Hamid Moeenfard۱ - School of Mechanical Engineering, Sharif University of Technology;
Ali Darvishian
Hassan Zohoor
Mohammad Taghi Ahmadian۴

The Current paper study the static pull-in of electrostatically actuated micromirrors under the effect of van der waals (vdW) force. first of all, the problem is modeled using energy method, the principal of minimum total potential energy. Then the stability of static equilibrium points is analyzed using the energy method. It is found that when there exist two equilibrium points, the smaller one is stable and the larger one is the unstable. Then the dependence of the mirror’s pull-in angle and pull-in voltage on several design parameters of the mirror are investigated and it isfound that vdW force can considerably reduce the stability limit of the mirror. At the end the nonlinear equilibrium equation is solved numerically and analytically using Homotopy Perturbation Method (HPM). It is observed that a sixth order perturbation approximation can precisely model the mirror’s behavior. The results of this paper can be used for stable design and safe fabrication of torsional nano/micro actuators

Nano/micromirror, Electrostatic actuation, vdW force, Pull-in. Homotopy Perturbation Method(HPM)