Study On The Design And Preparation Process Of Electrostatic Locking MEMS Inertial Switch

MEMS inertial switch has the characteristics of compatibility with convenience and flexibility,low cost and no power consumption in the condition of constant duty.With the further development of the Internet of things,MEMS inertia switch as a passive devices have been widely concerned in microelectronics applications.It can be widely used in networking system to monitor the vibration impact from the environment,and issue corresponding overload warning signals,especially for remote,harsh environment,implanting equipment and power consumption demanding application scenarios.When the vibration shock is applied in the sensitive direction of the MEMS inertial switch,the movable electrode moves in the direction of the fixed electrode under the action of inertia force.When the applied acceleration exceeds the threshold acceleration of the device,the movable electrode collides with the fixed electrode,and at the same time,outputs a pulse signal.The quality of contact is an important criterion to evaluate the performance and stability of MEMS inertial switch: the level of integration and the safety and reliability of the trigger depend on the contact performance of the electrodes.Too short contact time will make the analog circuit which is used to process the signal very complex.Many researchers have carried out relevant research on the promotion of collision performance,in which the schemes to prolong the contact time of the devices are mostly through the structure design.Prolonging the contact time is considered as an important technical way to improve the performance of the collision and optimize the performance of the device.In this paper,two kinds of electrostatic MEMS inertial switch are designed: the design I with reinforcing rib structure and II with flexible connection multi-plane moving electrodes.The design structure is theoretically analyzed,and the effect of static electric power on the performance parameters of the device is summarized.The analysis shows that the device can have many functions such as multi-threshold vibration detection,prolonging the contact time,detecting vibration and electrostatic locking function.The finite element simulation analysis of the design structure is carried out.The dynamic response process and the main performance parameters are obtained,including modal analysis,anti-overload performance,threshold acceleration and contact time.The standard drop hammer system is used to test the performance of the fabricated devices.The test results show that the contact time of the device with the designed I structure is extended to 192 ?s and 336 ?s when the voltage is 8V and 15 V.When the voltage is 8V and 15 V,the contact time of the device with the designed II structure is extended to 264 ?s and 540 ?s,and the electrostatic locking function is realized when the voltage is 25 V.The results of the test are in good agreement with the simulation results,and the function of static electricity to prolong contact time and to realize electrostatic locking is verified in the design.By introducing the effect of static electricity in MEMS inertial switch,adjusting voltage size and external applied acceleration load size,the function of the multi-threshold continuous inertial impact testing,contact time prolonging,judgment of whether the impact occurs and electricstatic locking.