Ratiometric Design of Optical Fiber Sensor with Temperature Correction for Detection of Hydroxyl Radicals

Detection of hydroxyl radicals (·OH) is often required in environmental governance and biomedicine. To enhance the sensing accuracy and stability, this study constructed a temperature-corrected and ratio-calibrated sensor for sensitive hydroxyl radical detection by loading upconversion nanomaterials and dye molecules methylene blue (MB) on optical fibers. Based on the multi-color emission of upconversion materials and the ·OH trapping of MB molecules, the ·OH detection and real-time temperature correction are achieved. The results show that the MB molecules can react sensitively and specifically with ·OH. Under near-infrared excitation, precise information on temperature and MB absorption is obtained by detecting the ratio of multiple characteristic wavelengths of light, thus enabling the quantitative detection of ·OH. The limit of detection (LOD) of ·OH can be reach as low as 0.26 μM. The method shows the advantages of high sensitivity, low cost, and ease of miniaturization and is expected to be applied in environmental and biomedical fields.