TiNi shape memory alloy thin films for microactuator application

Abstract

TiNi films were prepared by co-sputtering TiNi target and a separate Ti target. Crystalline structure and phase transformation behaviors of TiNi films were investigated. Results showed that TiNi films had fine grain size of about 500 nm and fully martensitic structure at room temperature. X-ray photoelectron spectroscopy (XPS) results indicated that there is adherent and natural TiO₂ film, which is beneficial to its corrosion resistance and biocompatibillity. Results from differential scanning calorimeter (DSC), in-situ X-ray diffraction (XRD) and curvature measurement revealed clearly martensitic transformation upon heating and cooling. The TiNi films were further deposited on micromachined silicon cantilever and membrane structures in order to form micro-gripper or microvalve with large deformation due to shape-memory effect.