High-Precision Synchronous Detection of Breath CO, CH₄, and CO₂ Using an NIR-WMS Sensor Based on a Dual-Channel...

Area of Science:

• Analytical Chemistry
• Biomedical Engineering
• Spectroscopy

Background:

• Tunable Diode Laser Absorption Spectroscopy (TDLAS) offers potential for clinical diagnostics due to its selectivity and speed.
• Current TDLAS systems for breath analysis face challenges in complexity, cost, and accuracy for multicomponent detection.

Purpose of the Study:

• To develop a TDLAS system for simultaneous, high-precision monitoring of carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) in breath.
• To overcome limitations of existing systems by reducing complexity and enhancing detection accuracy.

Main Methods:

• Integrated a novel, miniaturized dual-path multipass cell with time-division multiplexing (TDM).
• Selected a closely spaced spectral line pair for CO and CH4 detection (2.3 μm band) using a single laser.
• Incorporated a dedicated optical path for CO2 detection (2 μm band) within the same cell.
• Utilized spectral line optimization and selection strategies.

Main Results:

• Achieved a compact dual-path, single-detector architecture.
• Demonstrated excellent linearity with low detection limits: 1.49 ppb for CO, 1.86 ppb for CH4, and 720.2 ppb for CO2.
• Successfully differentiated CO levels between smokers and nonsmokers in breath tests.

Conclusions:

• Validated a reliable and practical TDLAS sensor for real-time, multicomponent breath analysis.
• The system provides a viable pathway for noninvasive, high-sensitivity diagnostic devices.
• The miniaturized, integrated design enhances system applicability in clinical settings.