Microactuators of free-standing TiNiCu films

Abstract

Ti50Ni47Cu3 films were prepared using magnetron sputtering deposition, and their martensitic transformation and mechanical properties were characterized. Free-standing TiNiCu films showed an intrinsic two-way shape memory effect which is attributed to a composition gradient through the film thickness. Different types of TiNiCu microactuators, including microtweezers and microcages, have been successfully fabricated which employ this two-way shape memory effect for operation. Upon heating/cooling, the microtweezers showed both horizontal and vertical displacement due to combined shape memory and thermal effects. The microcage actuators could be opened/closed through substrate heating with a maximum temperature of 90 °C, or by electrical heating with a power less than 5 mW and a maximum frequency of 100–300 Hz. Issues related to the fabrication and applications, such as stability and beam bending after release, have been addressed.