Basic theory of dielectrophoresis and electrorotation

This article presents a concise, unifying treatment of the electromechanics of small particles under the influence of electroquasistatic fields and offers a set of models useful in calculating electrical forces and torques on biological particles in the size range from /spl sim/1 to /spl sim/100 μm. The theory is used to consider DEP trapping, electrorotation, traveling-wave induced motion, and orientational effects. The effective dipole method, and its generalization to effective multipoles, makes it possible to treat multilayered concentric shells and particles exhibiting ohmic and dielectric loss. This method may be extended further to the case of nonspherical particles, where alignment torques can be considered. These capabilities are well suited to modeling DEP behavior of biological particles including cells. The models and methods presented in this review are sufficiently general to be of use in a broad range of applications for biological dielectrophoresis and particle electrokinetics. The range of validity can be stated confidently to cover particles having diameters approximately 1μm and larger.