Separation of Plasma from Whole Human Blood in a Continuous Cross-Flow in a Molded Microfluidic Device

TLDR

The study designs a disposable microfluidic device that separates plasma from whole blood by size exclusion in a cross‑flow and proposes integrating it with on‑chip assays to enable low‑cost, rapid point‑of‑care diagnostics. The device is a disposable PDMS microfluidic chip fabricated from a single mold, sealed with cover glass, and operated with pulsatile pressure to maintain cross‑flow and prevent channel clogging. The device runs continuously for at least one hour, extracting about 8 % of blood volume as plasma at 0.65 µL/min with minimal hemolysis, producing assay‑grade plasma delivered within 30 s, and its integration with on‑chip assays could enable rapid, low‑volume point‑of‑care diagnostics.

Abstract

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.