COMPUTER-AIDED ANALYSES OF ELECTRIC-FIELDS USED IN ELECTROROTATION STUDIES

The spatial variations of the magnitude and phase of the electric field produced by electrodes used in electrorotation studies have been computed, using the charge density method, at 10-degrees intervals for one complete AC cycle of the applied voltages. These results, together with the development of a more general theoretical treatment than has hitherto been applied to this problem, enable the time-averaged rotational torque and dielectrophoretic force acting on a particle to be determined as a function of its location within the inter-electrode space. Correction factors that can be applied to electrorotation spectra to take account of the relative position, or change in position, of the test particle are provided for electrodes of polynomial and circular geometry.