title: Modifying the anti-wetting property of butterfly wings and water strider legs by atomic layer deposition coating: surface materials versus geometry.
abstract: Although butterfly wings and water strider legs have an anti-wetting property, their working conditions are quite different. Water striders, for example, live in a wet environment and their legs need to support their weight and bear the high pressure during motion. In this work, we have focused on the importance of the surface geometrical structures in determining their performance. We have applied an atomic layer deposition technique to coat the surfaces of both butterfly wings and water strider legs with a uniform 30 nm thick hydrophilic Al(2)O(3) film. By keeping the surface material the same, we have studied the effect of different surface roughness/structure on their hydrophobic property. After the surface coating, the butterfly wings changed to become hydrophilic, while the water strider legs still remained super-hydrophobic. We suggest that the super-hydrophobic property of the water strider is due to the special shape of the long inclining spindly cone-shaped setae at the surface. The roughness in the surface can enhance the natural tendency to be hydrophobic or hydrophilic, while the roughness in the normal direction of the surface is favorable for forming a composite interface.
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Ding
authors.forename: Sheng
authors.initials: S
authors.lastname: Xu
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.forename: Aurelia C
authors.initials: AC
authors.lastname: Wang
authors.forename: Melissa H
authors.initials: MH
authors.lastname: Wang
authors.forename: Yonghao
authors.initials: Y
authors.lastname: Xiu
authors.forename: Ching Ping
authors.initials: CP
authors.lastname: Wong
authors.forename: Zhong Lin
authors.initials: ZL
authors.lastname: Wang