Roadmap on printable electronic materials for next-generation sensors

The dissemination of sensors is key to realizing a sustainable, ‘intelligent’ world, where everyday objects and environments are equipped with sensing capabilities to advance the sustainability and quality of our lives—e.g., via smart homes, smart cities, smart healthcare, smart logistics, Industry 4.0, and precision agriculture. The realization of the full potential of these applications critically depends on the availability of easy-to-make, low-cost sensor technologies. Sensors based on printable electronic materials offer the ideal platform: they can be fabricated through simple methods (e.g., printing and coating) and are compatible with high-throughput roll-to-roll processing. Moreover, printable electronic materials often allow the fabrication of sensors on flexible/stretchable/biodegradable substrates, thereby enabling the deployment of sensors in unconventional settings. Fulfilling the promise of printable electronic materials for sensing will require materials and device innovations to enhance their ability to transduce external stimuli—light, ionizing radiation, pressure, strain, force, temperature, gas, vapours, humidity, and other chemical and biological analytes. This Roadmap brings together the viewpoints of experts in various printable sensing materials—and devices thereof—to provide insights into the status and outlook of the field. Alongside recent materials and device innovations, the roadmap discusses the key outstanding challenges pertaining to each printable sensing technology. Finally, the Roadmap points to promising directions to overcome these challenges and thus enable ubiquitous sensing for a sustainable, ‘intelligent’ world

Biogenic precious metal-based magnetic nanocatalyst for enhanced oxygen reduction

This work contributes to the development of electrocatalysts for use in polymer electrolyte fuel cells, specifically for the cathodic oxygen reduction reaction (ORR). To achieve this, electrochemical analysis was conducted using biofabricated platinum (bio-Pt) catalyst. Bio-Pt per se was found to be a poor catalyst for the ORR, attributed to the platinum being inaccessible to the reactants. Various ‘cleaning’ techniques were tested to partially remove biomass, providing improved catalytic activity. Bio-Pt was found to possess ferromagnetism under bulk magnetic analysis. Local magnetic analysis of this phenomenon focussed predominantly upon biofabricated palladium (bio-Pd) rather than bio-Pt as the origin of the magnetism appears to be the same in both cases and the effect was stronger in bio-Pd samples. This showed that bio-Pd possessed multiple magnetic types, which were suggested to arise from different types of Pd structure by comparison with electron microscopy studies. Oxygen is paramagnetic, thus it can be expected to experience a force towards an increasingly strong non-uniform magnetic field. Bio-Pt was exposed to a magnetic field prior to electrochemical testing to magnetise the nanoparticles. Magnetised bio-Pt produced superior diffusion limited current, suggesting that magnetic bio-Pt catalyst enables the enrichment of oxygen from air at the catalyst site