Bioinspired Programmable Biaxial Rolling Gel Sheets for Complex 3D Morphing

Shape-morphing gels have shown promising applications in widespread fields, including soft robotics, flexible electronics, and smart medicine. The majority of efforts have been focused on rapid response and multi-responsiveness of shape-morphing materials with bilayer structure. However, achieving biaxial rolling with controllable curvature remains a critical challenge. Herein, inspired by the hygroscopic heterostructures in pine cone scale, we report a sinusoidal-patterned hydrogel-semi-embedded-organogel (HSEO) sheet constructed by wetting-enabled 3D interfacial polymerization (WET-DIP) strategy. The sinusoidal pattern serves as a programmable geometric template to redistribute anisotropic stress spatially. By tuning sinusoidal pattern parameters, we realize biaxial morphing and the modulation of longitudinal and transversal curvatures, consistent with the results of finite element analysis (FEA). The semi-embedded heterostructure offers compressive force on the organogel to overcome isotropic stress limitations. Notably, this design leverages the sinusoidal periodic topology and semi-embedded structure to precisely modulate stress distribution, enabling counterintuitive rolling behaviors and complex 3D transformations. This work pioneers a counterintuitive and programmable shape-morphing mechanism for complex 3D architectures, offering a perspective for novel soft actuators.