Extrusion-based additive manufacturing of complex three-dimensional ultra-lightweight materials using the basidiomycete Fomes fomentarius†

Abstract

Fungal mycelium-based materials harness the full potential of lignocellulosic resources in a sustainable way. Additive manufacturing can enhance design flexibility and reduce the use of plastic moulds in producing fungal mycelium-based materials. Here, we explored additive manufacturing of living Fomes fomentarius for precise fabrication of fungal mycelium-based materials. Using a 1.6 mm nozzle, we extruded a paste containing living fungal mycelium, rapeseed straw, and sodium alginate into various sizes and shapes. The aerial mycelium (consisting of fungal hyphae that grow away from the substrate surface into the air) formed was manually compressed during growth to maintain the desired shapes. For inactivation, freeze drying was found to maintain the original dimensions and shapes of the printed structures more effectively than convection oven drying. In addition to the printed composite materials, pure three-dimensional fungal mycelium skins could also be produced. Electron scanning microscopy, Fourier transform infrared spectroscopy, X-ray microtomography, hydrophobicity testing, compressive and tensile testing were used to investigate the morphological, physical and mechanical characteristics of the printed structures. Our results demonstrate that living F. fomentarius mycelium can be successfully used to manufacture lignocellulose–fungal mycelium-based materials with defined growth and hydrophobicity, which further expands its potential for future application as renewable biomaterials.