Passive microfluidic gas valves using capillary pressure

Abstract

In this study, we developed micro gas valves which can control the gas pressure inside microfluidic systems in a simple and passive way. We designed a microfluidic chip having a liquid reservoir, a gas chamber and a microchannel connecting them to demonstrate both a micro relief valve and a micro regulator on a chip. We fabricated and tested the microfluidic chip to check the feasibility of the proposed micro valves. Test results show that when the gas pressure is greater than the relief pressure the micro relief valve discharges the gas decreasing the system pressure down to the atmospheric pressure. Also, the micro regulator kept the system pressure constant regardless of the degree of the over-pressure at pressure source. The proposed valves would be good candidates for cheap and reliable gas pressure controller in various microfluidic systems using gases.

Passive Control of Viscous Flow via Elastic Snap-Through

“…These properties may find application in microfluidic systems such as cell-sorting or, as we have shown, provide a means to protect microfluidic systems from high fluxes. Similarly, the discontinuous transition we observe is similar to that seen in capillary burst valves [27] and gas release valves [28]. A simple analysis [30] shows that when scaling down to the microscale, the expected range of snap-through fluxes are well within experimentally obtainable values.…”

A Magnetically Tunable Check Valve Applied to a Lab-on-Chip Nitrite Sensor

“…The Tesla valve, for example, uses an in-channel geometric pattern to increase fluidic resistance in one direction and not the other [15]. Passive valves can also be made by exploiting capillary pressure differences in microchannels [16], or by using an air bladder to create a capillary stop-valve [17]. Other types of valves include using comb-like structures [18] or centrifugal elastic valves [19].…”