  In this work, we present a paradigm bridging electromagnetic (EM) and
molecular communication through a stimuli-responsive intra-body model. It has
been established that protein molecules, which play a key role in governing
cell behavior, can be selectively stimulated using Terahertz (THz) band
frequencies. By triggering protein vibrational modes using THz waves, we induce
changes in protein conformation, resulting in the activation of a controlled
cascade of biochemical and biomechanical events. To analyze such an
interaction, we formulate a communication system composed of a nanoantenna
transmitter and a protein receiver. We adopt a Markov chain model to account
for protein stochasticity with transition rates governed by the nanoantenna
force. Both two-state and multi-state protein models are presented to depict
different biological configurations. Closed form expressions for the mutual
information of each scenario is derived and maximized to find the capacity
between the input nanoantenna force and the protein state. The results we
obtain indicate that controlled protein signaling provides a communication
platform for information transmission between the nanoantenna and the protein
with a clear physical significance. The analysis reported in this work should
further research into the EM-based control of protein networks.
