On-demand adhere to and detach from soft and wet surfaces are crucial for hydrogels for applications in tissue engineering, soft machines, and soft robotics. Whereas strong adhesion has been achieved between hydrogels, on-demand switching from strong adhesion to weak adhesion for benign detachment is still under explorations. Herein, we report an approach for switchable adhesion between hydrogels by invoking a mechanical process, wrinkling. The approach is demonstrated by bonding two hydrogel adherends with a wrinkled hydrogel adhesive, with the formation and characterizations of wrinkles tailored by regulating the prestretch of adherend and optimizing the ingredients of adhesive synergistically. On one hand, the formation of wrinkles enhances adhesion by creating a tortuous path for crack propagation and an extended energy dissipation zone. The resulting adhesion is robust to elicit bulk dissipation within the adherend and transform the once adhesive failure to cohesive failure. On the other hand, the suppression of wrinkles deactivates the adhesion enhancement mechanism to facilitate effortless debonding. As a proof-of-concept, a hydrogel patch that can strongly adhere to a damaged hydrogel device for repair and gently detach after repairing, based on the switchable hydrogel adhesion, is demonstrated. The proposed method expands the design space for hydrogel adhesion.

对于在组织工程，软机和软机器人中应用的水凝胶，按需附着在软和湿表面上以及与软表面分离至关重要。尽管在水凝胶之间已经实现了强粘附性，但仍在探索从良性脱离的强粘附到弱粘附的按需转换。在本文中，我们报告了通过调用机械过程，起皱来在水凝胶之间进行可切换粘合的方法。通过将两个水凝胶被粘物与起皱的水凝胶粘合剂粘合来证明该方法，并通过调节被粘物的预拉伸并协同优化粘合剂的成分来定制皱纹的形成和特征。一方面，皱纹的形成通过为裂纹扩展形成曲折路径并扩展了能量耗散区，从而增强了附着力。产生的粘合力很强，可以引起被粘合体内部的大量散逸，并将曾经的粘合失败转变为内聚失败。另一方面，皱纹的抑制使粘附增强机制失活，从而促进了轻松的剥离。作为概念验证，证明了一种水凝胶贴剂，该贴剂可以牢固地粘附在损坏的水凝胶装置上进行修复，并且基于可切换的水凝胶粘附力，可以在修复后轻轻剥离。所提出的方法扩大了水凝胶粘附的设计空间。展示了一种水凝胶贴片，它可以根据可切换的水凝胶粘附力牢固地粘附在受损的水凝胶装置上进行修复，并在修复后轻轻脱离。所提出的方法扩大了水凝胶粘附的设计空间。展示了一种水凝胶贴片，它可以根据可切换的水凝胶粘附力牢固地粘附在受损的水凝胶装置上进行修复，并在修复后轻轻脱离。所提出的方法扩大了水凝胶粘附的设计空间。