  Terahertz-based nano-networks are emerging as a groundbreaking technology
able to play a decisive role in future medical applications owing to their
ability to precisely quantify figures, such as the viral load in a patient or
to predict sepsis shock or heart attacks before they occur. Due to the
extremely limited size of the devices composing these nano-networks, the use of
the Terahertz (THz) band has emerged as the enabling technology for their
communication. However, the characteristics of the THz band, which strictly
reduce the communication range inside the human body, together with the energy
limitations of nano-nodes make the in-body deployment of nano-nodes a
challenging task. To overcome these problems, we propose a novel in-body
flow-guided nano-network architecture consisting of three different devices: i)
nano-node, ii) nano-router, and iii) bio-sensor. As the performance of this
type of nano-network has not been previously explored, a theoretical framework
capturing all its particularities is derived to properly model its behavior and
evaluate its feasibility in real medical applications. Employing this
analytical model, a thorough sensitivity study of its key parameters is
accomplished. Finally, we analyze the terahertz flow-guided nano-network design
to satisfy the requirements of several medical applications of interest.
