A comparison of PZT-based and TiNi shape memory alloy-based MEMS microactuators

Microactuators based on PbZr1-xTixO3 (PZT) and TiNi shape memory alloys (SMAs) are compared using microelectromechanical systems (MEMS) micropumps and microvalves as typical devices. The advantages of PZT-based microactuation include large actuation forces and high operating frequencies, leading to high operating pressures and flow rates. Disadvantages include high operating voltages and low strains. TiNi SMA-based microactuators can achieve high flow rates at low operating voltages, due to their high recoverable strains; however, they suffer from low operating frequencies and high power consumption. For both microactuation schemes, additional structures are usually required to realize the reciprocating motion required for MEMS devices. When used in MEMS, the thicknesses of PZT and TiNi SMA films range up to several microns. The thickness dependence of properties relevant to microactuation of PZT and TiNi SMA thin films are discussed and compared.