| Jan 24, 2025 |
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(Nanowerk News) Hydrogels have a network of water-attracting (hydrophilic) molecules, allowing their structure to swell substantially when exposed to water. Researchers Daisuke Nakagawa and Itsuo Hanasaki from Tokyo University of Agriculture and Technology (TUAT) are looking into new options for making “kirigami hydrogels” that swell into complex 3D structures.
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This emerging materials field is named after the Japanese art of cutting papers. It involves patterns cut into a nanopaper that can later swell into hydrogels with varied applications, including tissue engineering.
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The research is published in the journal Science and Technology of Advanced Materials (“Adaptive plasticity of auxetic Kirigami hydrogel fabricated from anisotropic swelling of cellulose nanofiber film”).
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The researchers worked with an initially dry film composed of nanofibres of cellulose, the natural material that forms much of the structure of plant cell walls. They used laser processing to cut patterns into the nanopaper.
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This particular design of the kirigami pattern works in such a way that the width increases when stretched lengthwise.
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| They used lasers to cut structures into the film (left), allowing it to swell into complex 3D structures (right) when water is added. (Image: Modified from original image by STAM)
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“As kirigami literally means the cut design of papers, it was originally intended for thin sheet structures. Our two-dimensional mechanism manifests when the thickness of the sheet is sufficient, enabling a three-dimensional hydrogel structure to emerge when swelled. This allows easy storage in the dry state before use, without keeping the same water content level of the hydrogel,” says Hanasaki.
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Furthermore, this property is maintained even with repeated use.
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Potential applications for the adaptive hydrogels include soft components of robotic technologies, soft switches, and sensors. Hydrogels are also being explored for medical applications, such as tissue engineering, wound dressings, drug delivery systems, and materials that can adapt flexibly to movement and growth.
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“Keeping the designed characteristics while showing adaptivity to the environmental condition is advantageous for the development of multifunctionality,” Hanasaki concludes.
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