A Fiber Sensor for VOC Gas Detection Based on Modulated Aggregation of Fluorescence Indicator

Volatile organic compounds (VOC) are the main source of indoor pollution. Inhalation of excess VOC gas will cause respiratory system damage. Therefore, VOC gas detection is essential for environment monitoring. In this article, an optical fiber device for rapid detection of VOC gas was proposed. Rhodamine 6G (R6G) was taken as the fluorescence indicator. The VOC gas sensor was designed for the modulation of aggregation-caused quenching of R6G. The sensing device was fabricated with three simple steps: in the first step, a multimode fiber was tapered; in the second step, the hydrogel was coated on the tapered fiber tip; and in the last step, aggregated R6G was loaded in the hydrogel. When the senor was probed into a VOC gas chamber, the gas molecules penetrated into the hydrogel and deaggregated the R6G dimer, and then, the fluorescence of R6G was strengthened. With this spectrum change, the concentration of VOC gas could be obtained. Compared with other fiber devices for VOC gas detections, the proposed sensor has the advantages of single-end, low cost, simple preparation, fast response, and large detection range, which means a great potential for in situ detecting applications.