Simultaneous reconstruction of electrode contact impedances and internal electrical properties: I. Theory
Simultaneous reconstruction of electrode contact impedances and internal electrical properties: I. Theory
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DOI：
10.1088/0957-0233/13/12/307
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发表时间：
2002-12-01
影响因子：
2.4
通讯作者：
Vauhkonen, M
中科院分区：
文献类型：
--
作者：
Vilhunen, T;Kaipio, JP;Vauhkonen, M
在电阻抗断层扫描 (EIT) 中，通过附着在物体表面上的电极施加电流，并使用相同或附加的电极测量所得电压。根据电流和电压数据估计内部导纳率分布。当在载流电极上测量电压时，电极-表面界面中存在的接触阻抗会导致电压降。在某些情况下，电极的这种效应是已知的。然而，情况并非总是如此，在图像重建中必须考虑接触阻抗。在本文中，我们提出了一种在估计物体的导纳率的同时估计电极的接触阻抗的方法。完整的电极模型（CEM）用于估计过程。我们将所提出的方法与基于众所周知的样品电阻率定义的简单方法进行比较。通过估计圆柱形测试单元中等渗盐溶液的导纳率并在三维圆柱形域中进行模拟，通过实际测量来测试所提出的方法。基于 CEM 的方法所产生的结果与测试单元案例中使用简单方法获得的结果相似。基于 CEM 的方法相对于简单方法的优点是完整的电极模型没有任何几何约束，这使得它可以在 EIT 研究中使用。结果表明，基于 CEM 的方法效果良好，可用于实际测量的实际接触阻抗估计。这将在本文的第二部分进一步研究。
In electrical impedance tomography (EIT) currents are applied through the electrodes attached on the surface of the object and the resulting voltages are measured using the same or additional electrodes. The internal admittivity distribution is estimated based on the current and voltage data. When the voltages are measured on the current carrying electrodes the contact impedance that exists in the electrode-surface interface causes a voltage drop. In some cases this effect of the electrodes is known. However, this is not always the case and the contact impedance has to be taken into account in the image reconstruction. In this paper we propose an approach for estimating the contact impedance of the electrodes simultaneously with the estimation of the admittivity of the object. The complete electrode model (CEM) is used in the estimation procedure. We compare the proposed approach to a simple method which is based on the well known definition of the sample resistivity. The proposed approach is tested with real measurements by estimating the admittivity of isotonic saline solution in a cylindrical test cell and with simulations in a three-dimensional cylindrical domain. The CEM-based approach is shown to produce results that are similar to the results obtained with the simple approach in the test cell case. The advantage of the CEM-based approach over the simple approach is that the complete electrode model does not have any geometrical constraints, which makes it possible to utilize it in EIT studies. The results show that the CEM-based approach works well and can be used in practical contact impedance estimation with real measurements. This will be further studied in part II of this paper.