Improving detection limit of non-dispersive infrared gas sensor with high precision by matched filtering

Non-dispersive infrared (NDIR) gas sensors have the disadvantage of high limit of detection (LOD), and the signal-to-noise ratio (SNR) has a significant impact on LOD. This paper proposes the application of matched filtering to NDIR gas sensors, a weak signal detection method that maximizes the SNR, improving the LOD. Experimental results show that matched filtering outperforms traditional methods, achieving an LOD of 1.131 ppm, while the LOD based on lock-in amplification is 7.350 ppm. The full-scale relative error and relative standard deviation (RSD) of the sensor in detecting different gas concentrations were optimized and improved. This approach provides a significant algorithmic improvement in the detection accuracy of NDIR gas sensors, offering potential for the detection of gases with less prominent absorption peaks, such as hydrogen.非分光红外（Non-dispersive infrared, NDIR）气体传感器存在检测限（Limit of Detection, LOD）偏高的固有缺陷，且信噪比（Signal-to-Noise Ratio, SNR）对检测限存在显著影响。本文提出将匹配滤波（matched filtering）应用于非分光红外气体传感器的方案：该弱信号检测方法可最大化信噪比，从而改善检测限性能。实验结果表明，匹配滤波的检测性能优于传统方法，其LOD可达1.131 ppm，而基于锁相放大（lock-in amplification）的LOD仅为7.350 ppm。该传感器在检测不同气体浓度时的满量程相对误差与相对标准偏差（Relative Standard Deviation, RSD）均得到了优化与提升。本方案为非分光红外气体传感器的检测精度带来了显著的算法层面改进，为吸收峰较弱的气体（如氢气）的检测提供了应用潜力。