Capacitance Tomography for Dynamic Process Imaging

Piotr Brzeski1, Jacek Mirkowski1, Tomasz Olszewski1, Andrzej Pląskowski2, Waldemar Smolik1, Roman Szabatin1

1Division of Nuclear and Medical Electronics, Warsaw University of Technology, 00-665 Warszawa, ul. Nowowiejska 15/19, r.szabatin@ire.pw.edu.pl

2Mikromax, 02-777 Warszawa, ul. Kulczynskiego 22/72

ABSTRACT

The first capacitance tomograph has been designed at the Division of Nuclear and Medical Electronics of Warsaw University of Technology. Its design, performance and first results are presented in the paper. The tomograph can operate with one or two sensors with up to 32 electrodes altogether. Twelve or sixteen electrode configuration is commonly used and a twin twelve or twin sixteen electrode setup is provided for flowmeter applications. Additionally the device can be used as a 16- channel capacitance meter. The tomograph has a modular structure. It consists of 16 analog signal cards, a motherboard and a control module with an analog to digital converter. The measurement is based on a charge-discharge method. The signal card can work both as a transmitter and a receiver during the measurement process. The motherboard provides communication between signal cards and the control module, using a custom digital bus. The control module contains a 16-bit analog to digital converter, a control logic and a serial communication interface. All digital circuits are designed using programmable logic devices (PLDs).

Keywords Capacitance measurement, capacitance tomography, measurement system