Room-temperature ammonia sensor based on ZnO nanorods deposited on ST-cut quartz surface acoustic wave devices

Using a seed layer-free hydrothermal method, ZnO nanorods (NRs) were deposited on ST-cut quartz surface acoustic wave (SAW) devices of ammonia sensing at room-temperature. For a comparison, a ZnO film layer of 30 nm thick was also coated onto ST-cut quartz SAW device using a sol–gel and spin-coating technique. The ammonia sensing results showed that the sensitivity, repeatability and stability of the ZnO NRs coated SAW device were superior to those of the ZnO film coated SAW device due to the large surface-to-volume ratio of the ZnO NRs.