An electro-thermally driven microactuator with two dimensional motion

Abstract

In previous literatures, most of the microactuators were designed to deflect in one dimension only. Here, an electro-thermally driven microactuator with out-of-plane and in-plane two dimensional motion is designed, fabricated and tested. This microactuator comprised of a series of bimorph beams, a moving plate, a lateral driven unit, and contact pads. The out-of-plane motion is produced due to the bimorph effect and residual stress between the layers of Au and polysilicon when they are heated. The in-plane motion is obtained by heating the lateral driven unit which consists of two adjacent beams with different cross sections but the same length, then the asymmetrical thermal expansions in two adjacent beams lead to lateral deflection. The microactuator proposed here is fabricated by surface micromaching technique. A twostep releasing method is used here to free the microactuator successfully. The testing results show that the lateral driven unit can produce 10 mum lateral displacements at input voltages of 5 V, and bimorph structures at the same voltage can produce about 12 mum downward displacement. It is also found that this two dimensional motion can be controlled almost independently.