  The possibility to guide and control magnetic nanoparticles in a non-invasive
manner has spawned various applications in biotechnology such as targeted drug
delivery and sensing of biological substances. These applications are
facilitated by the engineering of the size, selective chemical reactivity, and
general chemical composition of the employed particles. Motivated by their
widespread use and favorable properties, in this paper, we provide a
theoretical study of the potential benefits of magnetic nanoparticles for the
design of molecular communication systems. In particular, we consider magnetic
nanoparticle based communication in a microfluidic channel where an external
magnetic field is employed to attract the information-carrying particles to the
receiver. We show that the particle transport affected by Brownian motion,
fluid flow, and an external magnetic field can be mathematically modeled as
diffusion with drift. Thereby, we reveal that the key parameters determining
the magnetic force are the particle size and the magnetic field gradient.
Moreover, we derive an analytical expression for the channel impulse response,
which is used to evaluate the potential gain in the expected number of observed
nanoparticles due to the magnetic field. Furthermore, adopting the symbol error
rate as performance metric, we show that using magnetic nanoparticles can
enable reliable communication in the presence of disruptive fluid flow.
Numerical results obtained by particle-based simulation validate the accuracy
of the derived analytical expressions.
