Other research teams have tried mixing spider silk with metals to get electrical conductivity, but the silks don't stretch as far as pure silk. Coating the silk in metal also cuts off moisture, so it can't shrink or expand the way it normally does. Steven said he wanted a material that was porous enough to let water in, so he decided to try carbon nanotubes.
To make the conductive threads, the group collected threads from the webs of golden silk spiders Nephila clavipes, which are common orb weavers in the American south. The chief advantage of these spiders is that the webs are often large -- three feet across -- making it easy to gather the dragline silk, which is what anchors the web in place.
Next, they mixed the threads with dry nanotubes, which stuck to the threads, but not strongly. Adding drops of water to the bundles of the carbon-covered silk encouraged adhesion and then they pressed the wet threads between two Teflon sheets.
Single fibers pulled from the bundle were covered with the nanotubes. "It was really quite surprising," Steven said. "The way we coat the fiber, we only use water and pressure."