Characterization and analysis of vertically comb-driven micromirrors

Because of their simple structure, IC compatibility, and large force output per unit energy, electrostatic micromirrors have been widely used in displays, barcode scanning, optical switches, endoscopes and so on. Among the electrostatic micromirrors, vertically comb-driven micromirrors have drawn more attention recently, due to low driving voltage for achieving large angular motion, lower abrasion consumption, and less pull-in effect. However, the existence of dimensional uncertainty due to the fabrication imperfection, the electrostatic-structural coupling effect, and the nonlinearly dynamical behavior of the vertically comb-driven micromirrors result in that the devices cannot be precisely characterized and well analyzed. Consequently, the applications of the devices may be limited because of unable to accurately grasp its dynamics. In order to characterize the vertically comb-driven micromirror, this paper analyzes the dynamics and the mechanical properties, including its damping ratio, stiffness, and resonant frequency. For verification, the finite element software (ANSYS) was employed to perform the simulation. ANSYS and CoventorWare software were used and experiments were conducted to verify the results.