Simple Check Valves for Microfluidic Devices

NASA’s Jet Propulsion Laboratory, Pasadena, California A simple design concept

NASA's Jet Propulsion Laboratory, Pasadena, California

A simple design concept for check valves has been adopted for microfluidic devices that consist mostly of (1) deformable fluorocarbon polymer membranes sandwiched between (2) borosilicate float glass wafers into which channels, valve seats, and holes have been etched. The first microfluidic devices in which these check valves are intended to be used are micro-capillary electrophoresis (microCE) devices undergoing development for use on Mars in detecting compounds indicative of life. In this application, it will be necessary to store some liquid samples in reservoirs in the devices for subsequent laboratory analysis, and check valves are needed to prevent cross-contamination of the samples. The simple check-valve design concept is also applicable to other microfluidic devices and to fluidic devices in general.

A typical sequence for fabricating a microfluidic device for the original intended microCE application includes the following steps:

The ideal cut for forming a check-valve flap is an arc somewhat greater than a semicircle but less than a full circle. The resistance to flow through the check valve can be reduced by increasing the arc length of the punch. It is worth emphasizing that implementation of this concept entails nothing more than the use of additional punches for forming the flaps in the fabrication process.

This work was done by Peter A. Willis, Harold F. Greer, and J. Anthony Smith of Caltech for NASA's Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Mechanics/Machinery category. NPO-45933

(reference NPO-45933) is currently available for download from the TSP library.

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This article first appeared in the May, 2010 issue of NASA Tech Briefs Magazine.

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Simple Check Valves for Microfluidic Devices