45 / 2019-06-26 09:03:54

Strong anisotropic wet attachment surface bioinspired from the toe pad of tree frog

Tree frog,Bioinspired surface,wet friction,anisotropic friction

全体主题 > Medical diagnosis and surgical robotics

Wearable flexible electronics and minimally invasive surgeries attract worldwide attention recent years owing to their superiorities of low damage, fast healing and real time health monitoring. However, undesirable slipping is inevitably happened during their contact to soft tissues and skins that always covered with mucus or sweat, which could easily lead to severe consequences such as soft tissue damages in surgical grasping and signal distortion in wearable sensors. Common solutions with strong adhesives and vacuum sucking structures are hampered by their low reusability and the requirement of high squeezing force to form vacuum pressure. In this manuscript, the wet attachment mechanisms of tree frog have been studied to design a strong anisotropic wet attachment surface. Its toe pad is constructed by micropillar array with a inclining angle to the toe pad’s front direction. With liquid volume decreasing, the uniform liquid self-splitting effect has been observed on micropillar array surface, and anisotropic boundary friction appears on both tree frog’s toe pad and bioinspired surface. This strong boundary friction mainly comes from the thin liquid film induced strong capillary force and leads to strong friction without any normal force, and the incline of pillar remarkably affects the stability of thin liquid film to generate the anisotropy. Finally, the effectiveness of bioinspired surgical grasper surface was confirmed and a wet climbing robot built with the anisotropy of friction was demonstrated.