基于SAW表面气液相效应和GC分离柱的气敏传感器的研究

限于传统涂敷敏感膜的声表面波（SAW）气敏传感器存在成膜困难和选择性差、重复性差以及再生性差等问题，本研究提出一种基于压电基底表面气体气液相转换效应机理的瑞利波传感器。首先建立了挥发性有机气体(VOCs)液相凝聚体薄层负载下的SAW波传模型，并仿真计算了其波传频散和波传衰减。然后在此基础上开发了一种基于瑞利声表面波传感器和气相色谱（GC）分离柱的便携式气体检测系统。最后实验论证了方案的可行性，初步的实验结果表明该系统具有分析时间短、选择性好、灵敏度高（可检测ppb浓度的混合VOCs）以及成本低等优势，因此其在痕量挥发性有机气体检测和分析应用上有良好的潜力和前景。

The study of surface acoustic wave gas sensors integrated GC separation column based on gas-liquid phase transition

Due to the problems of selectivity, repeatability and reproducibility, as well the difficulty of sensitive film coating, the polymer coated surface acoustic wave (SAW) sensors have limits for the application of gas detection. In this study, a novel Rayleigh SAW sensor based on the gas-liquid phase transition on the surface of piezoelectric crystal substrate was developed to improve the limits of the current methods for trace gas detection. The model of surface acoustic wave propagation was deduced when a liquid thin layer induced by the condensation of volatile organic compounds (VOCs) was loaded on the surface of piezoelectric substrate. The frequency disperses and attenuation of wave propagation were also emulated and calculated. The result showed that the sensitivity of this Rayleigh wave sensor could be increased up to a 1,000 fold compared with the polymer coated SAW sensor. A portable prototype instrument based on this Rayleigh wave sensor integrated with capillary column for selective separation was designed and developed for fast gas detection and analysis. The instrument is an enhanced portable gas analyzer with a preconcentrator, tunable separation module, programmed temperature controller, thermal electric cooler (TEC) and SAW sensor. At last experiments were conducted to test the feasibility of the scheme. The preliminary experimental result shows this system has good selectivity, high sensitivity, good repeatability and reproducibility, and low cost. It can detect and quantify the mixed VOCs at ppb level concentrations in several minutes, which demonstrate the potential and prospect for the application of trace VOCs gas detection.