Gas Sensing Property and Humidity Effect of Polypyrrole and SnO2 Composite Films

Conducting polymer (Polypyrrole) and tin oxide (SnO₂) composite films have been fabricated with layer-by-layer technique. SnO₂ film was screen-printed on Al₂O₃ substrate and then it was dip-coated with polypyrrole (PPy) solution. The microstructures of composite films were evaluated by a field emission scanning electron microscope (FE-SEM). It was observed the sensing properties of PPy/SnO₂ sensor to various VOCs. Methanol, ethanol, benzene and toluene were analyzed. The target vapors were vaporized using their vapor presents and their concentrations were precisely controlled using mass flow controller (MFC) and temperature controller. The reproducibility of sensing properties was evaluated and the humidity effect of PPy/SnO₂ was checked.