A comparative study of single- and multiwalled carbon nanotube sensitivity to ammonia

We interpret the measured sensitivity difference of single walled carbon nanotubes (SWNTs) and multiwalled carbon nanotubes (MWNTs) used as dielectric sensors of ammonia gas traces in terms of adsorption sites and effective coverages. The dielectric constant of a regular set of SWNTs deposited on a plane is compared to that of a single MWNT having the same size when the same pressure of ammonia molecules is applied on them. The corresponding resonance frequency shifts in the two sensors display an enhanced sensitivity of SWNT over the MWNT in excellent agreement with the experimental measurements. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3060242]