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.