基于聚酰亚胺材料的FBG湿度传感特性研究

Study on the characteristics of FBG humidity sensor based on polyimide

提出了一种基于光纤布拉格光栅(FBG)侧面镀膜感湿的新型全光纤湿度计,选取具有高湿敏特性和线膨胀系数(9.432×10-5%RH)的改性聚酰亚胺(PI)作为湿敏材料。通过在FBG侧面涂覆5种不同厚度的PI薄膜,检测厚度对传感器灵敏度和响应时间的影响,实验结果与理论计算符合很好,通过测试,PI薄膜厚为21μm时,传感器的湿度灵敏度为2.67×10-6/%RH,响应时间小于8s,有很好的实际应用前景。

This paper presents a new kind of all-optical hygrometer based on the sense of wet coating on the side of fiber Bragg grating（FBG）.We have selected modified polyimide（PI） as humidity materials because it has features of high humidity sensitivity and good linear coefficient moisture expansion of 9.431 2×10-5%RH.And we have detected the humidity sensitivity and the response time of 5 sensors with different coating thicknesses.We find that the results of experiment match well with theoretical calculations,and the humidity sensor has the best sensitivity and response time,with the coating thickness of 21 μm.Its sensitivity is 2.67×10-6/%RH,and the response time is less than 8 s.It has good prospects for practical applications.