Breakthrough Hydrogel Heals in Hours – A Game-Changer for Artificial Skin

Researchers have created a unique hydrogel that’s both tough and self-healing, thanks to nanosheet-enhanced polymer entanglement.

The material repairs itself in hours and could revolutionize artificial skin, robotics, and medical applications.

The Challenge of Mimicking Skin

Gels are everywhere in daily life, from hair products to the jelly-like textures in food. While human skin shares some gel-like qualities, it is uniquely difficult to replicate. Skin is both stiff and flexible, and it has an extraordinary ability to heal itself — often repairing completely within 24 hours after an injury.

Until now, artificial gels could either mimic skin’s stiffness or its self-healing ability, but not both. A research team from Aalto University and the University of Bayreuth has now overcome this limitation. They have developed a hydrogel with a unique structure that combines strength and self-repair, paving the way for advancements in drug delivery, wound healing, soft robotics, and artificial skin.

Strength and Self-Healing Through Entanglement

In this breakthrough study, researchers enhanced a hydrogel by adding ultra-thin, large clay nanosheets. Hydrogels are usually soft and squishy, but this new material forms a highly organized structure with densely entangled polymers between the nanosheets. This not only strengthens the hydrogel but also allows it to heal itself after damage.

The study was published today (March 7) in the prestigious journal Nature Materials.

A Simple Yet Powerful Process

The secret of the material lies not only in the organized arrangement of the nanosheets, but also in the polymers that are entangled between them – and a process that’s as simple as baking. Postdoctoral researcher Chen Liang mixed a powder of monomers with water that contains nanosheets. The mixture was then placed under a UV lamp – similar to that used to set gel nail polish. “The UV-radiation from the lamp causes the individual molecules to bind together so that everything becomes an elastic solid – a gel,” Liang explains.

“Entanglement means that the thin polymer layers start to twist around each other like tiny wool yarns, but in a random order,” adds Hang Zhang, from Aalto University. “When the polymers are fully entangled, they are indistinguishable from each other. They are very dynamic and mobile at the molecular level, and when you cut them, they start to intertwine again.”

Fast and Complete Healing

Four hours after cutting it with a knife, the material is already 80 or 90 percent self-healed. After 24 hours, it is typically completely repaired. Furthermore, a one-millimetre-thick hydrogel contains 10,000 layers of nanosheets, which makes the material as stiff as human skin, and gives it a comparable degree of stretch and flexibility.

“Stiff, strong and self-healing hydrogels have long been a challenge. We have discovered a mechanism to strengthen the conventionally soft hydrogels. This could revolutionise the development of new materials with bio-inspired properties,” says Zhang.

Nature-Inspired Innovation

“This work is an exciting example of how biological materials inspire us to look for new combinations of properties for synthetic materials. Imagine robots with robust, self-healing skins or synthetic tissues that autonomously repair,” says Olli Ikkala, from Aalto University. And even though there may be some way to go before real-world application, the current results represent a pivotal leap.“It’s the kind of fundamental discovery that could renew the rules of material design.”

Reference: “Stiff and self-healing hydrogels by polymer entanglements in co-planar nanoconfinement” by Chen Liang, Volodymyr Dudko, Olena Khoruzhenko, Xiaodan Hong, Zhong-Peng Lv, Isabell Tunn, Muhammad Umer, Jaakko V. I. Timonen, Markus B. Linder, Josef Breu, Olli Ikkala and Hang Zhang, 7 March 2025, Nature Materials.
DOI: 10.1038/s41563-025-02146-5

The collaboration was led by Dr. Hang Zhang, Prof. Olli Ikkala and Prof. Josef Breu. The synthetic clay nanosheets were designed and manufactured by Prof. Josef Breu at the University of Bayreuth in Germany.  

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