Lev-vection of highly polar and of dense particles: Dispersion effects in polar media

Particles, including biological cells, can be concentrated from suspension by combined dielectrophoretic levitation and thermal convection. This type of separation can be problematic where the particles are either extremely polarizable or dense. "Difficult" particles include certain biological cells, such as protoplasts with large vacuoles, which have polarizabilities close to that of water. In these cases it becomes necessary to substantially increase the polarizability of the medium in order to maintain levitation. However, dielectric dispersion may then become significant.