"My goal is to study the nanostructure of silk to understand not just how spider silk behaves as it does, but also why it behaves in such remarkable ways in hopes of someday creating better man-made fibers," said Koski.
The research was made possible by the use of a century-old-yet-overlooked measurement technique known as Brillouin spectroscopy. The technique shines laser light on the spider silks. The light produces sound waves in the silks, which, in turn, reflect some light back to the spectrometer. The researchers call the reflection "scattering."
"It is a bit like plucking the string of a violin, only we never have to physically touch the string to play it," said Koski.
The spectrometer measures small variations in the scattered light to ascertain the underlying tension of the silk being measured. The power of Brillouin scattering rests in the gentle way it gathers data enabling in situ measurements on spider webs, including mechanical properties at precise spots on the web such as silk intersections and glue spots.
Essentially, Koski and cohort have developed a non-invasive, non-destructive technique to measure the elasticity not just of individual strands of spider silk or even a few interconnected strands, as had those earlier studies, but of an entire intact spider web. Such exhaustive information was previously unobtainable with traditional stressstrain tests, which have to grip single strands or, at most, a few strands between two clamps to stretch them till they break.
"We don't have to touch the web to measure it," explained Koski.
The result is that Koski and collaborators are the first to quantify the complete linear elastic response of spider webs, testing for subtle variations in tension among discrete fibers, junctions, and glue spots for every type of deformation possibl
|Contact: Andrew Myers|
Stanford School of Engineering