Dynamic characterization of a linear electrostatic micromotor supported on microball bearings

We report the dynamic characterization of a six-phase, bottom-drive, linear, variable-capacitance micromotor (B-LVCM) supported on microball bearings. The B-LVCM was fabricated and tested using a new test-bed. The motion of the micromotor was captured using low- and high-speed video cameras, tracked using image processing software, and analyzed to obtain the instantaneous velocity (11 mm/s), acceleration (1.9 m/s2), and net force (0.19 mN) (all in amplitude) from the position data. The predicted (simulated) and measured net forces at different applied voltages are in good agreement. The micromotor was then modeled as a mass–spring–dashpot system and the lumped parameters were extracted from position measurement. This characterization methodology provides an understanding of the dynamic behavior of both the variable-capacitance micromachines and the microball bearings on which they are supported.