Ilene J. Busch-Vishniac
Dept. of Mech. Eng., Univ. of Texas, Austin, TX 78712
Recent attempts to build microactuators have centered on electrostatic actuators made of silicon. Three arguments have been repeatedly presented for favoring electrostatic approaches over magnetic: The stored energy densities are comparable or higher on micron scales, the efficiency can be higher, and the approach can be made compatable with semiconductor fabrication. In the work presented here, the arguments favoring electrostatic microactuators are reexamined and found to be flawed. In particular, magnetic fields are shown to be potentially greater than electrostatic fields even down to submicron scales, while the actuator efficiency is shown to be determined by the powering electronics rather than the actuator itself. Further, the need for a monolithic device based on semiconductor fabrication techniques is called into question by the incompatibility of most micromachining (3-D) and VLSI (2-D) processing steps. Other factors, such as robustness, suggest that the case for magnetic approaches to microactuators is quite strong.