Anisotropic Wetting Characteristics of Biomimetic Rice Leaf Surface with Asymmetric Asperities

Rice leaf surface has known as having functional performances such as self cleaning and antifouling as well as directional flowing due to a unique micro structure with groove. In this study, we investigated the effects of asymmetrical cone protrusions on the surface of droplet flow through the contact angle and contact angle hysteresis of the droplet. First, static and dynamic contact angles of droplet on the rice leaf are measured. We found that the rice leaf surface has a directional flow characteristic through the difference of the contact angle hysteresis with flow directions. We also fabricated the rice leaf-like surfaces with asymmetric asperities along microgrooves using rapid prototyping technique and evaluated anisotropic wettability properties for the produced biomimetic surfaces. The experimental results show that the direction of the micro asperity tip relative to the droplet flow and its inclined angle has a very important influence on the anisotropic flow. This research can help to clarify the anisotropic wettability by the surface structure.