An in-channel micro check valve fabricated using a simple two-mask process

Check valves play a pivotal role in many microfluidic and lab-on-chip systems. Many of these check valves are out of plane and are not integrated with microchannels. To address this issue we proposed an in-channel micro check valve design which enables a simple fabrication process and provides easy integration with other microfluidic devices. Parylene C was used as the structural material of the gate for the check valve. Due to the high flexibility of the parylene C gate, we can achieve a high flow rate with a relatively low pressure. Also due to the perfect position of our parylene gate, only minimal reverse flow (~1nl/min) was observed at reverse pressures as high as 50kPa.