Kirigami is a traditional craft technique that realizes various shapes by making cuts in various patterns on paper.In recent years, various engineering applications such as electrodes and solar cells have been rapidly advanced in the world by applying the structure of kirigami.However, research to clarify the physical principle was almost untouched.

Okumura et al. Are conducting research on basic technologies related to toughening porous polymer sheets used in lithium-ion batteries, etc., using a new technology called impressionist physics that simply captures the essence of complex phenomena. I have also been working on research on the structure of kirigami.

This time, pay attention to the paper-cutting pattern of the paper cushioning material that protects the wine bottle. The amount (elastic modulus) that expresses the softness of "cutting paper" and the deformation of "cutting paper" from in-plane deformation (deformation while maintaining a two-dimensional flat state) to out-of-plane deformation (three-dimensional three-dimensional) We succeeded in expressing the condition of transition (sudden change) to (transformation that takes a structure) with a simple and beautiful mathematical formula.Although it is simple, it has good consistency with the experimental data, and the elastic modulus formula and the transition conditional formula, especially in the case of in-plane deformation, were established with extremely high accuracy.It is said that these mathematical formulas will be a clear guiding principle when applying and developing the kirigami structure.

The results of this time are wide-ranging, such as electrodes and solar cells with great extensibility, graphene sheets (sheets with a thickness of one carbon atom), application to cell sheets attracting attention in the field of regenerative medicine, and supporters for medical and sports. It is expected to be applied to the field.