MEMS Inertial Switch for Military Applications

Abstract

We developed a MEMS inertial switch (hereafter, the switch) for an ignition system of missiles. The developed switch consists of four folded beams and a plate suspended by the beams, analogous to a well-known spring-mass system. The plate and four beams compose a single body, which is made from single crystalline silicon wafers by deep reactive ion etching techniques. This process gives high thermal stability and stress-free structure. The switching, either open or close a conductive path, is achieved by the movement of the plate suspended with four folded beams when the acceleration exceeds a predetermined threshold. With a spinning-rate table, the function of the switch was tested at various revolution speeds. The test results are compared with the calculation results by our analytical model.

Research Status and Development Trend of MEMS Switches: A Review

“…On the other, low-g inertial switches, widely used in the aviation and automotive industries, have acceleration responses ranging from several milli g to hundreds of g. Based on a feasibility study, Lior et al [84] proposed an idea of using a pair of bistable beams to suspend the proof mass and to sense the acceleration, in which the switch can be closed under sub-g inertias. Nam Lee et al [85] have developed an inertial switch with a threshold acceleration of no more than 10 g, and it can withstand unexpected shocks of up to 1000 g, making it suitable for harsh military environments. Rigid electrodes of MEMS switches have the problems of short contact time and signal bounce.…”

“…Based on a feasibility study, Lior et al [ 84 ] proposed an idea of using a pair of bistable beams to suspend the proof mass and to sense the acceleration, in which the switch can be closed under sub- g inertias. Nam Lee et al [ 85 ] have developed an inertial switch with a threshold acceleration of no more than 10 g , and it can withstand unexpected shocks of up to 1000 g , making it suitable for harsh military environments.…”

Micromachined threshold inertial switches: a review

“…The inertial switch is turned on when the missile is subjected to an acceleration at or above a predetermined threshold level. Lee et al [25] reported a MEMS switch that is applicable to the safe-and-arm device of a rocket motor ignition system for cold launched missiles. The main goal of the work is to realize a MEMS inertial switch, which can be triggered at a low-g level (about 10g) in the sensitive direction.…”

“…Therefore, micromachined inertial switches are designed for variety of different threshold levels, which can be applied to various applications. We can classify two main categories according to the threshold levels [23][24][25][26]: the relatively high-g (i.e. 100 g, 1000 g) switch and the low-g switch (i.e.…”

An Improving Model on Contact Time of The Inertial Impact Switch

“…The inertial impact switch is widely used as the priming control unit in fuze field. In the electromechanical trigger fuze, the inertia switch is used to control the working state of the first generation explosive element while it is used for the fuse proximity failure and landing backup firing in the shell radio fuze [1][2][3]. Due to the complex heat treatment process of materials, spring wire diameter , structural design as well as the adverse ballistic environment, most switches failure within the threshold range [4].…”