Dielectrophoretic manipulation of rod-shaped viral particles

The dielectrophoretic manipulation of a rod-shaped virus, tobacco mosaic virus (TMV) by means of non-uniform AC electric fields is described. An expression is derived for the dielectrophoretic force on a homogeneous dielectric cylinder suspended in a liquid medium which shows that the dielectrophoretic force varies over a wide range of frequencies and medium conductivities. Measurements of the dielectrophoretic behaviour of TMV particles in microelectrode arrays have been made as a function of frequency and applied field strength. The results are shown to be in quantitative agreement with the derived expression for the dielectrophoretic force. By measuring the threshold field strength for the onset of dielectrophoresis, the force on a single TMV particle has been estimated. The results point to the potential use of dielectrophoresis for the collection and manipulation of sub-micron particles using microelectrode arrays. (C) 1997 Elsevier Science B.V.