A Study of Pneumatic Microvalve with Polydimethylsiloxan Membrane

In this paper, a pneumatic microvalve with a polydimethylsiloxan membrane (PDMS) has been successfully made by the method of replica molding. Polydimethylsiloxane has been found exceptional mechanic property, including high elongation and good sealing. To make the microvale, the SU-8 negative photoresisit with the thickness of 50μm is produced by the method of exposure and develop. Then PDMS is poured on the SU-8 mold and peeled off after solidifying. Finally, the structure of PDMS combines with another by the treating of air plasma. An integrated normally open valve with a PDMS membrane has been tested. For a liquid flow, 4psi valve pressure is required to close the valve at the flowrate of 471.24 μl/min. For a air flow, 4psi valve pressure is needed to stop the air flow at inlet pressure of 4psi.Moreover, there is no leakage when the valve is closed pneumatically. Beside that, a liquid-bubble flow generator which combines the designed microvalve has been fabricated and performed. A microvalve plays a important role in a microfluidic system. The valve in this paper can be produced and combined with another component easily.