Fabrication and Characterization of an Electrostatic Contraction Beams Micromotor

We report on fabrication and experimental characterization of an electrostatic contraction beams motor that exhibits both reliable operation and high performance characteristics. This electrostatic linear stepper micromotor is fabricated in a single polysilicon layer combining vertical trench isolation technology with standard surface micromachining. The entire motor, including two voltage-controlled clamps and eight pairs of contraction beams, fits in an area of 470 µ m x 290 µ m. Bidirectional stepping motion has been successfully demonstrated, generating a stroke of ± 70 µ m by successively adding 10 nm steps. The motor was driven up to a cycling frequency of 80 kHz. An output force of 0.49 mN was measured for actuation voltages of 60 V on the beams and 50 V on the clamps. The motor was run for 160 hours at a cycling frequency of 10 kHz, generating nearly 5.8 billion steps.