Artificial materials that can simultaneously mimic the relative permittivity and conductivity of various human tissues are usually used in medical applications. However, the method of precisely designing these materials with designated values of both relative permittivity and conductivity at 3 T MRI resonance frequency is lacking. In this study, a reliable method is established to determine the compositions of artificial dielectric materials with designated relative permittivity and conductivity at 128 MHz. Sixty dielectric materials were produced using oil, sodium chloride, gelatin, and deionized water as the main raw materials. The dielectric properties of these dielectric materials were measured using the open‐ended coaxial line method at 128 MHz. Nonlinear least‐squares Marquardt–Levenberg algorithm was used to obtain the formula, establishing the relationship between the compositions of the dielectric materials and their dielectric properties at 128 MHz. The dielectric properties of the blood, gall bladder, muscle, skin, lung, and bone at 128 MHz were selected to verify the reliability of the obtained formula. For the obtained formula, the coefficient of determination and the expanded uncertainties with a coverage factor of k = 2 were 0.991% and 4.9% for relative permittivity and 0.992% and 6.4% for conductivity. For the obtained artificial materials measured using the open‐ended coaxial line method, the maximal difference of relative permittivity and conductivity were 1.0 and 0.02 S/m, respectively, with respect to the designated values. In conclusion, the compositions of tissue‐mimicking material can be quickly determined after the establishment of the formulas with the expanded uncertainties of less than 10%. Bioelectromagnetics. 2021;42:86–94. © 2020 Bioelectromagnetics Society.

中文翻译：

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在 128 MHz 下制造具有指定相对介电常数和电导率的组织模拟材料的可靠方法

可以同时模拟各种人体组织的相对介电常数和电导率的人造材料通常用于医疗应用。然而，缺乏在 3 T MRI 共振频率下精确设计具有相对介电常数和电导率指定值的这些材料的方法。在这项研究中，建立了一种可靠的方法来确定在 128 MHz 下具有指定相对介电常数和电导率的人造介电材料的成分。以油、氯化钠、明胶、去离子水为主要原料生产了六十种介电材料。这些介电材料的介电特性是使用开放式同轴线方法在 128 MHz 下测量的。使用非线性最小二乘法 Marquardt-Levenberg 算法得到公式，建立介电材料的成分与其在 128 MHz 下的介电特性之间的关系。选择血液、胆囊、肌肉、皮肤、肺和骨骼在 128 MHz 下的介电特性来验证所得公式的可靠性。对于得到的公式，确定系数和覆盖因子为k  = 2 的相对介电常数分别为 0.991% 和 4.9%，电导率分别为 0.992% 和 6.4%。对于使用开放式同轴线法测量得到的人造材料，相对介电常数和电导率的最大差异分别为 1.0 和 0.02 S/m，相对于指定值。综上所述，公式建立后可以快速确定组织模拟材料的成分，扩展不确定度小于10%。生物电磁学。2021；42:86-94。© 2020 生物电磁学学会。