To date, the physical phenomena with which information is transmitted by artificial systems has largely been through media such as wave modulation (electromagnetic / acoustic) and particle/wave modulation (optical). Modern day communication engineering has developed a diverse set of tools and theory to provide a clear understanding of how to use these media for information transfer. However, leveraging particles to exchange information between systems have, in all respects, been exclusively owned by biological systems (cell compartments, cells, tissues, organs, insects, etc) and understanding these processes from a communications engineering point of view as received very little attention.

Molecular communication can be defined as a measurable information exchange process between networked artificial or biological entities through the use of molecules. The discipline of molecular communication has emerged from efforts to model biological communication channels using Claude Shannon’s information theory. However this field is a much richer and broader field of study crossing into disciplines such as systems biology, microfluidics, medicine, synthetic biology, nanotechnology, pharmacology, chemistry to name but a few. The tools and theory available to the traditional telecommunications engineer can potentially dramatically change our understanding of how communication occurs through the molecular communication channel, leading to a new wave of technology that can leverage and control the molecular communication channel for artificial communication or provide a direct communication interface to the biological world.

The H2020 FETOpen project CIRCLE (Grant No. 665564) aims to coordinate european research on molecular communication. The highly cross-disciplinary community is growing rapidly and is beginning to develop new tools and theory that is being leveraged to address difficult problems and also develop new solutions within various domains. CIRCLE recently ran the 1st workshop on Molecular Communications in Cambridge, UK on the 11th and 12th April. This workshop saw about 40 young as well as leading researchers and scientists from various disciplines come together to discuss the future research direction of the area. A report will be released on the (www.fet-circle.eu) website outlining the strategic agenda and research roadmap for Molecular Communication in Europe.

There are many research challenges that need to be addressed for Molecular Communication, as a key enabling technology, to have considerable impact into the future. A FET-Proactive topic will enable a critical mass of foundational as well as proof of concept research to take place between a diverse set of disciplines to deliver solutions currently outside all other ‘discipline specific’ research roadmaps.

A representative set of application domains/solutions where molecular communications can play a key role include the following:

Artificial Molecular Communication

• Artificial communication between nanoscale devices operating within the human body to support a breath of medical applications such as precision drug delivery, localised cancer treatment, autoimmune systems support.
• Modelling and specification of coding and modulation techniques appropriate for various information carrying molecular communication channels.
• Analysis of the interaction of nanoscale-devices with existing biological systems, like the human immune system, to understand potential side effects of nanomedicine applications.
• Exploitation of molecular communication paradigm for the development of very smart textiles, which can sense, react, adapt and respond to external stimuli or environment to perform a function.
• Understanding the fundamental differences between molecular and wave-based signalling (i.e., propagation, energy efficiency, scalability). This will allow to understand natural selection and enable us to design superior nano systems.

Molecular Communication as a system modeling and analysis framework

• Using molecular communication to understand inter-cellular and intra-cellular signalling. For example, researchers have recently discovered that many cellular signalling processes use dynamic signals. Molecular communication can be used to understand why certain dynamic signals are chosen over the other, how decoding works (which is still a fairly open problem in biology) etc.
• Identification and development of communication patterns (allostery/allosteric networks) within and between proteins in order to mediate malfunctioning activity as well as design novel regulatory elements.
• Understanding the importance of protein and domain cooperativity (kinetics) for  efficient regulation (switching) in  regulatory pathways.  Cooperativity changes induced by variants disrupt signaling cascades
• Leveraging Molecular communication theory to understand drug repurposing and drug secondary effects within biological systems.
• Understanding and modelling the intra and intercellular interactome as a communications network. This can shed new light on how information is encoded transmitted, decoded by the biological entities involved.  
• Building a system-on-a-chip, which leverages molecular communication, to be used in forensic analysis of biological samples, with the goal of increasing not only reliability, but also decreasing costs.
• Building a system-on-a-chip able to exploit molecular communication to speed up drug discovery, which is the process in pharmacology by which new candidate drugs are discovered. Leveraging knowledge on inter-cellular and intra-cellular signalling could help to speed up this process, coupled with in-silico preliminary analysis, simplifying clinical trials by adopting the body/organ-on-a-chip paradigm.
• Exploiting the knowledge of inter-cellular and intra-cellular molecular communications to build virtual physiology models, so as to design in-silico tools for personalized diagnosis and treatment.
• Tuning the molecular Communicome towards health and longevity.

Communication interface between biological and artificial systems

• The engineering of bacteria (through synthetic biology) that can perform various communication and signaling mechanisms in response to environmental changes. This change could be sensing of pathogens within the environment, and this could be sensed by the engineered bacteria.
• The interconnection of heterogeneous molecular communication nanonetworks to allow information to be transferred between different types of cells or tissues, and even organs.
• Uncoupling the cell to cell, tissue to tissue spread of inflammation and diseases particularly to avoid the arise of comorbidity.
• Using molecular communication as a tool to correct any impairments in the communication process of biological systems that leads to disease. An example is the impairments in the communication process between the neurons.
• Building a connection between molecular communications and systems sciences such as Systems Biology, Systems Physiology and Systems Medicine. The key of connecting systems is communication, but this communication takes place in multiple temporal and spatial scales. Theory, methods and models are required to understand how communication takes place in multiple temporal and spatial scales.