We designed, fabricated, and tested a microfluidic device for separation of plasma from whole human blood by size exclusion in a cross-flow. The device is made of a single mold of a silicone elastomer poly(dimethylsiloxane) (PDMS) sealed with a cover glass and is essentially disposable. When loaded with blood diluted to 20percent hematocrit and driven with pulsatile pressure to prevent clogging of the channels with blood cells, the device can operate for at least 1 h, extracting approx8percent of blood volume as plasma at an average rate of 0.65 (mu)L/min. The flow in the device causes very little hemolysis; the extracted plasma meets the standards for common assays and is delivered to the device outlet approx30 s after injection of blood to the inlet. Integration of the cross-flow microchannel array with on-chip assay elements would create a microanalysis system for point-of-care diagnostics, reducing costs, turn-around times, and volumes of blood sample and reagents required for the assays.
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