Measurement and Hemodialysis Effect of Complex Relative Permittivity for Blood of Kidney Patients Using Open-Ended Coaxial Measurement Probe

摘要

Before evaluating the quality of hemodialysis from the limited volume of human blood using a commercially available open-ended coaxial probe, we previously measured the complex relative permittivity of pure water from 200 MHz to 6 GHz with respect to its measured liquid volume, and found that 1.9 ml of water in a beaker with a diameter of 24 mm and a depth of 2 mm gives a variation within ±0.5% for the real part and ±7% for the imaginary part. Based on the above finding, we measured the dielectric properties of 2.5 ml whole blood at 25 ℃ for 10 normal healthy subjects and 9 hemodialysis patients. The measured results on healthy subjects show good agreement with the data reported by Gabriel for human blood at 37 ℃, while they provide different dispersion characteristics of straight lines for their Cole-Cole plots. The measured results on the patients give further different dispersion characteristics versus the healthy subjects. In an investigation of the above differences statistically, Student's t-test revealed that the permittivity at infinite frequency for the Cole-Cole plots is significantly different with a level of 1% among its averaged values for normal healthy subjects and patients before dialysis.