Due to the noncontact, nonradiative, and low-cost features, magnetic induction tomography (MIT) is highly applicable in conductive medium imaging. To meet the demands of low-conductivity medium imaging in industrial and biomedical applications, a portable, flexible, and extensible MIT system with high-phase detection precision is proposed. The proposed system is designed with different modules. Therefore, it is flexible to extend and meet different applications. The sensor modules can be used as both the excitation and the detection. The detected signal is directly demodulated at the sensor end, which avoids the external interference that may be introduced into the transmission of the detected signal. A phase demodulation part is designed which can achieve 0.0068° phase detection precision. Furthermore, the designed system does not need to rely on other instruments to realize the signal generation and demodulation, which makes the MIT system independent and portable in the practical application. The sensing coils have high consistency, and the signal-to-noise ratio (SNR) of the demodulated signal is over 60 dB. To illustrate the performance of the system, the capability of reconstructing low-conductivity saline solutions is studied. The images of conductivity distribution are obtained using the Tikhonov regularization method. The minimum detectable volume of saline solution is 10 mL, with a spatial resolution of 16.6%. The minimum detectable conductivity is 0.1 S/m, and the maximum detectable depth is 40 mm. The reconstructed results indicate the feasibility of low-conductivity medium imaging in the industrial and biomedical applications by the proposed MIT system.

中文翻译：

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用于低电导率介质成像的模块化磁感应层析成像系统

由于具有非接触，非辐射和低成本的特点，磁感应断层扫描（MIT）在导电介质成像中非常适用。为了满足工业和生物医学应用中低电导率介质成像的需求，提出了一种具有高相位检测精度的便携式，灵活，可扩展的MIT系统。所建议的系统设计有不同的模块。因此，可以灵活地扩展和满足不同的应用程序。传感器模块既可以用作激励也可以用作检测。所检测的信号在传感器端被直接解调，从而避免了可能引入检测信号传输中的外部干扰。设计了一种相位解调部件，可以实现0.0068°的相位检测精度。此外，设计的系统不需要依靠其他仪器来实现信号的产生和解调，这使得MIT系统在实际应用中具有独立性和可移植性。感应线圈具有较高的一致性，并且解调信号的信噪比（SNR）超过60 dB。为了说明该系统的性能，研究了重建低电导率盐溶液的能力。使用Tikhonov正则化方法获得电导率分布的图像。盐溶液的最小可检测体积为10 mL，空间分辨率为16.6％。最小可检测电导率为0.1 S / m，最大可检测深度为40 mm。