E-Field Distribution in Ex-Vivo Porcine Skin Layer from a Subsurface UHF Transmitter

A tuned small slot antenna has been used for radio communications with internal transceivers/transmitters for in-vivo medical applications. The 2.45 GHz properties (permittivity and conductivity) shows that porcine skin tissue can be used as a substitute for human skin tissue in medical applications. In this study, a measure of the E-field distribution on the skin surface of human and porcine tissue is presented. Ex vivo measurements on boneless layered pork belly-fat (45mm thick 300mm × 150 mm sample of skin, fat and muscle) were compared with numerical modelling for a subdermal PIFA tuned antenna. The surface electric field distribution is quite well matched to an analytical formula over a 70dB dynamic range. The conductivity (σ = 4 S/m, ε
_r
= 10) and relative permittivity adjusted to fit the measurement profile aligned with previously reported values. These results support the strategy that field strength measurements can be used to locate an injects radio transmitter.