accurately modeling the capacitance between the movable and fixed combs. The analysis results are in good agreement with simulations, and allow optimization of scanner designs by combining pull-in deflection angle, capacitance maximum angle, and available torque.