Materials scientists in Germany have discovered a novel use for Aspergillus niger fungal mycelium waste from the citric acid industry: making it into biodegradable printed circuit boards for use in simple electronics (Clean. Mater. 2026, DOI: 10.1016/j.clema.2026.100416).
Although the prototype mycelium boards are not yet ready to replace the boards that currently dominate the market, the researchers showed that the mycelium boards could be used to make simple circuits. The material also has low flammability and is fully biodegradable.
“Our fungus-based printed circuit boards still need some improvements for high-level applications, but they could be used to make products with a short life span at some point in the future,” says co-lead investigator Nina Oehlsen, who is pursuing her PhD with Linus Stegbauer, a materials scientist and professor at the Technical University Bergakademie Freiberg.
Around 62 million tons of electronic waste were generated globally in 2022, but only about 22% of it was recycled; e-waste is now increasing five times as fast as documented recycling capacity around the world. Although printed circuit boards make up only 4-7% of all electronic waste, they are one of the most toxic fractions and are currently difficult to recycle.
To try and combat this problem, Oehlsen, Stegbauer, and colleagues made a prototype printed circuit board from pellets of A. niger mycelium, which is a by-product of citric acid manufacturing.
“This fungal biomass is industrially produced, which means it is under highly controlled conditions,” Stegbauer says. This is helpful for making materials, he adds, because “for large-scale application, you would need to have a consistent quality.”
The boards were made by mold-casting and air-drying the material to make AnimatRT, a dense base for the circuit board. Conductive inks were applied to the surface of the board, and other components were then soldered in place.
The electrical performance of the mycelium boards was lower than conventional boards made of phenolic paper laminate—often referred to as FR2 boards—but the material was good enough to make lowfrequency, lowcomplexity circuits. Heat treatment improved strength and water resistance but slowed biodegradation.
“The material is very strong under compression, but its flexural strength is only about one-fifth that of FR2. It is promising for low-load devices but not yet a direct mechanical replacement for all conventional boards,” says Tingyu Cheng, a computer scientist and engineer at the University of Notre Dame with an interest in sustainable electronics.
Oehlsen and Stegbauer acknowledge that some improvements need to be made to the material to scale it further.
The team was able to dissolve the board in water to recover the electrical components and then resolder them onto a standard circuit board with preserved function. But Stegbauer says scaling this kind of component recycling up commercially would be hard, as current electrical specifications and regulations currently cover only new components.
Balancing good functionality with biodegradability is also a challenge. “The biggest issue with this board . . . is the temperature stability,” says Jeff Kettle, an electrical engineer and independent expert on this topic based at the University of Glasgow. “As a result it cannot be used in a standard manufacturing process which needs a temperature of 235-260 degrees centigrade for solder reflow.
“You need to use a bismuth based solder. In my view this is going to achieve a less reliable electronic device in the long term. So whilst the initial product is more environmentally friendly, if it does not last as long as the existing product then it might end up as electronic waste sooner,” Kettle adds.
The Freiberg team is not the only one working to make electronics from mycelia or otherwise to produce more sustainable circuit boards.
Although the team’s mycelium prototype is at an early stage, the researchers say their work tackles some key problems in the electronics industry and creates a biodegradable product using biotechnological waste.
The mycelium material also uses much less carbon dioxide than conventional circuit boards. “Even if you don’t look at end of life, we are around 60% better than the FR2. That includes the citric acid production,” Stegbauer says. He and his team are now planning to work on further improving the properties of AnimatRT so it can be used for a wider range of applications.
