Swiss researchers are working on a new kind of chemical sensor — one made of light and spider's webs. This thin, yet ultra strong, material has two properties that make it ideal for this purpose: its ability to channel light and its reactivity. Put a laser at one end of a strand of undamaged spider's silk and the beam will be carried perfectly through to the other end. In this way, the silk is no different from fibre-optic cable. When it comes to chemical make-up, it differs considerably. While fibre optic cables are made of glass or plastic, and are designed to keep from reacting with the environment around them, spider's webs are made of proteins that react to a number of different chemicals.
Specifically, they react with polar molecules — molecules that have a concentration of positive charge on one end and a concentration of negative charge on the other. Modify the structure of the proteins, and you can modify the light that makes its way through the strand of silk. Put a light source (such as a laser) on one end of the strand of silk, and a light-sensor at the other, and the silk will react if it comes into contact with a polar molecule.
Scientists at the École Polytechnique Fédérale de Lausanne (EPFL) are excited about this for a number of reasons. First, once the molecule comes off the silk, the thread shifts back into its original shape, allowing the sensor to be reused several times. Second, the sensor is biodegradable. This makes it possible to implant these sensors in a "living body". No need to dig it out after — it will harmlessly disintegrate.
But only the real stuff works. Although many scientists are making synthetic spider's silk, they don't work as well channelling the light, and they're far more expensive than the stuff spiders produce themselves.
The research is in the early stages, but if all goes well, soon people could be implanted with molecular detectors made from spider's silk:
Update: EPFL located in Switzerland, not France as originally stated. This article has been updated.
Image: John Tann