Polysilicon angular microvibromotors

Two types of LPCVD polysilicon angular microvibromotors were designed, fabricated, and successfully operated in air and in vacuum. Each utilizes an electrostatically driven lateral resonant structure (the converter) to actuate a circular microrotor by means of oblique mechanical impact. Oscillatory linear motion is consequently converted into continuous angular motion. The microrotors are fabricated both 60 and 100 μm in diameter and are restrained at the center by a polysilicon hub. The converter tips are retracted by electrostatic comb drives and are propelled forward toward the rotor by elastic forces generated by folded beam flexures at frequencies ranging from 10 to 20 kHz. A preliminary measurement has shown the rotor to be driven at speeds as high as 60000 r/min. The rotors were operated both in low vacuum and in air. One operated continuously for as long as 4 h with no significant wear or degradation of performance. These polysilicon vibromotors have applications as high-response micromanipulators or positioners