Cleverly exploited natural potential: With the help of mushrooms, researchers create sophisticated material structures that could replace artificial foams as sound absorbers. For this purpose, structures are first produced from organic waste using the 3D printing process, which are then grown through and stabilized by a network of fungi. The material can then be sterilized by heating and used. In addition to the design of sustainable sound absorbers, the researchers are currently exploring the potential of the process for the production of other functional materials.
Noisy neighbors, street noise, chattering colleagues … As is well known, noise pollution can have a severe negative impact on our health, and pleasant acoustics in rooms also play an important role in human wellbeing. Sound-absorbing components are therefore used in many areas to influence the propagation of noise. However, the polyester foams or composite materials based on mineral fibers used up to now cannot be produced sustainably, nor are they easily recyclable. Environmentally friendly alternatives are therefore in demand.
For some time now, scientists from the Fraunhofer Institute for Environmental, Safety and Energy Technology (UMSICHT) have been researching the possibilities of producing environmentally friendly materials with the help of mushrooms together with the Fraunhofer Institute for Building Physics IBP. “As part of the material development, we focus on plant substrates and mushroom mycelium,” says Julia Krayer from UMSICHT. The “FungiFacturing” project is not about using the material from the fruiting bodies that we normally associate with the word mushroom. The scientists, on the other hand, use the widely ramified network of these organisms: The mycelium is a fine web of so-called hyphae that, in the case of forest mushrooms, grows underground or penetrates and decomposes biological materials.
In order to use mycelium as a structuring element in materials, the researchers let it grow in prefabricated structures made of biological materials that serve as food for the fungus. To do this, they create a substrate from straw, wood and waste from food production and mix it with the living fungal tissue. This mixture then serves as “ink” for printing complex objects. The structures are then exposed to the optimal growth conditions for the fungus. “The mycelium threads then grow through the entire substrate and form a solid structure,” explains Krayer.
Mushrooms turn biowaste into smart materials
After the mesh has penetrated and crosslinked the initially relatively crumbly substrate, the product is dried in the oven to kill the fungus. The material created in this way then has porous properties with special physical effects. The use of the 3D printer in the production of the substrate material enables a pore structure planned in advance that can optimally absorb sound, making the material suitable for use as a sound absorber, the scientists report.
They are currently producing various prototypes of the sustainable sound absorber that are being tested at Fraunhofer IBP. The process could even produce sound absorbers that are superior to currently available products in certain aspects, emphasize the scientists. “The solid structure, through which the mycelium grows, could make sound absorbers made of significantly thinner layers possible in the future,” says Roman Wack from Fraunhofer IBP in Stuttgart.
As the scientists finally emphasize, the potential of the mushroom-based material goes far beyond the acoustic area: They are already working on ways to manufacture elements for thermal insulation or materials such as mushroom leather, textiles and plastic. The researchers say that one day items of clothing, furniture or housings for electrical appliances could also be made from the eco-materials produced using natural technology.
Source: Fraunhofer Society