Design and development of SU-8 check microvalve based on MEMS technique

The SU-8 microvalve was fabricated by micro electro mechanical systems (MEMS) technique to solve one of stumbling blocks for liquid to flow in one way and lab on chip to miniaturize successfully. There exist some advantages such as low Young modulus and elastic constant, little turn-on pressure, low reverse leakage, fabrication easy and so on. Displacement and stress of microvalve with four thicknesses (10 μm, 15 μm, 20 μm and 25 μm) were discussed theoretically under different pressures. The displacement of SU-8 microvalve is 10 times greater than that of silicon microvalve with the same structure and pressure. Flow characteristics and resonance frequency were investigated under condition that microvalve work in the air and the damping environments. The performance of microvalve is influenced remarkably by dimension of microvalve's structure. Forward and backward flow characteristics were tested by experiment and fabrication processes were presented. The flow curves of three thicknesses of microvalve were achieved under different forward and backward pressure difference when using water as working media, and the maximal forward flow rate reached 7000 μL/min.