A dynamic model, including contact bounce, of an electrostatically actuated microswitch

TLDR

Microelectromechanical devices are increasingly integrated into electronic circuitry, and microswitches—acting like three‑terminal FETs—are among them, yet their dynamic behavior, including bounce before contact, remains poorly understood. This study models the transient dynamics of two electrostatically actuated microswitch configurations. The model employs dynamic Euler‑Bernoulli beam theory for cantilevered beams, incorporates electrostatic gate forces, squeeze‑film damping, and a spring model of contact tips, analyzed via time‑transient finite difference. The resulting model and simulations serve as design tools to enhance switch performance and mitigate bounce in future microswitch designs.

Abstract

Microelectromechanical devices are increasingly being integrated into electronic circuitry. One of these types of devices is the microswitch, which acts much like a three-terminal field-effect transistor (FET). While various microswitches are currently being developed, their dynamic behavior is not well understood. Upon closing, switches bounce several times before making permanent contact with the drain. In this paper, a time-transient finite difference analysis is used to model the dynamic behavior of two different electrostatically actuated microswitch configurations. The model uses dynamic Euler-Bernoulli beam theory for cantilevered beams, includes the electrostatic force from the gate, takes into account the squeeze-film damping between the switch and substrate, and includes a simple spring model of the contact tips. The model and simulation can be used as design tools to improve switch performance and reduce switch bounce in future designs.