Hierarchical polyaniline microspheres were prepared on polyethylene terephthalate (PET) film by facile and rapid in situ chemical oxidative polymerization of aniline, in the presence of ZnO microspheres, to construct a smart sensor for the detection of NH3. The sensor not only exhibits high sensitivity, good selectivity and a low detection limit at room temperature but also possesses the features of flexibility, portability and optical transparency compared with traditional sensors based on substrates of glass, quartz slide or ceramic tube. Particularly, the low operating temperature of 21 °C is favorable for saving energy, for safety and for the long life of the sensor. The mechanism of the ZnO microspheres enhanced sensing properties towards polyaniline is attributed to the morphology design, enhancement of crystallinity and protonation degree, which has been confirmed by XRD, SEM and XPS analysis. The study will also open a new window to develop a type of portable electronic device.
