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Enhanced Ambient Sensing Environment—A New Method for Calibrating Low-Cost Gas Sensors

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  • Hugo Savill Russell
  • Louise Bøge Frederickson
  • Szymon Kwiatkowski, AirLabs Denmark
  • ,
  • Ana Paula Mendes Emygdio, University of Surrey
  • ,
  • Prashant Kumar, University of Surrey
  • ,
  • Johan Albrecht Schmidt, AirLabs Denmark
  • ,
  • Ole Hertel
  • Matthew Stanley Johnson, AirLabs Denmark, University of Copenhagen

Accurate calibration of low-cost gas sensors is, at present, a time consuming and difficult process. Laboratory calibration and field calibration methods are currently used, but laboratory calibration is generally discounted due to poor transferability, and field methods requiring several weeks are standard. The Enhanced Ambient Sensing Environment (EASE) method described in this article, is a hybrid of the two, combining the advantages of a laboratory calibration with the increased accuracy of a field calibration. It involves calibrating sensors inside a duct, drawing in ambient air with similar properties to the site where the sensors will operate, but with the added feature of being able to artificially increases or decrease pollutant levels, thus condensing the calibration period required. Calibration of both metal-oxide (MOx) and electrochemical (EC) gas sensors for the measurement of NO2 and O3 (0–120 ppb) were conducted in EASE, laboratory and field environments, and validated in field environments. The EC sensors performed marginally better than MOx sensors for NO2 measurement and sensor performance was similar for O3 measurement, but the EC sensor nodes had less node inter-node variability and were more robust. For both gasses and sensor types the EASE calibration outperformed the laboratory calibration, and performed similarly to or better than the field calibration, whilst requiring a fraction of the time.

Original languageEnglish
Article number7238
Publication statusPublished - Sep 2022

Bibliographical note

Funding Information:
M.S.J., J.A.S. and S.K. are employees of AirLabs, who manufacture the sensor nodes. H.S.R. and L.B.F. are partially funded by AirLabs.

Funding Information:
The authors acknowledge AirLabs for the loan of the Gen 5 AirNodes and ACTRIS-DK for some of the reference instruments. The authors thank Archie Waller for their help. Prashant Kumar acknowledges the support from Innovate UK funded project ‘MyGlobalHome’ the pilot demonstrator under the Technology Strategy Board File Reference of 106168.

Funding Information:
H.S.R., L.B.F. and O.H. were supported by BERTHA—The Danish Big Data Centre for Environment and Health, funded by the Novo Nordisk Foundation Challenge Programme (grant NNF17OC0027864).

Publisher Copyright:
© 2022 by the authors.

    Research areas

  • calibration, calibration protocol, electrochemical sensor, low-cost sensors, metal oxide sensor

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