Surface micromachined leakage proof Parylene check valve

We report here a surface micromachined leakage proof Parylene MEMS check valve that has nearly ideal performance. This new check valve has a unique design that its valve membrane has a sealing ring directly deposited on, and hence in direct contact with, the gold-coated valve seat. The adhesion between Parylene and gold is studied along with the reduction of adhesion of the sealing ring to the valve seat when self-assembled monolayer (SAM) coatings are used on gold. Testing results clearly demonstrate the effectiveness of SAM coating. Experiments show that the valves have no observable leakage in the reverse flow direction up to 30 psi and a cracking pressure less than 1 psi in the forward flow direction. Integration of this valve with microchannels in a microfluidic system is also demonstrated. Testing shows the in-channel check valve also has nearly ideal performance under both forward and reverse flow.