Yongfeng Mei: Self-powered locomotion of a hydrogel water strider


2021年414日,我院梅永丰教授课题组在《科学·机器人学》(Science Robotics)上发表题为《仿生水黾的自驱动水凝胶》(“Self-powered locomotion of a hydrogel water strider”)的研究工作。博士研究生朱红为第一作者,梅永丰为通讯作者,该工作得到复旦大学高分子科学系和聚合物分子工程国家重点实验室共享仪器平台的大力支持。研究团队从“0”出发,原创性地合成了一种具有动态疏水特征的新型水凝胶智能材料。该水凝胶在水面上可自驱动运动,无需额外能量供给;饱和吸水后该活性水凝胶即停止运动,干燥处理可恢复活力,再次实现自驱动快速水面运动。


Figure 1. (A) Superimposed time-lapse snapshots and corresponding color-indicated trajectory of the living water strider moving on water surface. The left inset is the schematic illustration of propulsion mechanisms. (B) The velocity and displacement of the insect locomotion. (C) Superimposed time-lapse snapshots and corresponding color-indicated trajectory of the hydrogel water strider moving on water surface. The left inset is the schematic illustration of the propulsion mechanism of the hydrogel water strider locomotion. The right inset is an enlarged photo of the hydrogel water strider. (D) The velocity and displacement of the hydrogel water strider locomotion. (E) The superimposed time-lapse snapshots and corresponding trajectory of hydrogel water strider moving in the maze solving motion. (F)The superimposed time-lapse snapshots of the hydrogel water strider climbing the meniscus and the trajectory of one tip of the pentagram-shaped hydrogel water strider.


    Hydrogels are a class of three-dimensional network-structured polymer smart materials with hydrophilic groups, which can rapidly swell in water and retain a large volume of water without dissolving in the swollen state. Due to the good biocompatibility and similarity of biological systems, hydrogels are widely used in daily life such as wound dressings and contact lenses, as well as cutting-edge researches such as tissue engineering and soft robotics. However, since hydrogels are rich in hydrophilic groups, they are inherently hydrophilic and generally not hydrophobic, so there are basically no pure hydrogel materials with hydrophobic characteristics.

    On April 14, 2020, the research group of Prof. Yongfeng Mei of IIINN published a paper entitled Self-powered locomotion of a hydrogel water strider in Science Robotics. Doctoral student  Hong Zhu is the first author and Yongfeng Mei is the corresponding author. This work is strongly supported by the shared instrument platform of the Department of Polymer Science of Fudan University and the State Key Laboratory of Molecular Engineering of Polymers. Starting from '0', the research team innovatively synthesized a new type of hydrogel smart material with dynamic wetting process. The hydrogel can self-propelled move on the water surface without  without additional energy supply; the active hydrogel stops motion after saturated water absorption, and can be rejuvenated by drying treatment, realizing self-driven fast water surface motion again.


    The research team explored and found that its movement mechanism has something in common with the movement of water striders in nature on the water surface. As shown in Figures 1A and 1C, they both drive themselves to move on the water surface through the difference in surface tension; and as shown in Figures 1B and 1D, the variation of the movement rate is also very consistent. By designing the shape of the active hydrogel material, the asymmetry of material distribution, and the surface hydrophilicity and hydrophobicity of the surrounding environment, the research team controlled the active hydrogel material to perform various controllable trajectories and directional movements, such as simulating ball motion and mazing solving motion (Figure 1E) and so on. Further, by introducing new stimuli-responsive chemical components, the active hydrogel can deform synchronously during self-driven motion, thereby intelligently changing the corresponding motion trajectory; Similar to the shore-climbing action of a water strider in nature. The research team invented a hydrogel material that can dynamically adjust the wetting properties, endow it with new active motion characteristics, and exhibit a novel actuation mode and motion behavior. This work provides a new material choice for the design and research of flexible soft robots, enriches the types of hydrogel materials, and thus provides a new path for its application in important fields such as drug release and tissue engineering.

文章信息:Hong Zhu, Borui Xu, Yang Wang, Xiaoxia Pan, Zehua Qu, Yongfeng Mei*. Self-powered locomotion of a hydrogel water strider, Science Robotics, 2021, 6: eabe7925.