From biotechnological residues to biodegradable printed circuit boards: Aspergillus niger mycelium as a structural support material

The electronics industry urgently seeks sustainable, biodegradable alternatives to conventional substrates for printed circuit boards (PCBs) to reduce the environmental impact of electronic waste and CO 2 emissions. Here, we introduce a biobased, plastic-like material derived from Aspergillus niger mycelium, Animat RT . This material is produced from residual biomass generated in industrial citric acid production, offering a circular-economy approach. The raw mycelial biomass, consisting of spherical pellets, is processed via mold casting and air-drying, consolidating the pellets into a dense, plastic-like monolith (1.23 g cm −3 ). When formed into sheets, Animat RT serves as a viable substrate for low-complexity PCB fabrication, allowing for direct ink writing and manual soldering of electronic components. Although its electrical properties are lower than those of FR-2 (flame retardant 2), a common, low-cost PCB laminate made of paper bonded with a phenolic resin, it remains suitable for low-frequency and proof-of-concept applications and, on average, has 56% lower embodied carbon. The mycelium boards disintegrate in water, allowing recovery of operative electronic components, whose functionality was demonstrated by re-soldering them onto a conventional PCB. The material exhibits high mechanical performance, with compressive strengths of up to 121 MPa, a flexural modulus of 2.3 GPa, and a flexural strength of 30 MPa. It is fully biodegradable (ISO 20200), redispersible in water, has low flammability, and favorable thermal insulation properties (0.21 W (mK) −1 ). Heat treatment at 120 °C enhances the mechanical properties, improves water resistance, and slows biodegradation. This study demonstrates the first use of biotechnology–derived A. niger mycelium as a biodegradable substrate for PCBs, addressing circularity and end-of-life challenges in electronics.