Functionalized Single Wall Carbon Nanotubes Based Gas Sensor

In this paper we report on functionalized single wall carbon nanotube (SWNT) based gas sensor. SWNT were functionalized with sodium dodecyl sulfate (SDS) which improved solubility of SWNT in the DI water significantly. Solutions of SWNTs were deposited on the alumina substrate prepatterned with Pt contacts and heater to form sensor. The morphology of the SWNT films were characterized by atomic force microscope (AFM) and transmission electron microscope (TEM) imaging and their gas sensing properties were studied using voltamperometric technique. Sensors sensitivity were tested in presence of O₃ (70-350 ppb), NO₂ (0.1-5 ppm), CO (500 ppm) ethanol (500 ppm), and NH₃ (5 ppm) diluted in humid air (50% RH). The working temperature was varied in the range 20degC-70degC. The sensors demonstrated response to ethanol gas with long response and recovery times more than one hour. Sensors showed an appreciable response to low concentrations of 70 ppb of ozone and 100 ppb of NO₂ while showing virtually no response to CO and NH₃.