Structural Analysis and Static Responses of Electrostatic Actuators for 3-DOF Micromanipulators in Phonomicrosurgery

While the searching for electrostatic actuators with large displacements is going on, this paper will demonstrate the parameters that influence the performances of linear electrostatic actuators. A comparison of theoretical calculations and experimental results for linear electrostatic actuators will also be presented for phonomicrosurgery. Theoretically, transverse displacement of electrostatic comb drive depends on supplied voltage, pull-in voltage, and length of spring suspension. In this study, two types of spring suspension (single beams and double-folded beams) are studied for different behaviors of linear electrostatic actuators. Normally, the folded-beam are implemented with the guilded-axis along at the center. There are still contradictions about the deflection of the single beam suspension and the folded-beam. Engineers and scientists predicted the deformations for their own designs. Some results show that the single beam can provide higher deformation, while the other reported the result for both design are relevant or higher. Calculations of stiffness and allowable transverse displacement are also compared to the simulation results among different types. The calculations are used for designing the performances of electrostatic actuators with a fitcurve for different parameters. Then, the experimental results indicate characteristics of linear electrostatic actuators for different suspension designs and different parameters. Next, these electrostatic actuators will be implemented for a 3-DOF (tip-tilt-piston) micromirror in phonomicrosurgery by using a micro-assembly approach with marker and assembly block to place three electrostatic combdrives in the precise position. With this development, MEMS-based micro-mirror designs can enhance capability of biomedical apparatus that require high speed, low power consumption, and high reliability.