Separation of plasma from whole human blood in a continuous cross-flow in a molded microfluidic device.

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 20% 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 approximately 8% of blood volume as plasma at an average rate of 0.65 microL/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 approximately 30 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.