Design of Coaxial Probe with Semispherical Termination for the Dielectric Characterization of Biological Tissues

Currently, dielectric spectroscopy emerges as a promising diagnostic tool due to its ability to easily differentiate between biological tissues. Among the various methods employed, the open-circuit coaxial probe stands out for its ease of use, portability, and non-invasive nature. However, this probe has limitations due to its flat termination geometry, which affects penetration depth and requires good contact with pressure application. This article presents, for the first time, the design and construction of a coaxial probe with spherical termination to perform dielectric spectroscopy on biological tissues, aiming to improve contact and penetration depth. This model was validated through simulations in HFSS and verified with physical measurements on phantoms, comparing it with measurements using the Speag DAK 3.5 probe. The results indicated that the penetration depth reaches up to 1.7 cm, with a minimum required pressure of 17 KPa.