Saw based CO2 sensors using carbon nanotubes as the sensitive layer

A surface acoustic wave based CO2 sensor using carbon nanotubes as the sensitive layer fabricated by combining surface acoustic wave (SAW) devices and nanotechnology. The device structure consists of the gas sensitive material between the input and output interdigital transducers (IDTs) of a SAW device. The CO2 gas gets adsorbed on nanotubes when the carbon nanotube based SAW sensor is exposed to CO2 at room temperature and/or at elevated temperature, which in turn changes conductivity of the carbon nanotube. This conductivity change will affect the velocity of the SAW traveling across the nanotubes and will give a frequency change which corresponds to the percentage of the CO2 molecules adsorbed by the nanotubes.