Quasi-Elastic Light Scattering Studies on Yeast Cells Undergoing Dielectrophoresis

The technique of dielectrophoresis (the resultant motion of a neutral particle in a nonuniform electric field) has been successfully applied by several authors in the past for the purposes of characterization/ separation of intact biological cells and their components. In these studies the frequency-dependent dielectric response of the cells (dielectrophoretic spectrum) was obtained by measuring either the collection rate of the cells at the electrodes or the net translational displacement over a range of applied field frequencies. An alternative method is presented for obtaining the dielectrophoretic spectra using quasi-elastic light scattering. Here the cell sample is subjected to a nonuniform field using specially shaped electrodes, and the ensuing translation velocity is determined from the autocorrelation function of the scattered light. This should enable the dielectrophoretic spectra to be obtained with improved resolution and repeatability.