Take the gecko, famed for its ability to scale walls, and the mussel, renowned for its clamping quality, and you have the inspirations for a superglue that can stick, unstick and stick again.
The glue, dubbed "geckel," can have innumerable uses, say the inventors, whose research was published on Wednesday in Nature, the weekly British journal.
Geckos have long fascinated engineers because of their ability to skip up vertical surfaces and scurry along ceilings, yet without using any adhesive.
The lizards employ a mechanical principle called contact splitting. Their feet have a pad of ultra-fine hairs, called setae, each of which are split up into hundreds of flat tips. The ends temporarily rearrange electrons on the walking surface, creating an electrodynamic attraction.
On a dry surface, geckos can stick and unstick their feet like a Post-it office note — but their magic fails in water, where their sticking power falls dramatically.
Phillip Messersmith, a professor of biomedical engineering at Northwestern University, Chicago, and colleagues mimicked a gecko’s foot with nano-scale arrays of silicone pillars that, like setae, were so flexible they could adapt to a rough surface.
They then coated the strands with a polymer modelled on an amino acid that is one of the building blocks of the "glue" protein in mussels.
The result is "geckel" (gecko + mussel) — an adhesive that has been tested to stick through 1000 contact/release cycles, but remains highly adhesive when underwater, too.
A long road lies ahead before the new glue hits the commercial market, but Messermith is confident that the adhesive could be used in all sorts of areas, including medicine, industry, consumer products and military hardware.
"I envision that adhesive tapes made out of geckel could be used to replace sutures for wound closure and may also be useful as a water-resistant adhesives for bandages and drug-delivery patches," he said in a press release.
"Such a bandage would remain firmly attached during bathing but would permit easy removal upon healing."