Dielectric Characterization of Limited Volume of Human Blood by Open-Ended Coaxial Measurement Probe

To evaluate the quality of hemodialysis from the limited volume of human blood using a commercially available open-ended coaxial probe, we used pure water in lieu of blood to measure the complex relative permittivity in the frequency range from 200 MHz to 6 GHz with respect to its measured liquid volume. We then obtained the measurement errors relative to the calculated values from an empirical formula Udo developed for water permittivity. As a result, we found that 0.9 ml 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. Taking into account the finding for water, we measured for normal healthy subjects the dielectric properties of 2.5 ml whole blood with a temperature of 25℃ in a syringe with a diameter of 20 mm and a depth of 8 mm. There was an agreement between the measurement and the data Gabriel reported for human blood with a temperature of 37℃.