Fabrication and characterization of a hybrid valve for microfluidic applications

A hybrid valve for lab on chip applications is presented. The valve is assembled by bonding poly (methyl methacrylate), PMMA, and silicon based elastomers. The process used to promote the hybrid bonding is based on the deposition of an organosilane (TMSPM) on the thermoplastic polymer which acts as interface with the elastomers. An elastomer membrane has been bonded in correspondence of the end of two microfluidic channels of a fabricated PMMA chip. Prior the bonding, a plasma etching process has been used to remove the TMSPM in specific areas of the PMMA allowing to bond only the edge of the elastomeric membrane while it is free to move in the central part. Actuating the membrane with an external pressure or vacuum is possible, respectively to obstruct or to connect the microfluidic channels of the chip. The microvalve is easy to integrate in microfluidic devices and allows the control of microvolumes of fluids in processes such as transport, separation and mixing. The deposition of the TMSPM, the bonding of the valve and its actuation has been characterized and tested. The flow rate control of liquids through the valve has been characterized. The results have been discussed and commented. The valve can stand up to 14 psi without showing leakages.