蚊子腿表面多级微纳结构的超疏水特性

蚊子是一种能够在水面自由起落、行走、产卵而从不溺水的两栖昆虫.报道了蚊子腿表面的超疏水机理.单根蚊子后腿在水面上的静态承载力平均可达600μN,是整个蚊子体重的20多倍,而利用柔软细钢丝做成的外观形状、结构和尺寸与蚊子腿几乎一致的"钢丝腿",其水面承载力仅为85μN.扫描电子显微镜观察发现,蚊子腿表面被大量有序排列的、瓦片状的、尺寸在十微米级的空心鳞片覆盖,鳞片表面整齐排列了亚微米级的纵肋和纳米级的横筋结构蚊子腿部表面具有很强的疏水性,静态接触角约为153°.理论分析表明,蚊子腿表面上的微纳多级结构是其具有超疏水性和高可靠性表面承载力的根本原因.

Superior water repellency of mosquito legs with hierarchical micro-nano structures

Mosquitoes are a type of amphibian insects with remarkable ability to walk freely, lay eggs and safely take off or land on the water surface without drowning. This article reports the water repellency mechanism of mosquito legs. The maximal supporting force of a single hind leg against water surprisingly reaches up to 600 μN, over twenty times the total body weight of this insect. While for the artificial leg made with the wire which has the same diameter, shape and structure to the mosquito leg, the supporting force is only 85 μN, far less than the value of mosquito leg. Scanning electron microscope (SEM) observations reveal the uniquely hierarchical micro-nano structure on the legs, consisting of numerous oriented ten-micro scales with uniform sub-micro longitudinal ridges and nanometer cross ribs. The surface of mosquito leg has superior water repellency, and its static contact angle is about 153°. We theoretically demonstrate that the hierarchical micro-nano structure on the surface of the mosquito leg renders such superior water repellency and high water-supporting force. This finding might be helpful in the design of innovative non-wetting materials.