Design And Application Of Portable Electrical Impedance Tomography System

Electrical impedance tomography(EIT)is an emerging technology for functional imaging of biological tissues.It has the advantages of low equipment cost,low detection cost,non-invasive and harmless,non-invasive,dynamic imaging and so on.Aiming at the problem that the existing electrical impedance tomography system is complex,difficult to carry and not suitable for popularization in the home,this paper develops a portable,low-cost EIT system.Firstly,the principle of EIT is introduced.The assumption and simplification of the EIT model are made.The mathematical model of image reconstruction is established.The mathematical model is used to divide the imaging problem into positive and inverse problems.The problem is to propose a solution to the positive and inverse problems.Secondly,an EIT hardware system is designed,which includes Red Pitaya STEMlab development board,voltage control current source and analog multiplexer module.Two types of electrode sensors are designed for different detection objects: the sink electrode sensor and the bracelet electrode sensor.The design of the wristband sensor focuses on the influence of contact impedance.In order to increase the portability of the system,a test box was designed.The portability of the developed EIT hardware system was verified by comparison between the EIT system and the high precision impedance analyzer.Next,a numerical analysis method for EIT is proposed.The inverse problem of EIT is solved by the Tikhonov regularization algorithm based on sensitive matrix and the generalized vector pattern matching method(GVSPM).Not only the characteristics of the two image reconstruction algorithms are analyzed,but also the application scenarios of the two algorithms are determined according to the characteristics of the algorithm.In order to evaluate the quality of reconstructed images,two evaluation indicators were introduced: image correlation and voltage error.According to the evaluation index,the optimal iteration number of the GVSPM algorithm is studied,and the resolution of the reconstructed image is improved.Finally,an experimental platform for EIT was built,and the experimental system was verified and applied.The image reconstruction experiment was carried out on the bones and muscles and the eggs with different degrees of structural change by using the verified system,and the portability of the system was fully utilized.Experiments were carried out for the application of human gesture recognition.The experimental results show that the portable developed in this paper EIT systems can be widely used for biological tissue detection.