Chemical sensing based on biomimetic principles

Our ability to sense chemistry and biology in challenging scenarios, such as implantable devices for monitoring our health, or the quality of water in rivers and lakes has not advanced significantly since the fundamental breakthroughs in chem/bio-sensors of the 1970’s and 1980’s. It is becoming clear that in order to meet challenging performance specifications in terms of price and performance, these devices will have to be much more sophisticated, and in particular, adopt bio-inspired strategies to deliver platforms that can function autonomously for years. For example, many sensing platforms employ fluidic systems, and increasingly microfluidic systems to integrate functions such as sample transport, reagent addition, filtering, and detection. In the future, these fluidic systems will have a more active role in monitoring, reporting and maintaining the overall functionality of the platform. Like our own blood circulation system, fluidics in chem/bio-sensing devices will contain micro/nano-vessels and in-channel active components (e.g. integrated soft-polymer valves) capable of detecting damage, leaks, fouling, channel blockage etc., and furthermore, undertake appropriate remedial action (detect leak location & perform repairs, open blocked channels or provide alternative fluidic pathway) in order to dramatically extend the functional lifetime of the platform. Access to 3D additive technologies, in combination with directed polymer self-assembly, now enables such soft polymer actuators to be created with nano-scale resolution inside microfluidic channels for fluid control, or to provide channels with switchable characteristics such as surface roughness [1], or controlled uptake and release of molecular guests. In addition, fluidic coatings can optically report their condition (e.g. whether they are in binding or passive form, or molecular guests are bound) reflecting the chemical status along the entire length of the fluidic system, rather than at a localised detector [2]. The same characteristics can be integrated into micro-vehicles such as droplets, beads and vesicles, or microrobots that can also move spontaneously or be externally directed to specific locations, where they can perform these and other tasks [3, 4]. In this paper, we will present routes through which these exciting concepts can be practically realized