一种涂覆水凝胶的模间干涉型光纤pH传感器

A intermodal interferometric fiber optic pH sensor coated with hydrogel

为了实现pH值测量的微型化和智能化,提出了一种涂覆水凝胶的模间干涉型光纤pH传感器,满足了对光纤pH传感器结构紧凑、灵敏度高、稳定性好的需求。模间干涉型光纤干涉仪采用标准单模光纤错位熔接制得,对干涉仪进行拉锥提高其对外界折射率的响应灵敏度。将水凝胶涂覆在拉锥后的光纤干涉仪表面,当传感器周围pH值变化时,会引起感应区折射率的变化进而引起传输光谱发生变化,通过测量干涉仪光谱的漂移即可得到对应溶液的pH值。实验结果表明,传感器拉锥8 000μm后在pH值为1.88~7.61的测量灵敏度为0.76 nm/pH,线性相关系数为0.994。所提出的传感器pH值测量范围广、灵敏度高且成本较低,在pH值检测中具有广阔的应用前景。

In order to realize the miniaturization and intelligence of pH measurement,a hydrogel-coated intermodal-type fiber optic pH sensor is proposed to satisfy the demand for fiber optic pH sensors with compact structure,high sensitivity and good stability.The intermodal fiber interferometer is made by staggered fusion splicing of a standard single-mode fiber,and the interferometer is tapped to improve its response sensitivity to the external refractive index.The hydrogel is coated on the surface of the fiber optic interferometer after pulling the cone.When the pH value around the sensor changes,it will cause the refractive index of the sensing area to change and then cause the transmission spectrum to change,and the pH value of the corresponding solution can be obtained by measuring the drift of the interferometer spectrum.The experimental results show that the sensitivity of the sensor is 0.76 nm/pH and the linear correlation coefficient is 0.994 in the measurement range of pH 1.88~7.61 after pulling the cone of 8000μm.The proposed sensor with wide pH measurement range,high sensitivity,and low cost has a broad application prospect in pH detection.