Quantitative assessment of dielectrophoresis as a micro fluidic retention and separation technique for beads and human blood erythrocytes

In order to provide important quantitative information on particle retention by dielectrophoresis (DEP), we performed systematic quantitative experiments with both, polystyrene beads (with diameters of 500 nm, 2 µm and 6 µm) and erythrocytes (red blood cells, diameter approximately 6 µm) in buffers with various conductivities. We determined the cross-over frequencies for these systems. We demonstrated the retention of beads and red blood cells and the separation of beads with different sizes in micro fluidic flow-through devices utilizing syringe pump activated pressure-driven flow. For the first time we provide important quantitative data regarding the maximum allowed flow velocities in DEP retaining devices for beads and red blood cells. We also roughly estimated the active DEP forces from the experimental data. Based on the results of our experiments, we present a device idea.