Micro-volume dielectric measurements on high permittivity solutions: correlation with results from single-particle electro-manipulation

The forces that determine the a.c. electrokinetics of microparticles depend on the relative dielectric properties of the particles or biological cells with respect to their suspending media. A method for measurement of the properties of very small quantities of medium is therefore desirable. A suitable measurement chamber consisting of a planar interdigitated electrode array surrounded by an insulating pedestal can be fashioned by lithographic and micro-machining techniques. Volumes of 1 μl or even less are measurable. The original purpose of the electrode structures, namely to microposition particles and single cells, is also described