Multiphysical computation of the structural bending in a bottom-drive VCM

Abstract

Purpose This paper intends to lay a background knowledge towards the feasibility of developing a bottom-drive variable capacitance micromotor (VCM) using a surface micromachining process (SMP). The purpose of this paper is to determine the possibility of neglecting the bending of the rotor plates caused by the electrostatic normal forces when deploying a set of mechanical supports. Design/methodology/approach A multiphysics simulation approach is considered in order to analyse the coupled electromechanical effects in a steady state and to evaluate if the proposed geometries are useful to reduce the bending of the plates. Findings A surfaced micromachined bottom-drive VCM requires mechanical reinforcement in order to eliminate the risk of an electrical short circuit caused by the deformation in the rotor plates. The combination of an external supporting ring and anchored structural ribs on top of the rotor poles is sufficient to neglect the deformation in the poles of the rotor. Originality/value An original analysis with the objective of setting a background in the development of a bottom-drive electrostatic micromotor using a SMP is presented.