Teflon-seated one-lambda microvalves for PDMS chips

We have fabricated and tested minimum sized (25times25 mum²) pneumatic valves that can be easily integrated within two-level PDMS microfluidic chips. Minimum valve footprint is achieved through the reduction of the valve gap (0-3 mum) and the incorporation of an anti-stiction teflon valve seat that prevents the bonding of the valve diaphragm during chip assembly. The pneumatic teflon-seated valves can be actuated with a pressure differential of 25 PSI using conventional PDMS control valve hardware. The microvalve flow resistance of 3.5 PSImiddotsmiddotL^-1 was estimated from flow visualization measurements The microvalves can switch flows up to 5 Hz frequencies.