Waseda University paves way for practical implementation of high-performance stretchable electronic components through application of kiri-origami structure

Recently, wearable devices that use displays and electronic equipment that can be stretched and attached have attracted attention, but it was difficult to incorporate a very large number of rigid electronic elements into bendable and stretchable structures. A research group led by Professor Eiji Iwase and Graduate Student Nagi Nakamura (at the time of the research) of the Faculty of Science and Engineering at Waseda University has developed "kiri-origami structure." To develop this new technology, they applied traditional origami and kirigami concepts to enable collective folding along folding lines across wide areas in structures mounted with rigid and fragile electronic elements. They also successfully demonstrated a stretchable display with 145 LEDs, with future applications expected in wearable devices and the medical/welfare fields. Their research was published in npj Flexible Electronics.

There are two approaches to making electronic devices flexible so they can bend and stretch: "development of materials with stretch resistance" and "structural innovations that don't require stretch resistance in materials (structural flexibility)." While conventional rigid electronic elements are prone to damage when bent or stretched, they often excel in performance and stability compared with materials with stretch resistance, such as organic materials. With this in mind, flexible electronic devices that make use of origami and kirigami structures have attracted attention since the 2010s, and methods have been devised to make entire devices deformable through structure design, even when the materials and electronic elements themselves are rigid, by utilizing folds and cuts.

While origami and kirigami structures had attracted attention as structures for bendable and stretchable electronic devices, each has its own advantages and disadvantages. Origami structures have non-deforming flat panel sections, making them suitable for mounting rigid and fragile electronic components, but it is difficult to fold up multiple units. Kirigami structures allow relatively easy collective deployment of multiple units by stretching the entire structure, but they are not suitable for mounting rigid and fragile electronic components because they lack flat panel sections.

The research group designed a kiri-origami structure that combines origami and kirigami structures. This structure is a kirigami structure with folding lines, which maintains flat surfaces for mounting electronic components while enabling collective folding along folding lines in multiple units by stretching the entire structure.

Furthermore, two innovations enabled accurate folding operations. First, there are spring-like deforming sections (buffers) at the edges of the structure to evenly distribute tensile forces. This prevents strain and torsion occurring at the structure's edges, enabling stable folding of the entire structure. Additionally, the group adjusted the structure to fold naturally along the folding line shapes by stretching it evenly in both vertical and horizontal directions. This achieved precise folding without forcing unwanted deformation in areas other than the folding lines.

In fact, they successfully achieved accurate folding of 512 hinges after 145 LEDs were mounted. Even after folding, the electronic elements maintained their functionality and operated as a practical flexible display. This technology can be widely applied to next-generation electronics fields, such as wearable devices attached to the body and smart sensors mounted on curved and movable surfaces. The flexible implementation of high-performance electronic components, which was previously difficult, is expected to become reality.

This research achieves large-scale folding operations through structural innovations alone, and this structure is also characterized by high degrees of freedom in manufacturing processes and material selection. If practical implementation progresses through collaboration with companies in the future, it may be possible to create new forms of electronic devices that are closely integrated with daily life, are easy to carry and resistant to breakage.

Iwase commented: "Origami and kirigami are familiar to even children in Japan, yet they possess many academically interesting characteristics, which is why the words 'origami' and 'kirigami' have become international academic terms. I hope that the word 'kiri-origami' that we have proposed will also be used internationally, following the words 'origami' and 'kirigami'."

Journal Information
Publication: npj Flexible Electronics
Title: Stretch-based kirigami structure with folding lines for stretchable electronics
DOI: 10.1038/s41528-025-00409-4