光纤干涉型石墨烯膜压力传感器性能的影响机理与实验研究

Diaphragm-type optical fiber pressure sensors with high sensitivity have become an international research focus and frontier in current advanced pressure sensor technologies. More attentions have been paid to silicon-based or polymer-based pressure sensors. However, a thinner film thickness limits severely the anti-overload ability and the sensitivity of such sensors. In this research project, graphene is used as a pressure-sensitive diaphragm because of its ultra-thin, high-intensity material properties. Considering the factors including membrane intrinsic mechanical property, molecular adhesion behavior between the graphene/substrate surface and temperature effect, a pressure-deflection theoretical model for suspended graphene diaphragm is established. According to the large-deflection theory of circular diaphragm and the molecular dynamics simulation method, the micro/nano-scale pressure-sensitive mechanism of graphene diaphragm which is suspended on the different substrates, and the effects on fiber-optic Fabry-Perot (F-P) cavity interference characteristics are analyzed. Then, in combination with sensor pressure-sensitive experiments, the sensor performance optimization methods, relating to the graphene-based pressure-sensitive membrane preparation and transfer, the diaphragm-type fiber-optic pressure sensor fabrication and the nonlinear error correction, are studied to achieve ultra-high sensitivity and good consistency. This research lays a solid theoretical foundation and instruction method for the high-performance implementation of graphene-based pressure sensors which have important potential applications in aerospace and biomedical fields.

高灵敏度膜片式光纤压力传感器是当前国内外先进压力传感器技术的研究热点与前沿，多集中于以硅、聚合物为敏感膜，但其膜厚制约传感器抗过载能力与灵敏度性能。本项目以超薄高强度石墨烯为压敏膜片，应用薄膜大挠度理论与分子动力学方法，考虑薄膜的内在力学性质、薄膜/基底间的分子力吸附行为与温度敏感性等影响，建立悬浮石墨烯膜压力－挠度模型，系统研究微纳尺度下悬浮于不同基底材料的石墨烯膜压力传感特性影响机理及其对光纤Fabry-Perot 腔干涉特性的影响规律。在此基础上，结合压力传感特性实验，开展石墨烯基压力敏感膜制备与基底转移、膜片式光纤压力探头设计和传感器非线性误差校正的优化方法研究，实现石墨烯膜光纤干涉型压力传感器的超高灵敏度与良好的一致性。本项目的研究可为石墨烯膜压力传感器高性能实现提供坚实的理论基础和方法指导，在航空航天、生物医疗等领域具有重要的潜在应用价值。

提高膜片式光纤Fabry-Perot（F-P）压力传感器灵敏度的关键因素主要取决于膜片的材料与厚度。本项目基于超薄石墨烯膜，开展高灵敏度光纤F-P压力传感器的影响机理与实验研究。主要完成的研究工作如下：.(1)基于悬浮石墨烯膜的初始张力与边界吸附力特性，引入吸附能参数，构建吸附能与预应力之间关系，获取了常温条件下吸附能对石墨烯膜压力敏感特性的影响规律，提出了一种基于F-P干涉的吸附能间接测量方法，获取了传感器线性工作范围的理论最大压力值。.(2)为准确评估石墨烯膜/SiO2基底间吸附力学行为，设计实现了一种基于纳米金颗粒填充石墨烯膜泡的吸附能直接测量方法。实验结果表明，单层、3~5层和~13层厚石墨烯膜与/SiO2基底间吸附能约为0.453J/m2、0.317J/m2和0.277J/m2。.(3)利用薄膜大挠度理论和F-P多光束干涉原理，建模分析适于小腔长解调的峰值法，设计实现了石墨烯膜F-P腔的单-双峰解调方法，并应用介质膜理论，获取了石墨烯膜反射率的影响因素及其对F-P干涉解调的影响规律。.(4)应用薄膜大挠度理论、光学介质膜理论与理想气体热力学模型，分析温度对石墨烯膜的反射率及其热变形的影响，获取了F-P传感器的温度敏感机理，并基于薄膜/基底间的吸附能与膜内预应力的关系，开展了悬浮石墨烯膜热吸附力学特性的实验研究。.(5)实验研究石墨烯膜的微观结构、制备转移过程对薄膜压力传感特性的影响，获取了高质量石墨烯膜制备与转移方法，并结合熔接的布拉格光栅，对制作的石墨烯F-P压力传感器进行了温度补偿实验。.(6)对制备的石墨烯膜光纤F-P压力传感器进行了湿敏影响实验，其波长偏移量的湿度灵敏度为0.02 nm/%RH，验证了石墨烯膜的疏水性及其F-P压力传感器的湿度不敏感性。并在此基础上，制备实现了一种超快响应的氧化石墨烯膜光纤F-P湿敏探头。.(7)利用薄膜-基底界面局部温控方法，实验研究了薄膜热应力对传感器声压灵敏度的影响，并3D打印制作了声压放大结构，声压测试初步验证了该结构的有效性，为传感器增敏结构设计与性能优化提供了支持支撑。