We have developed a shape memory alloy (SMA) actuated micropump as a compon
ent for use in micro analysis or micro dosage systems. In this paper, we wi
ll discuss the fabrication process and dynamic actuation properties of an S
MA actuator, as well as the first result of pumping properties of a complet
ed SMA micropump. TiNi thin film of about 6 mum in thickness was deposited
onto a Si wafer with a square recess on its reverse side, and memorized an
initial flat shape. The TiNi thin film and a Pyrex glass cap with a square
recess were then anodically bonded together in a vacuum to form a chamber t
o which a bias pressure was to be applied to deform the TiNi thin film. Aft
er removing the remaining Si layer beneath the TiNi thin film by RTE in SF6
plasma, a shape memory actuator of 5 mm square in size was completed. A Si
check valve structure was also fabricated through a process of anisotropic
etching and fusion bonding and was assembled with the actuator. The fabric
ated micropump with a size of 10 mm x 20 mm x 1.4 mm was driven by thermal
cycles of resistive heating and air-cooling under bias pressure which was a
pplied by a nitrogen gas flow. The completed SMA micropump proved to give a
flow rate of 0.4 mul per cycle at a bias pressure of 100 kPa. (C) 2001 Els
evier Science B.V. All rights reserved.