Capacitance estimation for electrical capacitance tomography sensors using digital processing of time-domain voltage response to single pulse excitation.

Posted on: 27 July 2023

Abstract: A new approach for capacitance measurement for electrical capacitance tomography (ECT)

sensors is proposed. The method is based on the digital processing of the time domain voltage

measurements at the sensor electrodes. A robust capacitance estimation algorithm is developed to

convert the measured time-series voltages to inter-electrode capacitances. The method simplifies

the electronic design of the sensor. The measurement technique is suitable for fast scanning using a

compact device and could have possible applications in fields like medical imaging. A prototype

sensor with open curved geometry is used to test the method. The sensitivity of the estimated

capacitance to noise levels is analyzed in detail with numerical simulations. An analysis of the

parameters that affect the accuracy of estimated capacitances is carried out. The method is immune

to effects like stray capacitances between the electrodes and the ground. The initial experimental

demonstration of the method is presented with measurements on a millimeter scale prototype

sensor. The results obtained for measurements with mineral oil and water are shown and compared

against capacitances obtained using a physics based forward model of the sensor. The inter-electrode

capacitances in the range of tens of femtofarads to a few picofarads are estimated and close match

with the forward model results is obtained.

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