The application of CNT/Nafion composite material to low humidity sensing measurement

Composite humidity sensing films were made from carbon nanotube (CNT) and Nafion. The sensing films were prepared using the spin-coating method. Sensing films coated on the electrode of a Quartz Crystal Microbalance (QCM) were used for low humidity measurement. This low humidity system was set up with a divided flow generator and calibrated by an optical chilled dew-point hygrometer in the measuring range from 8.50 to 15,300 ppmv. The detection limit of this sensing system was about 15.76 ppmv. In this low humidity sensing system, the CNT/Nafion sensing material coated on the gold electrode of QCM showed excellent sensitivity, linearity (Rsqr = 0.995), short response and recovery time (less than 5 s, at testing point of 15.76 ppmv).