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Open AccessArticle

Design and Fabrication Challenges of a Highly Sensitive Thermoelectric-Based Hydrogen Gas Sensor

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IMSAS—Institute for Microsensors, -actuators and -systems, University of Bremen, 28359 Bremen, Germany
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IAPC—Institute of Applied and Physical Chemistry, University of Bremen, 28359 Bremen, Germany
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Author to whom correspondence should be addressed.
Micromachines 2019, 10(10), 650; https://doi.org/10.3390/mi10100650
Received: 30 August 2019 / Revised: 24 September 2019 / Accepted: 24 September 2019 / Published: 27 September 2019
(This article belongs to the Special Issue MEMS/NEMS Sensors: Fabrication and Application, Volume II)
This paper presents a highly sensitive thermoelectric sensor for catalytic combustible gas detection. The sensor contains two low-stress (+176 MPa) membranes of a combination of stoichiometric and silicon-rich silicon nitride that makes them chemically and thermally stable. The complete fabrication process with details, especially the challenges and their solutions, is discussed elaborately. In addition, a comprehensive evaluation of design criteria and a comparative analysis of different sensor designs are performed with respect to the homogeneity of the temperature field on the membrane, power consumption, and thermal sensitivity. Evaluating the respective tradeoffs, the best design is selected. The selected sensor has a linear thermal characteristic with a sensitivity of 6.54 mV/K. Additionally, the temperature profile on the membrane is quite homogeneous (20% root mean standard deviation), which is important for the stability of the catalytic layer. Most importantly, the sensor with a ligand (p-Phenylenediamine (PDA))-linked platinum nanoparticles catalyst shows exceptionally high response to hydrogen gas, i.e., 752 mV at 2% concentration. View Full-Text
Keywords: thermopile; thermoelectric; hydrogen; gas sensor; silicon nitride; membrane; high sensitivity; temperature field thermopile; thermoelectric; hydrogen; gas sensor; silicon nitride; membrane; high sensitivity; temperature field
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Pranti, A.S.; Loof, D.; Kunz, S.; Zielasek, V.; Bäumer, M.; Lang, W. Design and Fabrication Challenges of a Highly Sensitive Thermoelectric-Based Hydrogen Gas Sensor. Micromachines 2019, 10, 650.

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