一种溶解氧敏感膜荧光发射效率光谱检测系统的研制

荧光猝灭法是快速测量污水、地表水以及渔业养殖水环境中溶解氧含量的先进技术之一，氧敏感膜是荧光猝灭法检测技术的核心，高荧光发射效率的氧敏感膜具有灵敏度高、特异性强、信噪比高的优点，检测结果更为准确。高效率是优选氧敏感膜的依据，也是溶解氧检测元器件、检测电路和检测光路优化设计的关键。现有溶解氧荧光检测装置中未有对氧敏感膜进行质量评估的标准方法，基于对已有传感器探头光路和电路的研究，该研究分析了全波段的荧光发射效率，选用大功率氙灯作为激发光源，基于连续单波长逐级扫描进行单色分光，构建了氧敏感膜的激发光-荧光光谱扫描装置，然后通过扫描测定氧敏感膜的激发光光谱和荧光光谱，提出并建立了荧光发射效率计算方法，提出的方法能客观地评估荧光发射能力，准确寻找最佳激发波长。为验证该方法的可行性，对来自国内外的多个氧敏感膜样品进行了实验测定，测试结果表明：单张氧敏感膜荧光发射效率随波长变化，呈多峰分布，同一型号的样品荧光效率曲线相似，但荧光发射效率差异较大，同一激发波长下荧光发射效率最大者较最小者高出14.5%，三张氧敏感膜的最大峰值波长均不同，分别为：401，543和435 nm，但发射峰值波长均为650 nm；不同型号的氧敏感膜相比较，最大荧光发射效率可相差1～2个数量级；实测传感器中使用的激发波长，其所选用的激发波长并非最大发射峰值波长，其荧光发射效率仅为最大荧光发射效率的1/2，表明传感器光源可以进一步优化选型。综上所述，本文建立了一种溶解氧敏感膜荧光发射效率检测系统，提出了以荧光发射效率评估氧敏感膜的方法，并开展了相关实验测定。本文工作可望用于新型氧敏感膜材料、工艺的研究及传感器优化设计与制造。

Development of a Spectral Measurement System for the Determination of the Fluorescence Efficiency of Dissolved Oxygen Membrane

Fluorescence quenching technology is one of the advanced technologies for rapid measurement of oxygen content in sewage, surface water and aquaculture water. Oxygen sensitive membrane is the core of fluorescence quenching detection technology. Oxygen sensitive membrane with high fluorescence emission efficiency owns high sensitivity, strong specificity and high signal-to-noise ratio，which makes the detection results more accurate. High efficiency is not the basis of selecting oxygen sensitive film and the key to the optimization design of dissolved oxygen detection components, detection circuit and detection optical path. There is no standard method for evaluating the quality of oxygen-sensitive membranes in existing dissolved oxygen fluorescence detection devices. Based on the research on the optical path and circuit of existing sensor probes, this paper proposes a method to evaluate the quality of oxygen-sensitive membranes using the fluorescence emission efficiency of the whole wavelength range. In this method, the high-power xenon lamp was selected as the excitation light source, and the monochromatic spectroscopy was performed based on the continuous single-wavelength scanning method. Then of oxygen-sensitive membranes were determined by scanning the excitation light spectrum and fluorescence spectrum, and the fluorescence emission efficiency calculation method was put forward and established. The method could objectively evaluate the fluorescence emission ability and find the optimum excitation wavelength accurately. In order to verify the feasibility of this method, this article conducted experimental measurement on a number of oxygen-sensitive film samples from home and abroad. The test results showed that: the fluorescence emission efficiency of a single oxygen-sensitive film varied with wavelength and exhibits a multimodal distribution. The fluorescence efficiency curves of the samples of the same type were similar, but there were significant differences in the fluorescence emission efficiency. The fluorescence emission efficiency of the samples with the largest excitation wavelength was 14.5% higher than that of the ones with the smallest excitation wavelength. The wavelength of the highest peak of the given three films were located differently, respectively lying at 401, 543 and 435 nm, meanwhile, all emission peaks were at 650 nm. it is great different of magnitude from 10 to 100 times of the maximum fluorescence emission efficiency for every oxygen sensor membrane. In practice, the observed fluorescence efficiency is only half of the highest, because the exit light wavelength used is not the best one with highest fluorescence, which indicates that it is necessary to optimize the wavelength selection of exit light in order to obtain the highest efficiency. In conclusion, this paper established a dissolved oxygen-sensitive membrane fluorescence emission efficiency detection system, proposed a method to effectively evaluate the quality of oxygen-sensitive membranes based on fluorescence emission efficiency, and carried out the experimental determination of oxygen-sensitive membrane samples. The work in this paper is expected to be used in the research of new oxygen-sensitive membrane materials and processes and the optimal design and manufacture of sensors.