An evanescent-field technique for dielectrophoresis studies of colloidal particles

Dielectrophoretic collection rates have been used to measure the dielectric properties of particles. For accurate collection-rate measurements it is important to be able to discriminate between particles collecting on an electrode and particles that are in the bulk solution. In this paper we demonstrate how evanescent-imaging methods can be used to observe only those particles that are in the plane of the electrode array, so that significant improvements in the signal-to-noise ratio compared with conventional imaging methods are achieved.