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

Abstract

Electrical Impedance Tomography (EIT), is one of the safest medical imagingtechnologies and can be used in industrial process monitoring. In this method, image of electricalconductivity (or electrical impedance) distribution of the inner part of a conductive subject can bereconstructed. The image reconstruction process is done by injecting an accurate current into theboundary of a volume conductor (Ω), measuring voltages around the boundary (∂Ω) andtransmitting 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 iterativealgorithm. A precise instrumentation (EIT hardware) plays a very important and vital role in thequality of reconstructed images. In this paper, we have proposed a practical design of a low-costprecise EIT hardware including, a high output impedance VCCS (Voltage-Controlled CurrentSource) with pulse generation part, precise voltage demodulator and measuring parts, a highperformance multiplexer module, and a control unit. All the parts have been practically andaccurately 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 theimplemented system), confirms the accuracy of the proposed EIT hardware.