Continuous-flow particle and cell separations in a serpentine microchannel via curvature-induced dielectrophoresis

Particle and cell separations are critical to chemical and biomedical analyses. This study demonstrates a continuous-flow electrokinetic separation of particles and cells in a serpentine microchannel through curvature-induced dielectrophoresis. The separation arises from the particle size-dependent cross-stream dielectrophoretic deflection that is generated by the inherent electric field gradients within channel turns. Through the use of a sheath flow to focus the particle mixture, we implement a continuous separation of 1 and 5 mu m polystyrene particles in a serpentine microchannel under a 15 kV/m DC electric field. The effects of the applied DC voltages and the serpentine length on the separation performance are examined. The same channel is also demonstrated to separate yeast cells (range in diameter between 4 and 8 mu m) from 3 mu m particles under an electric field as low as 10 kV/m. The observed focusing and separation processes for particles and cells in the serpentine microchannel are reasonably predicted by a numerical model.