Dielectric and Optical Properties of Blood with Different RBCs Concentrations in the THz Band Ahmed Salem

Contents: Introduction Motivation Related work Methodology Numerical results Conclusion

Introduction Nano-technologies have been experiencing a plethora in its possible applications. Nanodevices communicate between each other by using molecular communication or electromagnetic communication. From the electromagnetic perspective, the miniaturization of the conventional antenna to meet the nano scale resulted in extremely high resonant frequencies in the THz range.

Motivation The propagation of THz signals in the in-vivo medium is hugely affected by the existence of the liquid water molecules, due to their absorption in THz band. That fact highlights that as the concentration of the water molecules increase, the THz signal will be more contaminated. Needless to mention the other biomaterials/fluids that might reduce the reliance of the whole clinical setting.

Related work Evaluating the dielectric and optical parameters of the medium is a crucial task to start investigating the losses that the signal will be experiencing in the medium of interest in the THz band. The best approximations of complex permittivity for polar liquids at frequencies up to 1 THz can be accomplished by double Debye equations.

Related work (cont.) In [1], THz-TDS measurements are presented for whole human blood, RBCs, plasma and blood clot. In [2], a model was developed, in which the absorption coefficient of the blood can be derived by identifying the volumetric fraction and the absorption coefficient of the RBCs and plasma.

Methodology We use some specific EMTs and validate using them by comparing the results obtained from using them with the results obtained from using double Debye equations. We used 3 EMT models that will suit our needs, namely: The model proposed in [3] LLL model [4] The Complex Refractive Index (CRI) model [5]

Methodology (cont.) The model proposed in [14]: It is designed for heterogeneous mixtures while considering a quasi-static system. It overcomes the low particle concentration restriction and offered the flexibility of choosing from 3 different particle shapes, which are spheres, discs and rods.

Methodology (cont.) LLL model: It was chosen due to its flexibility in applying it to any mixture despite the mixture's particles shape, which means that LLL model can be employed independently of the particle shape. It offered a good advantage in our work as it is restricted to the low dielectric contrast mixtures as it employs Taylor approximation. The CRI model linearly connects the complex refractive index to the volumetric content of the mixture.

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Conclusion We developed an electromagnetic model in THz regime for blood while considering the different RBCs concentrations and particle shapes. Results illustrated that blood with higher RBCs concentration will serve as a better medium for THz communication. It has been deduced that the particle shape of RBCs has no effect on the dielectric and optical properties of blood.