New phosphorescent oxygen-sensitive materials based on nanostructured high density polyethylene and polypropylene films are described. The polymer substrates undergo treatment by a solvent crazing process to create a well-developed network of controlled, nanometer-size pores. Indicator dye molecules are then embedded by physical entrapment in such nanostructures which subsequently can be healed. Such sensors demonstrate improved working characteristics and allow simple, cost-efficient production and disposable use. They are well suited for large-scale applications such as nondestructive control of residual oxygen and "smart" packaging.
This study investigated the capacity of optical oxygen sensors to nondestructively detect containment packaging failures in commercial vacuum packed cheddar cheese. Unacceptable oxygen levels in packs lead to product deterioration and can significantly reduce shelf life. Vacuum packed cheddar cheese was monitored for oxygen levels over time at 4 °C with optical sensors prefitted to packaging laminates polyethyleneterephthalate/polypropylene. Oxygen levels present in packs immediately after packaging were 3% on average. Further ingress of oxygen into all packs occurred over storage time and levels ranged from 3.6% to 8.2% after 6 days. Information obtained using oxygen sensors led to further assessments and identification of the causes of packaging containment failure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.