As fibers go, there's never been anything quite like spider silk. Stretch it. Bend it. Soak it. Dry it out. Spider silk holds up. It is five times stronger than steel and can expand nearly a third greater than its original length and snap right back like new. Ounce-for-ounce spider silk is even stronger than Kevlar, the man-made fiber used in bulletproof vests.
It would be understandable to think that science knows all there is to know about the remarkable physics of spider silk, but the truth is far from that. Now, using a long-known-but-underutilized spectroscopy technique, a Stanford researcher has shed new light on the mysteries of spider silk.
On January 27, in a paper in the journal Nature Materials, post-doctoral scholar Kristie Koski described how she was able, for the first time, to non-invasively, non-destructively examine the mechanical properties of an intact, pristine spider web just as it was spun by the spider that created it. Koski is a researcher in the Yi Cui Group in the Department of Materials Science and Engineering at Stanford University and the first author of the study. The work was performed when she was a post-doc under Professor Jeff Yarger at Arizona State University.
The complete elastic response of spider silk is described by five elastic constants that define how the web reacts to any possible combination of forcespulling, twisting or shearing in any direction. All five have never been measured in a pristine spider web. At best, earlier studies have measured one or two of the five constants at a time and, even at that, only in isolated sections of a web. Structurally speaking, the old techniques are the equivalent of testing individual steel beams and cables and trying to extrapolate conclusions about the strength of a bridge.
Looking ahead, Koski believes that understanding the complete properties of a spider web exactly as it exists in nature is key to the engineering of improved "
|Contact: Andrew Myers|
Stanford School of Engineering