Permittivity measurements of biological samples by an open-ended coaxial line

TL;DR

This paper presents practical guidelines for accurately measuring the permittivity and conductivity of biological samples across a broad frequency range using an open-ended coaxial line, addressing challenges like electrode polarization effects.

Contribution

It provides detailed correction methods and validation procedures for reliable permittivity and conductivity measurements of biological samples with high dc conductivity.

Findings

Developed correction scheme for electrode polarization effects.

Validated measurement accuracy with control samples.

Extended measurement techniques from 3 MHz to 40 GHz.

Abstract

We previously reported on the complex permittivity and dc conductivity of waste-activated sludge. The measurements, spanning a frequency range of 3 MHz to 40 GHz, were made using an open-ended coaxial transmission line. Although this technique is well established in the literature, we found that it was necessary to combine methods from several papers to use the open-ended coaxial probe to reliably characterize biological samples having a high dc conductivity. Here, we provide a set of detailed and practical guidelines that can be used to determine the permittivity and conductivity of biological samples over a broad frequency range. Due to the electrode polarization effect, low frequency measurements of conducting samples require corrections to extract the intrinsic electrical properties. We describe one practical correction scheme and verify its reliability using a control sample.