Programmable multistable structures via bioinspired, mechanically guided 4D printing

Multistable structures, characterized by rapid shape morphing, instantaneous force amplification, and zero standby power, are pivotal for soft robotics and energy harvesting. However, achieving multistability while systematically controlling the accessible deformation modes remains a significant challenge. Here, we report a bioinspired, mechanically guided 4D printing approach to design and fabricate programmable multistable structures, including octastable and various bistable units, mimicking the growth-induced morphing of plant leaves and fruits. The stability landscapes of these units can be tuned by varying dimensionless geometric parameters and validated through buckling analysis. By integrating multiple octastable units, we demonstrate a compact, 10-cm-scale strip and a shape-morphing metasurface with configuration spaces of over one billion and four sextillion stable states. Furthermore, by modulating the dimensionless geometric parameters of multiunit structures, we identify a transition from bending to folding, enabling the creation of bistable hinges. As proof-of-concept demonstrations, we developed devices for directional droplet routing and mixing, reconfigurable electrical switching, conforming grasping of irregular objects, and programmable mechanical display. This work establishes a versatile framework for the design and fabrication of next-generation reconfigurable morphing systems and programmable flexible devices.