Abstract
ZnO nanorods arrays were prepared in an open system by using a low temperature hydrothermal method. The morphology of the ZnO nanorods is strongly influenced by the thickness of seed layer and pH value. ZnO nanorod arrays with different morphology and size were studied by scanning electron microscopy (SEM), and contact angle measurement (CAM). Their surface wettability were studied in relation to their surface morphologies. The superhydrophobic surface was obtained by reacting stearic acid (SA, Carbon 18) with ZnO nanorod. However, the surface of ZnO nanorod became Hydrophilic after being irradiated by UV light. The change of surface wettability will led to contact angle change which can drive droplet movement. There are two motion that occurred in this process, Pushing motion and Pulling motion. Pulling motion occurred when half of the droplet part were exposured by UV light, the droplet will move towards UV light pattern. Pushing motion occurred when the droplet were exposure by the edge of UV light pattern. The droplet will moving away from UV light pattern. These two motion were affected by two factors: contact angle effect and heating. The manipulation of droplet is achieved by using these two factors.