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Extracting Analytes with the H-Filter

Previously the Yager lab developed a pump-driven microfluidic device called the H-filter, which allowed extraction of small analytes from complex samples. Separation of two species and subsequent extraction of a purified solution of the faster-diffusing species can be achieved when one inlet contains a mixed sample and the other a collection buffer. The efficiency of the extraction depends onthe diffusion coefficient of each species, the contact time, and the dimensions of the common channel; no intervening membrane is required as long as the Reynolds number in the device is low. We recreated the classic H-filter in a 2DPN shown below.

The paper H-filter was used it to separate a small molecule (yellow dye) from a large molecule (blue protein). The yellow extract was recovered by simply cutting out the yellow part of the 2DPN outlet. Paper H-filters could be used to extract analytes from complex samples for downstream analysis.

For more information on the paper H-filter see:

“Microfluidics without pumps: reinventing the T-sensor and H-filter in paper networks,” Lab on a Chip (2011).

Jennifer L. Osborn, Barry Lutz, Elain Fu, Peter Kauffman, Dean Y. Stevens, and Paul Yager.

Department of Bioengineering, University of Washington, Seattle, WA, USA

Original microfluidic H-filter:

“A planar microfabricated fluid filter,” Brody, Osborn, Forster, and Yager. Sensors and Actuators A (Physical), A54 (1-3), 704-708, (1996).

“Microfluidic diffusion-based separation and detection,” Weigl and Yager. Science, 283 (5400), 346-347 (1999).