LINEAR MICROACTUATORS BASED ON THE SHAPE-MEMORY EFFECT

The static and dynamic performance of a new kind of linear microactuat ors of 4x4x0.1 mm(3) size is presented, providing large work outputs. The actuators consist of a stress-optimized active microdevice of a sh ape memory alloy with one-way effect connected to a biasing device. Th e biasing device is either a superelastic microspring or a second acti ve 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. Ti me-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 a re achieved by making use of partial phase transformations. (C) 1998 E lsevier Science S.A. All rights reserved.