Size based separation of microparticles using a dielectrophoretic activated system

This work describes the separation of polystyrene microparticles suspended in deionized (DI) water according to their dimensions using a dielectrophoretic (DEP) system. The DEP system utilizes curved microelectrodes integrated into a microfluidic system. Microparticles of 1, 6, and 15 mu m are applied to the system and their response to the DEP field is studied at different frequencies of 100, 200, and 20 MHz. The microelectrodes act as a DEP barrier for 15 mu m particles and retain them at all frequencies whereas the response of 1 and 6 mu m particles depend strongly on the applied frequency. At 100 kHz, both particles are trapped by the microelectrodes. However, at 200 kHz, the 1 mu m particles are trapped by the microelectrodes while the 6 mu m particles are pushed toward the sidewalls. Finally, at 20 MHz, both particles are pushed toward the sidewalls. The experiments show the tunable performance of the system to sort the microparticles of various dimensions in microfluidic systems. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3457226]