Label-free molecular detection with capped carbon nanotubes

We present a theoretical proof-of-principle analysis of a device composed of mutually faced capped carbon nanotubes for the selective detection of hardly distinguishable gas molecules in binary mixtures (methanol/formaldehyde and H2O/H2S). Selectivity arises, on one side, from I-V responses of the sensor in the presence of different gases trapped between the nanotube caps. On the other side, the different dipole moments and polarizabilities of the molecules lead to different population probabilities in the sensing region, acting as a highly selective electrostatic trapping device. The selectivity can be tuned by the bias voltage and by the gap distance between the nanotubes.