Beyond Conventional Probes: Comparing the Impact of the Geometry on Coaxial Probe Aperture for Medical Applications

Escobedo-Segovia F.; Fernandez-Aranzamendi E.; Castillo-Aranibar P.; Castillo E.S.R.; Amor-Martin A.; Segovia-Vargas D. · Annual Symposium of the Antenna Measurement Techniques Association, AMTA (2025) · DOI: 10.23919/amta66658.2025.11317867

Resumen

The use of open-ended coaxial probes for dielectric characterization of breast tissue requires precise coupling between the probe and the skin surface, avoiding air gaps and excessive pressures. Since dielectric properties are very sensitive to these conditions, improper adaptation can compromise the precision and repeatability of the measurements, limiting their effectiveness in clinical applications such as tissue grading or pathology monitoring. This article evaluates the geometric performance of four open-ended coaxial probe tip configurations (flat, conical, beveled, and semispherical) with the objective of evaluating their fit to biological tissues. A custom-built measurement system operating between 1 and 8 GHz was employed to computationally simulate and analyze the S11 response for each probe geometry, assessing both precision and effective penetration depth. The results show that the conical and beveled probes provide shallow penetration depths (<2 ~\text{mm}), making them suitable for in vivo or ex vivo procedures, such as biopsies. The semispherical probe achieves deeper penetration (approximately 2 mm deeper than the flat probe), which is beneficial in surgical settings or before more complex imaging techniques, such as mammography. In terms of precision, the semispherical and conical probes demonstrated the best performance for breast tissue and tumor characterization, with an effectiveness rate exceeding 80 %. These findings allow for the assignment of complementary functions to each probe type, improving their integration into clinical settings for rapid and reliable tissue diagnosis and assessment.

Instituciones: Universidad Católica San Pablo