Researchers at the University of Washington have developed a 3D printing technique that transforms coffee grounds and Reishi mushroom spores into a compostable alternative to plastic.
The method, detailed in a study published in 3D Printing and Additive Manufacturing, could offer a sustainable packaging solution for small businesses, the university said in a news release.
The innovation is led by Danli Luo, a doctoral student in human centered design and engineering at UW, who recognized the potential of used coffee grounds as a growth medium for fungi.
Luo noted that coffee grounds, sterilized through brewing and rich in nutrients, provide an ideal environment for mycelium—the root-like structure of fungi—to develop a durable, water-resistant material.
To create the material, the research team developed a paste called “Mycofluid” by mixing used coffee grounds with brown rice flour, Reishi mushroom spores, xanthan gum, and water.
A specially designed 3D printer head for the Jubilee 3D printer, developed by UW’s Machine Agency lab, allows the paste to be shaped into various objects, such as packaging, vases, and statues.
Over a 10-day period, the mycelium grows around the printed objects, forming a tough outer layer before being dried to halt further fungal growth.
“We’re especially interested in creating systems for people like small business owners producing small-batch products,” Luo said.
“For example, small, delicate glassware that needs resilient packaging to ship. So we’ve been working on new material recipes that can replace things like Styrofoam with something more sustainable and that can be easily customized for small-scale production.”
Testing showed that the material has a density similar to cardboard or charcoal and absorbs only a small amount of water, maintaining its structure and strength comparable to polystyrene and expanded polystyrene foam.
While the research team did not formally test the compostability of the material, they confirmed that all of its components are biodegradable.
Scaling up production presents challenges due to the need for uniform coffee grounds, but the researchers are exploring alternative food waste sources to create similar bio-based pastes.
“We’re interested in expanding this to other bio-derived materials, such as other forms of food waste,” Luo said.
“We want to broadly support this kind of flexible development, not just to provide one solution to this major problem of plastic waste.”
The study was co-authored by Junchao Yang, a former master’s student in human centered design and engineering at UW, with Nadya Peek, an associate professor in the same department, serving as the senior author.
The research was funded by the National Science Foundation.
