Dielectrophoretic investigations of sub-micrometre latex spheres

A non-uniform AC electric field induces a motion in polarizable particles, called dielectrophoresis. The force responsible for this motion is governed by the dielectric properties both of the suspending medium and of the particles, as well as the geometry of the field. The dielectrophoretic properties of sub-micrometre latex spheres have been studied using micro-fabricated electrode structures. The electric field geometry for electrodes used in the measurements has been solved using numerical analysis. Measurements of the dielectrophoretic properties of the spheres have been made over a range of medium conductivities and applied field frequencies and strengths. Comparisons between the observed behaviour and that expected from theory are presented.