基于银/二氧化钛复合膜的表面等离子共振气体传感器

表面等离子体共振是一种免标记的传感技术，当介质周围的介电常数发生改变时，则SPR谐振光谱特性也会随之改变。因此表面等离子体共振传感技术已广泛应用于生物化学和环境监测等领域。由于二氧化钛（TiO₂）覆盖层不仅可以保护金属层，还能调谐SPR谐振的光谱强度和谐振波长于近红外波段，应用于1550 nm的光纤传感，其氧化还原反应还能使其用于检测气体。由于氢气易燃易爆性，随着氢能源的广泛应用，因此对低浓度氢气检测技术研究具有特殊的意义。提出一种可更换银/二氧化钛复合膜的表面等离子共振的气体传感器，研究了SPR传感器在1 550 nm近红外波段对气体的敏感特性。研制了可更换银/二氧化钛复合膜的表面等离子共振（SPR）气体传感器。研究了在近红外波段对气体的表面等离子体共振光谱特性。仿真计算Kretschmann棱镜耦合的四层结构模型的共振光谱强度与银膜厚度，二氧化钛厚度和棱镜材料的关系，优化了Ag和TiO₂层的厚度以获得最大灵敏度，得到的最佳膜厚是45 nm Ag和110 nm TiO₂。Ag/TiO₂薄膜设计为可更换的一次性气敏膜，采用蒸镀和溅射方法镀膜，制备成本文所使用的 SPR传感器。利用Ag/TiO₂薄膜在复合界面产生SP共振光谱的移动，对气体进行测试。采用Kretschmann棱镜耦合结构的光谱波长检测实验系统。固定光源和入射角，测量波长的偏移量。宽光源（波长范围：1 462～1 662 nm）通过环形器、准直器，照射到棱镜和可更换的Ag/TiO₂敏感膜，经全反射(TIR)后，再由高反射镜反射回传感膜，并以相同的TIR角和光路再次反射回到准直器，从而被光谱仪检测。实验结果表明，Ag/TiO₂复合膜可以调谐共振波长到1 550 nm近红外波段，增强该传感器的光谱灵敏度，低浓度（14.7%～25%）氢气下的灵敏度可达-8.305 nm·%-1。并且可通过更换气敏膜检测不同的气体，增加生物相容性和气体传感能力。

Surface Plasmon Resonance Gas Sensor Based on Silver/Titanium Dioxide Composite Film

Surface plasmon resonance is a label-free sensing technology. When the dielectric constant around the medium changes, the SPR resonance spectral characteristics will also change. Because the titanium dioxide (TiO₂) covering layer can completely protect the metal layer, it can be converted into a 1 550 nm optical fiber sensor through the spectral intensity and reflection wavelength of SPR reflection at the near-infrared wavelength, and its redox reaction can also realize the effective use of detection gas. Due to the flammability and explosiveness of turbines and the wide application of converted hydrogen energy, it has special significance for researching low-concentration gas-phase detection technology. This paper proposes a replaceable silver/titanium dioxide composite film surface. Plasma resonance gas sensor studied the SPR sensor near 1 550 nm. Surface plasmon resonance spectral characteristics. The relationship between the resonance spectrum intensity of the four-layer structure model coupled with the Kretschmann prism and the thickness of the silver film, the thickness of titanium dioxide and the prism material was calculated by simulation, and the maximum sensitivity of the thickness of Ag and TiO₂ layers were optimized. The best film thicknesses obtained were 45 nm Ag and 110 nm TiO₂. The Ag/TiO₂ film is designed as a replaceable one-time gas-sensitive film coated by evaporation and sputtering methods to prepare the SPR sensor used in this article. The Ag/TiO₂ film is used to generate the SP resonance spectrum shift at the composite interface to test the gas. Spectral wavelength detection experimental system using Kretschmann refractive index conversion structure. Fix the light source and the incident angle, and measure the displacement of the wavelength. The 1 550 nm wide light source (wavelength range: 1 462～1 662 nm) is irradiated to the prism coating and the replaceable Ag/TiO₂ sensitive film through the circulator and collimator. It then is reflected by the high reflector after the total reflection (TIR) The sensing film is reflected to the collimator again with the same TIR angle and light path, to be detected by the spectrometer. Experimental results show that the Ag/TiO₂ composite film can convert the resonance wavelength to 1 550 nm near-infrared spectrum, enhancing the sensor’s spectral sensitivity, and the sensitivity under low concentration (14.7%～25%) microns can reach -8.305 nm·%-1. Moreover, it can detect different gases by replacing the gas-sensitive membrane with increasing biocompatibility and gas sensing capabilities.