Open-Ended Coaxial Probe Technique for Dielectric Measurement of Biological Tissues: Challenges and Common Practices

Abstract

Electromagnetic (EM) medical technologies are rapidly expanding worldwide for both diagnostics and therapeutics. As these technologies are low-cost and minimally invasive, they have been the focus of significant research efforts in recent years. Such technologies are often based on the assumption that there is a contrast in the dielectric properties of different tissue types or that the properties of particular tissues fall within a defined range. Thus, accurate knowledge of the dielectric properties of biological tissues is fundamental to EM medical technologies. Over the past decades, numerous studies were conducted to expand the dielectric repository of biological tissues. However, dielectric data is not yet available for every tissue type and at every temperature and frequency. For this reason, dielectric measurements may be performed by researchers who are not specialists in the acquisition of tissue dielectric properties. To this end, this paper reviews the tissue dielectric measurement process performed with an open-ended coaxial probe. Given the high number of factors, including equipment- and tissue-related confounders, that can increase the measurement uncertainty or introduce errors into the tissue dielectric data, this work discusses each step of the coaxial probe measurement procedure, highlighting common practices, challenges, and techniques for controlling and compensating for confounders.

Broadband lung dielectric properties over the ablative temperature range: Experimental measurements and parametric models

“…The broadband dielectric properties of ex vivo lung tissue were measured with the well‐known open‐ended coaxial probe technique . This method employs a vector network analyzer (VNA) connected to an open‐ended coaxial probe terminated with the tissue sample.…”

“…Furthermore, the heating protocol was repeated with an additional two fiber optic temperature sensors positioned in tissue at distances 2 and 3 mm away from the dielectric measurement probe. These measurements were conducted to assess the variation in temperature within the sensing volume of the dielectric probe . Figure illustrates the experimental setup.…”

“…The broadband dielectric properties of ex vivo lung tissue were measured with the well-known open-ended coaxial probe technique. 17,19,[26][27][28] This method employs a vector network analyzer (VNA) connected to an open-ended coaxial probe terminated with the tissue sample. The dielectric properties of the sample at a specific temperature and frequency relative permittivity e r ðf ; TÞ and effective conductivity r ef ðf ; TÞare extracted from the measured complex reflection coefficients C c ðf ; TÞ at each frequency.…”

“…These measurements were conducted to assess the variation in temperature within the sensing volume of the dielectric probe. [28][29][30][31][32] Figure 2 illustrates the experimental setup.…”

Frequency spectrum analysis of lightweight foamed concrete using microwave dielectric measurement technique

“…The frequency spectrum analysis in various fields is become more significant in recent year . Among all, the open ended coaxial is one of the popular non‐destructive dielectric sensor for frequency spectrum analysis.…”