Towards ultrastretchability, multimodal instability, and static nonreciprocity in kirigami metamaterials

Kirigami, known for its ultra-softness, ultra-lightness, and high stretchability, is at the forefront of research in advanced materials and structural design. However, its inherent flexibility and sensitivity pose significant challenges for mechanical characterization, as conventional rigid-body assumptions are inadequate. Key hurdles include developing flexible tensile mechanics and designing high-curvature structures to prevent fracture at cut edges. Despite advancements in nanoscale synthesis and large-scale deployable kirigami systems that enhance geometric and material design, the lack of robust models to describe complex in-plane and out-of-plane buckling under extreme conditions hampers further theoretical and applied progress. Current reciprocal mechanics theories struggle to capture the nonlinearities, multi-stability, and asymmetry characteristic of kirigami deformation. Static nonreciprocity offers a promising alternative by distinguishing forward and reverse mechanical responses, breaking time-reversal symmetry, and providing deeper mechanical insights. Moving forward, establishing a framework based on nonreciprocal properties will be essential to overcoming existing challenges, driving breakthroughs in kirigami mechanics, and enabling innovative applications in areas such as soft robotics, deployable systems, and flexible electronics.