Ammonia sensing characteristics of quartz resonator coated with ZnO nanowires sensitive layer

In this paper, we present our recent study on the fabrication and characterization of ammonia gas sensors based on quartz thickness shear mode (TSM) resonators employing ZnO nanowires as the sensitive coating layer. c-axis vertically aligned ZnO nanowire arrays were synthesized on the quartz resonator through a simple hydrothermal synthesis route. The ZnO nanowires were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The sensing characteristics, including sensitivity, stability, reproducibility, and response time of the acoustic wave gas sensors have been studied under different concentration levels of ammonia at room temperature. It is demonstrated that the use of the ZnO nanowire arrays on quartz TSM acoustic wave resonator can greatly enhance the sensitivity and sensor response speed due to the fast surface/interface reaction and large surface/volume ratio of the nanowire arrays.