Desiccation of biological tissue measured by photonic millimeter-wave ellipsometry

The temporal variations of the complex relative dielectric constants for water-containing materials in the desiccation process have been measured by photonic millimeter wave ellipsometry. Both the real and imaginary parts decrease exponentially with time due to water evaporation from the samples. It is found that the variation of the imaginary part for a biological tissue sample is more gradual than that of the real part, reflecting the temporal change of the water distribution in the sample.