Linear microactuators based on the shape memory effect

The static and dynamic performance of a new kind of linear microactuators of 4×4×0.1 mm³ size is presented providing large work outputs. The actuators consist of a stress-optimised active microdevice of a shape memory alloy with one-way effect. As a biasing mechanism, a superelastic microspring or a second active device with opposite actuation direction are used. For a maximum strain of 1.3%, strokes above 500 μm and maximum forces of 110 mN are achieved. Time-resolved experiments with an optical transmission scheme reveal for a driving power of 190 mW heating and cooling times of 300 ms and 1.5 s, respectively. Considerably shorter switching times are achieved by making use of partial phase transformations