  The design of communication systems capable of processing and exchanging
information through molecules and chemical processes is a rapidly growing
interdisciplinary field, which holds the promise to revolutionize how we
realize computing and communication devices. While molecular communication (MC)
theory has had major developments in recent years, more practical aspects in
designing components capable of MC functionalities remain less explored.
Motivated by this, we design a microfluidic MC system with a microfluidic MC
transmitter and a microfluidic MC receiver based on chemical reactions.
Considering existing MC literature on information transmission via molecular
pulse modulation, the proposed microfluidic MC transmitter is capable of
generating continuously predefined pulse-shaped molecular concentrations upon
rectangular triggering signals using chemical reactions inspired by how cells
generate pulse-shaped molecular signals in biology. We further design a
microfluidic MC receiver capable of demodulating a received signal to a
rectangular output signal using a thresholding reaction and an amplifying
reaction. Our chemical reactions-based microfluidic molecular communication
system is reproducible and well-designed, and more importantly, it overcomes
the slow-speed, unreliability, and non-scalability of biological processes in
cells. To reveal design insights, we also derive the theoretical signal
responses for our designed microfluidic transmitter and receiver, which further
facilitate the transmitter design optimization. Our theoretical results are
validated via simulations performed through the COMSOL Multiphysics finite
element solver. We demonstrate the predefined nature of the generated pulse and
the demodulated rectangular signal together with their dependence on design
parameters.
