A passive through hole microvalve for capillary flow control in microfluidic systems

A passive through hole microvalve is proposed to stop the capillary-driven flow in microchannels with small static contact angle (θs < 45°). Its gating condition on regulating flow is derived based on contact line theory. Using numerical simulations in certain limits and some experiments, we investigated the valve performance of a few different valve designs. A kind of converging through hole microvalve is found which can stop the relative faster capillary flow and is easier to fabricate and integrate. It is shown that allowable flow velocity for DI water could reach 0.5 m/s, and the height of microvalve could be as short as to 20 μm.