Large Deflection Electrostatic Spiral Actuator with Twisted-beams

Abstract

In this paper, we propose a large-deflection electrostatic spiral-actuator with novel twisted-beams fabricated by surface micromachining. The stress-induced or bimetal-like actuators have merits of simple structure and fabrication steps with relatively large stroke. The novel stress-induced actuator presented here is composed of “twisted-beams", which have not only out-of-plane curvature but also rotation along its longitudinal direction. When the twisted-beams are used as components of a spiral actuator, the total stroke of the actuator becomes a sum of each deflection of the beams, and the stroke is much larger than conventional stressinduced spiral actuators. The experimental results of the spiral actuator show the maximum deflection of about 750 μm, which is extremely large for stress-induced-actuators.