Particle motions and segregation in dielectrophoretic microfluidics

We studied, experimentally and theoretically the motion and segregation of positively polarized particles flowing through dielectrophoretic microfluidics. The batch fabrication technique which we present enables one to construct an apparatus featuring a large number of mechanically robust and chemically inert microdevices having a very low ratio of dielectrophoretic-to-fluid residence time. Several apparatuses of this type can easily be integrated into a higher-level system able to handle flow rates several orders of magnitude larger than those in a single microdevice. Experiments were conducted on microfluidics with electrodes of different sizes arranged parallel and perpendicular to the flow. The simulations of the particle motions and their segregation required no fitting parameters because the suspension properties were measured independently. We demonstrate that the presence of the interparticle dipolar interactions imposes a lower bound on the size of the electrodes below which the miniaturization o...