呼出气体分析是一种测量呼出气体成分和含量的新技术,在人体健康的无创检测和分析中应用得越来越广泛。基于低成本微型垂直腔面发射激光二极管(VCSEL)搭建了可调谐激光吸收光谱(TDLAS)气体分析系统,实现了人体呼出CO2的在线测量。该系统主要由激光管、驱动控制电路、光电探测器、放大电路、数据采集卡、控制软件、锁相放大器及赫里奥特气体池构成。该检测池的体积为400 mL,有效光程为20 m,激光光源的中心波长为1579.57 nm。采用波长调制吸收光谱技术中的二次谐波幅值反演计算人体呼出CO2的浓度。该系统可以实现精准、无损、高效地在线测量人体呼出CO2气体的浓度,波动范围小于±0.06%,灵敏度为0.14%。这一研究为近红外TDLAS技术研究人体呼出气体与相关疾病标志物的无创检测提供了新的研究思路。

The analysis of exhaled gas is a new technology for measuring the composition and content of exhaled gas, which has wide application in non-invasive detection and analysis of human health. In this paper, we build a tunable semiconductor absorption spectroscopy (TDLAS) gas-analysis system using a low-cost vertical-cavity surface-emitting laser (VCSEL) to realize online measurements of human-exhaled end-tidal carbon dioxide (CO2). The system mainly comprises a laser diode, drive control circuit, photodetector, amplifier circuit, data acquisition card, control software, lock-in amplifier, and Herriot gas cell. The gas cell has a volume of 400 mL and an effective optical path of 20 m, and the laser source has a center wavelength of 1579.57 nm. The system uses the second-harmonic amplitude in wavelength-modulated absorption spectroscopy to determine the concentration of CO2 exhaled by a human body. It achieves a fluctuation range of less than ±0.06% and a sensitivity of 0.14%, which satisfies the detection requirements for human-exhaled CO2, and it can accurately, non-destructively, and efficiently measure human-exhaled gas online. This study provides a new strategy for non-invasive detection of human-exhaled gas and related diseases by near-infrared TDLAS technology.