Exhaled Breath Analysis Through the Lens of Molecular Communication: A Survey
Sunasheer Bhattacharjee, Dadi Bi, Pit Hofmann, Alexander Wietfeld, Sophie Becke, Michael Lommel, Pengjie Zhou, Ruifeng Zheng, Ulrich Kertzscher, Yansha Deng, Wolfgang Kellerer, Frank H. P. Fitzek, Falko Dressler
TL;DR
The survey reframes exhaled breath analysis as an air-based Molecular Communication problem, treating the human body as a natural transmitter, the ambient environment as a propagation channel, and engineered sensors as receivers. It delineates comprehensive transmitter models (emission mechanisms, particle-load distributions, and respiratory-tract dynamics), channel mechanisms (diffusion, advection, buoyancy, and noise sources), and receiver architectures (sampling, detection, and decision-making) for noninvasive disease detection. By reviewing experimental ABMC testbeds and cross-domain sensing platforms, the work highlights practical pathways and critical bottlenecks for real-world deployment, including variability across populations, environmental noise, and privacy concerns. The paper maps a trend toward a macroscale IoBT and proposes a structured future research agenda spanning life sciences challenges, stochastic-channel modeling, system reliability, network protocols, and portable, privacy-preserving breath analysis devices. Overall, this survey advances a integrated, interdisciplinary framework for leveraging exhaled breath within MC to enable scalable, noninvasive healthcare diagnostics.
Abstract
Molecular Communication (MC) has long been envisioned to enable an Internet of Bio-Nano Things (IoBNT) with medical applications, where nanomachines within the human body conduct monitoring, diagnosis, and therapy at micro- and nanoscale levels. MC involves information transfer via molecules and is supported by well-established theoretical models. However, practically achieving reliable, energy-efficient, and bio-compatible communication at these scales still remains a challenge. Air-Based Molecular Communication (ABMC) is a type of MC that operates over larger, meter-scale distances and extends even outside the human body. Therefore, devices and techniques to realize ABMC are readily accessible, and associated use cases can be very promising in the near future. Exhaled breath analysis has previously been proposed. It provides a non-invasive approach for health monitoring, leveraging existing commercial sensor technologies and reducing deployment barriers. The breath contains a diverse range of molecules and particles that serve as biomarkers linked to various physiological and pathological conditions. The plethora of proven methods, models, and optimization approaches in MC enable macroscale breath analysis, treating human as the transmitter, the breath as the information carrier, and macroscale sensors as the receiver. Using ABMC to interface with the inherent dynamic networks of cells, tissues, and organs could create a novel Internet of Bio Things (IoBT), a preliminary macroscale stage of the IoBNT. This survey extensively reviews exhaled breath modeling and analysis through the lens of MC, offering insights into theoretical frameworks and practical implementations from ABMC, bringing the IoBT a step closer to real-world use.