Identifying natural and artificial odours through noise analysis with a sampling-and-hold electronic nose

A sampling-and-hold type electronic nose was used to investigate "frozen" s ensor dynamics. The sensor was heated to the sensing temperature and expose d to a chemical environment for a short time. Then, while keeping the senso r in the chemical environment, the heating was switched off so that the sen sor cooled down to room temperature. Chemicals species become trapped in th e sensor film, and therefore, the current transport in the film is changed. The trapped chemicals are usually located at grain boundaries, and they in fluence the charge transport in the grains and between the grains. This giv es random fluctuations to the local conductivity. Resistance noise was empl oyed to extract chemical information from the sensor in the cold state. (C) 2001 Elsevier Science B.V. All rights reserved.