Sensitive detection of NO using a compact portable CW DFB-QCL-based WMS sensor.

Area of Science:

• Environmental Science
• Analytical Chemistry
• Spectroscopy

Background:

• Nitrogen monoxide (NO) is a critical air pollutant and signaling molecule.
• Accurate and portable NO detection methods are needed for environmental monitoring and medical diagnostics.
• Existing NO sensors may lack sensitivity, portability, or real-time capabilities.

Purpose of the Study:

• To develop a compact and portable sensor for sensitive nitrogen monoxide (NO) detection.
• To utilize mid-infrared absorption spectroscopy with a room-temperature quantum cascade laser.
• To enhance measurement performance through advanced signal processing techniques.

Main Methods:

• Employed a room-temperature continuous wave (CW) distributed feedback quantum cascade laser (DFB-QCL) at 1900.08 cm⁻¹.
• Utilized wavelength modulation spectroscopy (WMS) with a software-based digital signal generator and lock-in amplifier.
• Implemented a Gabor filter denoising method to improve signal-to-noise ratio.

Main Results:

• Achieved a minimum detection limit of 42 ppbv with a 3-second integration time.
• Reached a measurement precision of 450 ppbv at a 0.1-second time resolution.
• Demonstrated the sensor's performance through experimental verification.

Conclusions:

• The developed sensor is compact, portable, and highly sensitive for NO detection.
• The combination of DFB-QCL, WMS, and Gabor filtering offers robust performance.
• The sensor shows significant potential for field applications in sensitive NO sensing.