Microfabricated electrostatic actuators for hard disk drives

A dual-stage servo system which utilizes a high-bandwidth secondary actuator has been proposed for magnetic hard disk drives. Microfabricated actuators are promising candidates for this secondary actuator, since they offer the benefits of extremely small size and weight and may be batch fabricated for reduced production cost, This paper presents the design of an electrostatic microactuator which produces sufficient output force to move a 1.6-mg picoslider from a conventional disk drive at frequencies above 2 kHz. A linear second-order actuation model is developed and ht to experimental data. The prototype device is shown to have an open-loop resonance frequency of 532 Hz when loaded with the picoslider, and a dc-voltage-to-position gain of 0.12 mu m/V. A closed-loop bandwidth of 2.5 kHz is achieved using a simple proportional derivative controller.