Influence of Polymer Matrix Materials for Oxygen Sensors Based on Fluorescence Quenching by Molecular Oxygen

The influence of polymer matrix materials on oxygen sensors based on fluorescence quenching was investigated by molecular oxygen. Oxygen sensing films were prepared using tape casting technique with polystyrene (PS), polyvinyl chloride (PVC) and ethyl cellulose (EC) as matrices, and PtTFPP as a fluorescent indicator. The fluorescence lifetimes of these films were measured using the exclusive -or gate digital phase detection circuit. The results demonstrated that PVC exhibited lower oxygen permeability, with the fluorescence lifetime following a single -site Stern-Volmer equation in relation to oxygen partial pressure. Conversely, EC and PS, which had higher oxygen permeability, conformed to a two -site Stern-Volmer equation. Among the three polymer matrices, EC displayed the highest KSV constant, followed by PS, while PVC had the lowest, which were consistent with their respective oxygen permeabilities. Additionally, the effect of water vapor was investigated, revealing that the hydrophilic EC exhibited a prolonged fluorescence lifetime with increasing humidity in an oxygen -containing atmosphere, while the hydrophobic PS and PVC remained unchanged. Furthermore, the response characteristics of the oxygen -sensitive films were examined under cyclic switching conditions, showing that the higher the oxygen permeability of the polymer matrix, the shorter the response and recovery times. Based on the different extents of fluorescence quenching, it was recommended to use EC -based films for low oxygen concentration measurements, PS for medium to high oxygen concentrations, and PVC for high oxygen concentrations. This study improved the understanding of the influence of polymer matrix on fluorescence quenching, and provided reference for the application of fluorescence quenching -type oxygen sensors.