Complex permittivity of blood cells and E. coli suspensions

Abstract

The role played by micro-particles, such as leukocytes, erythrocytes and other lighter particles called micro light particles (MLPs), on the electric and dielectric properties of human blood has been studied for a vast frequency range (10 Hz–10 GHz). It has been found that leukocytes dominate these properties in the low frequency range (about 265 Hz), while erythrocytes control it at higher frequencies (around 1.2 MHz). MLPs dominate near 10 GHz. A theoretical model based on the relaxation of suspended micro-particles in plasma is presented which shows that each micro-particle has its own intrinsic frequency, f p. The electric conduction is at a maximum when the frequency of the applied field matches f p. In general, the theoretical approach gives consistent results compared to previously publish experimental results on human blood and E. coli, which have an intrinsic frequency of 232 Hz. The results suggest the utility of permittivity measurements for non-invasive studies of blood disorders and for microchip devices with corresponding extensions of the standard relaxation times model. In addition, these data shed some light on the mechanism by which bacteria can transfer energy.