针对光纤光栅pH值传感器的响应灵敏度低、交叉敏感等问题, 提出了一种包覆pH值敏感型智能水凝胶的极大倾斜角度光纤光栅(Ex-TFG)pH值传感器。理论上研究了Ex-TFG pH值传感器的响应原理, 分析了影响传感器灵敏度的因素, 提出了提高测量灵敏度的方法。结合pH值敏感型智能水凝胶独特的响应特性设计和制作了传感器, 并进行了相应的实验研究。实验结果表明, 相对基于光纤布拉格光栅和长周期光纤光栅的pH传感器, 基于Ex-TFG的pH值传感器可有效提高对pH值的响应灵敏度(最大可达-0.718 nm/pH), 并且可以扩大pH值的检测范围。通过增加水凝胶的包覆厚度, 可增加pH值传感器的测量灵敏度。

Aiming at the low response sensitivity and the cross sensitivity of fiber grating pH sensors, a pH sensor based on fiber grating with extremely large tilt angle (Ex-TFG) is proposed, and the sensor is coated with pH sensitive intelligent hydrogel. The responsive mechanism of the Ex-TFG pH sensor is studied theoretically, factors affecting the sensor sensitivity are analyzed, and a method to improve the measurement sensitivity is presented. Combined with the unique response performance of pH sensitive intelligent hydrogel, sensors are designed and fabricated, and corresponding experiments are conducted as well. The experimental results show that, compared with the pH sensors based on fiber Bragg grating and long period fiber grating, the pH sensor based on Ex-TFG can effectively improve the pH response sensitivity (with maximum of -0.718 nm/pH) and expand the pH detection range. The measurement sensitivity of the pH sensor can be enhanced when we increase the coating thickness of hydrogel.