Magneto-acousto-electrical tomography: a potential method for imaging current density and electrical impedance
Magneto-acousto-electrical tomography: a potential method for imaging current density and electrical impedance
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DOI：
10.1088/0967-3334/29/6/s04
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发表时间：
2008-06-01
影响因子：
3.2
通讯作者：
Xu, Y.
中科院分区：
文献类型：
--
作者：
Haider, S.;Hrbek, A.;Xu, Y.
首先，本报告概述了我们利用磁声电断层扫描（MAET）成像体积导体中的铅场电流密度的研究。当电流/电压源通过一对电极施加到样品时，获得铅场电流密度分布。这是第一次使用MAET呈现电流密度的高空间分辨率图像。我们还比较了其相应的数值模拟的样品中的电流密度的实验图像。为了对电极导线场电流密度进行成像，我们将样品置于静磁场中，并将超声脉冲聚焦在样品上，以模拟焦点处的点状电流偶极源，而不是直接向样品施加电流/电压源。然后，通过使用电极，我们测量的电压/电流信号的基础上，互易定理，是成比例的铅场电流密度的分量。在理论部分，我们推导出测量电压与电极导线场电流密度和超声引起的位移速度之间的关系式。实验数据包括MAET信号和薄样品的铅场电流密度的图像。此外，我们讨论了潜在的改进MAET，特别是要克服的观察，没有信号被检测到从内部的区域具有均匀的导电性的限制。作为辅助，我们提供了一个数学公式，从而铅场电流密度可以用来重建电阻抗的分布在一个分段光滑的对象。
Primarily this report outlines our investigation on utilizing magneto-acousto-electrical-tomography (MAET) to image the lead field current density in volume conductors. A lead field current density distribution is obtained when a current/voltage source is applied to a sample via a pair of electrodes. This is the first time a high-spatial-resolution image of current density is presented using MAET. We also compare an experimental image of current density in a sample with its corresponding numerical simulation. To image the lead field current density, rather than applying a current/voltage source directly to the sample, we place the sample in a static magnetic field and focus an ultrasonic pulse on the sample to simulate a point-like current dipole source at the focal point. Then by using electrodes we measure the voltage/current signal which, based on the reciprocity theorem, is proportional to a component of the lead field current density. In the theory section, we derive the equation relating the measured voltage to the lead field current density and the displacement velocity caused by ultrasound. The experimental data include the MAET signal and an image of the lead field current density for a thin sample. In addition, we discuss the potential improvements for MAET especially to overcome the limitation created by the observation that no signal was detected from the interior of a region having a uniform conductivity. As an auxiliary we offer a mathematical formula whereby the lead field current density may be utilized to reconstruct the distribution of the electrical impedance in a piecewise smooth object.