Spatial resolution in electrical capacitance tomography

TL;DR

This paper analyzes the spatial resolution of Electrical Capacitance Tomography sensors, focusing on how electrode configuration affects accuracy in localizing objects and distinguishing close objects.

Contribution

It provides a detailed analysis of how electrode geometry influences spatial resolution in ECT, offering guidelines for optimal sensor design.

Findings

50% electrode gap balances resolution and coverage

Increasing electrodes improves near-electrode resolution but reduces center resolution

3 or 4 electrodes optimize center resolution in cylindrical sensors

Abstract

Electrical Capacitance Tomography (ECT) is an imaging technique providing the distribution of permittivity in a medium by the mean of electrodes. As for any imaging systems, the reachable spatial resolution is a key parameter. In this paper the spatial resolution of ECT sensors is analyzed in terms of the accuracy of an object position and of the ability to distinguish between two close objects. Cylindrical geometry sensors are particularly studied and the example of a square geometry sensor is used to show how to study any other geometries. In cylindrical geometries, it is shown that a 50% gap between electrodes is a good compromise and that increasing the number of electrodes improves the spatial resolution near the electrodes but decreases the spatial resolution in the center. The best spatial resolution at the center of the sensor is obtained with 3 or 4 electrodes. In the square geometry studied, it is shown that a better distribution of the spatial resolution is obtained when there are electrodes in the corners.