Insulating dielectrophoresis for the continuous separation and concentration of Bacillus subtilis

This paper presents a novel microdevice for the dielectrophoretic manipulation of particles and cells for sample preparation and analysis. A two level isotropic etch of a glass substrate was used to create insulating ridges in micron sized channels. These ridges created a non-uniform field when a direct current field was applied across the channel and the dielectrophoretic force that resulted from the ridge was used to manipulate particles. We show the continuous concentration and separation of Bacillus subtilis from a two component sample mixture. When the applied voltage is at or above 30V/mm the flow of Bacillus subtilis was restricted to the central channel as a result of negative DEP away from the field concentration produced by the insulating ridges. Under the same applied electric fields the 200-nm polystyrene particles DEP away from the insulating ridges was negligible for the 200-nm particles, which flowed uninhibited down the three exit channels.