(2021) MYCELIUM MATTERS: An interdisciplinary exploration of the fabrication and properties of mycelium-based materials. VUBPRESS.

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Environmental pollution and scarcity of natural resources have led to an increased interest in developing more sustainable materials. The traditional construction industry, which is mostly based on the extraction of fossil fuels and raw materials, has therefore been called into question. Biological materials that are created by growing mycelium-forming fungal microorganisms on natural fibres can form a solution. In this process, organic waste streams – such as agricultural waste – are valorised, while biodegradable material is created at the end of its life cycle; a process fitting with the spirit of a circular economy. Despite this promise, these materials’ characteristics have remained mostly unexplored. More scientific insights into growing and fabrication processes are required before incorporating these biomaterials into our daily lives. Therefore, this dissertation’s main goal is to explore the principal factors affecting the biological and material properties of mycelium materials and to broaden the potential of new fabrication technologies for architectural applications using fungal organisms. Ultimately, the research provides novel insights and a comprehensive overview of several crucial aspects that come into play during the production of fungi-based lignocellulosic composites. A method for selecting fungal species that incorporates biological, chemical and mechanical performance criteria has been developed. The interaction between fungi and their feedstock and the material properties of different types of feedstocks are investigated. Then, the optimisation of mechanical properties with different types of additives is studied. A novel fabrication process to produce large-scale architectural formwork is developed. Finally, various digital additive fabrications and design strategies that improve the colonisation of the fungi in a given geometry are explored. This hybrid investigation across disciplines is guided by the motivation to explore the growth and fabrication possibilities of mycelium materials from a bioengineering, material engineering, computational fabrication and architectural perspective.

Elise Elsacker, Lars De Laet and Eveline Peeters. “Large-scale robotic extrusion-based additive manufacturing with living mycelium materials”. Sustainable Futures 4, 100085 (2022).

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Large-scale robotic extrusion-based additive manufacturing with living mycelium materials

Environmental pollution and scarcity of natural resources have led to an increased interest in developing more sustainable materials. Mycelium material fabrication is an emerging bio-based and circular technology to produce materials ranging from foam to particleboard applications. In this process, organic waste streams – such as agricultural waste – are valorised, while biodegradable material is created at the end of its life cycle; a process fitting with the spirit of a circular economy. Up to now, mycelium composites have mostly been grown in moulds, by packing a substrate of lignocellulosic fibres with a fungal strain. This fabrication method restricts not only the size and geometry of the final product, but also the access to oxygen needed for the organism to grow in the centre of the material. Additive manufacturing can potentially overcome those limitations. To establish the groundwork of 3D printing with living mycelium material, this paper provides guidance regarding the technological requirements for 3D-printing fungal material. The purpose is to generate scientific insights on all relevant challenges, processes, production steps by disentangling interdependent process variables ranging from biocompatibility with the living organism, the robotic fabrication system and hardware, the determination of the printing parameter and the sterile printing process to rheological, biological, and geometric properties. Therefore, an extrusion system is developed specifically for robotic printing living biological material. Various manufacturing processes, such as the concentration of ingredients, impact of autoclaving, and time on the viscosity, extrusion pressure, toolpath geometry, the nozzle size, printing speed and mycelium growth, are investigated in detail. These parameters, combined with the rheological and biological behaviour of living material deposition led to the emergence of an experimental fabrication methodology, using a custom robotic manufacturing set-up.

Elise Elsacker, Lars De Laet and Eveline Peeters. “Functional Grading of Mycelium Materials with Inorganic Particles: The Effect of Nanoclay on the Biological, Chemical and Mechanical Properties.” Biomimetics 2022, 7, 57.

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Functional Grading of Mycelium Materials with Inorganic Particles: The Effect of Nanoclay on the Biological, Chemical and Mechanical Properties

Biological materials that are created by growing mycelium-forming fungal microorganisms on natural fibers can form a solution to environmental pollution and scarcity of natural resources. Recent studies on the hybridization of mycelium materials with glass improved fire performance; however, the effect of inorganic particles on growth performance and mechanical properties was not previously investigated. Yet, due to the wide variety of reinforcement particles, mycelium nanocomposites can potentially be designed for specific functions and applications, such as fire resistance and mechanical improvement. The objectives of this paper are to first determine whether mycelium materials reinforced with montmorillonite nanoclay can be produced given its inorganic nature, and then to study the influence of these nanoparticles on material properties. Nanoclay–mycelium materials are evaluated in terms of morphological, chemical, and mechanical properties. The first steps are taken in unravelling challenges that exist in combining myco-fabrication with nanomaterials. Results indicate that nanoclay causes a decreased growth rate, although the clay particles are able to penetrate into the fibers’ cell-wall structure. The FTIR study demonstrates that T. versicolor has more difficulty accessing and decaying the hemicellulose and lignin when the amount of nanoclay increases. Moreover, the addition of nanoclay results in low mechanical properties. While nanoclay enhances the properties of polymer composites, the hybridization with mycelium composites was not successful.

Elise Elsacker, Simon Vandelook, Bastien Damsin, Aurélie Van Wylick, Eveline Peeters, and Lars De Laet. "Mechanical Characteristics of Bacterial Cellulose-reinforced Mycelium Composite Materials." Fungal Biology and Biotechnology.8.1 (2021): Fungal Biology and Biotechnology. , 2021, Vol.8(1).

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Mechanical Characteristics of Bacterial Cellulose-reinforced Mycelium Composite Materials.

Background: While mycelium is considered a promising alternative for fossil-based resins in lignocellulosic materials, the mechanical properties of mycelium composite materials remain suboptimal, among other reasons due to the weak internal bonds between the hyphae and the natural fibres. A solution could be provided by the hybridisation of mycelium materials with organic additives. More specifically, bacterial cellulose seems to be a promising additive that could result in reinforcing mycelium composites; however, this strategy is underreported in scientific literature.

Results: In this study, we set out to investigate the mechanical properties of mycelium composites, produced with the white-rot fungus Trametes versicolor, and supplemented with bacterial cellulose as an organic additive. A methodological framework is developed for the facile production of bacterial cellulose and subsequent fabrication of mycelium composite particle boards based on a hybrid substrate consisting of bacterial cellulose and hemp in combination with a heat-pressing approach. We found that, upon adding bacterial cellulose, the internal bond of the composite particle boards significantly improved.

Conclusions: The addition of bacterial cellulose to mycelium composite materials not only results in a strengthening of internal bonding of mycelium material, but also renders tuneable mechanical properties to the material. As such, this study contributes to the ongoing development of fully biological hybrid materials with performant mechanical characteristics.

Vandelook, Simon, Elise Elsacker, Aurélie Van Wylick, Lars De Laet, and Eveline Peeters. "Current State and Future Prospects of Pure Mycelium Materials." Fungal Biology and Biotechnology. 8.1: Fungal Biology and Biotechnology. , 2021, Vol.8(1).

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Current State and Future Prospects of Pure Mycelium Materials.

In the context of the ongoing transition from a linear to a circular economy, ecologically friendly renewable solutions are put in place. Filamentous fungi can be grown on various organic feedstocks and functionalized into a range of diverse material types which are biobased and thus more sustainable in terms of their production, use and recycling. Pure mycelium materials, consisting only of mycelial biomass, can adopt versatile properties and appear promising as a substitute for current petrochemically produced polymeric materials or, in the case of myco-leather, as a substitute for animal-based leather. In recent years, a handful of private companies have been innovating to bring products based on pure mycelium materials to the market while scientific interest in these promising biomaterials is now starting to gain momentum. In this primer, we introduce pure mycelium materials, frame different production methods, review existing and potential future applications, thereby offering a vision on future advances for this emerging fungi-based technology.

Aurélie Van Wylick, Antonielle Vieira Monclaro, Elise Elsacker, Simon Vandelook, Hubert Rahier, Lars De Laet, David Cannella, and Eveline Peeters. "A Review on the Potential of Filamentous Fungi for Microbial Self-healing of Concrete." Fungal Biology and Biotechnology. 8.1 (2021): Fungal Biology and Biotechnology. , 2021, Vol.8(1).

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A Review on the Potential of Filamentous Fungi for Microbial Self-healing of Concrete.

Concrete is the most used construction material worldwide due to its abundant availability and inherent ease of manufacturing and application. However, the material bears several drawbacks such as the high susceptibility for crack formation, leading to reinforcement corrosion and structural degradation. Extensive research has therefore been performed on the use of microorganisms for biologically mediated self-healing of concrete by means of CaCO3 precipitation. Recently, filamentous fungi have been recognized as high-potential microorganisms for this application as their hyphae grow in an interwoven three-dimensional network which serves as nucleation site for CaCO3 precipitation to heal the crack. This potential is corroborated by the current state of the art on fungi-mediated self-healing concrete, which is not yet extensive but valuable to direct further research. In this review, we aim to broaden the perspectives on the use of fungi for concrete self-healing applications by first summarizing the major progress made in the field of microbial self-healing of concrete and then discussing pioneering work that has been done with fungi. Starting from insights and hypotheses on the types and principles of biomineralization that occur during microbial self-healing, novel potentially promising candidate species are proposed based on their abilities to promote CaCO3 formation or to survive in extreme conditions that are relevant for concrete. Additionally, an overview will be provided on the challenges, knowledge gaps and future perspectives in the field of fungi-mediated self-healing concrete.

Elise Elsacker, Asbjørn Søndergaard, Aurélie Van Wylick, Eveline Peeters, and Lars De Laet. "Growing Living and Multifunctional Mycelium Composites for Large-scale Formwork Applications Using Robotic Abrasive Wire-cutting." Construction & Building Materials 283 (2021): 122732.

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Growing Living and Multifunctional Mycelium Composites for Large-scale Formwork Applications Using Robotic Abrasive Wire-cutting.

This paper presents four key developments that are leading to the scalability of the fabrication processes of mycelium material. We develop a biological and digital fabrication pipeline for (1) growing large mycelium composite blocks, (2) on-site robotic wire-cutting, (3) using mycelium materials as a multifunctional formwork, and (4) implementing the self-healing of fungal organisms. The purpose of the research is to investigate the processing approaches, variable material handling and materials properties of large biohybrid (composed of biological and non-biological material) foam blocks. The robotic tool provides the freedom to shape and structure this novel biological material and opens the possibility of making unique architectural modules. For the first time, mycelium materials are robotically wire-cut in situ, which results in two demonstrators. Departing from an application-based intention, we test the compatibility of thermal insulating mycelium formwork with a concrete slab. As such, we combine two different materials with hybrid physical and architectural properties. Additionally, we investigated the self-healing and living properties of mycelium components after robotic implementation. The combination of microbiological systems and fibrous substrates creates a unique class of bioactive composite materials, with potential applications at in the construction sector.

Elise Elsacker, Simon Vandelook, Aurélie Van Wylick, Joske Ruytinx, Lars De Laet, and Eveline Peeters. "A Comprehensive Framework for the Production of Mycelium-based Lignocellulosic Composites." The Science of the Total Environment. 725 (2020): 138431.

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A Comprehensive Framework for the Production of Mycelium-based Lignocellulosic Composites.

Environmental pollution and scarcity of natural resources lead to an increased interest in developing more sustainable materials. For example, the traditional construction industry, which is largely based on the extraction of fossil fuels and raw materials, is called into question. A solution can be found in biologically augmented materials that are made by growing mycelium-forming fungal microorganisms on natural fibres rich in cellulose, hemicellulose and lignin. In this way, organic waste streams, such as agricultural waste, are valorised while creating a material that is biodegradable at the end of its life cycle – a process that fits in the spirit of circular economy. Mycelium-based materials have properties that are promising for a wide range of applications, including the use as construction materials. Despite this promise, the applicability and the practicality of these materials are largely unexplored and moreover, individual studies use a wide range of different experimental approaches and non-standardized procedures. In this review, we critically evaluate existing data on the composition of mycelium-based materials and process variables with the aim of providing a comprehensive framework of the production process. The framework illustrates the many input factors during the production that have an impact on the final characteristics of the material, and the unique potential to deploy more tuneable levels in the fabrications process that can serve to prototype a diversity of new unprecedented applications. Furthermore, we determine the applicability of existing data and identify knowledge gaps. This framework is valuable in identifying standardized approaches for future studies and in informing the design and process of new applications of mycelium-based materials.

Peer-reviewers remark: “In fact, it is the best most scientific review on mycelium materials”.

Elise Elsacker, Vandelook, Simon, Brancart, Joost, Peeters, Eveline, De Laet, Lars. "Mechanical, Physical and Chemical Characterisation of Mycelium-based Composites with Different Types of Lignocellulosic Substrates." PloS One. 14.7 (2019): E0213954.

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Mechanical, Physical and Chemical Characterisation of Mycelium-based Composites with Different Types of Lignocellulosic Substrates.

The current physical goods economy produces materials by extracting finite valuable resources without taking their end of the life and environmental impact into account. Mycelium-based materials offer an alternative fabrication paradigm, based on the growth of materials rather than on extraction. Agricultural residue fibres are inoculated with fungal mycelium, which form an interwoven three-dimensional filamentous network binding the feedstock into a lightweight material. The mycelium-based material is heat-killed after the growing process. In this paper, we investigate the production process, the mechanical, physical and chemical properties of mycelium-based composites made with different types of lignocellulosic reinforcement fibres combined with a white rot fungus, Trametes versicolor. This is the first study reporting the dry density, the Young’s modulus, the compressive stiffness, the stress-strain curves, the thermal conductivity, the water absorption rate and a FTIR analyse of mycelium-based composites by making use of a fully disclosed protocol with T. versicolor and five different type of fibres (hemp, flax, flax waste, softwood, straw) and fibre processings (loose, chopped, dust, pre-compressed and tow). The thermal conductivity and water absorption coefficient of the mycelium composites with flax, hemp, and straw have an overall good insulation behaviour in all the aspects compared to conventional materials such as rock wool, glass wool and extruded polystyrene. The conducted tests reveal that the mechanical performance of the mycelium-based composites depends more on the fibre processing (loose, chopped, pre-compressed, and tow), and size than on the chemical composition of the fibres. These experimental results show that mycelium-composites can fulfil the requirements of thermal insulation and have the potential to replace fosile-based composites. The methology used to evaluate the suitability and selection of organic waste-streams proved to be effective for the mycelium-material manufacturing applications.