Characterization of metal oxide gas sensors via optical techniques.

Content Provider	Europe PMC
Author	Glöckler, Johannes Jaeschke, Carsten Tütüncü, Erhan Kokoric, Vjekoslav Kocaöz, Yusuf Mizaikoff, Boris
Abstract	Metal oxide (MOX) sensors are increasingly gaining attention in analytical applications. Their fundamental operation principle is based on conversion reactions of selected molecular species at their semiconducting surface. However, the exact turnover of analyte gas in relation to the concentration has not been investigated in detail to date. In the present study, two optical sensing techniques—luminescence quenching for molecular oxygen and infrared spectroscopy for carbon dioxide and methane—have been coupled for characterizing the behavior of an example semiconducting MOX methane gas sensor integrated into a recently developed low-volume gas cell. Thereby, oxygen consumption during MOX operation as well as the generation of carbon dioxide from the methane conversion reaction could be quantitatively monitored. The latter was analyzed via a direct mid-infrared gas sensor system based on substrate-integrated hollow waveguide (iHWG) technology combined with a portable Fourier transform infrared spectrometer, which has been able to not only detect the amount of generated carbon dioxide but also the consumption of methane during MOX operation. Hence, a method based entirely on direct optical detection schemes was developed for characterizing the actual signal generating processes—here for the detection of methane—via MOX sensing devices via near real-time online analysis.Graphical Abstract
ISSN	16182642
Journal	Analytical and Bioanalytical Chemistry
Volume Number	412
PubMed Central reference number	PMC7329784
Issue Number	19
PubMed reference number	32548766
e-ISSN	16182650
DOI	10.1007/s00216-020-02705-6
Language	English
Publisher	Springer Berlin Heidelberg
Publisher Date	2020-06-16
Publisher Place	Berlin/Heidelberg
Access Restriction	Open
Rights License	Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. © The Author(s) 2020
Subject Keyword	Metal oxide sensor MOX Substrate-integrated hollow waveguide iHWG Fluorescence sensor Gas sensors Infrared sensors Methane Carbon dioxide Oxygen
Content Type	Text
Resource Type	Article
Subject	Analytical Chemistry Biochemistry