Laser Driver and Analysis Circuitry Development for Quartz-Enhanced Photoacoustic Spectroscopy of NO2 for IoT Purpose

Proceedings

Alexander Bergmann¹  Philipp Breitegger²  Alexander Kerschhofer² 

[1] ;Institute of Electronic Sensor Systems, Graz University of Technology, 8010 Graz, Austria;

关键词: photoacoustic spectroscopy;    laser driver;    lock in amplifier;    DDS;    air pollution measurement;    internet of things;   

DOI  :  10.3390/proceedings2131062

来源: DOAJ

【 摘 要 】

The rising effort to track local air pollution measurements require low-cost air quality sensors that provide good accuracy, long-term stability and possibly Internet of Things (IoT) connectivity. To provide such a solution and avoid cost-intensive equipment the development of a low-cost environmental sensor system was started. To measure the pollutant NO₂, a quartz-enhanced photoacoustic spectroscopy (QEPAS) setup was established. A pulsed 450 nm laser diode excites NO₂ molecules due to its strong absorption at this wavelength and causes a vibrational-translational relaxation, which results in an acoustic wave. The acoustic wave is detected by a quartz tuning fork (QTF) which generates a weak electrical signal proportional to the NO₂ concentration. To realize this at low cost, a laser driver and an analysis circuit including a lock-in amplifier and analog-to-digital conversion were developed. We present first results, which proof the functionality of the circuitry compared to a more expensive laboratory setup.

【 授权许可】

Unknown