Department of Chemistry, University of Otago, Dunedin, New Zealand.
NIWA/University of Otago Centre for Oceanography, Department of Chemistry, University of Otago, Dunedin, New Zealand.
Talanta. 2021 Apr 1;225:121969. doi: 10.1016/j.talanta.2020.121969. Epub 2020 Dec 13.
This study presents the development of an optical fiber pH sensor based on evanescent wave absorbance for continuous pH measurements in marine microenvironments. The sensing layer consists of an optimized sol-gel matrix of tetraethoxysilane and dimethyldiethoxysilane, which substantially improves the entrapment efficiency of the pH indicator meta-cresol purple, leading to a long useable lifetime. The optical fiber pH sensor conforms to the Global Ocean Acidification Observing Network "weather" measurement quality guideline with precision of approximately 0.02 pH units, has a dynamic pH range of 7.4-9.7 in seawater, a response time of 2.5-6.5 min and a useable lifetime of 7 days. The optical fiber pH sensor has additional advantages of being self-referencing, without the need of an external sensor reference, having a simple fabrication method and basic spectrometer instrumentation. The suitability of the optical fiber pH sensor was demonstrated in real-time measurements of the ecologically significant green seaweed Ulva sp. The optical fiber pH sensor monitored pH variations due to metabolic activity over 7 days within the seaweed canopy and 4 days within the diffusion boundary layer interface, demonstrating the suitability for measurements in marine microenvironments.
本研究提出了一种基于消逝波吸收的光纤 pH 传感器，用于海洋微环境中的连续 pH 测量。传感层由优化的四乙氧基硅烷和二甲基二乙氧基硅烷溶胶-凝胶基质组成，大大提高了 pH 指示剂间甲酚紫的包埋效率，从而延长了可用寿命。光纤 pH 传感器符合全球海洋酸化观测网络“天气”测量质量指南，精度约为 0.02 pH 单位，在海水中的动态 pH 范围为 7.4-9.7，响应时间为 2.5-6.5 分钟，可用寿命为 7 天。光纤 pH 传感器具有自参考、无需外部传感器参考、制造方法简单和基本光谱仪仪器的额外优点。光纤 pH 传感器在实时测量具有生态意义的绿藻 Ulva sp.中的适用性得到了证明。光纤 pH 传感器监测了 7 天内在海藻冠层内和 4 天内在扩散边界层界面内由于代谢活动引起的 pH 变化，证明了其在海洋微环境中测量的适用性。
