差分微小型双谐振光声痕量气体定量检测方法研究

Trace gas detection is becoming a major research hotspot because of the need for sensitive sensors in various fields such as atmospheric monitoring and industrial application. The significance of developing mini-trace-gas detection technology lies in such practical situation where testing space is limited or gas sample is inadequate. Gas sensors based on photoacoustic spectroscopy (PAS) are well-established, thanks to their intrinsically high sensitivity, large dynamic range and non-pretreatment needed for gas sample. The detectability and anti-interference capability of PAS monitoring system are somehow compromised by its small dimension requirement. This proposal presents a quantitative analysis of multiple trace gas by PAS methodology mediated with integrated mini-dual-resonators, in order that high sensitivity and stability are materialized within a miniaturized PAS system. A dual-photoacoustic-resonator system is to be established. Each compact cell consists of a quartz tuning fork (QTF) and a mini T-cell the resonance of which is identical to the QTF eigenfrequency. Signal-to-noise ratio and gas detection sensitivity will be enhanced when synchronized dual-resonance is reached. Theoretical models of the mini-resonator photoacoustic trace gas detection and the multi-gas selectivity algorithm will be developed comprehensively. The sensitivity of this spectroscopic trace gas detection can be further improved by introducing the differential detection modality to the system which is able to sufficiently suppress baseline and eliminate unfavorable dominantly overlapping spurious absorption signal by non-target gas. The foregoing project provides a possible solution of trace gas detection in “rogue” testing condition with high accuracy, and contributes novel ideas to the development in spectroscopic detection technology.

痕量气体检测技术在环境质量监测和工业生产安全等领域有广泛应用需求和重要实践价值；高灵敏度是技术追求的核心，系统的微小型化是需求牵引下的必然趋势。光声光谱技术具有灵敏度高、测量动态范围大、样品无需前处理等优点，已成为一种重要的痕量气体检测手段。针对检测灵敏度提高、抗干扰能力增强与系统微小型化的矛盾，本申请提出一种基于差分调制原理的高灵敏度微小型光声痕量气体检测技术，拟从理论和实验方面开展以下定量检测研究：联合石英音叉和T型谐振腔，设计微小型一体化双谐振光声池来增强气体光声信号，提升系统信噪比和灵敏度；建立微小型光声痕量气体定量分析模型，研究多种气体成分选择算法；从差分调制原理和光声共振理论出发，分析抑制系统背景噪声和同吸收波段杂质气体强吸收的方法，从机理上探索灵敏度进一步提升的可能。本研究力争为复杂环境下的痕量气体高精度分析提供先进的检测方法，为光学无损检测领域同行的创新研究提供参考。

本项目针对痕量气体检测技术在环境质量监测和工业生产安全等领域的重要应用价值，提出高灵敏度T型增强光声光谱检测技术，重点突破吸收光路设计装调、微弱吸收光谱信号检测，高精度多组分物质浓度校准等关键问题，研制基于新型探模式的光声光谱痕量气体传感器。该成果已形成实验室原理样机将应用于某仓储环境安全检测，且发表SCI论文12篇，申请国家发明专利7项，获得授权3项。.1..T型增强多重谐振光声理论模型建立分析.以气体波动方程为基础，建立气体光声信号与入射光、气体浓度和光声池响应度之间的内在联系，并分析气体弛豫时间与光声池谐振频率（光声信号调制频率）之间的内在联系，理论上构建了光声池共振腔边界临界条件，为T型增强多谐振模式光声池的设计和优化打下理论基础。并分析入射光几何参数，优化入射光入射位置，提高光能信号利用率。该工作发表至无损检测领域一区期刊Photoacoustics上。.2..双谐振T型增强光声池的设计实现.通过光声信号理论模型分析，并构建有限元仿真模型，优化光声池共振频率点，保证了不同腔体间的有效声学独立。并构建光声池性能测试系统，对双谐振模式T型增强光声池的性能进行测试优化。以该内容申请并获取两项国家发明专利。.3..双谐振模式光声痕量气体检测系统的构建实现.以分析首要污染气体种类和成分信息为目标，同时考虑检测装置的抗流动性、抗震、抗电磁干扰等特性，优化气体检测装置性能。建立当污染气体的光谱吸收特征区域存在交叠干扰现象时，能够对多种污染气体同时检测的高精度定量光声光谱装置。该工作发表至一区期刊Photoacoustics上。.4..小型化双谐振模式光声痕量气体检测原理样机的制作测试.高灵敏度痕量气体成分检测系统整机根据痕量污染气体预警功能需求分析，集成了高性能气体传感模块核心功能模块、可调谐宽带稳定光源模块、缓冲分立式基模纵向共振光声池、嵌入式软件系统架构、浓度分析算法、智能预警模块等多个方面一体化结构设计。使整个原理样机体积缩小至原来装置的1/30，有效降低了系统的体积和功耗，可完成多种痕量气体的高精度检测。