Novel luminescent oxygen sensor systems for smart food packaging

摘要

For industrial applications, solid-state O2 sensors based on the quenching of photoluminescence, should be accurate, robust, easy-to-use in a calibration-free manner. These sensors generally consist of an O2 sensitive luminescent dye in a polymer matrix. The properties of this matrix such as dye compatibility, O2 permeability, mechanical strength and chemical resistance have a significant influence on the sensors final operating parameters. Although used in many applications, the existing solid-state sensing materials and manufacturing processes remain complex, rigid and expensive for large scale fabrication while incurring a substantial extra cost. Currently, as few sensors fit these ideals, there is a need for new sensor materials, fabrication techniques and integration technologies. We created and evaluated five new solid-state O2 sensitive materials: four based on microporous polypropylene fabric materials and one on polyphenylene sulphide films. The onus was on simplifying composition of sensors and ergo reduction in material consumption and manufacturing cost. The sensors exhibited lifetime signals and working characteristics suitable for use in food packaging. When tested in food simulants and in direct contact with food, the sensor based on ungrafted polypropylene membrane fabricated by the swelling method, outperformed the other sensors. This sensor is cheaper than commercial sensors, is easily incorporated into current packaging materials by means of heat-sealing or lamination and has a storage shelf-life of at least 12 months when stored in normal atmospheric conditions. Proof-of-concept tests, using commercial sensors, were carried out for industry customers. Sensors were used to track oxygen levels in meat packaging and also to select optimum packaging for a beverage product.