How Time-Sensitive are IoBNT Networks? An Age of Information Perspective for In-Body Monitoring

TL;DR

This thesis presents a theoretical framework using Age of Information to evaluate the monitoring capability of in-body nanosensor networks for disease detection, considering physiological and communication factors.

Contribution

It introduces a comprehensive model combining cardiovascular physiology and nanocommunication channels to assess information freshness in IoBNT networks.

Findings

Fresh information is available within tens of seconds under realistic conditions.

The network effectively monitors tissue-level processes like bacterial infections.

More advanced architectures are needed for cellular-scale process monitoring.

Abstract

This thesis develops a theoretical framework to evaluate the monitoring capability of IoBNT networks. We consider a scenario in which nanosensors passively flow in the bloodstream and detect biomarkers associated with potential diseases, reporting their detections to external gateways on the skin that host a monitoring device. The nanosensors thus realize an artificial point-to-point communication channel between the disease region and the monitor: some packets reach the destination directly, while others are lost through vessel paths that bypass the gateway. We evaluate the network's monitoring capability over this artificial channel using the \ac{AoI} concept, which jointly integrates sample generation (at the disease region), carrying (nanosensor travel through vessels), and delivery (nanosensor-to-gateway) as random events. These are modeled through (i) a Markov model that follows cardiovascular physiology and (ii) channel models of reported nanocommunication technologies. We compute the Markov transition probabilities using a cardiovascular simulator built as a low-complexity electric circuit model of the human vessels. For the nanosensor-to-gateway link, we model two well-known schemes: ultrasonic and terahertz channels. Integrating these components within the \ac{AoI} framework, we report information freshness via the average \ac{PAoI} metric. Under realistic physiological and communication assumptions, fresh information appears on the monitor within tens of seconds. The network is therefore suitable for monitoring tissue-level processes such as bacterial infections, while more adequate architectures are needed to monitor cellular-scale processes, which occur on timescales below tens of seconds.