An evanescent field technique for colloidal particle dielectrophoresis studies

Dielectrophoresis (DEP) has widely been used to probe the dielectric properties of particles, recently including the manipulation and study of colloidal particles. The ability to discriminate between particles collecting on an electrode against those particles in the bulk solution is required for collection rate measurements. In this paper we demonstrate how evanescent imaging methods can be used to observe only those particles in the plane of the electrode array, so that significant improvements in the signal to noise ratio is achieved.