Programmable Dual‐Responsive Actuation of Single‐Hydrogel‐Based Bilayer Actuators by Photothermal and Skin Layer Effects with Graphene Oxides
Programmable Dual‐Responsive Actuation of Single‐Hydrogel‐Based Bilayer Actuators by Photothermal and Skin Layer Effects with Graphene Oxides
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DOI：
10.1002/admi.202300169
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发表时间：
2023-08
影响因子：
5.4
通讯作者：
Minghao Li;J. Bae
中科院分区：
文献类型：
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作者：
Minghao Li;J. Bae
刺激响应性复合水凝胶的形状变形在不同的研究领域受到了相当大的关注。尽管研究了具有不同材料的各种多层结构以实现形状变形，但将可溶胀的水凝胶层与不可溶胀的层组合导致界面粘附和结构完整性的问题。在这项研究中，提出了基于单水凝胶的双层致动器，其包括聚（N-异丙基丙烯酰胺）（PNIPAM）基质和氧化石墨烯（GO）-PNIPAM铰链。在温度升高时，PNIPAM水凝胶由于在表面附近形成致密的微结构（即，表皮层效应），而GO-PNIPAM水凝胶用作活性层，由于GO的存在而进行的结构改性而保持多孔。在光照条件下，由于GO的光热效应，GO-PNIPAM铰链会发生选择性加热。因此，所得双层结构表现出可编程的双响应3D形状变形。此外，这些致动器的折叠动力学可以基于所施加的刺激（温度变化或光）来调整，因为它们分别由不同的机制、皮肤层或光热效应驱动。此外，基于铰链的双层结构通过曝光展示了行走和转向运动。这种方法可以导致软机器人，仿生系统和基于水凝胶的系统中的自主软致动器的进步。
Shape morphing of stimuli‐responsive composite hydrogels has received considerable attention in different research fields. Although various multilayer structures with dissimilar materials are studied to achieve shape morphing, combining swellable hydrogel layers with non‐swellable layers results in issues with interface adhesion and structural integrity. In this study, single‐hydrogel‐based bilayer actuators comprising poly(N‐isopropylacrylamide) (PNIPAM) matrices and graphene oxide (GO)–PNIPAM hinges are presented. Upon temperature rising, the PNIPAM hydrogel acts as the passive layer due to the formation of dense microstructures near the surface (i.e., the skin layer effect), whereas the GO‐PNIPAM hydrogel functions as the active layer, maintaining porous due to structural modification by the presence of GO. Under light exposure, the GO‐PNIPAM hinges experience selective heating due to the photothermal effect of GO. Consequently, the resulting bilayer structures exhibit programmable dual‐responsive 3D shape morphing. Additionally, the folding kinetics of these actuators can be adjusted based on the applied stimulus (temperature changes or light), as they are driven by different mechanisms, the skin layer, or photothermal effects, respectively. Furthermore, the hinge‐based bilayer structures demonstrate walking and steering locomotion by light exposure. This approach can lead to advances in soft robotics, biomimetic systems, and autonomous soft actuators in hydrogel‐based systems.