Continuous erythrocyte removal and leukocyte separation from whole blood based on viscoelastic cell focusing and the margination phenomenon.

The removal of erythrocytes from whole blood is an essential step during sample preparations intended for biomedical analyses and clinical diagnoses. To address the limitations of present methods, such as centrifugation and chemical lysis, we propose a novel microfluidic device for erythrocyte removal with high-efficiency and leukocyte separation from bulk flows of highly concentrated erythrocytes using a viscoelastic non-Newtonian fluid. The proposed device is designed based on the principle of viscoelasticity-induced particle migration toward the center of the microchannel. In addition, we based the functionality of our device on a bio-inspired phenomenon known as margination according to which erythrocytes migrate to the axial center of blood vessels. Fluorescent particles (10 μm) were added to blood suspensions of various concentrations (hematocrit) of erythrocytes in viscoelastic polymer solutions. Optimal hematocrit and flow rate conditions were determined for erythrocyte removal and for the separation of 10 μm particles. We also demonstrated the capability of our device to separate leukocytes with high efficiency (˜94%) and with a high-enrichment factor (10-fold).