Research On New Microfluidic Inertia Switch

Traditional mechanical fuze is becoming smaller, smarter and more intelligent. As an important component of fuze, the electrical connection switch is hunger to get a technical update. With the features of small size, light weight, strong anti-overload capability and large scale production, MEMS provides applicable technology for the research of the new type electrical connection switch. On the base of MEMS, a new type electrical connection switch, with liquid media is designed in this thesis. It has the ability of distinguishing acceleration loads of normal lunch and service drop situation.According to the research background, advantages and disadvantages of micromechanical and microfluidic switch designed domestic and foreign are analyzed, and a new design goal is proposed. A theoretical model is established which is based on the microscale effects and mechanical features of liquid. On the basis of fluid mechanics theory and finite volume numerical solution, software such as Gambit and FLUENT are used to improve the simulation results. A new type ultra-low temperature conductive liquid is made up to solve the problems of solidification of liquid at an ultra-low temperature and corrosion of electrodes in long storage period.Air-cushion principle is first brought into microfluidic switches, and it makes the switch smaller and solves the liquid dispersion problem. Drainage principle is used to solve the bubble problem when the liquid soak the electrodes. Structure of the switch is improved to ensure the stable connection of electrodes. Redundant safety circuit is designed for the switch to prevent false triggering in some unknown situation during storage and transportation, and it can also be used to check if the switch works.PC (polycarbonate) is selected as the base material according to the design requirements. With proper surface treatment, PDMS (polydimethylsiloxane) can get same surface properties as PC. So PDMS is used to replace PC in testing the ability of soak-and-retain structure. However, due to the soft texture of PDMS, it can’t be used in the loading test.Some experimental devices are produced to test the actual resistance of the new conductive fluid. Resistance of the switch is indirectly obtained according to the electrode area. Soak-and-retain ability of the switch is tested on the rotary bench, and the results are well matched with the software calculation. The actual effect of redundant safety circuit is tested too.