O3 meter (O3) is a common air pollutant and can cause short and long term health issues including respiratory ailments, lung infections and even some types of lung cancer. It is formed naturally in the stratosphere from oxygen (O2) and UV light by a complex reaction between them, but also occurs at ground level as a result of anthropogenic sources such as vehicle emissions, volatile organic compounds (VOCs) and industrial production processes. Consequently, o3 meter is one of the six criteria air pollutants monitored globally by regulatory agencies.

In this article we present the development of a miniaturised electrochemical O3 sensor for real-time measurements. The sensor is based on visible spectroscopy and methylene blue (MB) adsorbed on a mesoporous silica thin film. An experimental test bench was developed to produce controlled atmospheres for sensor evaluation and the sensor stability, sensitivity and selectivity to O3 were investigated. The sensor is connected to a LabJack and controlled by a real-time data acquisition software written in LabVIEW. The user can control the data acquisition rate, file-path of the measured data, auto-zeroing of WE and RE voltages, sensitivity setting (Voltage/ppb) and display the O3 concentration data continuously during the measurement.

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The performance of the sensor was evaluated at different RHs with eight different O3 mixing ratios. The resulting calibration curves show excellent consistency between the sensor and a UV photometric O3 analyser at each RH after a zeroing process to offset the baseline drifts caused by RH changes.