Sun Haiyue, Qiao Shunda, He Ying, Sun Xiaorong, Ma Yufei
National Key Laboratory of Laser Spatial Information, Harbin Institute of Technology, Harbin, 150001, China.
Zhengzhou Research Institute, Harbin Institute of Technology, Zhengzhou, 450000, China.
Light Sci Appl. 2025 Apr 30;14(1):180. doi: 10.1038/s41377-025-01864-4.
Highly sensitive gas detection plays a crucial role in advanced scientific and technological fields. This paper presents a parts-per-quadrillion (ppq) level ultra-highly sensitive light-induced thermoelectric spectroscopy (LITES) sensor for the first time. The artificial fish swarm algorithm auto-designed multi-pass cell (MPC) with double helix pattern, and the polymer modified round-head quartz tuning fork (QTF) with low-resonant frequency (f) were adopted to improve the gas absorption and QTF's detection ability. The obtained MPC, with a long optical path length (OPL) of 25.8 m and a small volume of 165.8 ml, is beneficial for increasing gas absorption while keeping the sensor compact. The novel QTF was structurally optimized to obtain low f (~9.5 kHz) and modified by polydimethylsiloxane (PDMS) to reduce heat diffusion and enhance vibration amplitude. A strong absorption line of carbon monoxide (CO) located in the mid-infrared region (4.59 μm) was chosen as the target line. The signal-to-noise ratio (SNR) of CO-LITES sensor based on the novel QTF was improved by 10.59 times, reaching the highest level when compared to the commercial QTF. The corresponding minimum detection limit (MDL) was calculated to be 23 ppt. When the integration time of the sensor system was increased to 500 s, the MDL could be improved to 920.7 ppq. Compared to the reported spectroscopy techniques for CO gas detection, the LITES sensor in this study offers an excellent result in terms of detection sensitivity.
高灵敏度气体检测在先进科技领域发挥着至关重要的作用。本文首次提出了一种用于检测万亿分之一（ppq）级别的超高灵敏度光致热电光谱（LITES）传感器。采用人工鱼群算法自动设计的具有双螺旋图案的多程池（MPC）以及具有低谐振频率（f）的聚合物修饰圆头石英音叉（QTF），以提高气体吸收和QTF的检测能力。所获得的MPC具有25.8 m的长光程长度（OPL）和165.8 ml的小体积，有利于在保持传感器紧凑的同时增加气体吸收。对新型QTF进行了结构优化以获得低f（约9.5 kHz），并用聚二甲基硅氧烷（PDMS）进行修饰以减少热扩散并增强振动幅度。选择位于中红外区域（4.59μm）的一氧化碳（CO）强吸收线作为目标谱线。基于新型QTF的CO-LITES传感器的信噪比（SNR）提高了10.59倍，与商用QTF相比达到了最高水平。计算得出相应的最低检测限（MDL）为23 ppt。当传感器系统的积分时间增加到500 s时，MDL可提高到920.7 ppq。与报道的用于CO气体检测的光谱技术相比，本研究中的LITES传感器在检测灵敏度方面提供了优异的结果。
