A Compact Multiplexed Hazardous Gas Sensing Platform for Real-Time Monitoring in Mining Scenarios.

Area of Science:

• Analytical Chemistry
• Environmental Science
• Sensor Technology

Background:

• Occupational health in confined environments like mines necessitates real-time hazardous gas monitoring.
• Traditional methods (GC-MS) are impractical due to size and lack of real-time data.
• Existing low-cost sensors (MOXs) suffer from poor selectivity and instability.

Purpose of the Study:

• To develop an integrated, compact analytical platform for real-time hazardous gas quantification in confined workspaces.
• To address the limitations of current gas sensing technologies in challenging environments.

Main Methods:

• Integration of multiple quantum-cascade lasers (QCLs) with substrate-integrated hollow waveguides (iHWGs) as miniaturized gas cells.
• Selective tuning of QCLs for specific hazardous gases (SO2, H2S, CO2, CH4, NO, NO2).
• Conversion of H2S to SO2 via UV irradiation for quantification; Arduino-based system for data acquisition and processing.

Main Results:

• Real-time quantification of target gases near permissible exposure limits (PELs) in underground mines.
• Achieved limits of detection (LODs) as low as 0.3 ppmv for SO2 and 3 ppmv for NO2.
• The compact system (470 × 320 × 100 mm) operates reliably in high humidity, dust, and vibrations.

Conclusions:

• The developed QCL-iHWG platform offers a viable solution for real-time hazardous gas monitoring in confined environments.
• High molecular selectivity and sensitivity are achieved, compatible with underground mine deployment.
• The system enhances safety by providing reliable, real-time data in harsh conditions.