Microfabricated PDMS Check Valves

This paper presents two types of novel micro check valves that are based on PDMS. The valves consist of a thin flap and a flow restriction block inside a microchannel. The flap is perpendicular to the flow and lies near the block, which forms a restricted fluid path inside the channel. The valves are fabricated entirely from PDMS through replica molding techniques and can be readily integrated in PDMS-based complex microfluidic systems. Testing results show that for a reverse flow, the 2D valve has a saturated leakage rate at higher pressures, leading to an interesting “fluid diode” phenomenon, while the 3D valve has zero leakage at higher pressures.