Study on a TiNi Thin Film Micro Actuator

Abstract

A TiNi thin film microactuator is designed and fabricated. In order to set the martensitic transformation temperature of the thin film to above room temperature, the compositions and annealing conditions are investigated. Ti-48at.%Ni thin films are prepared by sputtering. About 150 minutes pre-sputtering with a Ti-mesh on the target is needed to stabilize the film compo-sitions. For the experiment, the films were annealed at temperatures of 475°C, 500°C and 600°C for 20 and 60 minutes. Each of them shows the martensitic transformation temperature above room temperature. Also, the results indicated that the transformation temperatures of the films increase with increasing annealing temperature and time. Using the films, a micro clip mechanism is fabricated. The SMA actuator was used as a one-way actuator because of its simple structure that consists of the combination of beams.The microclip can clip a 0 250μm wire when 20 mA is applied to the structure. The clinging force of the micro clip measured about 800μN.