The synthesis of zinc oxide (ZnO) nanorods and their sensing properties with respect to nitric oxide (NO) gas were studied. The ZnO nanorods were grown by the hydrothermal method onto a ZnO thin film (∼ 150 nm), which was designated as the ZnO thin film/ZnO nanorods. The ZnO thin film was pre-sputtered on the Au interdigitated electrode. By repeating the growth in a fresh precursor from one cycle to four cycles, the aspect ratio of the nanorods increased approximately from 10 to 33. For NO gas sensor application, however, the sensitivity decreased as the aspect ratio of the ZnO nanorods increased. It's very likely that higher density and higher aspect ratio of ZnO nanorods prevent NO gas from penetrating into the ZnO nanorods. The optimal operation temperature for the ZnO thin film/ZnO nanorods with an aspect ratio of 10 was found to be 240 °C for sensing NO gas. The limit of detection reached 2 ppb which is applicable for asthma diagnosis. To simulate human breath, cross-sensitivities with respect to CO2 and O2 have been tested.
All Science Journal Classification (ASJC) codes
- Biomedical Engineering