HIGHLIGHTS
• Mycelium, a root-like structure present in mushrooms, has been found to be used as a raw material for use in sustainable composites that can be used in a number of applications such as packaging.
• A new approach for producing complex shapes of mycelium biocomposites involves the use of 3D printing using coffee grounds as the biomass. 
• The resulting biocomposites exhibit comparable strength and toughness compared to Styrofoam in packaging. 

As new technologies and processes are being developed in the push toward sustainability, the lubricant and tribology field has assumed a significant role. The ability of lubricants to improve the efficiency and productivity of automotive and industrial applications is leading end-users to realize that they can also reduce emissions, save energy and reduce operating costs.

This effort has led the lubricant and tribology field to reexamine its own efforts to improve sustainability. One issue that has arisen is what can be done to make packaging such as steel drums and plastic totes more sustainable, and even work with alternatives to packaging materials such as Styrofoam.

In determining potential sustainable packaging options, researchers are evaluating renewable sources that can be derived from natural materials. Mycelium, the root part of a mushroom fungus, has emerged as a raw material that can be used in the manufacture of sustainable packaging.

Danli Luo, graduate student in the Department of Human-Centered Design and Engineering at the University of Washington in Seattle, Wash., says, “Mycelium is a root-like structure that grabs nutrients in the soil for mushrooms in a similar manner to what conventional roots conduct for green plants. Composites based on mycelium have been developed and demonstrated potential for use in a number of applications including packaging, building materials and insulation.”

The approach taken to produce mycelium biocomposites has been to introduce the fungal root to an organic substrate such as byproducts and waste streams from forestry and agriculture. When placed on a substrate under favorable conditions, the long branching filaments (hyphae) in mycelium entwine a three-dimensional linkage through the organic material forming the composite.

Mycelium biocomposites can typically be processed into bulk substrates that are then converted into a rigid mold that has a specific shape. Luo says, “Certain shapes such as those that are hollow structures or have intricate undercuts cannot be prepared using current techniques without a great deal of difficulty. Preparation of pliable, organic molds by knitting, or through the use of a rigid frameworks and soft fabrics, and then filling it with a mycelium-based biomass, leads to inconsistencies in structural integrity.”

Luo and her colleagues have now developed an approach for processing mycelium biocomposites that involves the use of 3D printing.

Coffee grounds
The use of additive manufacturing or 3D printing was found by the researchers to be an attractive approach for generating complex shapes of mycelium biocomposites without the need of a rigid mold. Luo says, “Past work was rarely reported in using this technique with mycelium. Such work exists but is very niche; we see the potential hence we contribute in this effort.”

The additional component that assisted with 3D printing of mycelium biocomposites is the use of coffee grounds as the biomass. Luo says, “Coffee grounds are a byproduct in the manufacture of the beverage and are already sterilized due to the high pressure steam processing conditions. This provides us with an excellent substrate for growing mushrooms, which are a source of mycelium. The approach is also sustainable because coffee grounds can be recycled.”

The preparation of the mycelium biocomposite starts with blending a Mycofluid formulation. Luo says, “We mixed the spent coffee grounds with brown rice flour, ground grain spawn, xanthan gum and water. The purpose of the brown rice flour is to be a source of carbohydrate that is widely used for growing mushrooms. Xanthan gum is a rheological modifier and binder that provides viscosity to the Mycofluid so it can be used in 3D printing. Ground grain spawn is used to introduce mycelium into the substrate.”

Inoculation of the ground grain spawns derived from Rishis mushrooms with the rest of the Mycofluid formulation led to the growth of mycelium colonies if the proper moisture, air exchange and temperature and lighting was used. 

The Mycofluid is now transformed into a biopaste that is ready to be converted into mycelium biocomposite by 3D printing. Prior to taking this step, the researchers developed a screening method for assessing the amenability of the biopaste to be 3D printed. Once this is completed, the Mycofluid is loaded onto a setup known as a Fungibot (see Figure 3) that transports the biopaste by a motor-driven plunger and an extruder into the inlet of the 3D printer.


Figure 3. The Fungibot is used to transport a Mycofluid, prepared from mycelium, to the 3D printer for conversion into a part that can be used in packaging. Figure courtesy of the University of Washington.

Then a specific product (mycelium biocomposite) is manufactured using the layer-by-layer process typical of how a 3D printer operates. An example of an object produced by this technique is the vase shown in Figure 4.


Figure 4. A vase was produced from mycelium through the assistance of a 3D printer. Figure courtesy of the University of Washington.

Standard structural integrity and physical property testing were conducted on the mycelium biocomposite objects fabricated in this manner. Luo says, “We found that the growth of mycelium colonies on the biopaste leads to the formation of a ‘skin’ layer that imparts hydrophobicity to the object produced. While complete water repellency and water proofing is not achieved, this barrier is effective in reducing water absorption over time.”

In comparison to Styrofoam, the mycelium biocomposite displays comparable strength and toughness. Luo says, “The mycelium biocomposite is heavier than Styrofoam and closer in density to cardboard or charcoal.”

This study demonstrated that mycelium biocomposite can be used as an alternative to Styrofoam in packaging. The material will eventually solubilize in water and is compostable. 

Luo indicates that future work will involve working with local coffee shops to gain access to different types of coffee grounds that can be evaluated. She hopes that other bio-derived materials can be developed that will offer compostable (sustainable) alternatives.

Additional information can be found in a recent article¹ or by contacting Luo at danlil@uw.edu. 
 
REFERENCES
1. Luo, D., Yang, J. and Peek, N. (2025), “3D-printed mycelium biocomposites: Method for 3D printing and growing fungi-based composites,” 3D Printing and Additive Manufacturing, https://doi.org/10.1089/3dp.2023.0342.