Low-friction large step-size micromotor driven by a scratch-drive actuator with bounceback mechanism

摘要

This study presents a rotary micromotor with low-friction and large-step displacement driven by a scratch drive actuator (SDA) with bounceback driving mechanism. The present SDA device has a shorter plate and wider bushing compared to those of the existing SDA, resulting in a new electrostatic scratch-and-bounceback driving mechanism with larger stepping size. The new scratch-and-bounceback actuating mechanism markedly reduces the friction and damping effect between the SDA plate and the nitride insulator surface and eliminates effectively the sudden reverse rotation of SDA-based micro rotary motor. This investigation incorporated three design features (corners-rounded supporting-beam, flanged cover, and corrugated/ribbed/dimpled inside ring) into the structure of a SDA-based rotary micromotor to further decrease the rotating abrasion between the rotor inside ring and the cover, the anchor, and the inside rail. The bouncing SDA-based micromotors developed in this work (with 398 μm diam) were fabricated using the MEMSCAP? Poly-MUMPs process and achieved many improvements, including low friction, large stepping size (196 nm), small damping effect, and no sudden reverse rotation phenomenon (from dc to 25 kHz).