Papers by Keyword: Electrical Impedance Tomography

Abstract: Electrical impedance tomography (EIT) is a perspective vital imaging method in medicine. Although the paper deals mainly with medicine application, the potential of EIT is also in the field of a novel material testing. EIT belongs to non-invasive methods. It is used mainly for the area of thorax since thorax exhibits the biggest changes in impedance. The lungs are mostly filled with air while surrounding flesh has impedance similar to water. However EIT has several drawbacks: relatively big measurement inaccuracy, blurred obtained images, difficulties in application of electrodes and problems with repeatability of measurements. Many drawbacks can be limited when an absolute tomography is used, though absolute tomography is very challenging and is rather only a laboratory concept then a real working method. This article deals with a robust method which is closely related to absolute tomography imaging while viable in clinical practice and to non-invasive material description in general. A unique measuring device VERA was developed. Such a device helps with fast application of electrodes and enables to get reproducible and reliable images of thorax or other volumes in engineering. The paper also discusses challenges when choosing a mediator material or liquid for EIT function. The concept of stiff framework for electrodes which is applied to patient is unusual but exhibits many advantages resulting in better images.

Abstract: Carbon fiber-reinforced polymer (CFRP) composites are lightweight, durable, and corrosionresistive materials that are popular for constructing automotive bodies and aircraft structures. However, their heterogeneous composition and anisotropic mechanical behavior make design of their service lives challenging. To address challenges in monitoring CFRP’s structural behavior, a cheap, weightless, and reliable sensor shall be developed for CFRPs to monitor their damage-to-failure mode. In this study a carbon nanotube (CNT)-embedded thin film is inkjet-printed onto a flexible substrate and applied over a tensile testing coupon. Coupled with the algorithm of electrical impedance tomography, the sensor with 16 electrodes is able to reconstruct the strain distribution of a surface under 8 sec. Non-uniform strain distribution can also be reconstructed at strain levels down to 0.001%.

Abstract: This paper describes a quality power module design for Biological Electrical Impedance Tomography (BEIT) system based on FPGA. As the electrical signals on the boundary of subject are too weak to measure effectively, it is essential to design a data acquisition system with high SNR and extremely low noise. This paper is focus on the power module design because the quality of the power module impacts the performance of the data acquisition system directly. The BEIT system needs several kinds of power supply to work effectively, such as 12V, 5V. In this paper, the power module is supplied by DC18V, using Buck-type DC/DC and LDO technologies, a set of independent power supply scheme is carried out, and provides stability and low noise power sources. The expected powers with ripple less than 20mV are achieved, which can preferably meet the BEIT system power supply requirements.

Abstract: The LSQR algorithm is always used to solve the inverse problem of electrical impedance tomography (EIT). However, it always has relatively low reconstruction speed. In this paper, WALSQR (wavelet multi-resolution based Least Square QR-factorization) algorithm is proposed for EIT imaging. With the aid of wavelet transformation, the LSQR solution is obtained in the low-dimension scale space, where important information on the reconstructed image is contained. Hence the computational complexity of reconstruction is reduced without affecting the image quality. In order to verify the effectiveness of the new method, experiments of 2D and 3D EIT imaging are conducted. It lays the foundation for the study of 3D dynamic EIT image reconstruction algorithm.

Abstract: In recently years, Electrical Impedance Tomography caused concern for people in the areas such as non-destructive testing and structural health monitoring. This paper took the disk structure composed of carbon fiber felt for example, designed and built the experiment platform for Electrical Impedance Tomography in a couple of different ways: one was traditional and the other was distributed acquisition system based on wireless sensor network. The imaging result showed that the data collected from wireless distributed system were more accurate and efficient.