The sensing behavior of SnO₂-based thick-film gas sensors at a low concentration of chemical agent simulants

A semiconductor gas sensor based on SnO₂ was studied using chemical agent simulants such as acetonitrile, DMMP, DPGME and dichloromethane at a low concentration range from 0.02 to 0.8 ppm at 350 °C. The sensing behavior of SnO₂-based gas sensors that included sensitivity, response, recovery and reproducibility were investigated by using a flow measuring system. In the case of acetonitrile and dichloromethane, the sensor prepared from a precipitated small SnO₂ particle (15 nm) was more sensitive than that prepared from the commercial SnO₂ (40 nm). The addition of NiO or Nb₂O₅ promoters also increased the sensitivity of the commercial SnO₂ sensor. The experimental results could be explained by the effects of particle size, pore size and promoters. The recovery of the SnO₂-based sensors seemed to be possible for acetonitrile and DPGME. In the cases of DMMP and dichloromethane, the complete recovery of SnO₂-based sensors was not possible because of poisoning.