Electrostatic parallelogram actuators

Abstract

Surface micromachined actuators composed of polysilicon, parallelogram flexible supports are described. The parallelogram actuators transform both the direction and the magnitude of the attractive, electrostatic force developed between the drive electrodes. In a typical configuration, one vertex of the parallelogram is fixed, two opposing, suspended vertices are pulled by the attractive electrostatic force, and the fourth, suspended vertex moves towards the fixed vertex. Parallelogram actuators with beam lengths of 200 approximately 600 mu m and beam widths of 2 approximately 7 mu m were fabricated in 4- mu m-thick LPCVD (low-pressure chemical vapor deposited) polysilicon. Best device yields were obtained when a t-butyl alcohol freeze-dry rinse was used. A parallelogram actuator with 283- mu m-length and 2.5- mu m-width beams moved repeatably and showed 5- mu m displacement by an applied voltage of 19 V.<>