Microfluidic inertial switch with delay response characteristics

Abstract

This paper proposes an innovation microfluidic inertial switch structure with precise time delay response characteristic, which can be used in the fuze safety and arming system. The switch works on the principle of fluidic inertial force and capillary valve, which makes it sensitive to the unidirection acceleration load and has the ability to recognize the acceleration amplitude. The microfluidic inertial switch has a structure of a J-shaped reservoir, capillary valves, a serpentine delay microchannel and a U-shaped latching microchannel. The acceleration threshold is analyzed theoretically considering the surface tension coefficient of the gas-liquid interface. The delay response time of the switch is studied by finite element simulation based on the Gambit 2.4 and Fluent 6.3 software. The prototype is fabricated by wet etching technology and magnetron sputtering metal technology. Many tests have been done to verify the functions of the switch. The experimental results are matched well to the results of calculation and simulation. When the capillary valve throat widths are 80μm, 120μm, 160μm, the thresholds of the switch are 75.1g, 46.6g, 36.5g. When the switch is loaded with a 75g acceleration load, the delay response is 146.7ms. Finite element simulation and experimental results show that the switch can effectively identify the acceleration threshold, and can achieve a precise delay response under a certain load.