Platinum and palladium doped indium oxide sensors have been successfully fabricated by a screen printing method and tested as oxygen sensors at low temperature (150-400 °C) in a humid environment (~80-85% RH). The sensors, complying with a power law relationship, showed good differentiation at lower temperatures with highest response observed at 200 °C. Platinum had sensitivity of 2.2% per %O2 and power law exponent α = 0.72 vs. 0.3% per %O2 for palladium with power law exponent α = 0.51. Overall, the response of platinum doped indium oxide was higher than the palladium doped version.

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In this paper we report on the development tungsten oxide based chemiresistive sensors for the monitoring of oxygen at low temperatures (T ≤ 400 °C) in dry and humid air. The sensors were deposited onto alumina substrate by a combination of spin coating and a photolithographic process to define the sensing area. Our results show that the sensors comply with a linear relationship over a 0 to 20% concentration range, with a high response towards oxygen. The highest response was observed at 350 °C (ΔR/Ra = 7.8) in humid and in dry air (ΔR/Ra = 18). This result is a significant improvement over our previous experiments and we believe to take the concept of a metal-oxide based oxygen sensor a step closer.