Growth Propagation of Liquid Spawn on Non-Woven Hemp Mats to Inform Digital Biofabrication of Mycelium-Based Composites

From the paper

Abstract

Mycelium-based composites (MBC) are valued for converting low-value organic materials into high-performance building materials, offering significant potential for decarbonizing the construction sector. MBC properties are influenced by mycelium species, substrate materials, and fabrication growth parameters. In traditional applications, grain spawn is combined with loose particle substrates to achieve specific functional properties, such as strength, acoustic absorption, or thermal insulation, tailored to a single purpose. However, recent advancements have shifted toward creating graded materials—materials in which properties vary gradually throughout the structure. This approach allows for multiple local optimized properties to be incorporated within a single material. As a result, graded materials can support applications that require complex, multifunctional performance, making them ideal for fields like construction where multiple properties are often needed within a single component. This study, part of a digital biofabrication framework, explores controlling mycelium growth via liquid spawn. While liquid spawn has improved mechanical properties, its effects on growth performance have not been fully studied. Non-woven mats, offering flexibility and mold-free fabrication, are proposed as substrates. This paper investigates the growth kinetics of Ganoderma lucidum and Pleurotus ostreatus on hemp non-woven mats using liquid inoculation, comparing it to traditional grain spawn inoculation. By integrating graded properties into digital biofabricated materials, researchers can develop more sustainable, efficient, and specialized solutions using fewer resources, enhancing the adaptability and functionality of MBC.The experiment involved pre-cultivating P. ostreatus and G. lucidum in yeast peptone dextrose (YPD) and complete yeast (CYM) media under static (ST) and shaking (SH) conditions. Four mycelium dilutions (1:10, 1:2, 1:1, and 2:1) were prepared and analyzed through imagery to assess growth kinetics, aesthetics, and potential material properties. Results showed that lower dilutions promoted faster growth with full coverage, while higher dilutions offered slower growth with partial coverage, providing more control during incubation. Shaking conditions resulted in slightly higher coverage and faster growth. CYM medium resulted in G. lucidum and P. ostreatus closely matching the grain spawn growth curve across all dilutions, compared to YPD medium. To optimize the control of material properties within the digital biofabrication system, it is recommended to use CYM ST for P. ostreatus and YPD SH for G. lucidum, as their growth curves show clear separation between dilutions, reflecting distinct growth efficiencies and speeds that can be selected for desired outcomes. P. ostreatus should be preferred for acoustic absorption qualities due to its thin, fibrous growth, while G. lucidum is ideal for strength and aesthetic properties, thanks to its dense growth and color-changing characteristics.