Exploitation of a low-cost electronic system, designed for low-conductance and wide-range measurements, to control metal oxide gas sensors with temperature profile protocols

This work is the continuation of two previous works: in the former we developed a WO3 based gas sensor featuring high sensitivity to NO2 but with the drawbacks of low conductance values (below 1 nS) and long recovery times (over 20 min); in the latter we developed a low-cost control electronic circuit suited to measure a wide range of conductance values (10 pS-100 mu S). Here, we use this electronic system to control this WO3 sensor according to temperature profile protocols, with the aim to show the possibility to handle such low conductance devices by means of cheap instrumentation, featuring at the same time reduce response times and a degree of selectivity arising from the temperature profile protocol. In particular, we focus on two target applications: detection of NO2 and detection of reducing gases, namely ethanol and methane, in different humidity conditions, showing the usefulness of time constants extrapolated from the response dynamics for the purpose. (C) 2012 Elsevier E.V. All rights reserved.