The Mechanism Of The Super-supporting Force Of Super-hydrophobic Biological And Its Bionic Research

The wettability is an important feature of the solid surface, Wettability of the surface is measured by contact angle of water droplets, Super-hydrophobic is a special phenomenon which the contact angle of water droplets on the solid surface is more than150°. Lotus leaf, water strider and many other creatures of the natural world have evolved for billions of years, and their super-hydrophobicity of surfaces have achieved a number of excellent function, many Studies have shown that super-hydrophobic surfaces can be prepared by changing the chemical composition of the solid surface and designing special micromorphology of super-hydrophobic surfaces, then mimic superhydrophobic biological excellent function.A floating body with super-hydrophobic can utilize effectively surface tension, pressing dimple on water surface, increasing displacement, improving its supporting force on water surface. The maximum supporting force closely related to its contact angle, cross-sectional shape, geometric dimensions and other factors, contact angle is the major factorContact angle of water striders, mosquitoes and water spiders’legs, abdomens and backs was measured by contact angle measuring instrument, and it was found that surfaces of these Arthropod’ bodies are almost super-hydrophobic. Super-hydrophobic surface’s micro structure of water striders, mosquitoes and water spiders’bodies was observed by electron microscope, micro-nano structure is the main reason for super-hydrophobic surface, the lipid layer of the surface play a supporting role. The self-made measuring device was used to measure maximum supporting force of water striders, mosquitoes and water spiders’ legs on water surface. The maximum Supporting-force-coefficients of living water striders and water spiders is23.6and24.8, respectively. Mechanical analysis on water strider’legs floating on water surface was conducted, and the supporting force model of water strider’s flexible legs was established. Furthermore, the maximum supporting forces of water strider, mosquitoes and water spiders’legs were respectively calculated according to the established model, and then they were compared with the measured values, whose maximum error rate is3.9%,3.8%and6.5%, respectively.Similarly, contact angle of5kinds the leaves including lotus, canna. green poplar, grape and pumpkin were measured by contact angle measuring instrument, whose contact angles were150.6°,135.5°,110.4°,101.3°and94.8°, respectively. Super-hydrophobic surface’s microstructure of those5kinds of hydrophobic plant leaves was observed by electron microscope, the hydrophobic mechanism of plant leaf is the same with water striders other test animals. These plant leaves were adhered to rectangular box by double-sided adhesive tape as experimental model. The maximum supporting force of these models on water surface was measured by analytical balance. Analyze the experiment data, draw two conclusions:the supporting force is increased with the increase of the contact angle of the hydrophobic surface; the contribution of buoyancy and surface tension for the supporting force is closely related to the hydrophobic plant leaves model geometry, The geometric size increases, the contribution of the buoyancy also increases for supporting force, the contribution of surface tension decreases for supporting force; on the contrary, the geometric size decreases, the contribution of the buoyancy also decreases for supporting force, the contribution of surface tension increases for supporting force.Two bionic floating model were designed and produced with Copper, copper surface has a superhydrophobicity by chemical processing, whose contact angle is154°. The bionic floating model I has4supporting legs, supporting legs are produced by solid copper wire with a diameter of0.45mm, The maximum supporting force was measured as28.5mN, The maximum supporting force coefficients is8.1. The bionic floating model II has4supporting legs, supporting legs mimicries water strider legs’hollow structure, which are produced by thin copper with0.1mm thickness, The maximum supporting force was measured as73.1mN, The maximum supporting force coefficients is9.8; Assume that the cross-sectional area of supporting legs is equal, design of cross-sectional shape is equilateral triangle, circle, oval, and square, supporting force of equilateral triangular cross-section is the maximum, Followed by oval (λ=1.5), Again a circle, square and oval, Finally.This research can Lay the foundation for designing water strider robot and other micromechanical of super-supporting force.