Characterization and MEMS application of low temperature TiNi(Cu) shape memory thin films

Shape memory thin films offer a unique combination of novel properties, which promise some exciting application potentials in micro-electromechanical systems (MEMS). In this study, Ti48.9Ni46.3Cu4.8 (at.%) driving thin films were successfully prepared by radio-frequency magnetron sputtering. Crystallographic structure, surface morphology and phase transformation temperatures were investigated by X-ray diffraction, scanning electron microscopy, atomic force microscope and differential scanning calorimeter, respectively. Applying a MEMS process, a valve-less micropump of Ti48.9Ni46.3Cu4.8 shape memory thin film for low temperature application is fabricated. The results show that the phase transformation between martensite and austenite is rather low, below 290 K, and the surface of the thin films is smooth. The displacement measurement clearly revealed the TiNi(Cu) diaphragm valve-less pump has superior performance such as high diaphragm displacement (up to 6 μm) and high working frequency (up to 85 Hz).