Improving the Spatial Resolution of Electrical Capacitance Tomography by Utilizing Different Chemical Media of High Dielectric Constant

Abstract

The purpose of this project was to investigate the improved resolution of electrical capacitance tomography (ECT) by using a chemical contrast agent of substantially different dielectric constant compared to the material under measurement. Two prototype sensor arrangements of different dimensions were constructed and flooded with ethylene glycol or water as contrast agents. Capacitive measurements were then taken over a range of frequencies with polyethylene dowels having variable feature sizes. Sensitivity was characterized by the percent change in the signal over the feature size. When increasing the dielectric constant of the chemical medium by 37% sensitivity was increased by up to 20% for the larger sensor and 48% for the smaller sensor. Experiments confirm that ECT sensor resolution may be increased greatly by use of a dielectric contrast agent, and that also the sensitivity is largely affected by the geometry.