EFFECT OF ELECTRODE SIZE ON IMPEDANCE IMAGES OF 2-DIMENSIONAL AND 3-DIMENSIONAL OBJECTS

The sensitivity of an impedance imaging system to small cylindrical in homogeneities in two-dimensional (2-D) and three-dimensional (3-D) sal ine tanks was studied for different height electrodes and different he ight targets. Experimental results were compared with analytical model s. Inhomogeneities in the 3-D tank having limited vertical extent were detected by electrodes of vertical size comparable to that of the inh omogeneity. Taller electrodes had increased sensitivity to short targe ts to only a limited extent. When the electrode height was more than t wice that of the target, sensitivity decreased or remained the same wi th further increases in electrode height. The system was less sensitiv e to inhomogeneities in the 3-D tank than to those in the 2-D tank. Th e distinguishability of conductors was greater than that of insulators in the 3-D tank, and the opposite was true in the 2-D tank, consisten t with an analytical result.