微型光纤压力传感器的研究

The design, fabrication and testing of miniature fiber optic pressure sensor based on MEMS technology is mainly studied. The combination of optical fiber technology and microfabrication technology to the production of pressure sensors is proposed. The principle of pressure measurement based on Fabry - Perot multiple beam interference, the FP cavity length changes when loaded the pressure, resulting in the reflectance spectrum changes by tracking the change of the reflectance spectra to test the size of the applied external pressure. The structure of pressure-sensitive diaphragm using the mesa-diaphragm based on silicon substrate, the mechanical model derived the formula of the maximum deflection of the membrane. Both the deflections and the parallelism of the planar and mesa diaphragm are simulated by ANSYS. The average effect of the two membrane-type is analyzed, which declares that the mesa diaphragm is superior to the planar one on the parallelism and can reduce the signal averaging effect. The diaphragm is fabricated by the MEMS techniques, the wet etching process to create cavities in borosilicate fiber end face. Sensitive film and fiber bonded together by anodic bonding process.The test system is carried out and the reflection spectrum of the signal are demodulated by wavelength demodulation. The proposed sensor is made of commercial silica fibers only,the major advantages of the optical fiber sensors over the conventional electrical sensors include the immunity to electromagnetic interference, resistance to harsh environment and capability of multiplexing. And has wide application prospects in the petrochemical and aerospace sectors.

本项目主要研究基于MEMS工艺的微型光纤压力传感器的设计、制作及其测试。提出用光纤技术和微细加工技术相结合制作压力传感器，传感原理主要基于法布里-珀罗多光束干涉，外界压力作用在敏感膜上引起FP腔长发生变化，从而导致反射光谱发生变化，通过追踪反射光谱的变化测试出所加外界压力的大小。压力敏感膜采用硅为基底的台面膜结构，建立台面膜的力学模型，推导膜的最大挠度公式。ANSYS仿真模拟平面膜与台面膜受压后挠度变化曲线，并对其进行平行度分析,分析信号平均效应对两种膜型的影响。避免了膜片产生非平动变化，降低信号平均效应产生的影响。采用MEMS工艺制作压力敏感膜，湿法腐蚀工艺在硼硅酸盐光纤端面制作凹腔。敏感膜与光纤通过阳极键合工艺粘结在一起。建立测试系统，采用波长法解调反射谱信号。研制的传感器直接加工在光纤上，体积小，适用于强电磁干扰、易燃易爆等恶劣环境，在石油化工和航空航天领域有广泛应用前景。

本项目研究微型光纤MEMS压力传感器，包括传感器的理论设计、加工以及信号解调。有望解决传感器向微型化发展和批量生产时遇到的问题，适用于强电磁干扰、易燃易爆等恶劣环境，为开发适用于航空等工业领域应用的新型光纤传感器提供理论依据和实验证明。制作的样品压力传感器，在0-0.1MPa范围内，线性拟合度是99.95％，灵敏度5.2nm/MPa，零点输出为-0.00182 MPa～0MPa，重复性好。. 本项目的主要研究内容及创新点：.（1）设计了独特的FP腔结构，直接利用硅片与光纤的静电键合工艺形成，并采用LM算法对静电键合后的薄膜形变量做了拟合修正，对于实际硅膜的挠度变化具有一定的指导意义。.（2）提出了微型的台面结构的压力敏感膜，利用ANSYS建模仿真，在一定程度上提高了FP腔的平行度，并用光学模型了验证了信号的非平均效应，确定了设计参数。.（3）利用光传输矩阵理论描述光波在光纤法珀传感器中的传播，分析光纤的几何参数（曲率半径和腔长）以及硅膜作为反射膜对传感器整体性能的影响，确定了优化的光纤曲率半径和腔长，确定了光纤腐蚀工艺参数。.（4）提出了单、双峰相结合的峰值解调法，解调精度高，避免了光强度解调法中光源扰动的影响，也避免FFT相位解调法需要整个光谱范围内的信号。.（5）设计制作了一种基于双金属膜相应的光纤MEMS温度传感器，为硅基底类的光纤MEMS传感器起到很好的温度补偿作用。