Scientists knit a futuristic eco-building design using mushroom tissue

Scientists hoping to reduce the environmental impact of the construction industry have developed a way of growing building materials using crochet molds and tissue of mushroom roots. Although researchers have experimented with such composites before, the shape and growth constraints of organic materials have made it difficult to develop the wide range of applications that fulfill their potential. Using knitted molds as a flexible framework or ‘formwork’, the scientists created a composite called ‘mycocrete’ that is stronger and more versatile in shape and form, enabling scientists to develop a construction material that is lightweight and relatively environmentally friendly.

“Our ambition is to transform the look, feel and well-being of architectural spaces using mycelium in combination with bio-based materials such as wool, sawdust and cellulose,” said Dr Jane Scott from the University of Newcastle, corresponding author of the paper in Frontier in Biotechnology and Biotechnology. The research was carried out by a team of designers, engineers and scientists at the Living Textiles Research Group, part of the Hub for Biotechnology in the Build Environment at the University of Newcastle, which is funded by Research England.

Root network

To make the composites using mycelium, part of the fungus’ root tissue, scientists mix mycelial spores with seeds they can eat and materials they can grow. This mixture is packed into molds and placed in a dark, moist, and warm environment for the mycelium to grow, bonding the substrate tightly. Once it reaches the right density, but before it starts to produce the fruiting bodies we call mushrooms, it dries up. This process can be a cheap and sustainable substitute for foam, wood, and plastic. But the mycelium needs oxygen to grow, which limits the size and shape of conventional rigid molds and limits its current applications.

Knitted textiles offer a possible solution: an oxygen-permeable mold that can change from flexible to rigid with the growth of mycelium. But textiles can melt too much, and it’s hard to pack prints consistently. Scott and his colleagues designed a mycelium mix and production system that could harness the potential of the knit form.

“Knitting is a very versatile 3D manufacturing system,” says Scott. “Lightweight, flexible, and moldable. The main advantage of knitting technology compared to other textile processes is the ability to knit 3D structures and shapes without stitches and without waste.”

A conventional mycelium composite sample was prepared by the scientists as a control, and grown alongside the mycocrete sample, which also contained paper powder, paper fiber wadding, water, glycerin, and xanthan gum. The paste is designed to be delivered into knitted formwork with an injection gun to improve packing consistency: the paste needs to be liquid enough for the delivery system, but not so liquid that it fails to hold its shape.

The tubes for the planned test structure were knitted from merino yarn, sterilized, and fixed to a rigid structure when filled with paste, so that changes in fabric tension would not affect the performance of the mycocrete.

Build the future

After drying, the samples were subjected to tensile, compressive and flexion strength tests. The mycocrete samples proved to be stronger than conventional mycelium composite samples and outperformed mycelium composites grown without knitted formwork. In addition, the formwork’s porous knitted fabric provides better oxygen availability, and samples embedded in it shrink less than most mycelial composite materials when cured, indicating more predictable and consistent manufacturing results can be achieved.

The team was also able to build a larger proof-of-concept prototype structure called BioKnit – a complex freestanding dome built in one piece with no joints proving to be a weak point, thanks to the flexible shape of the knit.

“The mechanical performance of mycocrete used in combination with permanently knit formwork is a significant result, and a step toward using mycelium and textile biohybrid in construction,” said Scott. “In this paper we have defined the specific threads, substrates and mycelium needed to achieve certain goals. However, there are wide opportunities to adapt these formulations for different applications. Biofabricated architecture may require new machine technologies to move textiles into the construction sector.”