Size-selective deposition of particles combining liquid and particulate dielectrophoresis

Rapid, size-based, deposition of particles from liquid suspension has been demonstrated using the nonuniform electric field created by coplanar microelectrode strips patterned on an insulating substrate. The scheme uses the dielectrophoretic force both to distribute aqueous liquid containing particles and, simultaneously, to separate the particles. Tests conducted with solutions containing equal volume fractions of 0.53 and 0.93 mm polystyrene beads, tagged with different fluorescent dyes, reveal size-based separation within nanoliter droplets formed along the structure after voltage removal. The relative volume ratio of the two sizes varies smoothly from 1:1 to ,3:1 sfavoring the smaller particlesd along the electrodes. Using the Clausius–Mossotti factor KI as the only adjustable parameter, the experimental data correlate to a numerical simulation of the process at RefKI g <0.5, a value consistent with expectation for polystyrene beads at ,100 kHz in aqueous suspension. © 2005 American Institute of Physics. fDOI: 10.1063/1.1852694g