Khalighi M, Mikaeili M
Biomedical Engineering Group, Department of Engineering, Shahed University, Tehran, Iran.
Rev Sci Instrum. 2018 Aug;89(8):085107. doi: 10.1063/1.5028435.
The quality of reconstructed images in Electrical Impedance Tomography (EIT) depends on two essential factors: first, precision of the EIT hardware in current injection and voltage measurement and second, efficiency of its image reconstruction algorithm. Therefore the current source plays an important and a vital role in EIT instruments. Floating-load current sources constructed using sink and source drivers have better performance and higher output impedance than grounded-load (single-ended) current sources. In addition, a main feature of this kind is that the current source is not connected to the ground potential directly but via a large impedance. In this paper, we first focus on recent studies on designed EIT current sources, and after that, a practical design of a floating-load high output impedance current source-operating over a wide frequency band-will be proposed in detail. Simulation results of the proposed voltage-controlled current source (VCCS), along with some other models, will be shown and compared. At the end, the results of practical tests on the VCCS and a few EIT images, taken using our prototype EIT system coupled with the mentioned VCCS, will be illustrated which proves the quality of the proposed current source.
电阻抗断层成像（EIT）中重建图像的质量取决于两个关键因素：其一，EIT硬件在电流注入和电压测量方面的精度；其二，其图像重建算法的效率。因此，电流源在EIT仪器中起着至关重要的作用。采用 sink 和 source 驱动器构建的浮动负载电流源比接地负载（单端）电流源具有更好的性能和更高的输出阻抗。此外，这类电流源的一个主要特点是，它不是直接连接到地电位，而是通过一个大阻抗连接。在本文中，我们首先关注近期关于EIT电流源设计的研究，之后，将详细提出一种在宽频带上工作的浮动负载高输出阻抗电流源的实际设计方案。将展示并比较所提出的压控电流源（VCCS）以及其他一些模型的仿真结果。最后，将说明对VCCS进行实际测试的结果以及使用我们的原型EIT系统结合上述VCCS拍摄的一些EIT图像，这证明了所提出电流源的质量。
