High Spatial Resolution Sensor Networks for Air Quality Monitoring

Abstract

The increasing need to protect the environment has stimulated the development of chemical gas sensors for monitoring air pollutants, such as carbon monoxide, nitrogen dioxide and ozone. Future improvements in the response of these sensors depends on developing a better understanding of the principles governing their operation and the influence of the microstructure and morphology of the semiconducting metal oxide layer on adsorption of gas molecules. Doping this layer with a noble metal such as platinum or palladium combined with the application of thin film technology allows a significant improvement in the performance of these devices due to the catalytic effect of the metal on reactions between the oxide and adsorbed gas molecules. Microelectronic fabrication techniques combined with thin film synthesis methods are used to develop integrated CMOS compatible microsensor arrays. Field testing of air quality monitoring systems based on these metal oxide sensors has been carried out to compare their performance with conventional analytical instruments. Further improvements in sensitivity will be possible due to the development of novel oxide architectures such as nanowires and nanobelts, which provide a much larger surface area in contact with the gas molecules, and the integration of these structures in miniaturised integrated devices. Solid state sensor systems, integrated with advanced signal processing and data transmission via the telecommunications infrastructure, will allow the implementation of sensor networks to provide real time information on air pollution with high spatial resolution.