SMA Microvalves for Very Large Gas Flow Control Manufactured Using Wafer-Level Eutectic Bonding

This paper presents a novel gas microvalve design concept, in which a flow control gate is opened by a pneumatic pressure and closed by a shape memory alloy actuator, allowing large flow control. Two different design variations were fabricated using a novel wafer-level Au–Si eutectic bonding process for TiNi to silicon integration. The resulting microvalves demonstrate a record pneumatic performance per footprint area; a microvalve with a footprint of only
$1 \times 3.3\ \hbox{mm}^{2}$
successfully controls a flow difference of 3100 sccm at a pressure drop of 70 kPa using a power of 0.35 W.