Dielectric single particle spectroscopy for measurement of dispersion

Measuring the frequency-dependent behaviour of single particles or biologic al cells in inhomogeneous and/or rotating electric fields is a sensitive me thod for characterising their dielectric properties, This technique is able to detect broad dispersion in the megahertz range of homogeneous artificia l Sephadex G15 spheres. Recent progress has opened up the possibility of ca rrying out dielectric spectroscopy in cell culture media, Dielectrophoretic and electrorotational spectra of different cells in media of varying condu ctivity can only be explained by the introduction of dispersive cell compar tments. The cytoplasm of animal cells typically exhibits a broad dispersion around 15 MHz and there is evidence for membrane dispersion around 50 MHz.