Design and simulation of a MEMS analog micro-mirror with improved rotation angle

This paper presents design and simulation of a MEMS analog torsional micro-mirror with improved rotation angle. The working range and consequently the rotation angle limitation of electrostatically actuated torsional micro-mirror due to pull-in instability are solved. Pedestal and suspension beams are presented to achieve electrostatically actuated torsional micro-mirror with extended working range. In the electrostatically actuated torsional micro-mirror, increasing the applied voltage decreases the equivalent stiffness of the structure and leads the system to an unstable condition by undergoing to a saddle node bifurcation. In the proposed structure to eliminate pull-in instability and increase the rotation angle range, mechanical stiffness of the structure is increased by adding a pedestal and locating auxiliary fixed-free beams in the free ends of the micro-mirror. The governing equations in relation to the proposed structure are derived. To verify, the numerical results are compared with simulated results.