MICROWAVE DIELECTRIC MEASUREMENTS OF ERYTHROCYTE SUSPENSIONS

Complex dielectric constants of human erythrocyte suspensions over a f requency range from 45 MHz to 26.5 GHz and a temperature range from 5 to 40 degrees C have been determined with the open-ended coaxial probe technique using an automated vector network analyzer (HP 8510). The s pectra show two separate major dispersions (beta and gamma) and a much smaller dispersion between them. The two major dispersions are analyz ed with a dispersion equation containing two Cole-Cole functions by me ans of a complex nonlinear least squares technique. The parameters of the equation at different temperatures have been determined. The low f requency behavior of the spectra suggests that the dielectric constant of the cell membrane increases when the temperature is above 35 degre es C. The real part of the dielectric constant at similar to 3.4 GHz r emains almost constant when the temperature changes. The dispersion sh ifts with temperature in the manner of a thermally activated process, and the thermal activation enthalpies for the beta- and gamma-dispersi ons are 9.87 +/- 0.42 kcal/mol and 4.80 +/- 0.06 kcal/mol, respectivel y.