微机电系统光开关的扭臂式静电驱动结构设计

Design and Stress Analysis of a Torsion Electrostatic Micro-Actuator for MEMS Optical Switch

基于扭臂式静电驱动微执行器的基本模型,运用力矩法推导出该结构的Pull-in电压和角度,并设计了用于微机电系统(Micro Electronic Mechanical System,MEMS)光开关的单晶硅扭臂式静电驱动结构参数.在所选结构参数下,运用力电耦合分析方法,研究了空气阻尼作用对扭臂式静电驱动结构Pull-in电压的影响.对所设计的驱动结构,考虑空气阻尼作用时,Pull-in电压增大约7%.对单晶硅扭臂式静电驱动结构进行应力分析得到,当上下极板发生吸合时,结构应力均匀分布在上电极,且扭臂的最大内应力仅为72.848MPa,远小于单晶硅的屈服强度,整个驱动结构的设计是稳定可靠的;用力矩法推导出的该结构的Pull-in电压适用于该微静电驱动系统.研究结果为扭臂式微驱动器参数选择提供了依据.

Based on the model of torsion electrostatic micro-actuator,the pull-in voltage and pull-in angle of the torsion electrostatic micro-actuator were derived using the method of moment.Then,based on it,reasonable parameters were designed for the torsion electrostatic micro-actuator to be used for a MEMS optical switch.Taking the influence of air damping into account,the electro-mechanical coupling method was used for accurate analysis of the torsion electrostatic micro-actuator.The result shows that the pull-in voltage increases over original data by 7% when considering the effect of air damping.Finally,stress analysis showed that the stress distributed evenly on the top electrode when the top electrode touches bottom electrode.The largest stress of the torsion beam was 72.848 MPa,which was far less than the yield strength of Si.So the actuator is stable and can bear the effect of the gravity and electrostatic force.The pull-in voltage derived by the method of moment for this structure is applicable for the micro electrostaticsystem.This paper offers a good method for parameter selection of torsion electrostatic micro-actuator.