Reversible super-glue inspired by snails strong enough to hold a person's weight

Medical journals have described people glueing up their ears and eyelids after mistaking adhesive for ear/eye drops.

Inspired by snails, scientists have created a reversible super-glue that can stick strongly to surfaces and still be removed when required.

Achieving both strong adhesion and or the ability to reverse the adhesion is challenging. Adhesives usually fall into one of two classes: strong but irreversible, like superglues, or reversible and reusable but weak.

Snails secrete a mucous that acts like super-glue, allowing them to adhere to rough surfaces like rocks.

Taking inspiration from this aspect of snail biology, scientists from University of Pennsylvania and Lehigh University in the US have created a super-glue-like material that is "intrinsically reversible." In other words, it can easily come unglued.

A snail’s epiphragm. Image courtesy: Beocheck

A snail’s epiphragm. Image courtesy: Beocheck

"We report a hydrogel-based, reversible, superglue-like adhesive by combining the benefits of both liquid and dry adhesives in a single material," said Anand Jagota, a professor at Lehigh University.

When hydrated, the softened gel they created conformally adapts to the target surface by low-energy deformation, which is then locked upon drying in a manner similar to the action of the epiphragm of snails.

An epiphragm is a temporary structure created by snails and mollusks. Made of dried mucus it holds in moisture during periods of inactivity and enables snails to adhere to surfaces, like rocks.

Snail shells swirl in both directions — the secret is in their genes.

Snail shells swirl in both directions — the secret is in their genes.

The scientists show that reversible super-strong adhesion can be achieved from a non-structured material when the criterion of shape adaption is met, with minimal residual strain energy stored in the system.

According to the researchers, the new material can be applied to both flat and rough target surfaces.

"We demonstrate that in this system adhesion strength is based on the material's intrinsic, especially near-surface, properties and not on any near surface structure, providing reversibility and ease of scaling up for practical applications," said Shu Yang, a professor at the University of Pennsylvania.

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