A thermally actuated microfluidic relay valve

This work demonstrates a new 2-stage valving concept for microfluidic systems based on polydimethylsiloxane (PDMS) that uses the reversible gelation of a thermally responsive polymer solution in a control channel to deflect a membrane into the main flow channel for flow control. This method can control flow through a system of PDMS channels using integrated electric heating elements and only one control pressure source, compared to the off-chip pressure manifold needed in existing systems. This valve technology therefore enables the formation of portable diagnostics tools for biomedical applications and environmental monitoring allowing on-site analysis. Valves with zero leakage rates and a response time of about 5 seconds have been achieved.