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 of conventional electrostatic microac tuators associating parallel-plate configurations with rotary mode, the sha pe 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 oute r region from the center of rotation; hence force generation capability is inherently limited. To overcome the limitation of conventional rotary micro actuators and enhance the capability, a tilting configuration is invoked an d 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 curr ent fabrication technology. This study demonstrates that the proposed optim al shape integrating tilting configuration increases the force generation c apability dramatically over conventional shapes.