仿生结构气敏光栅的大幅增敏机制及在氢泄漏监测中的应用研究

For fiber optic hydrogen sensor, there is no any successful application. That is mainly result from its lower sensitivity. And the film is easy to flake off when it exposure in H2 gas repetitiously. A new idea is proposed, i.e. bionic structure was ablated in fiber cladding by femtosecond laser, including snakeskin microstructures added with sweat gland holes, the sensitivity of the coating FBG would be enhanced about 10 times. This method can prevent the film invalidation and prolong its life. The key points of this study include: 1) study the sensitivity enhancing mechanism of FBG with bionic structures, such as mechanical theory, material modification mechanism; study microstructure fabricating method by femtosecond laser; investigate the effect on FBG reflective spectrum. 2) Study the fabrication quality controlling of the microstructures and films, seek an optimal matching of sensitive films and microstructures. 3) trial-manufacture the new-type fiber optic hydrogen sensor, perform the H2 concentration tests; study the signal processing method, compensation method and calibration method of the gas concentration.4) To large range of hydrogen leak, a demonstrating network for FBG H2 monitoring will be established, introducing the temperature and humidity compensation. By way of parenthesis, a new fiber optic humidity sensor with microstructures will be trial-fabricated. With this project, it is not only expected to solve the difficult problems for FBG hydrogen sensor, but also promising to develop FBG CH4 sensor. It is important to the safety of energy and national defense industry.

光纤氢气传感器尚无实用案例，瓶颈在于灵敏度低，氢敏膜多次反应易开裂失效。申请人提出利用飞秒激光在光纤光栅(FBG)包层加工仿生微结构（汗腺微孔+蛇皮状或叶齿状微结构），镀膜后有望增敏10倍左右，还能防止薄膜开裂延长寿命。研究要点包括：1）研究FBG仿生结构的增敏机制，诸如力学原理, 材料改性机理等；研究仿生微结构的飞秒激光制备方法,激光辐照对FBG反射谱的影响机制；2）研究仿生结构与氢敏膜的制备质量控制规律，诸如微结构与薄膜表征，工艺参数影响，多种膜与微结构的匹配性。3）试制仿生结构光纤氢气传感器，进行氢浓度测试；研究相应的信号处理、补偿措施及浓度标定方法。4）针对广域氢泄漏，组建光纤氢传感示范网络进行模拟监测试验，考虑温度/湿度补偿，为此附带研制微结构光纤湿气传感器。本研究不仅能解决光纤氢传感器的实用化瓶颈难题,还为光纤瓦斯气体传感器提供一种潜在途径,对能源与国防工业的安全监测意义重大。

光纤氢气传感器由于灵敏度不足、氢敏膜开裂失效、测量范围窄等问题，较难应用于实际测量中。因此，开发一种本质安全、灵敏度高，可分布式测量的光纤氢气传感系统十分必要。.本项目利用飞秒激光在光纤光栅(FBG)包层加工仿生微结构，包括直槽（叶齿型）、单螺旋、交叉螺旋（蛇皮型）以及复合型微结构，并研究了相应镀膜微结构光纤传感探头的增敏机制；其次，探索了仿生结构与氢敏膜的制备质量控制规律；再次，制备了钯合金膜微结构和铂催化型三氧化钨微结构氢气传感器，并分别对其性能进行测试；最后，研究了光纤氢传感器的分布式组网技术，对氢泄漏的大范围监测进行了模拟试验与技术验证。实验结果表明，最优的螺旋微结构的加工参数为螺距60-120μm，激光能量为15-35μJ，直槽微结构为15-40μJ，直槽个数4-8个。钯合金膜微结构传感器响应时间在120-140s，恢复时间约为60-80s。纳米线形状的铂催化型三氧化钨微结构光纤传感探头具有最快的响应速度，其响应时间范围为15-100s，恢复时间为10-180s。本研究成果对石化与国防工业的安全监测具有重要意义。