Theoretical and experimental investigations of the interdependence of the dielectric, dielectrophoretic and electrorotational behaviour of colloidal particles

Abstract

New theoretical relationships are derived to link the dielectric properties of a suspension of colloidal particles to both the dielectrophoretic (DEP) and electrorotation (ROT) behaviour exhibited by a single suspended particle. It is found that the relaxation frequencies that characterize the dielectric spectrum of a colloidal suspension are close to, but different from, those that characterize the DEP and ROT responses. The extent of this difference is dependent on particle volume fraction and the intrinsic dielectric properties of both particle and suspending medium. Experimental results obtained for yeast cells in the frequency range from 1 kHz to 10 MHz provide confirmation of the theory.