A three-dimensional shape memory alloy loop actuator

Shape Memory Alloy (SMA) actuators can produce large displacement/force and are robust against external overload. Their structure is simple because an SMA element serves as both structural and functional parts. This paper deals with deposition of thin films, heat treatment and patterning of titanium-nickel (TiNi) SMA. Microactuators have been fabricated by this process. Typical dimensions of the actuator were 10 μm in thickness, 30 μm in width and 800 μm in length. They produced large displacement up to 300 μm, and large force of more than 5 mN was generated thanks to the intrinsic recovery stress of the SMA. A three-dimensional SMA loop actuator unit composed of two SMA cantilevers is widely described. The dimensions of the loop actuator were 1000 μm in length and 600 μm in height. The loop actuator has been successfully operated. It features repeatable motion up to 20 Hz. The three-dimensional loop actuator is found to be very attractive to perform external work for MicroElectroMechanical Systems (MEMS)