Microfluidic blood/plasma separation unit based on microchannel bend structures

Most clinical chemistry tests are performed on cell-free serum or plasma. Therefore micro assay devices for blood tests require integrated on-chip microfluidics for separation of plasma or serum from blood. These requirements of a convenient and inexpensive integrated microfluidics for blood separation are achieved by novel blood/plasma separation units based on microchannel bend structures. The microchannel bend technique combines two separation mechanisms, the centrifugal force and the so called "plasma-skimming" effect. A separation unit consists of a simple microchannel arrangement with branching channels. Prototype chips with separation units have been fabricated in COC polymers by micro injection molding or hot embossing. The red blood cell separation efficiency of different separation units has been tested with human whole blood or diluted blood samples. The results show different separation efficiencies up to 100 % for blood cells affected by channel geometry and fluid properties as well. As compared to present microfluidic devices like filters or filtration by diffusion, the results suggest the microchannel bend structures as an alternative and easily implementable separation technique for lab-on-a-chip systems.