Interconnect Design Group, Hybrid Materials Unit, National Institute for Material Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
Proc Biol Sci. 2012 Oct 22;279(1745):4236-42. doi: 10.1098/rspb.2012.1297. Epub 2012 Aug 8.
For the first time, we report the remarkable ability of the terrestrial leaf beetle Gastrophysa viridula to walk on solid substrates under water. These beetles have adhesive setae on their feet that produce a secretory fluid having a crucial role in adhesion on land. In air, adhesion is produced by capillary forces between the fluid-covered setae and the substrate. In general, capillary forces do not contribute to adhesion under water. However, our observations showed that these beetles may use air bubbles trapped between their adhesive setae to walk on flooded, inclined substrata or even under water. Beetle adhesion to hydrophilic surfaces under water was lower than that in air, whereas adhesion to hydrophobic surfaces under water was comparable to that in air. Oil-covered hairy pads had a pinning effect, retaining the air bubbles on their feet. Bubbles in contact with the hydrophobic substrate de-wetted the substrate and produced capillary adhesion. Additional capillary forces are generated by the pad's liquid bridges between the foot and the substrate. Inspired by this idea, we designed an artificial silicone polymer structure with underwater adhesive properties.
我们首次报道了陆生叶甲 Gastrophysa viridula 在水下固体表面行走的非凡能力。这些甲虫的足部有粘性刚毛，其分泌的液体在陆地上的附着中起着关键作用。在空气中，附着是由刚毛覆盖的液体与基底之间的毛细作用力产生的。一般来说，毛细作用力不会促进水下的附着。然而，我们的观察表明，这些甲虫可能会利用被困在其粘性刚毛之间的气泡在被淹没的倾斜基底上甚至在水下行走。甲虫在水下的亲水表面的附着力低于在空气中的附着力，而在水下的疏水表面的附着力与在空气中的附着力相当。涂有油的毛垫具有固定作用，可将气泡保留在脚上。与疏水基底接触的气泡使基底去湿并产生毛细附着。垫子与基底之间的液体桥产生额外的毛细作用力。受此启发，我们设计了一种具有水下附着性能的人工硅树脂聚合物结构。
