DESIGN AND IMPLEMENTATION OF PRECISE HARDWARE FOR ELECTRICAL IMPEDANCE TOMOGRAPHY (EIT)

Electrical Impedance Tomography (EIT), is one of the safest medical imaging
technologies and can be used in industrial process monitoring. In this method, image of electrical
conductivity (or electrical impedance) distribution of the inner part of a conductive subject can be
reconstructed. The image reconstruction process is done by injecting an accurate current into the
boundary of a volume conductor (Ω), measuring voltages around the boundary (∂Ω) and
transmitting them to a computer, and processing on acquired data with software (e.g. MATLAB).
The image would be reconstructed from the measured peripheral data by using an iterative
algorithm. A precise instrumentation (EIT hardware) plays a very important and vital role in the
quality of reconstructed images. In this paper, we have proposed a practical design of a low-cost
precise EIT hardware including, a high output impedance VCCS (Voltage-Controlled Current
Source) with pulse generation part, precise voltage demodulator and measuring parts, a high
performance multiplexer module, and a control unit. All the parts have been practically and
accurately tested with successful results, and finally the proposed design was assembled on PCB.
The quality of experimental results at the end of this paper, (reconstructed images by using the
implemented system), confirms the accuracy of the proposed EIT hardware.