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NO2 photoacoustic sensing system based on resonant cell and UV-LED sensor

In this work the feasibility of a NO2 detection system based on photoacoustic effect is presented. The developed system takes advantage of low-cost components such as a commercial UV-LED as excitation source and a MEMS microphone as acoustic transducer. A cylindrical shaped structure has been used as a photoacoustic resonant cell and the light source modulated near its acoustic resonance frequency. Acoustic simulations have been carried out to investigate the acoustic coupling between the considered medium and the mechanical structure, and to determine the requirements of the readout electronic system. Preliminary gas measurement results are shown, obtained by exploiting an ad hoc realized characterization system. The gas sensing performances of the system have been tested in the range 0-50 ppm of NO2 concentration.