Carbon nanotubes based transistors as gas sensors: State of the art and critical review

In this paper we present recent studies concerning gas sensors based on carbon nanotube field effect transistors (CNTFETs). Although these devices have allowed one to realize sensors with an impressive sensitivity compared to existing technologies, the physical interpretation of the interaction between the gas molecules and the CNTFETs has not been clarified yet. In this contribution, we try to find some consistency between the physical interpretations advanced by the different scientific teams working on the subject and to answer some unsolved questions. Moreover, considering that the selectivity is the main issue, we analyze the different routes that have been proposed to overcome this problem: functionalization using polymers, diversification of the source/drain metal electrodes, metal decoration of SWCNT mats, exploitation of the desorption time of the different gases. For each technique we try to evaluate the advantages and the drawbacks.