为了实现高温高湿环境下氢气浓度稳定准确的检测,提出了一种新的光纤布拉格光栅(FBG)氢气传感器制作方法。首先,在FBG表面自聚合组装聚多巴胺涂层,并将组装成的涂层用于吸附氯化钯溶液中的钯离子、形成钯核,以增强钯核在光纤表面的黏附强度。其次,利用还原剂为钯离子提供还原位点,将钯核生长为致密的钯膜。再次,在钯膜表面涂覆一层氧化硅超疏水薄膜,以增强光纤在高湿环境下运行的稳定性。最后,引入温度补偿单元,消除温度对氢浓度测量产生的影响。实验研究了聚多巴胺厚度、还原剂种类、钯膜厚度和温湿度对传感器氢敏响应特性的影响。研究发现,在温度为30~70 ℃、相对湿度为20%~90%的范围内,传感器能稳定准确地响应氢气浓度的变化,灵敏度达10.80 pm/%、相对误差小于7.2%。

In order to stably and accurately detect the hydrogen concentration in a high-temperature and high-humidity environment, we proposed a new fabrication method of fiber Bragg grating (FBG) hydrogen sensors in this paper. Firstly, a polydopamine coating, assembled on the surface of FBG by auto-polymerization, was used to adsorb the palladium ions in the palladium chloride solution and form palladium seeds, thus enhancing the adhesion of the palladium seeds on the fiber surface. Secondly, a reducing agent was used to provide a reduction site for the palladium ions so that the palladium seeds were grown into a dense palladium film. Thirdly, a layer of SiO₂ superhydrophobic film was coated on the surface of the palladium film to enhance its stability in a high-humidity environment. Finally, a temperature compensation unit was introduced to eliminate the influence of temperature on the measurement of hydrogen concentration. Furthermore, the effects of polydopamine thickness, the type of the reducing agent, the thickness of the palladium film, temperature, and humidity on the hydrogen-sensitive response characteristics of the sensor were experimentally studied. It is found that the sensor can respond stably and accurately to the changes in hydrogen concentration at the temperature of 30-70 ℃ and the relative humidity of 20%-90%, with a sensitivity of 10.80 pm/% and a relative error of less than 7.2%.