Resonant Photoacoustic Detection of NO₂ with an LED Based Sensor

• Main Authors: Christian Weber, Johannes Kapp, Katrin Schmitt, Hans-Fridtjof Pernau, Jürgen Wöllenstein
• Format: Article
• Language: English
• Published: MDPI AG 2018-11-01
• Series: Proceedings
• Subjects: resonant photoacoustic sensor; LED; NO₂ detection
• Online Access: https://www.mdpi.com/2504-3900/2/13/1036
• ISSN: 2504-3900

In times of steadily increasing air pollution especially in urban areas, the monitoring of nitrogen dioxide (NO₂) has gained in importance and with it the search for compact, low-cost sensors. We present a novel approach to measure NO₂ in sub-ppm concentrations with a photoacoustic sensor utilizing a T-shaped resonance cell. An inexpensive single LED with a peak wavelength of 410 nm was used as radiation source and the acoustic detection was done with a commercial MEMS microphone. For optimal coupling of the divergent LED light into the cell, the T-shaped resonator was developed and fabricated with rapid prototyping methods. The resonator shows a acoustic Q-factor >10 while having nearly no zero gas signal.