Use of the Open-Ended Probe Technique for the Dielectric Characterization of Biological Tissues at Low Frequencies

The open-ended probe is a popular technique adopted for the measurement of the dielectric properties of biological tissues. Commercial probes are commonly used for measurements at frequencies higher than 500 MHz because under this frequency limit the error of reconstruction increases and reaches not acceptable values. The aim of this paper is to understand how to improve the accuracy of this technique for the dielectric characterization of samples at low frequencies. Theorical studies have shown that the measurement accuracy is related to a capacitive parameter of the probe which is dependent on the radial dimensions of the probe itself. Starting from this assumption, in this work some experimental measurements have been done on known liquids finding that the dimensions of the probe can influence the results. It is demonstrated that the choice of the probe with the optimal structure can improve the measurement accuracy at low frequencies.