Analysis of fluid flow and deflection for pressure-balanced MEMS diaphragm valves

Based on the linear plate theory for an elastic thin plate and the Bernoulli equation for a steady incompressible and inviscid fluid flow, the effect of fluid flow on the deformation of microelectromechanical systems (MEMS) diaphragm valve is investigated both analytically and numerically. For a given configuration of diaphragm valve, a relationship between the applied pressure and resulting contact area between diaphragm and valve seat is derived. Possible instability of such a system under the pressure-balanced mechanism is demonstrated with both analytical and numerical solutions for the deflection. Deflection as a function of flow speed, radius of outlet orifice, inlet gap, and bending stiffness of diaphragm are presented. In addition, the effect of diaphragm making contact with the valve seat due to pressure differential and fluid flow is analyzed and a relation between the contact zone and the external pressure is obtained. The results of the analysis suggest important parameters in the design of MEMS diaphragm valves and can be used as a basis in the design of such valves.