Qin Yangchun, Yang Lin, Fu Feng, Dai Meng, Zhang Liang
Department of Military Biomedical Engineering, Air Force Medical University, Xi'an 710032, P. R. China.
Department of Aerospace Medicine, Air Force Medical University, Xi'an 710032, P. R. China.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2023 Oct 25;40(5):886-893. doi: 10.7507/1001-5515.202303066.
In this paper, the differences between air probe and filled probe for measuring high-frequency dielectric properties of biological tissues are investigated based on the equivalent circuit model to provide a reference for the methodology of high-frequency measurement of biological tissue dielectric properties. Two types of probes were used to measure different concentrations of NaCl solution in the frequency band of 100 MHz-2 GHz. The results showed that the accuracy and reliability of the calculated results of the air probe were lower than that of the filled probe, especially the dielectric coefficient of the measured material, and the higher the concentration of NaCl solution, the higher the error. By laminating the probe terminal, liquid intrusion could be prevented, to a certain extent, to improve the accuracy of measurement. However, as the frequency decreased, the influence of the film on the measurement increased and the measurement accuracy decreased. The results of the study show that the air probe, despite its simple dimensional design and easy calibration, differs from the conventional equivalent circuit model in actual measurements, and the model needs to be re-corrected for actual use. The filled probe matches the equivalent circuit model better, and therefore has better measurement accuracy and reliability.
本文基于等效电路模型研究了空气探头和填充探头在测量生物组织高频介电特性方面的差异，为生物组织介电特性的高频测量方法提供参考。使用两种类型的探头在100 MHz - 2 GHz频段测量不同浓度的NaCl溶液。结果表明，空气探头计算结果的准确性和可靠性低于填充探头，尤其是被测材料的介电常数，且NaCl溶液浓度越高，误差越大。通过对探头终端进行层压，可以在一定程度上防止液体侵入，提高测量精度。然而，随着频率降低，薄膜对测量的影响增大，测量精度降低。研究结果表明，空气探头尽管尺寸设计简单且易于校准，但在实际测量中与传统等效电路模型存在差异，实际使用时模型需要重新校正。填充探头与等效电路模型匹配更好，因此具有更好的测量准确性和可靠性。
