Analysis of the dynamic behaviour of a torsional micro-mirror

In this paper, the results of the dynamic pull-in voltage characteristics of a micro-mirror using electrostatic actuation are analyzed. Based on torsional dynamic theory, appropriate equations are developed that allowed to give insight into the actuating voltage, switching time and other dynamic parameters. The analytical results are discussed in detail without and with considering air squeeze film damping, respectively. This is equivalent to assuming the mirror is operated in vacuum or at ambient pressure. When the effect of the damping is considered, the movement trajectory of the cantilever beam is changed, and the calculated results of the pull-in voltage and switching time are considerably different compared to those without considering damping. Therefore, the effect of the air squeeze film damping is an important factor in the design and fabrication of micro-electro-mechanical systems. Finally, the experimental results in the air environment are discussed and compared to the theoretical analysis.