Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China.
Nat Chem. 2022 Feb;14(2):208-215. doi: 10.1038/s41557-021-00837-5. Epub 2021 Nov 29.
Water-walking insects can harness capillary forces by changing their body posture to climb or descend the meniscus between the surface of water and a solid object. Controlling surface tension in this manner is necessary for predation, escape and survival. Inspired by this behaviour, we demonstrate autonomous, aqueous-based synthetic systems that overcome the meniscus barrier and shuttle cargo subsurface to and from a landing site and a targeted drop-off site. We change the sign of the contact angle of a coacervate sac containing an aqueous phase or of a hydrogel droplet hanging from the surface by controlling the normal force acting on the sac or droplet. The cyclic buoyancy-induced cargo shuttling occurs continuously, as long as the supply of reactants diffusing to the sac or droplet from the surrounding aqueous phase is not exhausted. These findings may lead to potential applications in autonomously driven reaction or delivery systems and micro-/milli-robotics.
水上行走的昆虫可以通过改变身体姿势来爬上或爬下水面和固体物体之间的弯月面，从而利用毛细作用力。以这种方式控制表面张力对于捕食、逃脱和生存是必要的。受此行为启发，我们展示了自主的、基于水相的合成系统，这些系统克服了弯月面障碍，可以将货物在地下运输到着陆点和目标投放点，并从那里返回。我们通过控制作用在囊或液滴上的法向力来改变含有水相的凝聚囊或悬挂在表面的水凝胶液滴的接触角的符号。只要从周围水相向囊或液滴扩散的反应物供应没有耗尽，循环浮力引起的货物运输就会持续不断地发生。这些发现可能会导致在自主驱动的反应或输送系统以及微/毫机器人技术方面的潜在应用。
