Particle characterization by AC electrokinetic phenomena 2. Dielectrophoresis of Latex particles measured by dielectrophoretic phase analysis light scattering (DPALS)

Particle polarization in AC fields depends on the temporal and spatial prop erties of the inducing field and on the dielectric properties of the suspen sion medium and the particles. In inhomogeneous fields the interaction of t he induced dipole moment with the inducing field may give rise to particle translation (dielectrophoresis, DP). The frequency dependence of DP is medi ated by the dispersions of different interfacial polarization processes. Co nsequently, DP spectroscopy yields information on internal particle structu res. Common methods microscopically analyze the frequency behavior of the i nduced motion. Phase analysis light scattering (PALS) is a suitable light s cattering method for the registration of extremely slow particle translatio n. We used PALS to analyze the DP behavior of polystyrene Latex particles i n an optical two-electrode chamber. The dielectric particle data obtained a re in correspondence to those of the literature. Our method offers statisti cal significance and computerized operation for dielectric particle spectro scopy. (C) 1999 Elsevier Science B.V. All rights reserved.