ABSTRACT
Nanosized structures show outstanding properties in gas-sensor applications, especially at low operating temperatures, and, high sensitivity, particularly with lower grain sizes. Therefore, ultra™ne layers or any feature that resembles lower feature sizes allow various improvements in their performance. The sensitivity of the sensor largely increases with the reduction of the feature size. To explain this property, we select a simple example. Lu et al. [107] showed that the nanosized SnO2 material is sensitive to 500 ppm concentration of CO at near room temperatures, as shown in Figure 7.1. In this ™gure, the effect of nanoparticle size is compared to the sensitivity of CO gas. There is hardly any change in the sensitivity values observed for the particle size that is larger than 50 nm. Slow raising trend is noticed between particle sizes between 50 and 15 nm. When the particle sizes are smaller than 10 nm, the sensitivity shoots up to give a quick increase in the sensitivity values. This type of advantage is expected with almost all the metal-oxide nanostructures for gas-sensing applications.
