Optimization of a probe for the spectroscopic electrical characterization of biological tissues

¹ Ampère, CNRS, UMR 5005, École Centrale de Lyon, 69134 Ecully, France
² Ampère, CNRS, UMR 5005, Université Lyon 1, 69622 Villeurbanne, France
³ Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brasil

Corresponding author: laurent.bernard@ec-lyon.fr

Received: 18 January 2007
Revised: 15 March 2007
Accepted: 22 March 2007
Published online: 10 May 2007

Abstract

The spectroscopic electrical characterization of biological tissues between 10 Hz and 10 MHz is generally based on four-electrode impedance measurement. An array of four aligned needle-electrodes is commonly used for the probe. The electrode/sample interface impedances and the parasitic capacitances of the system induce measurement inaccuracies respectively in the low and high parts of the studied frequency range. These inaccuracies cannot be removed by any usual calibration method but can be minimized by modifying the geometry of the probe. Using a 3D finite element model of the probe coupled with a deterministic optimization algorithm, it is shown that the configuration of the electrodes should be different at 10 Hz and 10 MHz to improve the performances of the measurement system.