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Impact Analysis of Temperature and Humidity Conditions on Electrochemical Sensor Response in Ambient Air Quality Monitoring

School of Energy and Environment, City University of Hong Kong, Tat Avenue, Kowloon, Hong Kong, China
Environmental Protection Department, the Government of the Hong Kong Special Administration Region, 33/F Revenue Tower, 5 Gloucester Road, Wan Chai, Hong Kong, China
Author to whom correspondence should be addressed.
Sensors 2018, 18(2), 59;
Received: 23 November 2017 / Revised: 25 December 2017 / Accepted: 28 December 2017 / Published: 23 January 2018
(This article belongs to the Special Issue Signal and Information Processing in Chemical Sensing)
PDF [5716 KB, uploaded 23 January 2018]


The increasing applications of low-cost air sensors promises more convenient and cost-effective systems for air monitoring in many places and under many conditions. However, the data quality from such systems has not been fully characterized and may not meet user expectations in research and regulatory uses, or for use in citizen science. In our study, electrochemical sensors (Alphasense B4 series) for carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO2), and oxidants (Ox) were evaluated under controlled laboratory conditions to identify the influencing factors and quantify their relation with sensor outputs. Based on the laboratory tests, we developed different correction methods to compensate for the impact of ambient conditions. Further, the sensors were assembled into a monitoring system and tested in ambient conditions in Hong Kong side-by-side with regulatory reference monitors, and data from these tests were used to evaluate the performance of the models, to refine them, and validate their applicability in variable ambient conditions in the field. The more comprehensive correction models demonstrated enhanced performance when compared with uncorrected data. One over-arching observation of this study is that the low-cost sensors may promise excellent sensitivity and performance, but it is essential for users to understand and account for several key factors that may strongly affect the nature of sensor data. In this paper, we also evaluated factors of multi-month stability, temperature, and humidity, and considered the interaction of oxidant gases NO2 and ozone on a newly introduced oxidant sensor. View Full-Text
Keywords: electrochemical sensor; correction method; urban air pollution; low cost sensors electrochemical sensor; correction method; urban air pollution; low cost sensors

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Wei, P.; Ning, Z.; Ye, S.; Sun, L.; Yang, F.; Wong, K.C.; Westerdahl, D.; Louie, P.K.K. Impact Analysis of Temperature and Humidity Conditions on Electrochemical Sensor Response in Ambient Air Quality Monitoring. Sensors 2018, 18, 59.

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