High-performance shuffle motor fabricated by vertical trench isolation technology

Abstract

Shuffle motors are electrostatic stepper micromotors that employ a built-in mechanical leverage to produce large output forces as well as high resolution displacements. These motors can generally move only over predefined paths that served as driving electrodes. Here, we present the design, modeling and experimental characterization of a novel shuffle motor that moves over an unpatterned, electrically grounded surface. By combining the novel design with an innovative micromachining method based on vertical trench isolation, we have greatly simplified the fabrication of the shuffle motors and significantly improved their overall performance characteristics and reliability. Depending on the propulsion voltage, our motor with external dimensions of 290 ±m × 410μm displays two distinct operational modes with adjustable step sizes varying respectively from 0.6 to 7nm and from 49 to 62nm. The prototype was driven up to a cycling frequency of 80kHz, showing nearly linear dependence of its velocity with frequency and a maximum velocity of 3.6mm/s. For driving voltages of 55V, the device had a maximum travel range of ±70μm and exhibited an output force of 1.7 mN, resulting in the highest force and power densities reported so far for an electrostatic micromotor. After five days of operation, it had traveled a cumulative distance of more than 1.5km in 34 billion steps without noticeable deterioration in performance. © 2010 by the authors.