A Bistable Shape Memory Alloy Microvalve With Magnetostatic Latches

This paper presents the layout, fabrication, and characterization of a first-of-its-kind bistable shape memory microvalve. The main functional components are two counteracting shape memory alloy microbridges for switching and magnetic layers to maintain two stable switching states in power-off condition. The high demands on alignment accuracy are met by a novel fabrication process, where all components are assembled to a self-aligning valve stack. This allows full electrical, mechanical, and fluidic performance tests as well as fine adjustment of layer thicknesses prior to final bonding. The overall dimensions of first demonstrators are 11 mm × 6 mm × 3 mm. Bistable operation is shown for differential pressures up to 300 kPa for gas (N₂) at high flow rates of 2200 seem.