Dielectrophoretic Modification of Carbon Nanotube with ZnO Nanoparticles for NO2 Gas Sensing

We developed dielectrophoresis (DEP) - based fabrication method of a carbon nanotube (CNT) NO2 gas sensor that integrates CNT on a microelectrode. The dielectrophoretic integration method can also be used to deposit nanoparticles on CNT surface. This study demonstrates that the modification of the CNT with zinc oxide nanoparticles (ZnO NPs) by dielectrophoresis This sensor were tested by measuring resistance change of the sensor against 1ppm concentration of NO2 at room temperature. The resistance of 0.025 mg/ml and 1.25 mg/ml ZnO NPs-decorated CNT gas sensor rapidly increased followed by slow decreased. This rapid resistance change was saturated by deposition of 25 mg/ml ZnO NPs, and behaved similar to ZnO NW gas sensor. The resistance decrease can be considered as CNT response. The rapid resistance increase cannot be explained by simply summing the responses of the SWCNT sensor and ZnO sensor. The depletion layer of pn-junction due to connection of the CNT and ZnO can be concerned.