A Novel Flexible Room Temperature Ethanol Gas Sensor Based on SnO(2) Doped Poly-Diallyldimethylammonium Chloride

A novel flexible room temperature ethanol gas sensor was fabricated and demonstrated in this paper. The polyimide (PI) substrate-based sensor was formed by depositing a mixture of SnO(2) nanopowder and poly-diallyldimethylammonium chloride (PDDAC) on as-patterned interdigitated electrodes. PDDAC acted both as the binder, promoting the adhesion between SnO(2) and the flexible PI substrate, and the dopant. We found that the response of SnO(2)-PDDAC sensor is significantly higher than that of SnO(2) alone, indicating that the doping with PDDAC effectively improved the sensor performance. The SnO(2)-PDDAC sensor has a detection limit of 10 ppm at room temperature and shows good selectivity to ethanol, making it very suitable for monitoring drunken driving. The microstructures of the samples were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM) and Fourier transform infrared spectra (FT-IR), and the sensing mechanism is also discussed in detail.