Towards low-cost QEPAS sensors for nitrogen dioxide detection

Area of Science:

• Environmental Science
• Analytical Chemistry
• Sensor Technology

Background:

• Growing concerns about air pollution's health impacts drive demand for effective nitrogen dioxide (NO2) monitoring.
• Existing low-cost sensors struggle with accuracy, stability, and gas cross-sensitivity.
• Quartz-enhanced photoacoustic spectroscopy (QEPAS) offers a promising alternative for precise gas detection.

Purpose of the Study:

• To develop and present a novel bare fork QEPAS setup for sensitive NO2 detection.
• To demonstrate the system's suitability for environmental trace gas analysis.
• To overcome the limitations of micro-resonator-based QEPAS systems in varying environmental conditions.

Main Methods:

• Utilized a bare fork QEPAS configuration without micro-resonators for NO2 sensing.
• Integrated a low-cost temperature and humidity sensor for environmental robustness.
• Employed acoustic filters to enhance sensitivity at a continuous flow rate of 200 std cm3/min.

Main Results:

• Achieved ppb-level detection of NO2.
• Demonstrated a noise-equivalent concentration of 21 ppb NO2 in synthetic air for a 120s measurement time.
• The system proved robust and adaptable to changing environmental conditions.

Conclusions:

• The bare fork QEPAS setup provides a robust and sensitive method for NO2 detection.
• This technology is well-suited for environmental trace gas monitoring, meeting health and safety standards.
• The simplified design offers advantages over traditional QEPAS systems using micro-resonators.