Indium oxide thick-films decorated with PdO and PtO₂ particles for oxygen detection in humid environments

Abstract Thick film indium oxide chemiresistive sensors decorated with PdO and PtO 2 particles were investigated for oxygen detection under humid conditions (tested ranging from 20%–80% RH) across a temperature range of 50 °C to 400 °C. The PtO 2 -decorated In 2 O 3 sensors demonstrated a significantly higher response to oxygen, showing a 500% increase at 200 °C compared to the PdO-decorated sensors (response values of 41 and 8, respectively). Tests in dry air were conducted to assess the effect of humidity on sensor performance, revealing a maximum response of 74 for PtO 2 -In 2 O 3 at 400 °C, more than three times higher than the response of 22 for PdO-In 2 O 3 . Selectivity tests confirmed that the sensors responded more strongly to oxygen than to interfering gases. The integration of an active carbon cloth (ACC) filter effectively reduced interferences from isobutylene and ethylene, enhancing sensor’s selectivity. A comparison of both sensors demonstrated that PtO 2 -decorated In 2 O 3 has greater potential as an alternative to existing Pb-based electrochemical oxygen sensors, particularly in humid environments.