Analysis on the sticking failure of micro-comb driving structure

As an important part of MEMS, the micro-comb electrostatic driving structure is the main source of mechanical movement in many MEMS devices. Its reliability will directly affect the using performance of the MEMS devices. The electrostatic driving system of micro-comb capacitive micro-machined gyroscope can be equivalent to a second order system. If the applied voltage is less than the pull-in voltage, the movable micro-comb will maintain a steady state. Otherwise, the micro-combs will stick together because the applied voltage is greater than the calculated pull-in voltage. If the distance between micro-combs is too narrow, the role of these micro forces will be very significant. The pull-in phenomenon occurring in the process that the micro-machined gyroscope is applied on a phase step input voltage will lead to the very narrow comb spacing. As a result that the role of micro-forces such as the capillary force, Van der Waals force and Casimir force will become very significant, and the micro-combs will stick together permanently.