%0 Journal Article
%A Zimmermann, E.
%A Kemna, A.
%A Berwix, J.
%A Glaas, W.
%A Vereecken, H.
%T EIT measurement system with high phase  accuracy for the imaging of spectral  induced polarization properties of soils  and sediments
%J Measurement science and technology
%V 19
%@ 0957-0233
%C Bristol
%I IOP Publ.
%M PreJuSER-62873
%P 094010
%D 2008
%Z Record converted from VDB: 12.11.2012
%X A powerful method for the non-invasive structural characterization of material is electrical impedance tomography (EIT) combined with the capabilities of impedance spectroscopy. This method determines the complex resistivity magnitude and phase images at a set of different measurement frequencies. We are particularly interested in the application of such an advanced approach for the improved characterization of soils and sediments, which only show a weak polarizability. Here, typical phase values lie between 1 and 20 mrad only, requiring instrumentation with relatively high phase resolution and accuracy. In this paper, we present a new spectral EIT data acquisition system for laboratory applications, which operates in the frequency range from 1 mHz to 45 kHz and which was developed to meet these requirements. In this context, we also present a new measurement method based on current injection swapping, which leads to significantly improved phase images, particularly for higher measurement frequencies. The system and the new measurement method are tested on a water-filled tank and column containing different 2D and 3D targets (metallic and biological objects). The tests prove a phase accuracy of 1 mrad for frequencies of up to 1 kHz and higher, resulting in a clear discrimination of the objects on the basis of the reconstructed phase images.
%K J (WoSType)
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000258317700011
%R 10.1088/0957-0233/19/9/094010
%U https://juser.fz-juelich.de/record/62873