Improvement in sensitivity and recovery of single-walled carbon nanotube-based gas sensors

In this paper, an improvement in sensitivity and recovery of the single-walled carbon nanotube (SWNT)-based gas sensors was reported. The sensors were fabricated from SWNT powder by a screen-printing method, followed by annealing for 2 h in open-air at various temperatures. The Raman spectra of the SWNT bundles and the response to ammonia (NH3) exposure of the sensors indicated that the annealing at a relevant temperature improved the sensor sensitivity. The sensor annealed at 200 degrees C exhibited a high sensitivity in NH3 detection. After 20 min of exposure to NH3 at room temperature, the resistance of the sensor increased up to 12% in comparison with its initial value. By evacuating combined with maintaining the flux of carrier gas at 300 sccm, the sensor recovery was significantly speeded. The sensor resistance retrieved to its initial value after only 25 min degassing. These results would be considered in the development of the SWNT-based gas sensors.