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Sensors 2015, 15(5), 12092-12102;

LED-Absorption-QEPAS Sensor for Biogas Plants

Fraunhofer Heinrich Hertz Institute
Clausthal University of Technology, IEPT, Am Stollen 19B, Goslar 38640, Germany
Clausthal University of Technology, EFZN, Am Stollen 19A, Goslar 38640, Germany
Author to whom correspondence should be addressed.
Academic Editor: Vittorio M.N. Passaro
Received: 20 March 2015 / Accepted: 13 May 2015 / Published: 22 May 2015
(This article belongs to the Section Physical Sensors)
Full-Text   |   PDF [3785 KB, uploaded 22 May 2015]   |  


A new sensor for methane and carbon dioxide concentration measurements in biogas plants is presented. LEDs in the mid infrared spectral region are implemented as low cost light source. The combination of quartz-enhanced photoacoustic spectroscopy with an absorption path leads to a sensor setup suitable for the harsh application environment. The sensor system contains an electronics unit and the two gas sensors; it was designed to work as standalone device and was tested in a biogas plant for several weeks. Gas concentration dependent measurements show a precision better than 1% in a range between 40% and 60% target gas concentration for both sensors. Concentration dependent measurements with different background gases show a considerable decrease in cross sensitivity against the major components of biogas in direct comparison to common absorption based sensors. View Full-Text
Keywords: optical sensing; spectroscopy; photoacoustic; absorption; biogas optical sensing; spectroscopy; photoacoustic; absorption; biogas

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Köhring, M.; Böttger, S.; Willer, U.; Schade, W. LED-Absorption-QEPAS Sensor for Biogas Plants. Sensors 2015, 15, 12092-12102.

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