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MEMS-based thermal conductivity sensor for hydrogen gas detection in automotive applications

  • Accurate detection of hydrogen gas in vehicle interiors is very important for the future of a fuel cell car. Since this type of gas is highly volatile and flammable, the measurement methods have to be very reliable and precise due to safety reasons. In this paper a thermal conductivity sensor for hydrogen gas detection is presented, exhibiting a lower detection limit of 2000 ppm hydrogen in laboratory air. The sensor element is realized by micro-fabrication techniques on silicon wafers. The heated filament is exposed by a selective wet etching process creating a micro-hotplate on a thin membrane. In order to minimize power consumption, the sensor is operated in pulsed mode. Hydrogen gas detection was carried out using a synthetic gas testbench. Measurements of hydrogen contents ranging from 0% to 4% with an increment of 0.5% were successfully performed for ambient gas temperatures between -15°C and 84°C. Including humidity, high moisture contents have the greatest influence on thermal conductivity. This was predicted in theoretical investigations and confirmed in experiments. For evaluation, both the change in resistance ΔR as well as the time constant τ were taken as sensor output. For both quantities, the previously established theoretical relationship with thermal conductivity could be confirmed.

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Metadaten
Author:Dominik Berndt, Josef Muggli, Franz Wittwer, Christoph LangerORCiD, Stephan Heinrich, Thorsten Knittel, Rupert SchreinerORCiDGND
DOI:https://doi.org/10.1016/j.sna.2019.111670
Parent Title (English):Sensors and Actuators A: Physical
Publisher:Elsevier
Document Type:Article
Language:English
Year of first Publication:2020
Release Date:2021/02/01
Volume:305
Issue:April
Article Number:111670
Institutes:Fakultät Angewandte Natur- und Kulturwissenschaften
Fakultät Angewandte Natur- und Kulturwissenschaften / Labor Mikrosensorik
Begutachtungsstatus:peer-reviewed
research focus:Sensorik
Licence (German):Keine Lizenz - Es gilt das deutsche Urheberrecht: § 53 UrhG