Touch a spider’s web, and it’s sticky. Pull a thread of a spider’s web, and it will stretch to forty times its length and return to its original structure, unaffected, when released. The web’s ability to remain taut, yet flexible and sticky, stems from its dual solid and liquid properties, which have earned it the name “capture silk”.
A team of scientists together from the University of Oxford and France’s Université Pierre et Marie Curie, have, inspired by the spider’s web’s, created something they’ve christened a “liquid wire”. This wire, like a spider’s web, will be able to stretch far and recoil with no noticeable sagging.
The duality of properties comes about because capture silk is actually a hybrid material, meaning that it is comprised of two different composite materials. Hybrid materials are by nature stronger than both their composite materials. A spider’s web is made of a core filament upon which a droplet of glue is suspended. The glue acts as both a trap for flies and the basis for the recoil.
When released, the filament spools and packs within the glue droplet until the tension of the thread reforms. The strands hold straight rather than sag, also preventing the glue droplets from sticking together. The capture silk is thus solid-like in extension and liquid-like in compression and has ten times the strength of natural or synthetic rubber.
The scientists were able to recreate this effect in the laboratory using oil droplets on a plastic filament. It was discovered that the droplet enabled the filament to contract as much was as required to stay taut:
Professor Fritz Vollrath of the Oxford Silk Group in the Department of Zoology at Oxford University said:
“The thousands of tiny droplets of glue that cover the capture spiral of the spider’s orb web do much more than make the silk sticky and catch the fly. Surprisingly, each drop packs enough punch in its watery skins to reel in loose bits of thread. And this winching behaviour is used to excellent effect to keep the threads tight at all times, as we can all observe and test in the webs in our gardens.”
The liquid wire could be used in industries from manufacturing to telecommunications, but for now, it’s impressive that scientists have unravelled the secret to one of nature’s most fascinating materials.