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 μm 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 μm 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.