Photothermal Modeling and Analysis of Intrabody Terahertz Nanoscale Communication

Abstract

Wireless communication among implanted nano-biosensors will enable transformative smart health monitoring and diagnosis systems. The state of the art of nano-electronics and nano-photonics points to the terahertz (THz) band (0.1-10 THz) and optical frequency bands (infrared, 30-400 THz, and visible, 400-750 THz) as the frequency range for communication among nano-biosensors. Recently, several propagation models have been developed to study and assess the feasibility of intra-body electromagnetic (EM) nanoscale communication. These works have been mainly focused on understanding the propagation of EM signals through biological media, but do not capture the resulting photothermal effects and their impact both on the communication as well as on the body itself. In this paper, a novel thermal noise model for intra-body communication based on the diffusive heat flow theory is developed. In particular, an analytical framework is presented to illustrate how molecules in the human body absorb energy from EM fields and subsequently release this energy as heat to their immediate surroundings. As a result, a change in temperature is witnessed from which the molecular absorption noise can be computed. Such analysis has a dual benefit from a health as well as a communication perspective. For the medical community, the presented methodology allows the quantization of the temperature increase resulting from THz frequency absorption. For communication purposes, the complete understanding of the intra-body medium opens the door toward developing modulations suited for the capabilities of nano-machines and tailored to the peculiarities of the THz band channel as well as the optical window.

Terahertz Band: The Last Piece of RF Spectrum Puzzle for Communication Systems

“…In particular, the authors in [196] presented an attenuation model of intrabody THz propagation to facilitate the accurate design and practical deployment of iWNSNs. In subsequent studies, the authors also demonstrated both the photothermal impact [197] along with the noise effect [198] of THz intrabody communication to further verify the feasibility and prosperity of such propagation mechanism.…”

Radiation Absorption Noise for Molecular Information Transfer

“…MNC is a bio-inspired approach as it is inspired by the natural phenomenon of biology and deals with the emission, propagation, and reception of molecules using Nanomachines (natural/artificial) [2]. EMNC is inspired by miniaturization of communication devices and deals with transmission propagation and reception of EM waves radiated by some novel nanodevice in the Terahertz band [3], [4].…”

“…In other applications, external EM radiation is used to heat the medium or influence a process. In such scenarios, an increase in temperature due to the absorption of EM energy by molecules results in radiation absorption noise in MNC [4]- [7].…”

“…It is noteworthy to mention that though Specific Absorption Rate (SAR) of EM radiation is studied in various literature [15], [16] demonstrating different thermal effects of it on human body tissues. However, the authors in [4], [17] introduces the effect of EM radiation as the noise may be termed as RAN. Closed-form expressions for the rise in temperature due to the absorption of EM energy have been proposed in [4] for both single-particle and multiple particle scenarios.…”

“…However, the authors in [4], [17] introduces the effect of EM radiation as the noise may be termed as RAN. Closed-form expressions for the rise in temperature due to the absorption of EM energy have been proposed in [4] for both single-particle and multiple particle scenarios. It also proposes expressions for an increase in temperature used for the analysis of the molecular absorption power at the receiver [4].…”