Mixed potential gas sensor with short response time

Miniaturized solid electrolyte sensors with mixed potential electrodes are prepared by screen-printing technique with different non-equilibrium electrodes made of Au/MeO-composites and tested with gases containing CO, H-2 and C3H6, respectively. Although sensitivities of different electrode materials do not vary more than 20% in CO containing gas, their response times can differ by nearly one order of magnitude. The response times of one sensor to upward concentration changes of the investigated combustibles increase in the same order and at a similar ratio as the sensitivities to these combustibles. Investigations show that the electrode morphology and layout have a deep impact on the response time of these sensors. Nevertheless, these parameters can be optimized in a way that enables the construction of sensors with response times t(10-90) < 100 ms by using nano-powders for the MeO additive. This range of response times is comparable to that of potentiometric solid electrolyte oxygen sensors and could be ensured in small series production as well as during long-term measurement of 4500 h. (C) 2007 Elsevier B.V. All rights reserved.