In this article we report on a planar miniaturized dielectrophoretic (DEP) microfluidic device developed for the purpose of continuous fractionation and purification of sample suspensions of microscopic particles or biological cells, employing specially shaped nonuniform (isomotive) electric fields. The device integrates three fully functional and distinct sub-units consisting of 1) sheath and sample injection ports, arranged to achieve hydrodynamic focusing of the cell stream; 2) the DEP

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... onation region and 3) two sample collection ports. In the DEP fractionation region, the magnitude of the field induced DEP force acting on the particle is essentially constant and independent of the particle's position and furthermore only dependent on the intrinsic polarization response of the particle, for identical sized particles. The operation and performance in terms of sample throughput, separation efficiency and repeatability of the device was evaluated using test microscopic sized dielectric particles and biological particles, including cancerous cell lines.