Kirigami-inspired rigid-foldable meta-structure with a bidirectional self-locking property

Self-locking is an attractive feature in origami structures that enables the foldable structure to withstand loads along the direction of deployment, without requiring extra locking elements. However, this feature is rarely observed in rigid origami because such structures can be easily folded or deployed along the deployment direction. Here, we introduce a novel origami meta-structure with both rigid foldability and bidirectional self-locking capacity based on a kirigami-inspired foldable icosahedron. The kinematic analysis demonstrates that a foldable icosahedron has two motion steps separated by a bifurcation point. By stacking two icosahedra together, we construct a rigid-foldable module capable of bearing both tensile and compressive loads along the direction of deployment. Through energy analysis and prototype experiments, we demonstrate that the bidirectional self-locking phenomenon originates from both the multiple motion steps of a foldable icosahedron and the torsional stiffness of creases. We arrange the module into a planar array and show its potential application in mechanical memory storage devices. This work paves a new way to design rigid-foldable and bidirectional self-locking origami structures.