Researchers turned to the Japanese art of Kirigami to create complex 3D structures that serve as modular and reconfigurable building blocks for new metamaterials.

Kirigami is a variation of Origami that aside from simply folding the paper to form shapes,it involves carefully cutting the material to generate more complex 3D structures. In the context of building materials, carefully "cut" 3D materials make them collapsible as well as modular, allowing their users to assemble and disassemble different fitting parts as needed to create specific metamaterials.

A Kirigami Structure of St. Paul's Cathedral
(Photo: Bharath Kishore via Wikimedia Commons)

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Taking a Modular Approach With Kirigami

The term Kirigami, which in Japanese literally translates to "paper cutting," was first coined in the western world through the instructional book "Kirigami, the Creative Art of Paper Cutting," according to the Origami Resource Center. Since the book was released by Florence Temko in 1962, the term has become synonymous with "paper cutting," as well as being known as a variant of the older, more popular artform Origami.

In the new study led by researchers from North Carolina State University (NCSU) and Yale University, researchers applied the same concept, traditionally used with 2D materials like paper, into 3D structures cut to create reconfigurable cubes.

"Applying Kirigami to three-dimensional materials offers a new level of reconfigurability for these structures," says Jie Yin, a corresponding author in the new study and an associate professor of mechanical and aerospace at NCSU, in a university press release

Metamaterials, on the other hand, are explained in the 2014 Progress in Optics as composite materials specifically engineered to attain particular electromagnetic properties. These are generally composed of small building blocks, usually metal-based, used for a variety of applications.

In the new study, researchers believe that the new approach to build metamaterials could be used in a host of new applications like construction, communications, or robotics.

3D Structures That Are Modular, Reconfigurable Building Blocks

To start, researchers modeled the new metamaterials fabrication technique around a series of eight cardboard cubes that are connected together and are open on two ends. Each set of these eight cubes, in theory, corresponds to a single building block. Depending on the specific arrangement of the cubes, with each of the smaller cubes movable with respect to the others, a single Kirigami building block can be reassembled into more than 300,000 unique designs.

Researchers then demonstrated the potential of the idea by creating more than a dozen of these macroscopic replicas, reconfiguring each building block differently, and connecting them together like a huge puzzle with a 3D structure. Furthermore, these blocks could be conveniently disassembled and reconfigured for a new application.

The mechanical properties of the resulting metamaterials depend on the configuration and orientation of the building blocks put into it, with the blocks having solid faces and open ones. For example, researchers can create a rigid structure or a collapsible one depending on the setup.

Researchers say that the next step in their study is to demonstrate actual applications for the revolutionary concept.

Researchers present their innovative approach to metamaterials fabrication in the journal Advanced Functional Materials in the report titled "3D Transformable Modular Kirigami Based Programmable Metamaterials."


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