Dielectrophoresis (DEP), the motion of particles in nonuniform electric fields, is a nondestructive electrokinetic transport mechanism can be used to concentrate and separate bioparticles. Traditionally, DEP has been performed employing microelectrodes, approach that is expensive due to the cost of microelectrode fabrication. An alternative is insulator-based DEP (iDEP), an inexpensive method where nonuniform electric fields are created with arrays of insulating structures.

This study presents the effects of operating conditions on the dielectrophoretic behavior of polystyrene microparticles under iDEP. Experiments were performed employing microchannels containing insulating structures that worked as insulators. The parameters varied were pH (8-9) and conductivity (25-100 µS/cm) of the bulk medium, and the magnitude of the applied field (200-850 V/cm). Optimal operating conditions in terms of pH and conductivity of the suspending medium were obtained, and the microdevice performance was characterized in terms of concentration factor and minimum electric field required (minimum energy consumption). This is the first report on improving iDEP processes when electroosmotic flow (EOF) is present and DC electric fields are employed. DEP and EOF have been studied extensively, however, this study integrates the effect of suspending medium characteristics on both electrokinetic phenomena. These findings will allow improving the performance of DC-iDEP microdevices achieving the highest concentration fold with the lowest energy consumption.

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