The Design Of Electrical Impedance Imaging System

Electrical Impedance Tomography(EIT) is aiming at organism resistivity distribution complete the reconstruction of tissue in the body image. It is a noninvasive imaging technology. When the body surface to join certain current or voltage, the different impedance distribution in body surface will be measured to different voltage or current. Therefore, the electrical impedance imaging technology is actually measuring the voltage caused by surface through injecting the known current. It calculates the impedance distribution with the human body in accordance with certain reconstruction method, using the measured voltage value.In this paper, it discusses the corresponding solutions of part of common problems which are existed in the study of EIT system nowadays, such as less amount of information, less accuracy data, poor on load capacity and large amount of calculation, etc. it is designed a set of 16 electrodes 2D- EIT imaging system based on laboratory salt water tank. Mainly finished the following work:(1) For the existed part of common problems of EIT system design, it takes a lot of measures, such as 16 electrode model, design of high output impedance of the constant current source, programmable gain amplifier and so on, to solve these problems, and presents a non-uniform finite element subdivision method which can obtain the better imaging result compared with traditional uniform subdivision.(2) The EIT system scheme is analyzed,including the physical model building based on basic medical establishment, the design of EIT data acquisition system and the analysis of the imaging software design.(3) It is Completed the EIT data acquisition system design. Based on the modular design thought, complete the design of the driver module, the electrode switch array module, the signal detection module and the control module, and analyzed the principle of each module in detail.(4) For image reconstruction algorithm, introduces the EIT forward problem solving, including Laplace equation, field subdivision problems and the establishment of the finite element equations solving, and mainly researches the two algorithms of the Tikhonov regularization method and the NOSER. Be using the MATLAB simulation platform to complete the EIT image reconstruction.(5) It complete the system performance test, mainly including constant current source performance assessment, channel conformance testing and so on.(6) Finally, it is completing the image reconstruction experiment based on laboratory salt water tank, and getting the impedance distribution of the reconstruction of the image, and analyzing the results, and putting forward the improvement measures.The last, it has been summarized the main work of this article, and put forward the outlook for next step.