Optimization of Sensing Stators in Capacitive MEMS Operating at Resonance

This paper describes capacitive sensing stators for microelectromechanical systems (MEMS) suitably designed to minimize damping effects without worsening the capacitive variation per unit displacement. Such optimization can be exploited to maximize the readout signal in resonant systems. Two structures are designed with the aid of finite-element method models for the electrostatic domain, and with the aid of a deterministic integral model for damping predictions. The structures, fabricated in a 22-μm-thick surface micromachining process, demonstrate a 3× sensitivity improvement when used as resonant MEMS magnetometers.