Shape Memory Alloy Bimorph Microactuators By Lift-Off Process

This study aims to develop a new fabrication process to create high-precision patterned shape memory alloy (SMA) bimorph micro-actuators by the e-beam evaporation technique. To examine the effect of the annealing process on nitinol (NiTi) thin film characteristics, the as-deposited and annealed NiTi thin films are, respectively, investigated. X-ray diffraction (XRD) results demonstrate the crystallization of NiTi thin films after annealing at 600 degrees C. The transformation behaviors of NiTi thin films during heating and cooling are studied using the differential scanning calorimeter (DSC). Furthermore, scanning electron microscopy (SEM) images indicate that SMA bimorph micro-actuators with high-precision features can be fabricated by the lift-off process, without any wet or dry etching procedures, and their thermomechanical behaviors are experimentally verified by comparing them with that of finite element analysis simulation results.