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

Abstract

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.

Microvalves and Micropumps for BioMEMS

“…Unfortunately, the pump's pumping rate decays exponentially with time as the air reservoir gets gradually refilled (operation times of >15 min were reported). In 2006, Bruce Gale's group at the University of Utah designed a different pump based on similar principles [117]. Here the idea was to inject air into microchannels at very small rates such that the air can in turn push plugs of fluids around (Figure 38).…”

“…Figure 38. Diffusion-based membrane pumping by gas permeation micropump for applied pressure (a) and vacuum (b) (from Eddings et al [117]). Figure contributed by Bruce Gale.…”

On the fabrication of PDMS micromodels by rapid prototyping, and their use in two‐phase flow studies

“…These techniques involve oxygen plasma [Duffy et al, 1998[Duffy et al, , 1999, corona discharge [Haubert et al, 2006], partial curing of PDMS in an oven [Go and Shoji, 2004;Eddings and Gale, 2006], use of a curing agent [Samel et al, 2007], and stamp/stick [Satyanarayana et al, 2005]. We tried two techniques : oxygen plasma and corona discharge.…”

Elastomer Application in Microsystem and Microfluidics

“…Elasticity of PDMS minimizes its stress relaxation and creep effect, which is severe in other polymer with low elasticity. The excellent elasticity of PDMS allows to release from microfluidic masters without damaging PDMS device 18,19 and significant deflection to occur when a pressure difference develops 20 . Therefore, it is important to characterize PDMS elasticity and understand how to improve such property for various applications.…”

“…Permeability has been employed to fabricate non-contact pump for the manipulation of aqueous solutions within PDMS microfluidic devices 20 or supply oxygen for large-scale culture of hepatocytes 31 . On the other hand, PDMS permeability limits its application to microfluidic technology, in which coating such as glass-like layer using sol-gel chemistry is developed on PDMS to minimize permeability 32 .…”