For her master’s work at Central Saint Martins, University of the Arts London, designer and researcher Jen Keane grew the upper of a shoe in a single piece, using a new form of ‘microbial weaving’.

For her project, aptly called ‘This is grown’, Keane uses the k. rhaeticus bacteria. This type of bacteria is best known for the part they play in the making of kombucha tea.

The bacteria grow a tiny fibre known as nanocellulose. This material is incredibly strong, 8 times stronger than steel and stiffer than Kevlar, which is used for bullet-proof vests. In addition, nanocellulose is transparent and incredibly lightweight. The material has already been used for medical applications.

What inspired Keane was the tiny trail of fibres the bacteria leave in their path as they grow. Essentially, they are weavers, she realised. “If we talk about the work in context to traditional weaving, I am weaving the warp, and the bacteria are growing the weft,” Keane explains. However, because the bacteria are so small, you don’t have the same restrictions of directionality that you would have with a traditional loom. This gives the weaver more control over the material properties and the ability to create patterns not possible with mechanical looms. Additionally, you can use yarn only where needed, reducing the overall amount of yarn and eliminating wastage.

To make the upper for the shoe, Keane developed a patent-pending process for the microbial waving to create a hybrid material, combining bacteria, a nutrient solution and biodegradable yarn.

Keane, along with Dr Koon-Yang Lee and postdoctoral researcher Dr Martin Herby from Imperial College, tested the three different samples for tensile strength, the results of which are encouraging. The tests showed that it is possible to design weave patterns with specific strength and properties in different directions. The grown samples are stronger than many synthetic films like polypropylene and polyethylene of the same thickness when it comes to tensile strength.

To show how her microbial weaving process could affect the way we make products in the future, Keane grew the upper of a shoe. The upper is grown in a single piece using no sewing. It consists of one continuous yarn held into place by cellulose produced by the bacteria.

“The really interesting part will come when we employ synthetic biology to control what the microbes produce and how and where they grow them,” Keane says. “But as we begin to exercise our new knowledge of nature to try and solve our material problems we have to question what is natural really, and accept that we may not actually be collaborating with nature anymore but controlling it.”

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