Microchip-based plasma separation from whole blood via axial migration of blood cells.

Highly efficient cell-free plasma separation from 200 µL of human whole blood was realized via axial migration of blood cells and cross-flow filtration in a microchip. Although various analyses of small volumes of blood have been reported, a large volume of blood is necessary for obtaining blood cells and plasma for the conventional plasma separation technique of centrifugation. A highly efficient plasma separation method using small volumes of blood without hemolysis is an important issue. We developed a plasma separation method based on a microchip with a filter, which utilizes the axial migration of blood cells observed in blood vessels. Clogging and hemolysis on the filter can be prevented by the axial migration of the blood cells. Using this method, 65% of the plasma from 200 µL of whole blood was successfully separated without hemolysis. When the plasma separation microchip interfaced with a micro-ELISA system was applied to C-reactive protein (CRP) analysis, the CRP concentration obtained by the microchip showed good correlation with that obtained by conventional centrifugation. Total analysis time, including plasma separation, was achieved in only 25 min.