Linear microactuators based on the shape memory effect

The static and dynamic performance of a new kind of linear microactuators of 4x4x0.1 mm(3) size is presented, providing large work outputs. The actuators consist of a stress-optimized active microdevice of a shape memory alloy with one-way effect connected to a biasing device. The biasing device is either a superelastic microspring or a second active device with opposite actuation direction. For a maximum strain of 1.3%, strokes of 570 mu m 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 down to 50 ms are achieved by making use of partial phase transformations. (C) 1998 Elsevier Science S.A. All rights reserved.