Ecovative has developed a process for producing full-size mycelium sheets that are up to 24 metres in length and 1.8 metres wide (© Ecovative )

The mycelium production process is similar to the Dutch Shelf System for growing white button mushrooms (© Mycelium Materials Europe)

Mycelium materials are among a range of bio-based interior fabrics employed in the latest Kia Concept EV3 concept car (© Kia)

Microfibre-based artificial leathers or microsuedes are now the preferred option to natural leather for many leading car manufacturers and their customers, with benefits including breathability, softness and scuff resistance. They have also increasingly found favour with luxury goods brands and manufacturers of high-end furnishings.
Such materials are generally based on ‘islands in the sea’ bicomponent fibres which are cut into staple fibres and have their ‘sea’ components dissolved out, before being needlepunched and dyed. They can take bold colours and provide car makers with flexibility in seat and component assembly, and as a result command premium prices – far above the square metre prices of conventional nonwoven roll goods.
The fact remains, however, that such fabrics are still largely based on oil-based synthetic fibres and responding to the requirements of a future circular economy is leading to the development of some very different biobased alternatives.
These are based on fungal mycelium – the vegetative stage of mushrooms – and have also recently been attracting the interest of car makers for potential new interior fabrics.

Networks
In many ways, these new mycelium materials perfectly comply with the ISO definition of nonwovens, as being ‘engineered fibrous assemblies which have been given a designed level of structural integrity by physical and/or chemical means, excluding weaving, knitting or paper making’.
The process for their production is, however, a million miles away from the conversion of conventional nonwoven roll goods, generally involving biofabrication in huge batch systems of trays on shelves. This is similar to the Dutch Shelf System recognised worldwide as the superior growing method for white button mushrooms.
The fungal mycelium organisms grow in network-forming structures called hyphae and are mainly composed of a polysaccharide called chitin.
Chemically, chitin’s structure is similar to cellulose, and it is a versatile molecule that can form a semi-transparent biomaterial. Chitin is also characterised by its biocompatibility, biodegradability, and non-toxicity.
A number of companies have now emerged dedicated to exploiting the useful properties of mycelium, with the major end-use application viewed as alternative leather for apparel and footwear, but also materials for automotive interiors, acoustic panels and floor tiles.

MycoWorks
In January this year, for example, California-headquartered MycoWorks announced that its commercial-scale plant had successfully harvested over a thousand sheets of Fine Mycelium, its leather-alternative biomaterial.
 MycoWorks has been exploring potential automotive applications with General Motors following investment by GM Ventures in the company, as part of an over-subscribed $125 million investment round for the establishment of the new  plant. It will produce several million square feet of Fine Mycelium materials annually, once at full capacity. Based in Union County, South Carolina, it is modelled after the company’s semi-automated Emeryville pilot plant which has successfully demonstrated the scalability of the process.
The patented Fine Mycelium process is a proprietary biotechnology platform that engineer’s mycelium to grow made-to-order and made-to-specification materials. The predictable and scalable tray-based process meanwhile offers freedom from supply chain constraints.

Ecovative
New York-based Ecovative – which has developed a process for producing full-size mycelium sheets that are up to 24 metres in length and 1.8 metres wide over the course of just nine days – has also explored the use of its materials with automotive  leader Ford, as well as partnering with fashion brands including Bestseller, Pangaia, PVH Corp., Reformation, Vivobarefoot.
Ecovative’s sheets can also be grown to meet specific performance in terms of tensile strength, density, and fibre orientation.

Mycel
Over in South Korea, start-up Mycel has partnered with car manufacturer Kia to develop another soft automotive fabric based on mycelium that can be produced in variety of textures and can also be dyed. The Mycel material is resistant to tearing and has a high tensile strength, both of which are key for car seats that take heavy usage. Kia has committed to eliminating both leather and PVC from all of its cars and is also exploring a bio-polyurethane derived from natural components such as corn and eucalyptus for interior applications.

MY-FI
Car makers Volkswagen and Stellantis have meanwhile been involved in the €6.5 million EU Horizon-funded MY-FI research project to develop new materials made of mycelium fibres which is now nearing its completion.
The project has been led by Mogu, located in Inarzo, near Milan, in Italy, which has substantially expanded its process for growing selected strains of mycelium on pre-engineered substrates made of agro-industrial residues.
Mogu’s mycelium is grown from starter spawn into the threadlike filaments of the hyphae on top of the substrates. When harvested and dried soft, silky white nonwovens are created in sheets of between 50 to 60 square centimetres which are completely stable, safe, durable and biodegradable. The delicate material is then made stronger and more durable through the addition of bio-based chemicals.
Within the MY-FI project, Volkswagen has been assessing the materials under development for potential use in automotive interiors.
“Customers increasingly want animal-free materials for interiors – from seat covers and door panels to dashboards and steering wheels – so adding a sustainable substitute for leather is an exciting prospect,” says Dr Martina Gottschling, a researcher at Volkswagen Group Innovation. “A fast-growing biological material that can be produced animal-free and with little effort, which also does not require petroleum-based resources, is a game-changer in interior materials and the mycelium material is also lighter than leather.”
Volkswagen’s involvement in MY-FI has been driving project researchers at Utrecht University in the Netherlands and ITECH (Institut textile et chimique de Lyon) in France to enhance the durability of the mycelium fabric, and samples continue to be assessed and improved on.
“It’s definitely a change of mindset working with mycelium in the manufacturing process,’ says Annalisa Moro, Mogu’s EU project leader. “You’re really collaborating with nature to grow something rather than creating it, so it’s kind of futuristic.”