DIELECTROPHORETIC CHARACTERIZATION AND SEPARATION OF MICROORGANISMS

The effective electrical conductivity values for a variety of Gram-neg ative and -positive bacteria have been determined in the frequency ran ge 10 kHz to 100 kHz. This information enabled experimental conditions to be selected where micro-organisms of different species can be sepa rated using dielectrophoresis-the movement of particles induced by non -uniform AC electric fields. Mixtures of micro-organisms of different species were separated locally on a microscope slide using micro-elect rodes of polynomial geometry, and their physical isolation into two se parate suspensions was accomplished using a dielectrophoresis chamber that incorporated interdigitated, castellated micro-electrodes.