An international team of scientists has created a "liquid wire" material that mimics a spiders' capture silk and sheds light on the physics of the materials that prevent it from sagging in the wind and throwing flies out of it like a trampoline.
The study reveals that when pulling a thread in a spider's web and letting it snap back, it always remains taut, even after stretching it multiple times. The reason for this lies in unique watery glue droplets that coat the core gossamer fibers of the web's capture spiral, allowing the web to spool any loose threads into these droplets in an instant.
After studying this unique liquid wire technique, the scientists were able to create their own composite fibers in the laboratory. These fibers possessed the ability to extend like a solid and compress like a liquid just like real spider silk, a discovery that could be integrated into new technologies.
'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," said Fritz Vollrath of Oxford University and co-author of the study. "Surprisingly, each drop packs enough punch in its watery skins to reel in loose bits of thread."
"And this winching behavior 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," he added.
Spiders' capture silk and the liquid wire materials created by the team rely on a fine balance between the elasticity of the fiber and droplet surface tension. Using oil droplets on a plastic filament, the team was able to successfully recreate this delicate balance in the laboratory, creating an artificial system that acted in the same way as spider silk.
"Spider silk has been known to be an extraordinary material for around 40 years, but it continues to amaze us," said Hervé Elettro of the Université Pierre et Marie Curie and first author of the study. "While the web is simply a high-tech trap from the spider's point of view, its properties have a huge amount to offer the worlds of materials, engineering and medicine."
"Our bio-inspired hybrid threads could be manufactured from virtually any components," he added. "These new insights could lead to a wide range of applications, such as microfabrication of complex structures, reversible micro-motors, or self-tensioned stretchable systems."
The findings were published in the May 16 issue of the Proceedings of the National Academy of Sciences.
