Optimized Ge-As-Se-Te chalcogenide glass fiber sensor with polydopamine-coated tapered zone for the highly sensitive detection of p-xylene in waters.

A novel Ge-As-Se-Te chalcogenide glass (ChG)-tapered fiber (ChG-TF) sensor for detecting environmentally relevant organic pollutants with p-xylene as the model was investigated. The prominent design feature of the sensor is that its tapered zone was coated with a polydopamine membrane by a facile in situ self-polymerization process. As the tapered zone exposed to the aqueous sample, the p-xylene molecules would be enriched into the polydopamine coating. The detection limit for p-xylene aqueous solution obtained by the polydopamine-coated sensor was decreased to 50 µg/mL, which was approximately 2.5% that of the uncoated one. To the best of our knowledge, this paper is the first report of a polymer membrane coating, which can significantly enhance the sensitivity of the ChG-TF sensor. The straightforward test features and the capacity of the sensor to detect organic pollutants with as low as ppm range revealed that this sensor has great potential for online, in situ environmental qualification.