Ozone sensors utilize various methods to detect and measure ozone (O3) concentrations in the air or water. The most common approaches are:
UV Absorption Spectroscopy
This method, as described in a source from November 6, 2022, involves exposing an air sample to ultraviolet (UV) light. Ozone molecules absorb specific wavelengths of UV light. The sensor measures the change in UV light intensity after passing through the sample. This change is directly proportional to the ozone concentration. A photodetector measures this change in light absorption, providing a reading of the ozone level. See animation
Electrochemical Sensors
Electrochemical sensors, frequently used for indoor ozone monitoring (Kaiterra, February 28, 2022), are a popular choice. When ozone comes into contact with the sensor's electrolyte, an electrochemical reaction occurs between the electrodes. This generates a measurable change in electrochemical potential or current, which is proportional to the ozone concentration. Aeroqual describes this process as a change in electrochemical potential leading to electron flow between electrodes.
Metal Oxide Semiconductor (MOS) Sensors
Certain MOS sensors, like the MQ-131, can detect ozone (Arduino Forum, June 25, 2020). However, the Arduino forum discussions highlight challenges with this sensor, indicating potential for inaccuracies or reversed readings. While they show high sensitivity and fast response times, they may not be as reliable as other methods. The sensing mechanism often involves a chemical reaction between ozone and the metal oxide, altering the sensor's conductivity. Note that the MQ-131 may not always provide accurate results. Example issue.
Choosing the Right Sensor
The best sensor type depends on the application. UV absorption spectroscopy is suitable for accurate, broad-range measurements. Electrochemical sensors offer reliability and consistency for indoor monitoring, while MOS sensors are a less expensive but potentially less reliable alternative. Factors like cost, accuracy requirements, and the environment being monitored will influence the choice of sensor technology.
