Layer-by-layer assembly carbon nanotubes thin film based gas sensors for ammonia detection

Single walled carbon nanotubes (SWNTs) were deposited on interdigital electrode (IDE) devices and quartz crystal microbalance (QCM) devices through layer-by-layer self-assembly method to fabricate resistance sensitive and mass sensitive gas sensors, respectively. Their ammonia gas-sensitive characteristics were detected at different temperature. It is revealed that the SWNTs based mass sensitive gas sensor has good sensing properties at room temperature. However, the SWNTs based resistance sensitive gas sensor has irreversible response for ammonia gas. When the temperature increases, the noise of SWNTs based mass sensitive gas sensor increases and the gas sensitive characteristic decreases. Meanwhile, the humidity effect is also discussed. It is important to optimize gas sensor by making it work at an appropriate external environment.