Dielectric relaxation spectroscopy of biological cell suspensions

This paper is concerned with dielectric behavior of biological cell suspensions in the radio frequency range. Attention is focused on the dielectric relaxation arising from interfacial polarization (Maxwell-Wagner mechanism). The following topics related to electrical cell models and measurement techniques are described: (1) analyses of dielectric relaxation spectra of various biological cells using electrical cell models in which intracellular structure is taken into account; (2) effects of cell shape on the dielectric relaxation spectra, which are examined using an ellipsoidal cell model; (3) dielectric monitoring of yeast growth in culture by the electrode-less method with an inductive probe, which is free from an artifact due to electrode polarization that is a serious problem in monitoring; (4) attempt at dielectric imaging of individual biological cells using the "scanning dielectric microscope", which can image local capacitance and conductance measured with a fine probe electrode that is scanned over a sample in an aqueous medium.