Bio Focus: Spider-inspired vibration sensor detects music
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Nanoscale crack junction-based sensor attached to a violin for sound wave recognition (top left), recorded wave functions of E (yellow, fundamental frequency of 659 Hz), A (green, 440 Hz), D (blue, 294 Hz), and G (red, 196 Hz) strings (top right), measured sound waves of music playing ("Salut d’Amour"; excerpt shown in the bottom panel). Reproduced with permission from Nature 516 (7530) (2014), DOI: 10.1038/nature14002; p.178. © 2014 Macmillan Publishers Ltd.
that of silkworms—isn’t a practical option. Spiders can become territorial and even cannibalistic when kept in close proximity to each other, and the labor required to harvest their silk is too great to make the process commercially viable. Instead, scientists are studying the molecular basis for spider silk’s valuable properties with the hopes of eventually creating a commercially viable biomimetic synthetic silk fiber. “One of the main obstacles to synthesizing true, biomimetic spider silks was, and still is, a lack of understanding about the natural material and processes by which it is created,” said Cameron Brown of the University of Oxford and
an author of a review paper on synthetic silk in the January 14 issue of the Journal of Materials Research. “We are getting much better at making proteins similar to the natural proteins, yet our processing capabilities lag behind.” The two main proteins believed to be responsible for silk production are large molecules called Spidroins, but over a hundred secondary proteins might help finesse the silk’s properties. Researchers have turned to a variety of organisms, from bacteria to goats, to recombinantly express these relevant proteins. None, however, has yielded synthetic fibers on par with natural ones in strength. Recombinant silk protein expression has suffered from
Spider-inspired vibration sensor detects music
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piders use crack-shaped slit organs near their leg joints to detect minute mechanical vibrations. This inspired Mansoo Choi and his team from Seoul National University to design their own version of a mechanical sensor based on nanoscale crack junctions. As the
Bio Focus Spinning artificial spider silk remains a challenge
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lthough spider webs can be torn apart with one well-aimed sweep of a broom, the silk that forms them is, by weight, one of the strongest materials found in nature. It’s also lightweight, biodegradable, sticky, and slightly stretchy— all properties that make it desirable for a variety of applications. Humans have been collecting silk from silkworm colonies for thousands of years to create textiles. However, using the same strategy to harvest natural spider silk—which is stronger and lighter than
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researchers describe in their December 2014 Nature publication (DOI: 10.1038/ nature14002), they fabricated their sensors by depositing a stiff 20-nm thin film of electrically conductive platinum on a flexible polymer (polyurethane acrylate). The material is then wrapped around glass rods of different diameters to induce controlled directional cracking with different spacing b
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