(220g) Electrokinetic Particle Separation by Charge In Spiral Microchannels

The separation of particles from a heterogeneous mixture is critical in chemical and biological analyses. Many methods have been developed to separate particles in microfluidic devices, the majority of which has been limited to be size based and binary. We present a continuous DC electric field driven separation of carboxyl-coated and non-coated polystyrene beads by charge in a spiral microchannel. This method exploits the inherent electric field gradients formed within the channel turns to manipulate particles by dielectrophoresis. The spiral microchannel is also used to demonstrate a continuous ternary separation of coated and non-coated polystyrene beads by charge and size simultaneously. The observed particle separation processes in different situations are all predicted with reasonable agreements by a numerical model.