Compensation of volatile-distributed current due to variance of the unknown contact impedance in an electrical impedance tomography sensor
Compensation of volatile-distributed current due to variance of the unknown contact impedance in an electrical impedance tomography sensor
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DOI：
10.1088/1361-6501/aafb22
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发表时间：
2019-03-01
影响因子：
2.4
通讯作者：
Takei, Masahiro
中科院分区：
文献类型：
--
作者：
Baidillah, Marlin Ramadhan;Kawashima, Daisuke;Takei, Masahiro
基于科尔阻抗模型中的细胞外液电阻，提出了一种加权参数向量chi（norm），以补偿挥发性分布电流。由于电阻抗断层成像（EIT）传感器中未知接触阻抗的变化引起的易失性分布电流扭曲了感兴趣对象的频率依赖行为的理想性，导致重建图像的不准确性。未知接触阻抗的差异来源包括使用阻抗值不一致的电极、电化学反应或电极与感兴趣对象的不正确连接。chi（norm）代表零频率下的电流路径长度，反映了挥发性分布电流，用于确定测量阻抗的来源。未知接触阻抗的来源可以是正常生理条件下的背景对象、异常生理条件下的包含对象或系统误差。新的重建方法是从频率差EIT（fd-EIT）和加权频率差EIT（wfd-EIT）使用chi（范数）。新的重建方法是频差电阻抗谱层析成像（fd-EIST）和加权频差电阻抗谱层析成像（wfd-EIST）。通过实验和仿真研究，对fd-EIST和wfd-EIST的性能进行了评价，并与fd-EIT和wfd-EIT的结果进行了比较。结果表明，使用chi（norm）减小了均方根误差、位置误差、振铃和形状变形。它还增加了频率相关行为的理想性，无论是对于不同频率的夹杂物还是背景物体。
A weighted parameter vector chi(norm) based on extracellular fluid resistance in the Cole impedance model is hereby proposed in order to compensate for the volatile-distributed current. The volatile-distributed current due to variance in the unknown contact impedance in an electrical impedance tomography (EIT) sensor distorts the ideality of the frequency-dependent behavior of the object of interest, leading to inaccuracy in the reconstructed images. The sources of variance in the unknown contact impedance include the use of electrodes with inconsistent impedance values, electrochemical reaction or the improper attachment of electrodes to the object of interest. chi(norm) represents the current pathway lengths at zero frequency which reflects the volatile-distributed current, and it is used to determine the source of the measured impedance. The source of the unknown contact impedance can be the background object in the normal physiological condition, an inclusion object in an abnormal physiological condition or systematic error. The new reconstruction methods are derived from the frequency-difference EIT (fd-EIT) and the weighted-frequency-difference EIT (wfd-EIT) using chi(norm). The new reconstruction methods are frequency-difference electrical impedance spectro-tomography (fd-EIST) and weighted-frequency-difference electrical impedance spectro-tomography (wfd-EIST). The performance of fd-EIST and wfd-EIST was evaluated by experimental and simulation studies using biomaterials with frequency measurements from f = 500 Hz to f = 100kHz and the results were compared with those from fd-EIT and wfd-EIT. The results showed that the use of chi(norm) reduces the root mean square error, position error, ringing and shape deformation. It also increases the ideality of the frequency-dependent behavior, either for the inclusions or the background objects at different frequencies.