Low power micro-gas sensors using mixed SnO2 nanoparticles and MWCNTs to detect NO2, NH3, and xylene gases for ubiquitous sensor network applications

Using mixed SnO2 nanoparticles with 1wt.% MWCNTs sensing materials, NO2, NH3, and xylene gas sensors were fabricated on micro-platforms. A micro-platform consists of micro-sensing electrode and micro-heater on 2I14m thick SiN x membrane. The fabricated gas sensors were characterized to NO2, NH3, and xylene gases, respectively, as a function of concentration at 300 degree C and temperature from 180 degree C to 380 degree C at constant concentration. The measured highest sensitivities for the NO2, NH3, and xylene were 1.06 at 1.2ppm and 220 degree C, 0.19 at 60ppm, and 220 degree C, and 0.15 at 3.6ppm and 220 degree C, respectively. So, it was found that 220 degree C was the optimum temperature to have the best sensitivities. From these results, mixed SnO2 nanoparticles with 1wt.% MWCNTs showed good sensitivity and selectivity at low power operation below 30mW. Fabricated micro-gas sensors could be used for ubiquitous sensor network applications to monitor environmental pollutants in the air.