The extraordinary adhesive capabilities of geckos and mussels have finally been combined to create a glue which unlike other adhesives that use only the ‘gecko’ principle work on both wet and dry surfaces.
It works by coating a fibrous silicone which is similar in structure to a gecko’s foot with a polymer that mimics the ‘glue’ used by mussels and the new product has been christened ‘“Geckel”’.
One of the researchers, Professor Phillip Messersmith from Northwestern University in Evanston which is near Chicago, U.S. stressed that the discovery could also have medical applications, “I envision that adhesive tapes made out of “Geckel” could be used to replace sutures for wound closures and may also be useful as a water-resistant adhesive for bandages and drug delivery patches. Such a bandage would remain firmly attached to the skin during bathing but would permit easy removal upon healing”.
Geckos have a hard to believe ability to stick to surfaces and some studies suggest that they can hold hundreds of times their own body weight and in 2000, a University of California team showed that this phenomenal adhesion was due to the very weak intermolecular forces produced by the billions of hair like structures that are known as setae on each gecko’s foot.
These “van der Waals” forces apparently arise when unbalanced electrical charges around molecules attract one another and the accumulative attractive force of billions of setae allows geckos to scurry up walls and even hang upside down on polished glass and the reptile’s grip is only released when it peels its foot off the surface.
The new “Geckel” material not only exploits this ability but also combines it with the sticking power of mussels and tests show that the material can be stuck and unstuck more than 1,000 times even when used under water.
In 2003 a team from the University of Manchester, U.K. produced small quantities of a sticky gecko tape using electron beam lithography that is a process by which a beam of electrons etches patterns in a surface but as of now it is too expensive and difficult to scale-up for mass production.
Last year however researchers at the aerospace and defence firm BAE Systems raised hopes of mass production when they showed off centimetre length strips of a plastic known as Synthetic Gecko.
“We’ve now got large pieces,” said Dr Sajad Haq, a research scientist at the company’s Advanced Technology Centre in Bristol, U.K. but he was unable to reveal the exact size of the sheets as the company has only recently applied for patents on the material. “It’s becoming more and more practical and it’s getting very close to a high maturity level”.
Once patented the firm plans to use the material for a wide range of applications from repair patches for tanks, aircraft and submarines to crawler robots.