Dielectrophoretic Cell Concentrator on EWOD-Based Chips

Dielectrophoretic concentrators were successfully developed on a EWOD-based chip. In such a chip, two major electrokinetic forces were exerted on objects on different scales. EWOD is used to pump droplets on a mm scale, while DEP manipulates bio-particles on a mum scale. Both cells and polystyrene beads were used to demonstrate the concentration abilities by pDEP and nDEP forces, respectively. Since electrodes are covered with a dielectric layer, instead of creating non-uniform electric fields in the liquid, low frequency signals are consumed in the dielectric layer and providing EWOD. It is necessary to use high frequency signals to generate DEP on a EWOD-based chip. Concentration efficiency, measured by cell count chamber before and after experiments, is around 1.62 with single cycle of pDEP attraction