Surface-micromachined gear trains driven by an on-chip electrostatic microengine

Test results for a polysilicon, surface-micromachined, electrostatically-actuated microengine driving multiple gears are presented. The microengine provides output in the form of a continuously rotating output gear (50 mu m in diameter) that is capable of delivering torque to additional geared mechanisms. The microengine can be operated at varying speeds and its motion can be reversed. A rotational speed of up to 200000 r/min while driving multiple gears has been obtained. Drive of a 1600 mu m diameter optical shutter has also been demonstrated. The resultant microengine and gear train, produced by polysilicon surface-micromachining techniques, are completely batch-fabricated without the need for piece-part assembly.