Optimization of the Geometry of the MEMS Electrothermal Actuator to Maximize In-Plane Tip Deflection

Abstract

AbstractSeveral microactuator technologies have been investigated for positioning individual elements in large-scale microelectromechanical systems (MEMS). Electrostatic, magnetostatic, piezoelectric and thermal expansion represent the most common modes of microactuator operation. This investigation optimized the geometry of the asymmetrical electrothermal actuator to maximize its in-plane deflection characteristics. The MEMS polysilicon surface micromachined electrothermal actuator uses resistive (Joule) heating to generate differential thermal expansion and movement. In this investigation, a 3-D model of the electrothermal actuator was designed, and its geometry was optimized using the finite-element analysis (FEA) capabilities of the ANSYS computer program. The electrothermal actuator's geometry was systematically varied to establish optimum values of several critical geometrical ratios that maximize tip deflection. The value of the ratio of the length of the flexure component relative to the length of the hot arm was discovered to be the most sensitive geometrical parameter ratio that maximizes tip deflection.