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 I wt % 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 2 mu m thick SiNx membrane. The fabricated gas sensors were characterized to NO2, NH3, and xylene gases, respectively, as a function of concentration at 300 degrees C and temperature from 180 degrees C to 380 degrees C at constant concentration The measured highest sensitivities for the NO2, NH3, and xylene were 1.06 at 1.2 ppm and 220 degrees C, 0.19 at 60 ppm, and 220 degrees C, and 0.15 at 3.6 ppm and 220 degrees C, respectively So, it was found that 220 degrees C was the optimum temperature to have the best sensitivities From these results, mixed SnO2 nanoparticles with 1 wt.% MWCNTs showed good sensitivity and selectivity at low power operation below 30 mW. Fabricated micro-gas sensors could be used for ubiquitous sensor network applications to monitor environmental pollutants in the air (C) 2010 Elsevier B.V. All rights reserved