Accurate Technique for Electrical Permittivity Measurement of Biological Tissue Specimens at Low Frequencies

This paper proposes a technique aimed at accurate measurement of electrical permittivity (EP) of small tissue specimens at low frequencies. Accurate measurement of EP of healthy and pathological tissues can facilitate the establishment of many medical applications such as electrical impedance imaging. The proposed novel technique employs hardware with high precision for impedance measurement of capacitive structures formed by the tissue specimen as its dielectric combined with two conductive plates placed at two ends of the specimen. To determine the EP of the tissue specimen, the capacitance part of the measured impedance is processed using an inverse finite-element framework. In this framework, accurate geometry and boundary conditions of the specimen are considered. The proposed technique was validated before it was employed to measure EP of several tissue specimens including bovine heart, liver, and bone. Results obtained in this investigation indicate that the proposed technique is reliable as it provides improved EP measurement accuracy and repeatability of homogeneous or multilayered tissue specimens, especially at low-frequency range.