Effects of standard coagulant agents on the dielectric properties of fresh human blood

In this paper, the effects of coagulation and temperature on the dielectric properties of human blood are investigated over the frequency range of 400 MHz-20 GHz using freshly extracted blood samples. The dielectric properties are measured using blood in four different sample collection tubes (bottles): one containing pure whole blood, two containing different anticoagulant agents, and one containing clot activator and serum separator. The collected data indicates that additive agents can have a significant impact on the measured dielectric properties of blood, both immediately after the sample is taken, and over longer time periods. This is an important finding as it suggests that measurements of blood properties conducted on sample repositories, or tissue banks, may not be representative of natural blood properties. Further, the results demonstrate that the dielectric properties of normal blood vary over time due to coagulation. Different clotting rates lead to dielectric properties of female and male blood samples that vary distinctly over time. The results also show that the relative permittivity of the anti-coagulated blood decreases with increasing temperature, up to the cross-over point around 10 GHz where the trend reverses.