壁虎刚毛的动态自清洁机理及其微颗粒操控应用仿生研究

This project aim at unrevealing self-cleaning mechanism of gecko seta array and its utilization for microsize particles smart manipulation. Gecko seta has series of properties include high adhesion, easy lifting, long fatigue life, and dry self-cleaning, attracted more and more attention among mechanical engineerings and materials scientists. Although bio-mimic gecko materials have strong adhesion, few of them show a high self-cleaning property as native gecko seta. The absence of self-cleaning property of biomimic materials limits their applicable conditions and usage life. The applicant’s previous research work reveals the adhesion forces between microparticles and surfaces increase corresponding with retraction velocities increasing in both air, nitrogen and aqueous solutions. For gecko seta, however, the adhesion forces does not increase that much as retraction velocities. The self-cleaning characteristic of gecko seta arrays is strongly regulated by the retraction velocities. The mechanism involved in it is still needed to be fully revealed. In this proposal, both theoretical and experiments will be performed to reveal the gecko unique self-cleaning property. By using atomic force microscope, analysis on retraction velocities vs adhesion forces between gecko seta arrays, single gecko seta and single gecko spatula on various substrates will be carried out. The dynamic self-cleaning mechanism of gecko can be revealed. We will also explore potential application about this self-cleaning materials to manipulate microparticles.

本项目旨在阐释壁虎刚毛的自清洁机理及探索其在微颗粒操控中的应用。壁虎刚毛除了具备强黏附，易脱附，可反复使用的性能外，还具有对微颗粒等污染物的自清洁特性，现有研究多关注壁虎刚毛仿生表面的强黏附性质，极少对其微颗粒自清洁性能进行仿生研究，而这种自清洁性能的缺失会严重影响仿生材料的使用范围及寿命。申请人的前期研究成果表明，微米小球与壁面的黏附力在空气、氮气和水中均与分离速度成正比，而壁虎刚毛末端的铲状薄板结构在与壁面的脱附过程中速度效应关联较弱，壁虎刚毛的微颗粒自清洁与脚掌和壁面的分离速度密切相关。这种剥离速度相关的自清洁机理亟待深入研究。本研究拟从实验与理论研究方面开展研究，利用原子力显微镜对多丛壁虎刚毛、单根刚毛和单根铲状薄板进行剥离速度效应的实验研究，并结合理论模型，揭示壁虎刚毛的动态脱尘自清洁机理，并可望为微颗粒操控的仿生研究提供新的思路。

本项目系统研究了单根壁虎刚毛，单根铲状触须，单根壁虎刚毛抓球系统的脱附力与分离速度的关系。试验发现，刚毛及铲状触须系统，其脱附力与分离速度关系不大。而微米小球脱附力随着脱离速度的增加，呈增加趋势，正是这种细微区别，让预先粘在壁虎刚毛上的小球，能够在壁虎快速移动的过程中，被壁虎刚毛轻易的甩掉。其接触的特定形状，是刚毛系统产生这种速度效应的根源。研究团队据此提出了新的干型自清洁机理，并根据此机理设计制备特定接触形状的仿生表面，可以自由的操控微米尺度小球抓起－移动－放下，摆出复杂图案，从而达到了微米尺度(1-100 μm)微颗粒操控目的，最新的工作通过模仿使用蒙拓土和羟乙基纤维素为原料制备出了高硬度耐冲击的仿生表面，其干性自清洁效率可以达到59%，并可以实现温度控制下的亲疏水微颗粒的定向筛分。本项目的成果未来有望在太空垃圾清理抓手、生物医学工程、油田压裂支撑剂设计等工程中发挥重要作用。