Center for Bio-inspired Energy Science, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA.
Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL 60208, USA.
Sci Robot. 2020 Dec 9;5(49). doi: 10.1126/scirobotics.abb9822.
The design of soft matter in which internal fuels or an external energy input can generate locomotion and shape transformations observed in living organisms is a key challenge. Such materials could assist in productive functions that may range from robotics to smart management of chemical reactions and communication with cells. In this context, hydrated matter that can function in aqueous media would be of great interest. Here, we report the design of hydrogels containing a scaffold of high-aspect ratio ferromagnetic nanowires with nematic order dispersed in a polymer network that change shape in response to light and experience torques in rotating magnetic fields. The synergistic response enables fast walking motion of macroscopic objects in water on either flat or inclined surfaces and also guides delivery of cargo through rolling motion and light-driven shape changes. The theoretical description of the response to the external energy input allowed us to program specific trajectories of hydrogel objects that were verified experimentally.
设计能够通过内部燃料或外部能量输入产生运动和形态转变的软物质，这种转变类似于生物体中的运动和形态转变，这是一个关键挑战。这类材料可以辅助完成各种生产功能，涵盖范围从机器人技术到智能化学反应管理，再到与细胞的通信。在这种情况下，能够在水介质中发挥作用的含水物质将是非常有意义的。在此，我们报告了一种水凝胶的设计，该水凝胶包含高纵横比铁磁纳米线的支架，其在聚合物网络中呈现向列有序分布，能够响应光并在旋转磁场中产生扭矩。协同响应使宏观物体能够在水的平表面或倾斜表面上快速行走，并通过滚动运动和光驱动的形状变化来引导货物的运输。对外能输入的响应的理论描述使我们能够对水凝胶物体的特定轨迹进行编程，实验验证了这些轨迹。
