Perancangan Pengukur Kapasitansi Orde Femtofarad Berbasis Rangkaian Aktif Differensial Untuk Sistem Electrical Capacitance Volume Tomography (ECVT)

Abstract

Electrical Capacitance Volume Tomography (ECVT) is an imaging technique based on the value of the capacitance from an object.  ECVT systems require signal conditioning circuit that is able to measure the capacitance value in femtofarad (fF) orde, then convert it into a voltage (C-V). The design of the signal conditioning circuit with a differential active methods created with the LTspiceIV software. The results of a design that has been prepared then realized by making the signal conditioning circuit. Tests conducted using sensors ECVT 8 channel by using multiple samples are air, water, and palm oil (crude palm oil). The calibration process is performed to determine the range of capacitance that can be measured, there are determined of normalization capacitance used object which has low permittivity, that is air (e = 1) has capacitance result of 81,7 fF for the closest of electrode pair and 700,5 fF for the farthest of electrode, meanwhile for the maximum value which has high permittivity, that is water (e = 80) had capacitance result of 2422,3 fF for the closest and the farthest of electrode. Meanwhile crude palm oil (e = 1,75) had capacitance value of 1156,9 fF for the closest electrode pair and 192,4 fF for the farthest electrode pair.  The result of sensitivity from experience was average of 1,5982 fF/mV

Keywords ECVT, LTspiceIV, Sensitivity, Femtofarad, signal conditioning