Characterization of metal oxide gas sensors via optical techniques

Glöckler, Johannes; Jaeschke, Carsten; Tütüncü, Erhan; Kokoric, Vjekoslav; Kocaöz, Yusuf; Mizaikoff, Boris

doi:10.1007/s00216-020-02705-6

Cited by 11 publications

(9 citation statements)

References 40 publications

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“…This catalyses SMO surface oxidation of reducing gases, thereby releasing electrons into the conduction band to lower resistance (Kohl, 1989;Ponzoni et al, 2017). For CH 4 , this initially produces a hydrogen atom and methyl radical (Kohl, 1989) before eventual formation of carbon dioxide (CO 2 ) and water (Suto and Inoue, 2010;Chakraborty et al, 2006;Glöckler et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

“…Following robust physical sensor characterisation, empirical gas testing may then be performed in preparation for field deployment (Kim et al, 1997;Barsan et al, 2007;Honeycutt et al, 2019;Zhang et al, 2019;Daugela et al, 2020). A field-ready SMO sensor includes a sensitive layer, a substrate, electrodes (Barsan et al, 2007;Kooti et al, 2019;Glöckler et al, 2020) and a logger (Ferri et al, 2009;Collier-Oxandale et al, 2018). Concurrent measurement of environmental conditions is invaluable (van den Bossche et al, 2017;Daugela et al, 2020;Cho et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

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Characterising the methane gas and environmental response of the Figaro Taguchi Gas Sensor (TGS) 2611-E00

et al. 2023

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Abstract. In efforts to improve methane source characterisation, networks of cheap high-frequency in situ sensors are required, with parts-per-million-level methane mole fraction ([CH4]) precision. Low-cost semiconductor-based metal oxide sensors, such as the Figaro Taguchi Gas Sensor (TGS) 2611-E00, may satisfy this requirement. The resistance of these sensors decreases in response to the exposure of reducing gases, such as methane. In this study, we set out to characterise the Figaro TGS 2611-E00 in an effort to eventually yield [CH4] when deployed in the field. We found that different gas sources containing the same ambient 2 ppm [CH4] level yielded different resistance responses. For example, synthetically generated air containing 2 ppm [CH4] produced a lower sensor resistance than 2 ppm [CH4] found in natural ambient air due to possible interference from supplementary reducing gas species in ambient air, though the specific cause of this phenomenon is not clear. TGS 2611-E00 carbon monoxide response is small and incapable of causing this effect. For this reason, ambient laboratory air was selected as a testing gas standard to naturally incorporate such background effects into a reference resistance. Figaro TGS 2611-E00 resistance is sensitive to temperature and water vapour mole fraction ([H2O]). Therefore, a reference resistance using this ambient air gas standard was characterised for five sensors (each inside its own field logging enclosure) using a large environmental chamber, where logger enclosure temperature ranged between 8 and 38 ∘C and [H2O] ranged between 0.4 % and 1.9 %. [H2O] dominated resistance variability in the standard gas. A linear [H2O] and temperature model fit was derived, resulting in a root mean squared error (RMSE) between measured and modelled resistance in standard gas of between ±0.4 and ±1.0 kΩ for the five sensors, corresponding to a fractional resistance uncertainty of less than ±3 % at 25 ∘C and 1 % [H2O]. The TGS 2611-E00 loggers were deployed at a landfill site for 242 d before and 96 d after sensor testing. Yet the standard (i.e. ambient air) reference resistance model fit based on temperature and [H2O] could not replicate resistance measurements made in the field, where [CH4] was mostly expected to be close to the ambient background, with minor enhancements. This field disparity may have been due to variability in sensor cooling dynamics, a difference in ambient air composition during environmental chamber testing compared to the field or variability in natural sensor response, either spontaneously or environmentally driven. Despite difficulties in replicating a standard reference resistance in the field, we devised an excellent methane characterisation model up to 1000 ppm [CH4] by using the ratio between measured resistance with [CH4] enhancement and its corresponding reference resistance in standard gas. A bespoke power-type fit between resistance ratio and [CH4] resulted in an RMSE between the modelled and measured resistance ratio of no more than ±1 % Ω Ω−1 for the five sensors. This fit and its corresponding fit parameters were then inverted and the original resistance ratio values were used to derive [CH4], yielding an inverted model [CH4] RMSE of less than ±1 ppm, where [CH4] was limited to 28 ppm. Our methane response model allows other reducing gases to be included if necessary by characterising additional model coefficients. Our model shows that a 1 ppm [CH4] enhancement above the ambient background results in a resistance drop of between 1.4 % and 2.0 % for the five tested sensors. With future improvements in deriving a standard reference resistance, the TGS 2611-E00 offers great potential in measuring [CH4] with parts-per-million-level precision.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterising the methane gas and environmental response of the Figaro Taguchi Gas Sensor (TGS) 2611-E00

et al. 2023

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“…With the development of science and technology, in situ techniques have been developed more and more intensively. [82][83][84][85] In situ and operando characterization methods (Figure 3) under real-time reaction conditions is of importance to reveal the structure of reactant intermediates and mechanisms. [69]…”

Section: In Situ and Operando Methodsmentioning

confidence: 99%

In Situ/Operando Methods for Understanding Electrocatalytic Nitrate Reduction Reaction

et al. 2023

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With the development of industrial and agricultural, a large amount of nitrate is produced, which not only disrupts the natural nitrogen cycle, but also endangers public health. Among the commonly used nitrate treatment techniques, the electrochemical nitrate reduction reaction (eNRR) has attracted extensive attention due to its mild conditions, pollution‐free nature, and other advantages. An in‐depth understanding of the eNRR mechanism is the prerequisite for designing highly efficient electrocatalysts. However, some traditional characterization tools cannot comprehensively and deeply study the reaction process. It is necessary to develop in situ and operando techniques to reveal the reaction mechanism at the time‐resolved and atomic level. This review discusses the eNRR mechanism and summarizes the possible in situ techniques used in eNRR. A detailed introduction of various in situ techniques and their help in understanding the reaction mechanism is provided. Finally, the current challenges and future opportunities in this research area are discussed and highlighted.

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“…MOSs are very popular and widely used in different areas to detect up to 150 different types of oxidizing and reducing gasses and vapours [79].…”

Section: Metal Oxide Gas Sensors: Mossmentioning

confidence: 99%

Nanotechnology and E-Sensing for Food Chain Quality and Safety

Poeta,

Liboà,

Mistrali

et al. 2023

Sensors

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Nowadays, it is well known that sensors have an enormous impact on our life, using streams of data to make life-changing decisions. Every single aspect of our day is monitored via thousands of sensors, and the benefits we can obtain are enormous. With the increasing demand for food quality, food safety has become one of the main focuses of our society. However, fresh foods are subject to spoilage due to the action of microorganisms, enzymes, and oxidation during storage. Nanotechnology can be applied in the food industry to support packaged products and extend their shelf life. Chemical composition and sensory attributes are quality markers which require innovative assessment methods, as existing ones are rather difficult to implement, labour-intensive, and expensive. E-sensing devices, such as vision systems, electronic noses, and electronic tongues, overcome many of these drawbacks. Nanotechnology holds great promise to provide benefits not just within food products but also around food products. In fact, nanotechnology introduces new chances for innovation in the food industry at immense speed. This review describes the food application fields of nanotechnologies; in particular, metal oxide sensors (MOS) will be presented.

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Characterization of metal oxide gas sensors via optical techniques

Cited by 11 publications

References 40 publications

Characterising the methane gas and environmental response of the Figaro Taguchi Gas Sensor (TGS) 2611-E00

Characterising the methane gas and environmental response of the Figaro Taguchi Gas Sensor (TGS) 2611-E00

In Situ/Operando Methods for Understanding Electrocatalytic Nitrate Reduction Reaction

Nanotechnology and E-Sensing for Food Chain Quality and Safety

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