Comparisons of Sensor Position for Electrical Capacitance Volume Tomography (ECVT): An Advanced Study

Tomography is a technique used to produce true reconstructed images from signal data. This data
projection is measured capacitance by numerous sensors located on the surface of the object at
different position. Sensitivity matrix with three-dimensional variation, especially in axial (z-axiz)
direction are required for imaging a three-dimensional object to differentiate the depth along the
sensor length so that the electrical field intensity can be distributed equally all over the three
dimension space. In ECVT, when a dielectric material is introduced into the vessel, the variation in the
electrical capacitance between all possible combinations of electrodes are measured. These changes
are caused by diference in the permittivity of that material. From these capacitance measurements, an
image based on the variation of the permittivity of the cross section contents can be obtained. In this
study a numerical model using combine COMSOL MULTIPHYSICS v3.5 and MATLAB 2008a for
imaging of an object was developed. Three different position of rectangular sensor: 1-sided sensor, 3-
sided and U-shape sensor was designed and analyzed. 1-sided sensor displayed comparatively more
uniform in both radial and axial direction in the comparisons of sensitivity distribution.