Reliable Method for Fabricating Tissue‐Mimicking Materials With Designated Relative Permittivity and Conductivity at 128 MHz

Abstract

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.

Research on the Relationship between Electrical Parameters and Relative Permeability of Tight Sandstone

“…However, whether the theoretical model is suitable for the study of the response law of rock electricity and relative permeability in tight sandstone gas reservoirs with complex pore-throat structures has not been verified experimentally. Based on the results of previous studies, − we found that the formation factors and resistance increase coefficients are all functions of pore structure parameters in the process of tight sandstone multiphase flow.…”

“…Irreducible water is negligible in the Poiseuille formula, but it is essential to calculate the resistivity parameters. This is because the irreducible water may not flow in a two-phase flow but can conduct electricity. − The model provides theoretical support for the study of the relationship between rock electrical properties and relative permeability. However, whether the theoretical model is suitable for the study of the response law of rock electricity and relative permeability in tight sandstone gas reservoirs with complex pore-throat structures has not been verified experimentally.…”

“…To further clarify the relationship between the electrical properties and relative permeability of rock under the microscopic pore structure parameters of tight sandstone, based on the findings of previous research, this study compared the theoretical model of relative permeability based on the electrical parameters of rock and the experimental model of relative permeability based on experimental data fitting. − The functional relationships among the pore structure index, formation factors, resistivity increasing coefficient, pore throat tortuosity, pore throat radius, permeability, and relative permeability were derived. The micropore structure of tight sandstone gas reservoir samples was analyzed, and the relationship between the electrical properties and permeability of the rock was further studied.…”

Sensitivity investigation of open-ended coaxial probe in skin cancer detection

“…To validate the accuracy of simulation, we conducted a phantom experiment. A skin phantom modeled as a single uniform layer because of the similar water content of epidermis and dermis was fabricated according to the recipe [30] . It was fabricated by dissolving 0.3 g of p-toluic acid and 15 ml of n-propanol with 51 g of gelatin and 285 ml of deionized water.…”