Measurement of micromotor dynamics in lubricating fluids

Results from step transient measurements of salient-pole, side-drive, polysilicon micromotors operated in different viscosity silicon lubricating oils under different temperatures and excitation voltages are presented. A preliminary dynamic model has been used to estimate the electrostatic motive torque, the velocity-dependent viscous drag torque, and friction torque. The results indicate that the total frictional torque may be an order of magnitude smaller in silicon oil than in gaseous environments in which no liquid lubricant is used. In oil, voltages as low as 12 V across 2.5-μm roto/stator gaps have been sufficient to operate the micromotors. Micromotor speeds up to 12500 rpm have been achieved with 110-V excitations across 1.5-μm rotor/stator gaps