Freiberg: Compostable Circuit Boards Made from Waste
Printed circuit boards are typically made of glass-fiber-reinforced epoxy resin, which makes them difficult to recycle, let alone biodegrade. The Freiberg University is now introducing a compostable alternative made from fungal mycelium, a byproduct of industrial citric acid production.
Instead of disposing of this biomass waste, the team at the Freiberg University of Mining and Technology (TUBAF) processes it into a plastic-like material using an innovative method: through molding and air-drying, a small plate about 0.5 centimeters thick is created with a density of 1.23 g / cm³—comparable to the density of conventional printed circuit boards. Using direct ink writing or a standard etching process combined with manual soldering, the researchers were able to apply electronic components directly to the fungal plates.
"In laboratory tests, the material made from Aspergillus niger mycelium exhibits high mechanical properties and good heat stability. Although the electrical properties are still below those of standard PCBs, fungal mycelium is sufficient for prototypes or low-frequency applications—such as environmental sensors, consumer goods, and toys,” explains Nina Oehlsen, a doctoral student at TUBAF and first author of the scientific publication. “In order for the board to be used in the future in a manner comparable to today’s PCBs, it must still be tested according to standards such as IPC-A-600 or DIN EN 60249-1 and optimized to reduce water absorption.”
The Challenge of End-of-Life Management
Worldwide, discarded electronic toys, computers, and smartphones are turning into ever-increasing masses of e-waste. According to the “Global E-waste Monitor,” approximately 82 million metric tons of e-waste are expected by 2030. The sustainable printed circuit board, called AnimatPCB, not only addresses the environmental impact of e-waste—which is difficult to recycle—but also offers a solution for preventing the accumulation of unwanted material at the end of the PCBs’ life cycle. The PCB itself is completely biodegradable, and the transistors applied to it could be recovered in working condition, according to Linus Stegbauer, assistant professor of biogenic engineering materials at TUBAF: “We have created a high-quality, functional material from an industrial waste product—without using any additional fossil-based raw materials. Compared to a conventional printed circuit board, fungal mycelium has a carbon footprint that is up to 56 percent smaller and can ultimately be easily dissolved in water without leaving any hazardous residues.”
This bio-inspired research can make an important contribution to the development of circular electronics: “We are proving that it is possible to develop high-quality electronic components without long-term environmental impact—and we are demonstrating solutions for a circular electronics industry,” emphasizes economist Professor Simon Glöser-Chahoud of the TUBAF, who calculated the CO2 footprint over the entire life cycle of this innovative material.