Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China.
State Key Laboratory of Fluid Power and Mechatronic Systems, Key Laboratory of 3D Printing Process and Equipment of Zhejiang Province, School of Mechanical Engineering, Zhejiang University, Hangzhou 310028, China.
ACS Appl Mater Interfaces. 2020 Dec 23;12(51):57497-57504. doi: 10.1021/acsami.0c19656. Epub 2020 Dec 15.
Shape deformations are prevalent in nature, which are closely related to the heterogeneous structures with a feature of fibrous elements embedded in a matrix. The microfibers with specific orientations act as either passive geometrical constraints in an active matrix or active elements in a passive matrix, which generate programmed internal stresses and drive shape morphing under external stimuli. Morphing materials can be designed in a biomimetic way, yet it is challenging to fabricate composite hydrogels with well-distributed fibers by a facile strategy. Here, we demonstrate the fabrication of microfiber-embedded hydrogels facilitated by the extrusion-based printing technology. Programmed deformations are achieved in these hydrogels with microfibers distributed in the upper and/or bottom layers of the gel matrix. Under external stimuli, the microfibers and the gel matrix have different responses that produce internal stresses and result in programmable deformations of the composite gel. Multiple shape transformations are realized in the hydrogel by embedding multiple types of responsive microfibers in the passive or active matrix, which is fabricated with the assistance of multinozzle printing. A soft hook is designed to show the capacity of the composite hydrogel to hold and move an object in a saline solution. This facile and versatile strategy provides an alternative way to prepare biomimetic hydrogels with potential applications in biomedical devices, flexible electronics, and soft robots.
形状变形在自然界中很常见，这与具有纤维元素嵌入基质特征的非均匀结构密切相关。具有特定取向的微纤维可以作为主动基质中的被动几何约束，或者作为被动基质中的主动元素，产生编程的内应力，并在外部刺激下驱动形状变形。可以通过仿生设计来设计变形材料，但通过简单的策略来制造具有均匀分布纤维的复合水凝胶具有挑战性。在这里，我们展示了通过基于挤出的打印技术制造嵌入微纤维的水凝胶。在这些具有微纤维分布在上层和/或下层的凝胶基质中的水凝胶中实现了编程变形。在外力刺激下，微纤维和凝胶基质的响应不同，产生内应力，导致复合凝胶的可编程变形。通过在被动或主动基质中嵌入多种响应性微纤维，在多喷嘴打印的辅助下，在水凝胶中实现了多种形状转换。设计了一个软钩来展示复合水凝胶在盐溶液中夹持和移动物体的能力。这种简单而通用的策略为制备仿生水凝胶提供了一种替代方法，在生物医学设备、柔性电子和软机器人中有潜在的应用。
