Operational characteristics of microfabricated electric motors

The authors report on the operational characteristics of LOGOS-based microfabricated radial-gap electric motors through lifetime tests, transient measurements, modeling, and parameter extraction. It is found that the reduction of static friction (stiction) in the bearings by the incorporation of a silicon nitride film permits these micromotors to spin in normal air ambients. Frictional drag from the bearing, which results from the electric-based side-pull of the rotor, is found to be the dominant rotor retarding force and to lead to motor wearout after approximately 10000 rotor revolutions. The frictional coefficient of the nitride on the polysilicon micromotor bearing is determined to be 0.36+or-004.<
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