Dielectric aspects of biological materials

The 1978 Conference on Electrical Insulation and Dielectric Phenomena (1) included a session on the Dielectric properties of Biological Systems. This session was chaired by Professor H. P. Schwan of the University of Pennsylvania and was organized by the present writer on behalf of the Dielectrics Society which co-sponsored it. The introductory paper concluded that while dielectric measurements on biological materials can be very sensitive and non-invasive they are seldom specific in a chemical or biological sense. The most important of the recent trends in dielectrics is towards combining the high sensitivity of dielectric measurements with the specificity of some other physical or chemical measurement made on the same system. There are a number of such examples to be found among the papers listed in this chapter. The most difficult overall problems are those of electrode effects with the highly conducting materials encountered and the difficulties of measuring an effective geometrical shape of the specimens. Professor R. H. Cole continues to make progress with the former problem and Professor H. A. Pohl and Dr. R. Pethig have developed dielectrophoresis techniques for measurement of the dielectric properties of biological materials, and which avoid the shape factor.