A reliable single-layer out-of-plane micromachined thermal actuator

Abstract

Out-of-plane electrothermal actuators have been applied to a variety of fields with the bimorph effect being the most commonly used driving method, due to simple fabrication process. However, such an actuator experiences a shear force at the interface of different materials, while actuated. Delamination therefore takes place and decreases its lifetime. In this study, a novel bi-directional out-of-plane electrothermal actuator is designed and fabricated. Unlike the bi-metal and hot-cold arm thermal actuator, this actuator can move in two directions. Since this actuator is consisted of only single-layer thin film material, it can prevent from delamination. According to the static load-deflection test, this actuator can achieve bi-directional actuation with amplitude near 6-7 μm when driven at 5 V. According to the vibration test, the dynamics of the actuator is influenced not only by the thermal characteristics but also by the vibration modes. Consequently, the thermal actuator still has a significant output when driven near 40 kHz. The actuator were experienced a fatigue test which shows that its resonant frequency remains unchanged after 109 cycles of continuous operation with driving voltage at 2.25 V. © 2003 Elsevier Science B.V. All rights reserved.