  Methane (CH_4) gas sensing properties of novel vanadium dioxide (VO_2)
nanostructured films is reported for the first time. The single phase
nanostructures are synthesized by pulsed dc-magnetron sputtering of V target
followed by oxidation in O_2 atmosphere at 550 ^oC. The partial pressure of O_2
is controlled to obtain stoichiometric VO_2 with the samples showing rutile
monoclinic crystalline symmetry and regions of rod shaped nano-architectures.
These nanostructured films exhibit a reversible semiconductor to metal
transition in the temperature range of 60-70 ^oC. Gas sensing experiments are
carried out in the temperature span from 25 ^oC to 200 ^oC in presence of CH_4.
These experiments reveal that the films respond very well at temperatures as
low as 50 ^oC, in the semiconducting state.
