DIELECTRIC-PROPERTIES OF LUNG-TISSUE AS A FUNCTION OF AIR CONTENT

Dielectric measurements were made on lung samples with different elect rode systems in the frequency range 5 kHz-100 kHz. In the case of plat e electrodes and spot electrodes, the effects of electrode polarizatio n were partly corrected. An air filling factor F is defined, which is determined from the mass and volume of the sample. The results indicat e that the electrical properties of lung tissue are highly dependent o n the condition of the tissue. Furthermore they show that the conducti vity sigma as well as the relative permittivity epsilon(r) decreases w ith increasing F. This is discussed using histological material. Using a simple theoretical model, the decrease of sigma and epsilon(r) is e xplained by the thinning of the alveolar walls as well as by the defor mation of the epithelial cells and blood vessels through the expansion of the alveoli.