Mechanical Design and Modeling of a New MEMS Vertical Actuator

Abstract

This paper presents a new micro electro-thermal actuator with vertical motion. In the traditional vertical electro-thermal actuators, the arms of actuators are fabricated with different widths to provide high and low electrical resistance for the hot and cold arms. Applying electrical current to the arms results in different thermal expansion between the hot and cold arm, which forces the tip of the device to bend. The new vertical electro-thermal actuator design eliminates the parasitic electrical resistance of the cold arm through the use of a ‘U’ shape structure. This U-shape structure results in a bi-directional vertical actuator with larger deflection and improved electrical efficiency by providing an active return current pass. The ‘U’ shape actuator is more efficient in applications such as variable capacitors where larger deflection can increase the tuning range. For analysis and design purposes, an effective method to transfer the continuous system to a lumped model is presented. Simulation results are provided to show the deflection and effects of design parameters on the actuator performance.