Graphene-munching silkworms make tougher, conductive silk

10 Oct 2016

Silkworms eating mulberry leaves. Image: fuyu liu/Shutterstock

It doesn’t sound like the ideal meal, but silkworms are loving the taste of carbon nanotubes and graphene and the resulting silk could bring enormous benefits to science and wearables.

As a creature, silkworms are already treasured within the fashion industry for their soft silk by-product, but once it starts munching away on graphene and carbon nanotubes, it becomes an awful lot tougher.

In a recent research paper published in Nano Letters, a team of researchers from Tsinghua University in China found that silkworms were quite happy to eat the artificially created material.

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Twice as strong as regular silk

To get the silkworms to eat it, the team fed them mulberry leaves that were sprayed with a solution containing 0.2pc by weight of either graphene or carbon nanotubes, according to Chemical & Engineering News.

Similar to typical silk production, the team then waited and gathered the silk produced by the creatures and found some fascinating results.

They discovered that the silk was twice as strong as regular fibres and was capable of being pushed to stress limits 50pc more than that of regular silk.

The most impressive aspect however, is that the silk has also been found to conduct electricity. The team heated the silk fibres up to very high temperatures of 1,050 degrees Celsius, resulting in the carbonisation of its protein.

By running Raman spectroscopy and electron microscopy on the samples, it was found the ingested graphene and carbon nanotubes created a more organised crystal structure in the fibres, making it conductive.

How do they eat it?

The biggest question remaining for the research team is how exactly the silkworm is able to ingest and build it into the produced silk?

Similar experiments have been run in the past; another Chinese research team fed silkworms titanium dioxide to create silk that was resistant to long-term ultraviolet exposure, but no findings indicated how the creature’s system could process such foreign material.

Due to the low nanoparticle content of the resulting silk from this latest experiment, it is almost impossible to find the carbon materials in the samples. However, Yingying Zhang and her team suggest further research from biologists would be needed to help crack this mystery.

While it is still early days for this research, it is hoped that it could one day contribute to an easy way to produce strong, conductive fibres that could be used in wearables, sensors and medical devices.

Colm Gorey was a senior journalist with Silicon Republic