S. Capone et al., Moisture influence and geometry effect of Au and Pt electrodes on CO sensing response of SnO2 microsensors based on sol-gel thin film, SENS ACTU-B, 77(1-2), 2001, pp. 503-511
Undoped tin oxide-based gas microsensors have been prepared by the sol-gel
deposition technique. The influence of the gaseous atmosphere (humidity and
carbon monoxide) on the electrical conductance of the samples has been inv
estigated. Then, the variation of the geometry and the nature of the electr
ic contacts has been considered as interesting factor that can modulate the
selectivity. SEM observations of the surface have shown a good quality of
the electrodes. A pre-deposited Ti thin layer improves the adhesion of the
contacts to the SnO2 film. A diversification of the sensors, when exposed t
o CO, was observed depending on two different electrodes materials (Au and
Pt) arranged in two different geometric configurations of the interdigitate
d fingers. Preliminary results have shown that CO response is enhanced by t
he use of interdigitated electrodes with a short separation gap (200 mum) a
s compared to those with wider one (400 mum) for both Pt and Au electrodes,
while the use of gold contacts seems to reduce the working temperature of
our sensors, probably due to some effects related to the diffusion of Au in
to the Ti and/or the active layer, but other drawbacks could also arise. (C
) 2001 Elsevier Science B.V. All rights reserved.