Printed fungus shows great potential as sound absorber and more

Eco-friendly sound absorbers made of fungus-based materials show great promise, their creators have said, and could lead to wider use of the natural materials.

The Fraunhofer Institute in Germany is developing the sound absorbers, which are made by 3D-printing materials including mycelium.

Sound absorbers can improve a room’s acoustics, reducing noise from music or speech. Many soundproofing panels are made of mineral fibres or synthetic foams, some of which are not sustainable or easily recycled.

Researchers at the Fraunhofer Institute for Environmental, Safety and Energy Technology (Umsicht) and the Fraunhofer Institute for Building Physics (IBP) aim to bring a more eco-friendly and effective alternative to market.

The original idea came from Julia Krayer, project manager at Umsicht, who has been working on biomaterials for many years. “There’s currently a focus on vegetal substrates and mycelium for the development of new materials,” she said.

Mycelium consists of a fine network of filament-like hyphae. In its natural habitat, mycelium grows underground, where it can span more than 1km².

In the current project, Krayer and colleagues grow hyphae in the lab, before mixing the mycelium with a vegetal substrate of straw, wood and waste from food production. The mixture is then printed into the desired shape by a 3D printer.

“The mycelial hyphae spread throughout the substrate and create a solid structure,” said Krayer.

Once the mycelium has permeated the fine-grained substrate, the product is dried in a kiln to kill the fungus. The cell walls of the resulting porous material are open, meaning it absorbs sound.

Sound absorbers made of fungus-based materials could have a range of advantages, a press release said: “They are effective, sustainable and help conserve resources.”

Using a 3D printer enables the creation of a predefined porous structure within the absorber. The team aims to progressively enhance the structures as the research advances, helping perfect the design.

Employees at Umsicht are producing a range of prototypes for sustainable sound absorbers, which will be tested at IBP.

The potential applications for the mycelial material are not limited to acoustics, the team said. “The end products could probably be used as insulating material, but this would require more intensive research,” said Krayer. It could also potentially be used as a base material for fungal faux leather, fabric and plastic. Furniture and housings for electric appliances are other possibilities being researched by the team.

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