additive manufacturing (2)

Cellulose Shoes...


Credit: Tom Mannion

Topics: Additive Manufacturing, Biology, Biotechnology, Environment, Genetics, Nanotechnology

For Hermes, the Greek god of speed, these bacterial sneakers would have been just the ticket. Modern Synthesis co-founders Jen Keane, CEO, and Ben Reeve, CTO, are now setting out to make them available to mere mortals, raising a $4.1 million investment to scale up production. Keane, a graduate from Central Saint Martins School of Art and Design in London, and synthetic biologist Reeve, then at Imperial College London, set up Modern Synthesis in 2020 to pursue ‘microbial weaving’.

Their goal is to produce a new class of material, a hybrid/composite that will replace animal- and petrochemical-made sneakers with a biodegradable, yet durable, alternative. The shoe's upper is made by bacteria that naturally produce nanocellulose—Komagataeibacter rhaeticus—and can be further genetically engineered to also self-dye by producing melanin for color.

The process begins with a two-dimensional yarn scaffold shaped by robotics, which the scientists submerge in a fermentation medium containing the cellulose-producing bacteria. The K. rhaeticus ‘weave’ the sneaker upper by depositing the biomaterial on the scaffold. Once the sheets emerge from their microbial baths, they are shaped on shoe lasts following traditional footwear techniques. “It’s more than the sum of its parts,” Reeves says of the biocomposite. “Initially the scaffold helps the bacteria grow, then the microbial yarn reinforces the material: it holds the scaffold together.” Once the shoe is made, it is sterilized and the bacteria are washed out.

Cellulose shoes made by bacteria, Lisa Melton, Nature Biotechnology

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4D Beetles...


Beetling along: Under the influence of moisture, the color of the 3D-printed beetle changes from green to red, and back again to red. (Courtesy: Bart van Overbeeke)

Topics: 3D Printing, Additive Manufacturing, Biomimetics

Researchers in the Netherlands have produced models of a beetle that changes color and a scallop shell that opens and closes in response to changing humidity in the surrounding air. Inspired by iridescent structures in nature, Jeroen Sol and colleagues at the Eindhoven University of Technology showed that they could integrate a specialized liquid crystal into standard 3D-printing techniques, creating “4D printed” devices that react to their changing environments.

Over millions of years, many organisms have evolved micro-scale structures in their anatomies that allow them to change their vibrant iridescent colors in response to stimuli. Recently, researchers have developed inks that change color in the same way and have begun to experiment with incorporating them into 3D-printed structures.

This technology has been dubbed 4D printing, where the fourth dimension represents reversible, time-varying changes to the structures after printing. One widely used technique in 4D printing is to deposit ink directly onto 3D printed structures. This approach can accommodate many types of material, as well as a versatile range of printing temperatures, speeds, and path designs.

4D-printed material responds to environmental stimuli, Sam Jarman, Physics World

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