Exploring extrusion-based printing application for the development of mycelium-based composites.

A recent emerging class of sustainable materials are fungal biomaterials, which can offer an alternative to petroleum-based products. A major component of fungal biomaterials is mycelium, the vegetative part of a fungus. Mycelium forms a dense network around its substrate, which can be comprised of low-grade agricultural residues. After a period of growth, a mycelium composite material is obtained with various mechanical properties, depending on multiple parameters such as selection of substrate, fungal species, and final processing techniques. Currently, the most adopted fabrication technique for mycelium composite production is through moulding, where the substrate is hand-packed into a form that resembles the desired final shape. This method is disadvantaged by the limitation of complex geometry formation and the lack of oxygen supply to the mycelium in the core of the substrate. Here, the application of additive manufacturing via extrusion-based printing shows promising results for addressing these limitations. This research provides insight into the importance of details which have been previously undetermined in literature in this field. Documentation of these details may be critical for allowing comparisons to be made between studies and therefore allowing a greater underlying understanding of the various factors, and challenges that must be overcome for successful extrusion-based mycelium composite development. Components such as particle interactions, rheological properties, a standardised procedure to aid in material selection, and the interaction between mycelium and substrate were explored which led to the development of an extrusion-based printed mycelium composite with successful integration of waste valorisation to harness the full sustainability potential of mycelium composites