A Bistable Shape Memory - Thermomagnetic Microactuator

We present the design, simulation and characterization of a compact microactuator with overall dimensions of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2.5\times 2.5\times 4\ \text{mm}^{3}$</tex> allowing for bistable switching a magnetic pin of 1.5 mm diameter with a stroke of 0.4 mm. This performance is achieved through the synergy of shape-memory (SM) and thermomagnetic (TM) microactuation leveraging the one-way SM effect and large magnetization change at the Curie temperature, respectively. A superelastic (SE) spring is designed to balance forces and ensure bistability. This approach enhances mechanical performance, reduces power consumption, and minimizes size compared to previous concepts. Integrating SM-TM microactuators in matrix arrays enables new options for ultra-compact digital micro-mechanical systems, such as haptic devices and Braille displays.