Low Temperature Co-Fired Ceramic-Based and Heater-Embedded Toxic Gas Sensors with Nanostructured SnO₂ Thick Films

In this study, we designed, prepared, and characterized Low Temperature Co-fired Ceramic (LTCC) toxic gas sensor devices with nanostructured SnO₂ semiconducting thick films. In order to promote the reaction of carbon monoxide (CO) toxic gas molecules on the SnO₂ thick films, a RuO₂ planar heater was inserted into the LTCC substrate. Using an optimized RuO₂ heater, the surface temperature of the LTCC substrate reached 360 °C within 25 seconds at an applied voltage of 5 V. The power consumption for the surface of the LTCC substrate to reach 300 °C was 778 mW. A nanostructured SnO₂ thick film as a gas sensing layer was prepared by the ink dropping method on Pt electrodes patterned on the LTCC substrate. The gas sensor device was packaged in a commercial housing to measure the CO gas response. The fabricated gas sensor showed a gas response (R_air/R_gas) of 5.26 at a CO gas concentration of 500 ppm and a temperature of 300 °C. Additionally, a mild plasma post-treatment using Ar discharge gas improved the gas response up to 6.35 at the equivalent measurement conditions.