Thin-Film NiTi Microactuator with a Magnetic Spring for a Tiny Launcher Mechanism

In this work, we present a thin-film shape memory alloy microactuator with a magnetic spring. This novel actuator design utilizes two permanent magnets and 3D-printed magnet holders to effectively apply a tensile strain on the NiTi thin- film. This actuator is expected to generate 8.7 mN of blocking force, and a free displacement of 30 μm is experimentally characterized. The actuator leverages bare NiTi film (∼1 μm thick) for actuation, enabling a high actuator bandwidth up to 50 Hz. A comprehensive analytical model is also studied, which was then validated by comparing to the experimental results. A launcher mechanism was designed and integrated with the NiTi actuator, and this mechanism was used to launch a microscale projectile (a salt grain) thereby demonstrating the relative high power actuation achievable with thin-film NiTi.