Dielectric properties of a protein–water system in selected animal tissues

Dielectric spectroscopy has been applied to study aspects of the organization of water in selected animal tissues (tendon, bone and horn). The measurements of the relative permittivity ɛ′ and the dielectric loss ɛ″ were carried over the frequency range of 10–100 kHz and at temperatures from 22 to 240 °C. The water content was 10% for bone and horn, and 22% for tendon by mass at room temperature at a relative humidity of 70%. The temperature dependencies of ɛ′ and ɛ″ reveal distinctively the temperature ranges corresponding to the release of water in temperatures up to about 200 °C for all tissues and the melting of the crystalline structure only for tendon and horn, above this temperature. The frequency dependencies of ɛ′ and ɛ″ show a remarkable dispersion in the low-frequency at selected temperatures up to 200 °C for all tissues due to the release of the loosely and strongly bound water. The results were discussed in terms of the interfacial (Maxwell–Wagner) polarization and polarization mechanism involving hopping charge carriers interacting with the bound water molecules. The information on the effect of temperature, water content and frequency of the electromagnetic field on the dielectric behaviour of the tissues studied is of importance in the design and construction of medical diagnostic or therapeutic instruments based on the use of electric signals.