Aging and Humidity Effects of Hydrocarbon Gas Sensor Based on Carbon Nanotubes Functionalized with Metal Oxide Nanocrystals

With the enhanced greenhouse effect and the increasing pollutants in the air, gas sensors applied in door or outdoors are in great demand. A hetero-structure gas sensors based on Multi-walled Carbon nanotubes (MWCNT) functionalized with metal oxide (MOX) nanoparticles are fabricated, which can be operated at room temperature with low power consumption. ZnO and TiO2 nanoparticles were deposited on MWCNT by Atomic Layer Deposition (ALD) at different temperatures from 17 ℃ to 220 ℃/225 ℃. The characteristics of hydrocarbon gas sensor fabricated at different temperatures were analyzed. MOX- MWCNT sensors have good sensitivities under low concentration (10ppm) of methane. Since this sensor is supposed to be used in common conditions at room temperature (RT) and room restive humidity (RH), aging process was in room relative humidity at RT. Humidity effects were investigated by comparing the performance of sensors at 2% RH and 50% RH. The humidity is strong effect on MOX-MWCNT sensor