Spider silk acts as fiber-optic molecular detector

Jan. 13, 2016
Cylindrical, transparent silk conducts light and interacts with chemicals (see video).
(Image: EPFL) Fiber-optics specialists at École polytechnique fédérale de Lausanne (EPFL; Switzerland) are using strands of spider silk as optical fibers that react in interesting ways to chemical contact, serving as optical molecular sensors. Picking up on an idea proposed by a discussion group of the European Space Agency, Luc Thévenaz, the professor in charge of EPFL's Group for Fibre Optics, shifted his attention away from traditional fibers made of glass and focused on the spider silk. These 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.Reusable chemical sensors "The helix in the silk strands unwinds whenever polar molecules like acetic acid and ammonia come into contact with its bonds," says Thévenaz. "This measurably modifies the way the strands conduct light, and it gave us the idea of using them to make chemical sensors." The researchers also discovered that the change in the helix structure was reversible; a sensor using spider silk could thus be used several times over. "We are looking at the possibility of creating silks by adding molecules meant to react with the substances to be tested," says Thévenaz. "That is often impossible with glass fibers, which we have to heat to more than 1000°C in order to stretch." At EPFL, doctoral student Desmond Chow and post-doc Kenny Hey Tow are working on natural silk strands with a diameter of 5 μm. They were produced by Australian Nephila edulis spiders grown at the Department of Zoology of the University of Oxford. Synthetic silks exist, but they are expensive and do not work as well as real ones.

(Video: EPFL) The researchers stretch a silk strand taut in a bracket and direct a laser beam at one end of the strand. At the other end, a polarization analyzer is used to measure small 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. Because silk is biodegradable, it is ideal for sensors that could be implanted in a living body without needing to be removed later on. Source: http://actu.epfl.ch/news/using-spider-silk-to-detect-molecules/

Sponsored Recommendations

Hexapod 6-DOF Active Optical Alignment Micro-Robots - Enablers for Advanced Camera Manufacturing

Dec. 18, 2024
Optics and camera manufacturing benefits from the flexibility of 6-Axis hexapod active optical alignment robots and advanced motion control software

Laser Assisted Wafer Slicing with 3DOF Motion Stages

Dec. 18, 2024
Granite-based high-performance 3-DOF air bearing nanopositioning stages provide ultra-high accuracy and reliability in semiconductor & laser processing applications.

Steering Light: What is the Difference Between 2-Axis Galvo Scanners and Single Mirror 2-Axis Scanners

Dec. 18, 2024
Advantages and limitations of different 2-axis light steering methods: Piezo steering mirrors, voice-coil mirrors, galvos, gimbal mounts, and kinematic mounts.

Free Space Optical Communication

Dec. 18, 2024
Fast Steering Mirrors (FSM) provide fine steering precision to support the Future of Laser Based Communication with LEO Satellites

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!