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

• Published in: Sensors (Basel, Switzerland) Vol. 22; no. 19; p. 7238
• Main Authors: Russell, Hugo Savill, Frederickson, Louise Bøge, Kwiatkowski, Szymon, Emygdio, Ana Paula Mendes, Kumar, Prashant, Schmidt, Johan Albrecht, Hertel, Ole, Johnson, Matthew Stanley
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 24-09-2022; MDPI
• Subjects: Air Pollutants - analysis; Air pollution; Algorithms; Calibration; calibration protocol; Chemical sensors; electrochemical sensor; Environmental Monitoring - methods; Gas sensors; Laboratories; Low cost; low-cost sensors; metal oxide sensor; Methods; Natural gas; Nitrogen dioxide; Nitrogen Dioxide - analysis; Outdoor air quality; Oxides; Pollutants; Regression analysis; Sensors; Telecommunications equipment industry; VOCs; Volatile organic compounds; Denmark; United States; United Kingdom; calibration protocol; metal oxide sensor; electrochemical sensor; calibration; low-cost sensors
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s22197238

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 NO
and O
(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 NO
measurement and sensor performance was similar for O
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.