COMPARISONS OF SENSOR GEOMETRIES FOR ELECTRICAL CAPACITANCE VOLUME TOMOGRAPHY

摘要

Proper electrode design to generate uniform sensitivity distribution is crucial for robust volumetric imaging based on electrical capacitance volume tomography (ECVT). Certain designs commonly used in electrical capacitance tomography (ECT), such as rectangular electrodes, form so-called "dead zones", i.e., regions with no variation in sensitivity among capacitance measurements between electrode pairs, making it impossible to differentiate the permittivity within a given region. For robust volumetric imaging, an electrode design that generates a sensitivity distribution that provides variation along all three directions with equal strength is required. In this work, several ECVT sensor electrode designs with various geometrical shapes were considered, and their performance in volumetric image reconstruction was evaluated based on experimental data. The electrode designs included regular square, triangular, trapezoidal and hexagonal shapes based on a 32-electrode capacitance sensor arranged with 8 electrodes along the radial direction and 4 electrodes along the axial direction. From the reconstruction results using experimental data, the horizontally aligned hexagonal electrode showed the best consistency in terms of the shape of the object that was reconstructed.