Measuring electrical properties of microbeads by dielectrophoretic mobility

A method for measuring the electrical properties of spherical microparticles is demonstrated. The method is based on measuring particle mobility caused by the dielectrophoretic (DEP) force set off by a linearly decreasing electric field. Polystyrene-carboxylate microbeads of various sizes were used as targets, conductive potassium chloride dilution was used as their carrier fluid and transparent hyperbolic quadrupole electrode geometry was used to produce the linear field gradient. The measured permittivities and conductivities of the microbeads show good repeatability irrespective of their size.