Selective Detection of Hazardous Indoor VOCs Using Metal Oxide Gas Sensors

Leidinger, M.; Sauerwald, Tilman; Conrad, Thorsten; Reimringer, W.; Ventura, Gabriela; Schütze, Andreas

doi:10.1016/j.proeng.2014.11.722

Cited by 55 publications

(27 citation statements)

References 4 publications

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“…Concentrations of VOCs are much higher indoors compared to outdoors because a wide range of consumer and personal care products, during their use, can release significant amounts of VOCs into the air. Therefore, in addition to CO 2 level, VOCs concentration is used as a parameter to establish the air quality in an indoor environment [44,45].…”

Section: Volatile Organic Compoundsmentioning

confidence: 99%

Two-Dimensional Zinc Oxide Nanostructures for Gas Sensor Applications

Leonardi

2017

Chemosensors

159

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Two-dimensional (2D) nanomaterials, due to their unique physical and chemical properties, are showing great potential in catalysis and electronic/optoelectronic devices. Moreover, thanks to the high surface to volume ratio, 2D materials provide a large specific surface area for the adsorption of molecules, making them efficient in chemical sensing applications. ZnO, owing to its many advantages such as high sensitivity, stability, and low cost, has been one of the most investigated materials for gas sensing. Many ZnO nanostructures have been used to fabricate efficient gas sensors for the detection of various hazardous and toxic gases. This review summarizes most of the research articles focused on the investigation of 2D ZnO structures including nanosheets, nanowalls, nanoflakes, nanoplates, nanodisks, and hierarchically assembled nanostructures as a sensitive material for conductometric gas sensors. The synthesis of the materials and the sensing performances such as sensitivity, selectivity, response, and recovery times as well as the main influencing factors are summarized for each work. Moreover, the effect of mainly exposed crystal facets of the nanostructures on sensitivity towards different gases is also discussed.

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Section: Volatile Organic Compoundsmentioning

confidence: 99%

Two-Dimensional Zinc Oxide Nanostructures for Gas Sensor Applications

Leonardi

2017

Chemosensors

159

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“…Improved spatial observations can support improved source apportionment, improved validation of emission and transport models and give better estimates of human exposure 1 . Arrays of air pollution sensors are now being deployed in both indoor 2,3,4,5 and outdoor 6,7,8 environments and there is increasing confidence in the quality of observations generated 4,7,8 .…”

Section: Introductionmentioning

confidence: 99%

“…Sensors typically have unique sensitivities towards both the target gas and towards cross interferences and raw signal data is often processed using multivariate regression models 6 and pattern recognition analysis 2,11 to correct for the multiple variables which impact sensor signals 7,10 . Experiments have shown that air flow 12 , temperature 10,12 , humidity 4,9,12 , exposure to other atmospheric gases 7,8 , drift over time 6,8 and sensor arrangements 7 cause signal variability 6,13 , lowering sensor reproducibility and impacting on data quality 11 . Approaches to improving the stability of sensor response include using temperature steps throughout a sample period 4 and noise reduction using well-designed circuit boards 7 .…”

Section: Introductionmentioning

confidence: 99%

“…Experiments have shown that air flow 12 , temperature 10,12 , humidity 4,9,12 , exposure to other atmospheric gases 7,8 , drift over time 6,8 and sensor arrangements 7 cause signal variability 6,13 , lowering sensor reproducibility and impacting on data quality 11 . Approaches to improving the stability of sensor response include using temperature steps throughout a sample period 4 and noise reduction using well-designed circuit boards 7 . However for an atmospheric instrument that will not have access to calibration materials during its period of operation, an understanding of how sensor responses change over the full range of timescales for which data may be collected and used is fundamental.…”

Section: Introductionmentioning

confidence: 99%

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Clustering approaches to improve the performance of low cost air pollution sensors

et al. 2017

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Article:Smith, Katie R., Edwards, Peter M. orcid.org/0000-0002-1076-6793, Evans, Mathew J. orcid.org/0000-0003-4775-032X et al. (5 more Low cost air pollution sensors have substantial potential for atmospheric research and for the applied control of pollution in the urban environment, including more localized warnings to the public. The current generation of single-chemical gas sensors experience degrees of interference from other co-pollutants and have sensitivity to environmental factors such as temperature, wind speed and supply voltage. There are uncertainties introduced also because of sensor-to-sensor response variability, although this is less well reported. The sensitivity of Metal Oxide Sensors (MOS) to volatile organic compounds (VOCs) changed with relative humidity (RH) by up to a factor of five over the range 19-90%RH and with an uncertainty in the correction of a factor two at any given RH. The short-term (second to minute) stabilities of MOS and electrochemical CO sensor responses were reasonable. During more extended use inter-sensor quantitative comparability was degraded due to unpredictable variability in individual sensor responses (to either measurand or interference or both) drifting over timescales of several hours to days. For timescales longer than a week identical sensors showed slow, often downwards, drifts in their responses which diverged across six CO sensors by up to 30% after two weeks. The measurement derived from the median sensor within clusters of 6, 8 and up to 21 sensors was evaluated against individual sensor performance and external reference values. The clustered approach maintained the cost competitiveness of a sensor device, but the median concentration from the ensemble of sensor signals largely eliminated the randomised hour-to-day response drift seen in individual sensors and excluded the effects of small numbers of poorly performing sensors that drifted significantly over longer time periods. The results demonstrate that for individual sensors to be optimally comparable to one another, and to reference instruments, they would likely require frequent calibration. The use of a cluster median value eliminates unpredictable medium term response changes, and other longer term outlier behaviours, extending the likely period needed between calibration and making a linear interpolation between calibrations more appropriate. Through the use of sensor clusters rather than individual sensors existing low cost technologies could deliver significantly improved quality of observations.

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“…The reason for the reduced sensitivity of the sensors integrated in the field test systems was investigated further (Leidinger et al, 2014). As the main problem, gas emissions from the sensor system hardware components were determined.…”

Section: Field Test Sensor System Characterizationmentioning

confidence: 99%

Selective detection of hazardous VOCs for indoor air quality applications using a virtual gas sensor array

Leidinger

Sauerwald

Reimringer

et al. 2014

J. Sens. Sens. Syst.

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Abstract. An approach for detecting hazardous volatile organic compounds (VOCs) in ppb and sub-ppb concentrations is presented. Using three types of metal oxide semiconductor (MOS) gas sensors in temperature cycled operation, formaldehyde, benzene and naphthalene in trace concentrations, reflecting threshold limit values as proposed by the WHO and European national health institutions, are successfully identified against a varying ethanol background of up to 2 ppm. For signal processing, linear discriminant analysis is applied to single sensor data and sensor fusion data.Integrated field test sensor systems for monitoring of indoor air quality (IAQ) using the same types of gas sensors were characterized using the same gas measurement setup and data processing. Performance of the systems is reduced due to gas emissions from the hardware components. These contaminations have been investigated using analytical methods. Despite the reduced sensitivity, concentrations of the target VOCs in the ppb range (100 ppb of formaldehyde; 5 ppb of benzene; 20 ppb of naphthalene) are still clearly detectable with the systems, especially when using the sensor fusion method for combining data of the different MOS sensor types.

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Selective Detection of Hazardous Indoor VOCs Using Metal Oxide Gas Sensors

Cited by 55 publications

References 4 publications

Two-Dimensional Zinc Oxide Nanostructures for Gas Sensor Applications

Two-Dimensional Zinc Oxide Nanostructures for Gas Sensor Applications

Clustering approaches to improve the performance of low cost air pollution sensors

Selective detection of hazardous VOCs for indoor air quality applications using a virtual gas sensor array

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