基于光纤倏逝波传感器的磷酸根离子检测

Measurement of phosphate anion based on optical fiber evanescent wave sensor

提出了利用光纤倏逝波传感器通过光吸收方法来测量溶液中磷酸根离子浓度的新方法。将通信用标准单模光纤(SMF)局部腐蚀到接近芯层后放入不同浓度的磷钼蓝溶液中,当以磷钼蓝光吸收峰值为探测光波长时,光纤表面的倏逝波会部分被溶液吸收,通过测量光纤输出光强来计算溶液中的磷酸根离子浓度。实验结果表明,磷钼蓝溶液中磷浓度为0.04～0.40mg/L范围内,溶液的吸光度与磷浓度近似成线性关系,探测灵敏度为0.53L/mg,线性相关系数为0.918。基于光纤技术的传感器件结构紧凑、制作简单、成本低,有利于实现传感器的微型化。

A new approach has been proposed to measure the concentration of phosphate anion in liquid via optical fiber evanescent wave method. A standard single-mode optical fiber is used and its extramural cladding is corrupted by hydrofluoric acid. The optical fiber sensor was put into phosphomolybclate blue solution with different concentrations. The evanescent wave of the fiber would be absorbed partly by the solution. The phosphate ion concentration can be obtained by measuring the optical output intensity of the fiber. The experimental results show that there is a linear relationship between the optical absorbance of the solution and the concentration of phosphor in the concentration range of 0. 04--0. 4 mg/L with the detection sensitivity of 0.53 L/mg and the linear dependent coefficient of 0. 918. The optical fiber sensors we have investigated are compact and deserve the opportunities for realizing the miniaturization of test equipment.