A novel comb-drive electrostatic stepper motor,

A novel side-drive, electrostatic variable capacitance micromotor has been fabricated. A technique involving the surface micromachining of the three LPCVD (low-pressure chemical vapor deposited) polysilicon layers and the sacrificial silicon dioxide layers was used. Compared to other side-drive motors realized with a similar technique, the comb-structured rotor allows a multiplication of the working air gaps, thereby increasing the drive torque. The key element of this construction is the introduction of linkage arms used to attach the rotor comb teeth to the hub. These arms may also support an outer gear, allowing easy adjacent coupling to a driven mechanism. The design and fabrication of a 540 mu m diameter prototype are presented.<>