International Society for Industrial Process Tomography

Compensation for the Unknown Contact Impedance Variance Using Frequency-difference Electrical Impedance Spectro-Tomography

Marlin. R. Baidillah^*, Martin W. Sifuna, and Masahiro Takei

Grad. School of Science and Engineering, Div. Fundamental Engineering, Dept. Mechanical Eng., Chiba University, Chiba, 263-8522, Japan

^*Email: mr.baidillah@c-techlabs.com

ABSTRACT

The volatile distributed current due to the unknown contact impedance variance causes the non-ideal frequency-dependent behaviour in the reconstructed image of frequency-difference electrical impedance tomography (fd-EIT). The unknown contact impedance variance limits the capacity of fd-EIT to exhibit more features. The non-ideal frequency-dependent behaviour in the reconstructed image also leads to image artefact hence false diagnosis. In this study, we proposed a reconstruction method called frequency-difference electrical impedance spectro-tomography (fd-EIST). This method considers the current pathway lengths which reflects the volatile distributed current due to the unknown contact impedance variance. The current pathway lengths are calculated based on electrical impedance spectroscopy method (EIS) from the whole range of measurements list. This proposed method is evaluated experimentally using bio-materials with frequency measurements from f = 500 Hz to 500 kHz and is then compared with fd-EIT. As compared with fd-EIT, fd-EIST shows relatively better performance in terms of root mean square error (RMSE), position error (PE), and shape deformation (SD), and ideally of the frequency-dependent behaviour during different frequencies. Considering the frequency-dependent behaviour based on fd-EIST in the analysis of reconstructed images is an advancement over the previous methods making them more accurate in such applications that need precise interpretation for long-term monitoring.

Keywords Electrical impedance spectro-tomography, Frequency-difference method, electrical impedance spectroscopy, Unknown contact impedance variance, frequency-dependent behaviour.

Industrial Application General