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

The 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 multicolor emission of upconversion materials and the OH trapping of MB molecules, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula>OH detection and real-time temperature correction are achieved. The results show that the MB molecules can react sensitively and specifically with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula>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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula>OH. The limit of detection (LOD) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula>OH can be reach as low as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.26~\mu $ </tex-math></inline-formula>M. 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.