High-Precision Synchronous Detection of Breath CO, CH 4 , and CO 2 Using an NIR-WMS Sensor Based on a Dual-Channel Multipass Cell

, as determined by Allan deviation analysis. The system was successfully deployed in breath testing, effectively distinguishing end-tidal CO levels between smokers and nonsmokers, with concentration trends consistent with those in the established literature. This work validates a reliable and practical TDLAS sensor for real-time, multicomponent breath analysis, offering a viable pathway toward noninvasive, high-sensitivity diagnostic devices.