Abstract
Out-of-plane electro-thermal actuators have been applied to a variety of fields. Among them, the actuators whose driving method is bi-metal effect have the advantage of simple fabrication processes and are thus most commonly used. However, such an actuator experiences a shear force at the interface of different materials, while actuated. Delamination consequently takes place and therefore decreases its lifetime. In an attempt to overcome the drawback inherent in a bi-metal actuator, a novel bi-directional out-of-plane electro-thermal actuator of single layer thin film material is proposed.The presented actuator comprises four parallel, identical beams. The two inner beams connect the two outer beams with a step, which enables the inner beams and the outer ones located at different planes. While a current only flows through the inner beams, they would experience a temperature rise; the accompanying thermal expansion therefore enables the actuator to bend upwards. On the contrary, while a current only flows through the outer beams, the actuator would bend downwards. The bi-directional out-of-plane motion is thus achieved. The design was examined in light of finite element analysis. The potential application lies in micro-relays, variable capacitors, and optical scanning system.