Optimal shape design of a rotary microactuator

Optimal shape designs of electrodes based on parallel-plate configurations are proposed for an electrostatic rotary microactuator to enhance actuating force generation capability. In most conventional electrostatic microactuators associating parallel-plate configurations with rotary mode, the shape of electrodes have not been rigorously evaluated in terms of optimality and straight shapes were simply adopted. As a result, two facing electrodes are spaced in the way of leading to relatively large clearance at the outer region from the center of rotation; hence force generation capability is inherently limited. To overcome the limitation of conventional rotary microactuators and enhance the capability, a tilting configuration is invoked and integrated into the optimal shape, which allows the gap size between two facing electrodes to be as small as the minimum gap size achievable by current fabrication technology. This study demonstrates that the proposed optimal shape integrating tilting configuration increases the force generation capability dramatically over conventional shapes.