基于PI湿敏薄膜的分布式光纤Bragg光栅湿度传感器

Research on relative humidity sensor based on distributed optical fiber Bragg grating coated with polyimide moisture sensitive film

研究了基于聚酰亚胺(PI)湿敏薄膜的分布式光纤Bragg光栅(FBG)湿度传感器。传感器利用PI薄膜湿膨胀效应,将湿应变作用于Bragg栅区,从而改变光纤FBG湿度传感器中心波长的原理,实现了对26～98%RH范围内环境相对湿度的监测。通过改进PI湿敏薄膜的制备及涂覆工艺,有效提高了FBG湿度传感器性能,并采取了相应温度补偿措施。在此基础上,针对空间多点湿度监测的实际需求,提出并研究了分布式FBG湿度传感系统。实验结果表明,所研制的FBG湿度传感器灵敏度为15pm/%RH,线性误差在2.75%以内,且具有良好的重复性和稳定性。

This paper presents a detailed study on relative humidity sensor based on distributed fiber Bragg grating （FBG） coated with polyimide （PI） as a moisture sensitive film. The wet expansion of PI film as wet strain on the FBG results in the shift of Bragg wavelength. The sensor realizes the relative humidity monitoring of 26%RH-98% RH. The method achieves FBG humidity sensor＇s better performance by improving the preparation and coating process of PI film and also compensates the temperature. On this basis, the distributed optical fiber Bragg humidity sensor system is prposed for the requirement of multi-point humidity monitoring. The experiments prove that the method can effectively improve the sensor performance, the humidity sensitivity of the sensor is 15 pm/% RH and the linearity error is less than 2.75%. The sensor also has good repeatability and stability.