A novel shape design of the comb drive to achieve digital switches while avoiding the unstable pull-in is presented. The statics and dynamics of switching are discussed and the voltage- displacement-transfer characteristic is demonstrated. The degradation of the transfer characteristic can be caused by either the overshoot of actuators in the transient switching or the actuator geometry. An optimal design of the actuator geometry is proposed to improve the quality of the transfer characteristic. On the other hand, the settling time of the comb drive's transient response to a step excitation will be minimized for high-speed switches. To achieve this, two non-dimensional control parameters are identified and physically interpreted. Then a transient optimization is carried out by introducing an optimal electrical damping and choosing a zero static comb overlap. The optimal transient response is obtained by analytically solving the linearized force/moment and electric equations. Finally numerical simulation is performed to verify the analytic solution and extend the analysis to the nonlinear regime.
Yijian Chen, Yijian Chen,
"Control and shape design of an electrically damped comb drive for digital switches", Proc. SPIE 4178, MOEMS and Miniaturized Systems, (22 August 2000); doi: 10.1117/12.396512; https://doi.org/10.1117/12.396512