Dielectrophoresis of microbioparticles in water with planar and capillary quadrupole electrodes.

Dielectrophoresis of single microbioparticles was measured in a planar quadrupole microelectrode (50 mum or 65 mum in working area radius) with a microscope. Carbon and polystyrene microparticles, yeast cells and DNA molecules (about 40 kbp) were adopted as a sample. Their dielectrophoretic mobilities were analysed quantitatively with their intrinsic and surface conductivity, their permittivities and their sizes as well as the conductivity and permittivity of aqueous media. Using the dielectrophoretic mobilities obtained with the planar quadrupole microelectrode, some instances of the separation performance between the microparticles were demonstrated with a fabricated capillary quadrupole microelectrode (82.5 mum in bore radius) under the field flow fractionation regime.