EPFL fiber optics specialists have discovered very promising and unique qualities of spider silk when it comes to conducting light and reacting to certain substances. Spider silk strands are perfectly cylindrical, smooth, transparent, and extremely solid - some of the same characteristics as glass-based fibers. But while glass is inert, spider silk is made up of very long proteins rolled into a helix structure whose bonds are sensitive to a number of chemical substances. The EPFL researchers are working on natural silk strands with a diameter of 5 microns. The researchers stretch a silk strand taut in a tiny bracket and direct a laser beam at one end of the strand. At the other end, a polarization analyzer is used to measure infinitesimal changes in the light passing through it. If a gas that interacts with the silk strand is present, the device will pick up on this immediately.