A TiNi shape-memory alloy actuated micropump with fluid isolation

The shape memory alloy (SMA) titanium-nickel (TiNi) is used in thin film form as the basis of actuation for a reciprocating micropump. A novel configuration comprising a TiNi actuator and a polyimide diaphragm is used to perform cyclic motion while utilizing the one way shape memory effect(OWSME). The polyimide diaphragm acts as a spring to provide the bias force required for cyclic motion using the OWSME of TiNi. It also isolates the TiNi from the liquid pumped. An electrical drive signal is passed directly through the TiNi thin film. The current results in joule heating and hence a phase transformation in the SMA causing the shape memory effect(SME). The cyclic motion of this actuation configuration cycles the volume of the pump chamber. Doubly fixed polyimide check valves ensure unidirectional flow through the pump chamber, resulting in pumping. The pump was tested with filtered DI water.