基于敏感膜折射率变化的光纤甲烷传感器

Optical fiber methane gas sensor based on refractive index change of sensing film

根据光波导理论,分析基于敏感膜折射率变化的光纤甲烷传感原理,设计并制作含笼形分子A的聚合物敏感膜的光纤甲烷传感器,通过甲烷传感实验评价传感性能,以现场瓦斯气体样品验证其有效性。数值计算表明,当敏感膜折射率n2介于1.441～1.447时,传感器归一化光功率随n2增加呈线性快速下降,适宜制作高灵敏度折射率型光纤甲烷传感器。实验结果表明,当甲烷浓度在0～27.0%范围内,传感器信号随甲烷浓度增加呈线性增大,其斜率为0.007,该结果与数值计算结果相符;甲烷最低检出限2.80%,响应时间约180 s,且传感器对CO、CO2、H2S、O2、N2等非甲烷类气体不产生响应,选择性良好;用于现场瓦斯气体样品中的甲烷检测时,其测量结果与气相色谱法一致,相对误差1.47%。

By optical waveguide theory,the sensing principle of optical fiber methane gas sensor based on refractive index change of sensing film was analyzed.The sensor coated with the inclusion of cryptophane A in a transparent polysiloxane film was designed and fabricated.To evaluate its sensing performance and validity,the sensor signal was investigated by means of different concentration methane gas and coal mine gaseous sample.According to numerical simulation result,it is shown that normalized light power of the sensor drops linearly with the increase in refractive index of sensing film from 1.441 to 1.447.It is suitable for fabricating optical fiber methane sensor with high sensitivity.Analyzed by sensing experimental result,the sensor signal enhances linearly in the methane concentration range of 0-27.0%,with slope of 0.007,which accords with numerical simulation result.The detection limit for methane is 2.80%,with response time of about 180 s.The sensor indicates good selectivity with almost no interferences from common gases such as CO、CO2、H2S、O2、N2.For coal mine gaseous sample,methane detection result of the sensor agrees with that of gas chromatography,with relative error of 1.47%.