Analysis and design of polysilicon thermal flexure actuator

Abstract

An analytical model that can accurately predict the performance of a polysilicon thermal flexure actuator has been developed. This model is based on an electrothermal analysis of the actuator, incorporating conduction heat transfer. Heat radiation from the hot arm of the actuator to the cold arm is also estimated. Results indicate that heat radiation becomes significant only at high input power, and conduction heat losses to both the substrate and the anchor are mainly responsible for the operating temperature of the actuator under routine operations. Actuator deflection is computed based on elastic analysis of structures. To verify the validity of the model, polysilicon thermal flexure actuators have been fabricated and tested. Experimental results are in good agreement with theoretical predications except at high input power. An actuator with a 240 μm long, 2 μm thick, 3 μm wide hot arm and a 180 μm long, 12 μm wide cold arm deflected up to 12 μm for the actuator tip at an input voltage of 5 V while it could be expected to deflect up to 22 μm when a 210 μm long cold arm is used.