A PDMS-based gas permeation pump for on-chip fluid handling in microfluidic devices

We demonstrate a non-contact pumping mechanism for the manipulation of aqueous solutions within microfluidic devices. The method utilizes multi-layer soft lithography techniques to integrate a thin polydimethylsiloxane (PDMS) membrane that acts as a diffusion medium for regulated air pressure and a vacuum. Pressurized microchannels filter air through the PDMS membrane due to its high gas permeability causing a pressure difference in the liquid channel and generating flow. Likewise, a vacuum can be applied to pull air through the membrane allowing the filling of dead-end channels and the removal of bubbles. Flow rates vary according to applied pressure/vacuum, membrane thickness and diffusion area. A gas permeation pump is an inexpensive alternative to other micropumps. The pump is easily integrated with highly arrayed multi-channel/chamber applications for micro-total analysis systems, fluid metering and dispensing, and drug delivery. Flow rates of 200 nl min(-1) have been achieved using this technique. Successful localized fluid turning at intersections, fluid metering and filling of dead-end chambers were also demonstrated.