A New Four-Electrode Focused Impedance Measurement (FIM) System for Physiological Study
- 296 Downloads
A recently developed Focused Impedance Measurement (FIM) system (by the authors’ group) uses six electrodes to localize a zone of interest. Because of 3D sensitivity it could give physiological information on large organs like stomach, lungs, etc. using surface electrodes in the frontal plane. This paper presents a modified FIM technique using four electrodes placed at the corners of a square matrix. Firstly current is driven through an adjacent electrode pair while the potential is measured across the opposite pair from which an impedance value is obtained. Then a similar measurement is made at 90° to the above by changing connections to the electrode pairs appropriately. The sum of these two impedance values has a dominant contribution from the central region within the square matrix, giving the desired focusing. Experimental sensitivity maps obtained from a 2D phantom have verified the focusing effect. Compared to the previous six-electrode FIM system the focusing effect is slightly less, but this new technique has less negative artifacts in the periphery. This new FIM method can be applied both in the frontal plane and in the transverse plane of the human thorax, giving a further advantage besides requiring fewer electrodes.
KeywordsFocused impedance measurement Electrical impedance measurement Focused admittance measurement
- 6.Rabbani, K. S., M. Hassan, A. B. M. H. Kabir, M. Ahmed, and S. Nahar. Electrical impedance tomography (EIT) in the frontal plane using ring electrode configuration. In: Proceedings, Regional Conference of IEEE-EMBS and 14th BMES-India, Delhi, 1995, pp. 1.43–1.44Google Scholar
- 9.Rabbani, K. S., M. Sarker, M. H. R. Akond, and T. Akter. Focused impedance measurement (FIM)—a new technique with zone localization. In: Proceedings, X International Conference on Electrical Bioimpedance, Barcelona, Spain, 1998, pp. 31–34Google Scholar
- 11.Sarker, S. A., P. K. Bardhan, K. S. Rabbani, N. H. Alam, M. Hassan, A. Kiber, R. Zaman, D. Mahalanabis, and K. Gyr. Noninvasive assessment of gastric acid secretion by applied potential tomography. Abstracts, 4th meeting of the European Society of Gastrenterology, Berlin, September 1995, pp. 19–24Google Scholar