Knots in nano-scale flat ribbon suggest a new method for improving material strength.
(Image courtesy of Schniepp Lab.)
Spider silk has long had a reputation as one of the toughest materials on Earth. Stronger than steel and lightweight, spider silk represents the type of blending of material properties that makes engineers drool.
But what’s most incredible about spider silk is that not every eight-legged Araneae creates the same type. In fact, there’s one notorious spider that creates stronger silk than any other of member of its species.
Researchers from the University of Oxford have found that, brown recluse spiders use a unique micro looping technique to make their threads stronger than that of any other spider.
In a joint effort between Oxford and Virginia’s College of William and Mary, researchers have observed that recluse spiders produce silk that is thin and flat, rather than the round variety made by other arachnids. While that difference might seem inconsequential, it gives the recluse’s silk a number of properties, most notably, the enhanced flexibility to keep it from breaking when knotted—and those knots make all the difference.
“The theory of knots adding strength is well proven. But adding loops to synthetic filaments always seems to lead to premature fibre failure,” said professor Hannes Schniepp from William & Mary. “Observation of the recluse spider provided the breakthrough solution; unlike all spiders its silk is not round, but a thin, nano-scale flat ribbon. The ribbon shape adds the flexibility needed to prevent premature failure, so that all the microloops can provide additional strength to the strand.”
Migrating their observations from the lab to a computer simulation, the researchers found that adding knots or loops to flat fibers yielded improved material strength. In the future, the researchers believe the recluse’s technique for spinning silk could be applied to carbon filaments, making them less brittle and allowing them to be used in impact-absorbing structures.
The results of their research are published under the title “Toughness-enhancing metastructure in the recluse spider’s looped ribbon silk” in the journal Materials Horizons.
Fritz Vollrath, of the Department of Zoology at Oxford University said he imagines, “spider-like webs of carbon-filaments floating in outer space, to capture the drifting space debris that endangers astronaut lives’ and satellite integrity.”
So for all of its venom, the Brown recluse might end up saving some lives one day, and in outer space no less.
For a very different application of spider silk, find out how Engineers Use Spider Silk to Create a Microscope Superlens.