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.