Planar Microfabricated Check Valves Utilizing Large Compliance of PDMS

This paper presents three types of planar check valves that uniquely exploit the large compliance of simple PDMS structures. The micro check valves consist of a thin compliant flap and a rigid stopper embedded in a microchannel. The flap is perpendicular to the flow and lies near the stopper, forming a restricted fluid path inside the channel. In particular, a novel “zero flap-stopper gap” valve design was proposed and fabricated using a special technique, in which the flap and stopper are in contact naturally forming a normally-closed device with high diodicity. Testing results show that the check valves can achieve a diodicity up to 105. The check valves can be fabricated using the standard replica molding technique from PDMS, and thus are highly amenable to integration with other PDMS-based microfluidic systems.