Quasi-static Pull-in Analysis Of Torsional Electrostatic Microactuator

Miniaturization has always been the important direction in the development of modern science and technology currently. With the development of microelectronics technology, micro-actuators are growing rapidly based on the micro-sensors of MEMS (micro-electromechanical system) technology. Among their various actuation methods, electrostatic actuation is the most important method and therefore it is necessary to study the electrostatic micro-actuators. In the process of studying electrostatic micro-actuators, there is a quick pull-in phenomenon, which is also known as pull-in instability phenomenon, and which is an important feature of the electrostatic micro-actuators. Presently, many people at home and abroad are studying the pull-in instability problem of electrostatic micro-actuators, but the study of taking into account the fringing field effect of electrostatic micro-actuators can be negligible. As the sensitivity of miniaturizational devices increases, it is very necessary to obtain accurate data of pull-in points.Based on the analysis of the research work at home and abroad, this paper presents the analysis of the pull-in instability phenomena of electrostatic micro-actuator in the use of energy method. The fringing field effect is taken into account in the model of electrostatic torsion micro-actuator in order to establish more realistic physical model. By comparing with the results of the ANSYS software, the accuracy of model can be demonstrated.Firstly, the pull-in mechanism of electrostatic micro-actuator is introduced by solving the pull-in parameters without considering the fringing field effect in this paper. It focuses on analyzing the control and influence of the different electrode positions relative to the plate of electrostatic torsion micro-actuator on pull-in parameters.Then it presents the influence of ignoring the fringing field effect on the micro-actuator pull-in parameters. And the model of the fringing field capacitances are set up. The relevant data of pull-in phenomenon are obtained in the case of taking into account the fringing field effect. The impact of the change of the micro-actuator parameters on the pull-in voltage and pull-in point is investigated through analyzing the cases. Finally, electrostatic torsion micro-actuator structure is established by ANSYS finite element analysis software. The actual data are obtained by taking into account the fringing effect between the upper and lower plates. Comparing with the data from the solve of model, the accurate of model is showed and the scope of model is given.