Machining of spider silk fibers using femtosecond lasers

Researchers have proven that they can machine and make strips, microstructures and sensors out of spider silk using femtosecond lasers. Just a few days ago it was announced that spiders exposed to water with graphene and carbon nanotubes can make spidersilk that is 3 times stronger than regular spider silk. The two developments could mean a very strong version of graphene reinforced spidersilk could be emerge for a range of new applications.

They managed to weld spider silk to metal, glass, and kevlar. Stress tests showed that the weld was roughly equivalent in strength to the spider silk itself. In one case, they even welded some silk to four corners of a tiny mirror, then welded it to a square frame, allowing them to suspend the mirror using nothing but spider silk.

The authors speculate on all sorts of potential applications for fine-tooled spider silk. Of course, those all depend on our ability to produce lots of silk threads, which is still an unsolved problem. But they also suggest we should look at the prospects for using the same approach to craft structures from a variety of other biomaterials—shells, exoskeletons, hair, and fur—that are far easier to obtain in bulk

Spider silk is a tough, elastic and lightweight biomaterial, although there is a lack of tools available for non-invasive processing of silk structures. Here we show that nonlinear multiphoton interactions of silk with few-cycle femtosecond pulses allow the processing and heterostructuring of the material in ambient air. Two qualitatively different responses, bulging by multiphoton absorption and plasma-assisted ablation, are observed for low- and high-peak intensities, respectively. Plasma ablation allows us to make localized nanocuts, microrods, nanotips and periodic patterns with minimal damage while preserving molecular structure. The bulging regime facilitates confined bending and microwelding of silk with materials such as metal, glass and Kevlar with strengths comparable to pristine silk. Moreover, analysis of Raman bands of microwelded joints reveals that the polypeptide backbone remains intact while perturbing its weak hydrogen bonds. Using this approach, they have fabricated silk-based functional topological microstructures, such as Mobiüs strips, chiral helices and silk-based sensors.

26 pages of supplemental material.

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