When compressed, most fibers sag if they are soft and buckle if they are hard. But the silken webs of some spiders do neither: They remain taut no matter how far they are stretched or compressed. Now, scientists say they have figured out just how these webs maintain their tension. Using a microscope and a nanoscale positioning system, a team of scientists artificially stretched and compressed a single-capture thread from a golden orb weaving spider. They found that the capture thread—used to build the sticky spirals of the web—behaves like an elastic solid when stretched. But when compressed, droplets of liquid silk that dot the fiber cause the solid silk to spool like a liquid (see video above). This keeps the silk taut even when it is compressed up to 95%, the researchers report today in the Proceedings of the National Academy of Sciences. Using this new insight, the team decided to build their own “liquid wire”: a hybrid material made from droplets of silicone oil on a polyurethane thread. The synthetic fiber displays the same properties as spiders’ capture silk, switching from liquidlike to solidlike behavior as tension across the thread changes. Any sufficiently thin fiber surrounded by a droplet should show these properties, the researchers say, which could one day be applied to robotics, artificial muscles, and even flexible, stretchable electronics.
(Video Credit: Science/AAAS)