A bistable shape memory microvalve

This paper presents the layout, fabrication and performance characteristics of a first-of-its-kind bistable shape memory microvalve that uses two counteracting shape memory alloy (SMA) microbridges for switching and magnetic layers to maintain the 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 11×6×3 mm³. Bistable operation is shown for a differential pressure up to 100 kPa at high flow rates of 800 sccm (N₂) and 3.5 ml/min (H₂O).