Distributed Bragg reflectors for the colorimetric detection of bacterial contaminants and pollutants for food quality control

Real-time monitoring of bacterial contaminants and pollutants in food is of paramount importance nowadays, owing to the impressive extension of the food production/supply chain and the consequent increase in foodborne outbreaks worldwide. This represents a serious risk for consumers' health and accounts for a large fraction of food wastage, especially in the developed countries. Therefore, modern sensors for food quality control should possibly afford low-cost, portability, and easiness of readout to enable widespread diffusion of the technology, thus allowing food quality monitoring from the production/supply chain to the consumers' table. In these regards, one-dimensional photonic crystals, also known as Distributed Bragg Reflectors (DBRs), can represent simple yet efficient all-optical and label-free colorimetric sensors, given their relatively high color purity, easiness of integration with a large number of stimulus responsive materials, and low-cost fabrication from scalable processes. In this perspective article, we discuss the development of DBRs-based colorimetric sensors for the monitoring of bacterial contaminants and pollutants of interest in the food quality sector. We aim at providing a systematic overview on the main approaches that have been employed to achieve selectivity and sensitivity in DBRs-based sensors, with the view to enable widespread use of this technology at both the industry/supply chain and customers' level.