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

Abstract

A tuned small slot antenna has been used for radio communications with internal transceivers/transmitters for invivo 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 x 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 ( = 4 S/m, 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.

In-vivo Experimental Validation of the Attenuation Path Loss Model for Localization of Wireless Implanted Transmitters at 2.45 GHz

“…In [14], [15], a flat phantom filled with a liquid simulating human muscle was used for the data acquisition, whereas in [17], a sucrose and sodium chloride solution in a cube-shaped container was used. Other papers report experiments on gelatin-based phantoms in the shape of a human body or ex-vivo animal tissue phantoms for investigating in-to-on body channels [19]- [21].…”

“…1 (a). The slot antenna performance as a receiving sensor with the transmitter surrounded by the ex-vivo porcine tissues was also tested [21] to confirm the suitability of the cavity-backed slot antenna for in-body to on-body measurements at 2.45 GHz. An example of the reflection coefficient measurements for the antenna when placed directly on the skin in the abdominal region of a living human is given in Fig.…”

“…In [21], a conventional IFA design was optimized to match the characteristics of human soft tissues when implanted inside the abdominal cavity. The reported results on the skin surface demonstrated the antenna resonated at 2.45 GHz with a reflection coefficient of -13.3 dB.…”