Valves for microfluidic systems have, for various reasons, proven to be difficult to fabricate, cumbersome to operate, and/or unreliable. We have explored the performance of a novel microfluidic valve formed by creating a flow channel past a Peltier junction, and developed methods for fabricating multiple such valves in an integrated device. Using the Peltier junction as a thermoelectric cooler causes the fluid in the valve to freeze, forming a plug that blocks flow through the valve. Reversing the current in the Peltier junction causes the fluid to melt, reopening the valve. This type of valve is fundamentally leak-free, has no moving parts, and is electrically actuated. We have also developed a finiteelement thermal model of the valve, and exercised it to optimize valve design. Current prototype valves have cycle times under 100 ms, and optimized valves are expected to be able to operate in less than 10 ms.
Valves for microfluidic systems have, for various reasons, proven to be difficult to fabricate, cumbersome to operate, and/or unreliable. We have explored the performance of a novel microfluidic valve formed by creating a flow channel past a Peltier junction. Using the Peltier junction as a thermoelectric cooler causes the fluid in the valve to freeze, forming a plug that blocks flow through the valve. Reversing the current in the Peltier junction causes the fluid to melt, reopening the valve. This type of valve is fundamentally leak-free, has no moving parts, and is electrically actuated. We have fabricated an experimental prototype capable of closing in less than one second, and of opening substantially faster. We have also developed a finite-element thermal model of the valve, and exercised it to optimize valve design. An optimized valve is predicted to have a cycle time on the order of 10 ms.
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