The role of surface interventions in bio-welding mycelium based-composites

The use of mycelium-based composites in large-scale bio-fabrication is limited due to the biomatter's low mechanical strength and the requirement for external reinforcement or permanent moulds holding the material in place. Utilising bio-adhesion in the fabrication process of mycelium-based composites may offer the potential to upscale the production of fungal biomatter and further expand its range of applications. However, studies on the effects of bio-welding on the properties and performance of mycelium composites are limited. This is the first paper investigating the use of different bio-welding interventions to bind mycelium-based composites and studying the impact of these interventions on the material's properties and performance through environmental readings, physical and chemical analysis and mechanical testing. Ganoderma lucidum grain spawn was used with hemp shivs to bio-fabricate mycelium composites. The surfaces of these composites were then subjected to environmental, nutritional, and abrasive interventions for five consecutive days before binding, and monitored during different stages of the bio-welding process. The temperature, relative humidity, and CO₂ of the mycelium-based composites were recorded during the five-day intervention phase. A chemical analysis was undertaken at the wet and dry stages of the composite samples. Furthermore, the final (dried) bio-welded components underwent mechanical testing (flexural, compressive, and tensile strength) for performance evaluation. This study found that surface interventions could affect and enhance the mechanical properties of bio-welded mycelium composites. The research demonstrated that adding nutrients to surfaces before binding significantly affected compressive, tensile, and flexural strength. Using interventions in the bio-welding process presented new opportunities for upscaling the production of mycelium-based composites and the potential to fine-tune their mechanical properties, adapting them for different applications.