Gentle Dielectrophoretic Focusing of Yeast Cells in Curved Microchannels

Focusing cells into a tight stream is usually a necessary step prior to counting, detecting and sorting them in, for example, microfluidic flow cytometers. We present herein a simple and gentle cell focusing technique in physiological solutions through a serpentine microchannel using DC-biased AC electric fields. This electrokinetic focusing eliminates sheath flows and in-channel microelectrodes. It results from the cross-stream dielectrophoretic motion of cells induced by the intrinsic channel curvatures. The effects of electric field magnitude, AC to DC electric field ratio, AC field frequency, and cell concentration on the focusing performance of yeast cells will be studied.