In Vivo Human Skin Dielectric Properties Characterization and Statistical Analysis at Frequencies From 1 to 30 GHz

Precise data acquisition and modeling of healthy dermal dielectric properties are critical for accurate skin anomaly detection studies. For this purpose, an extensive campaign of around 1000 measurements across a band of 1-30 GHz leads to the conclusion that each skin region of interest (ROI) provides unique dielectric properties. Therefore, a single-skin model would not suffice to represent the complete human body. The acquired dielectric data are predominantly from the skin layer; however, considering the sensing depth of the utilized coaxial cable, the subcutaneous layers do have a minor contribution toward the effective dielectric properties seen at the probe/skin interface. Palmar skin has the maximum mean absolute percentage deviation in dielectric properties (around 34%) with respect to hand dorsum skin. The remaining measured ROIs (anterior wrist and anterior forearm) generate 4% and 8% dielectric deviation, respectively. Furthermore, female dermal dielectric constant values are observed to be on an average 9% higher across all measured ROIs compared with respective male skin. Subsequent statistical analysis of the measured data leads to the conclusion of a significant dielectric constant dependence on gender. The skin type generates a moderate but insignificant correlation with conductivity values. A similar analysis of volunteer weight and age details determined a weak association with the measured data.