Dielectrophoretic manipulation and separation of particles in an S-shaped microchannel with hurdles

This paper presents a novel dielectrophoresis (DEP)-based microfluidic device, which incorporates multiple round hurdles within an S-shaped curved microchannel for continuous manipulation and separation of microparticles. Local nonuniform electric fields are induced by means of both constricted gaps formed between hurdles and outer channel wall, and variable current lengths in curved sections with equal width. Under the effect of negative DEP, particles will be directed away from either inner wall or hurdle edge, as they transport throughout the microchannel electrokinetically. Both experiment and numerical simulation were conducted, the results of which showed that fix-sized (i.e. 10 or 15 μm) polystyrene (PS) particles could be successfully switched, directed and focused by adjusting applied voltages at inlet and outlets, and size-based separation of 10 and 15 μm particles was achieved with a careful selection of applied voltages. Compared to other microchannel designs that make use of either obstacle or curvature individually for inhomogeneous electric fields, this design offers advantages such as improved controllability over particle motion, lower requirement of applied voltage, reduced fouling and particle adhesion, etc.