Prediction of pull-in phenomena and structural stability analysis of an electrostatically actuated microswitch

Abstract

The present study is concerned with the theoretical investigation of pull-in phenomena and their significance for assessing structural instability of a MEMS switch, modeled as electrostatically actuated micro-cantilever beam coupled with a rigid plate. The essential factors such as geometric and inertial nonlinearities, higher-order distribution of electrostatic pressure, and nonlinear squeeze film effect have been included in the dynamic model to accurately predict the pull-in voltages. The limit of structural stability due to pull-in behavior is numerically illustrated for both static and dynamic conditions of the device. The effects of varying the electrode length, structural nonlinearity, air-gap thickness, and plate length on pull-in instability are investigated. The pull-in voltage predicted numerically within the limit of operational voltage has been validated with the findings in 3D modeling software. It is perceived that a highly deformable micro-system loses its stability at high actuation voltage via static bifurcation due to pull-in instability. Furthermore, structural stability appears observed to be high by reducing the size of the device as the pull-in occurrence is at high applied voltage. The damping mechanism introduced into the device essentially stabilizes the device by switching the pull-in voltage to a high value. However, the obtained outcomes enable the satisfactory predictions of pull-in occurrence and subsequent understanding of structural instability and safe operating zones of the device.