Journal
SENSORS AND ACTUATORS B-CHEMICAL
Volume 247, Issue -, Pages 930-939Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.snb.2017.03.086
Keywords
Mid-LED; Methane detection; Photoacoustic detector
Funding
- German Federal ministry of Economic Affairs and Energy [KF2162032CL4]
- German Federal Environmental Foundation (Deutsche Bundesstiftung Umwelt-DBU) [20014/321]
- graduate school decentralized, sustainable energy systems (DENE)
- Institute of Physics of the University of Freiburg
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Here we present the development of a gas sensor system for the monitoring of the lower explosion limit (LEL) of methane. A mid-infrared light emitting diode (LED) with central emission wavelength of 3.4 mu m is used as light source to probe the nu(3) rovibrational absorption band of methane. To gauge the light intensity, photoacoustic detectors consisting of a microelectromechanical system (MEMS) microphone and pure methane gas inside a hermetically sealed miniature cell are employed. In order to provide means for compensating fluctuations of the LED intensity, we use two equal detectors at two different optical path lengths from the light source. The sensor has been characterized in our laboratory and the results show a limit of detection of about 2,500ppm at an optical path length of 12mm. No cross-sensitivities to humidity have been detected. The concept can be adapted to other gases with absorption bands in the infrared spectrum. (C) 2017 Elsevier B.V. All rights reserved.
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