将新型量子点荧光传感技术与光纤倏逝波传感技术相结合, 发展了一种基于量子点荧光效应并结合倏逝波传导进行溶液酸碱度检测的新型传感技术, 具有灵敏度高、 检测速度快、 便于微环境检测、 可实现远程探测、 实时监测和原位分析等特点。 详细介绍了用于倏逝波传感的锥柱组合型光纤荧光探头的制备方法, 量子点在光纤探头表面的修饰流程, 光谱与强度两种光纤pH传感平台的建立, 并分别从响应范围、 线性度、 重复性和稳定性等方面对CdSe/ZnS量子点应用于光纤pH传感进行了评价。 结果表明, 在pH值为2~12的范围内, CdSe/ZnS量子点的荧光光谱信号的峰位在强酸和强碱的情况下都会产生红移, 且红移量随pH值的变化呈线性关系, 其量子点荧光强度信号随pH值的减小呈线性降低关系, 通过在强酸和强碱下交替测试的实验表明其具有较好的重复性, 利用荧光强度传感平台进行实时监测的实验表明其具有较好的稳定性。 因此, 将CdSe/ZnS量子点用于倏逝波光纤pH传感具有可行性, 在生物化学、 环境监测、 医学临床、 食品安全等领域的pH值测量方面有着广泛的应用前景。

We propose a new pH sensing technology using fluorescence sensing based on quantum dots combined with optical fiber sensing based on evanescent wave, which owns the advantages of high sensitivity, fast testing, suitability for micro-environment measurement, remote detection, real-time monitoring, in situ analysis and so on. In this paper, we detail the preparation method of the combined taper-and-cylinder optical fiber probe for evanescent wave sensing, the modification process of quantum dots onto the surface of the optical fiber probe, the construction of two fiber pH sensing platforms based on spectrum and intensity, and the evaluation of the performance of CdSe/ZnS quantum dots applied for optical fiber pH sensing from the aspects of response range, linearity, repeatability and stability, respectively. The results show that in the pH range of 2 to 12, the fluorescence spectrum peak position of CdSe/ZnS quantum dots will produce a red shift in strong acid and alkaline, and the amount of the red shift has a linear relationship with the pH value. The fluorescence intensity of the CdSe/ZnS quantum dots also reduces linearly with the decreasing of pH value. Moreover, the alternating tests under the strong acid and strong alkali indicate that it is of good repeatability. The real-time monitoring experiment through the intensity sensing platform indicates that it has good stability. Therefore, it is feasible to combine CdSe/ZnS quantum dots and evanescent wave for fiber pH sensing, and this kind of fiber pH sensor would have a promising future for pH detection in the field of biochemistry, environmental monitoring, clinical medicine and food safety.