Study On Surface Modification Of Carbon Nanotubes And Application In Dew Sensors

Carbon nanotubes have many excellent properties, such as electrical conductivityand mechanical properties due to their special structure （hollow, large length todiameter ratio）. They are widely used in many fields, especially in sensors. Carbonnanotubes are one of the most important sensitive materials. The surface modificationof carbon nanotubes and their application in humidity and gas sensors wereresearched in this paper.The dispersibility of multiwall carbon nanotubes （MWCNTs） in the matrixmaterial was improved through acidic agents. Infrared spectroscopy andthermogravimetric analysis were used to character the structure of the resultantMWCNTs.MWCNTs were chosen instead of the traditional conductive materials--carbonblack. The condensation properties of the new dew sensor based on functionalizedmultiwall carbon nanotubes （MWCNTs）/hydroxyethyl cellulose （HEC） compositematerial were studied. The resistance of dew sensors remained almost unchangedbelow75%RH and increased sharply over85%RH. The chemically treatedMWCNTs/HEC composite film showed excellent switching characteristics, with asensitivity of35at100%RH.The sensitive properties to NO₂of the gas sensor based on MWCNTs/tin oxide（SnO₂） composite materials were tested at room temperature. The composite materialssensor showed higher sensitivity and faster response and recovery properties. At roomtemperature, the sensitivity is3.3, the response time is4s and the recovery time is3.3min. It can be realized that NO₂was detected through the gas sensor based compositematerials at room temperature.