A self-destructing, 3D printed fungi-based battery could one day power sensors all around you by feasting on sugar

• Biodegradable battery invented by scientists in Switzerland
• Fungi, which is the building block of mushrooms, is the core material used
• The fungi-powered battery generates enough electricity to power sensors

Fungi have fascinated scientists for decades - centuries, probably. There are roughly 200,000 known species across the planet, they are more closely related to animals than plants, the largest organism in the world is a fungus, and some can glow in the dark. If you’ve watched or played The Last of Us, you’ll know the parasitic Cordyceps fungus infects its host by colonizing and consuming its body (admittedly, in the real world, it takes over insects and won’t be invading humans any time soon).

Through a three-year project supported by the Gebert Rüf Stiftung’s Microbials funding program, researchers at Empa (Swiss Federal Laboratories for Materials Science and Technology) have found a novel use for fungi - as they’ve developed a 3D-printed, biodegradable fuel cell that requires feeding rather than charging.

Although the fungal battery (technically it’s a microbial fuel cell rather than a battery per se) produces only modest amounts of electricity, Empa says it can sustain devices such as temperature sensors for several days.

3D printed battery

Microbial fuel cells work by harnessing the metabolism of living organisms to produce electricity. In the past, this was done with bacteria. Empa’s breakthrough combines two fungi species: a yeast fungus on the anode side, which releases electrons, and a white rot fungus on the cathode side, which produces an enzyme that captures and conducts these electrons.

"For the first time, we have combined two types of fungi to create a functioning fuel cell," Empa researcher Carolina Reyes explains.

Rather than adding fungi to a pre-assembled battery, researchers integrated fungal cells into the 3D-printed battery structure itself. Electrodes were carefully designed to provide nutrients to the fungi while remaining biodegradable and conductive.

Traditional battery disposal poses environmental challenges, as many contain toxic materials that can contaminate soil and water if not properly managed. Empa’s living batteries don't have that problem as they cleverly self-digest - by consuming the cellulose-based ink the fungal cells are embedded in - once their purpose is fulfilled.

For the main nutrient source, the researchers add simple sugars to the battery cells. "You can store the fungal batteries in a dried state and activate them on location by simply adding water and nutrients," says Reyes.

Although it’s a promising idea, the project faces challenges due to the complexity of working with living materials, blending microbiology, materials science, and electrical engineering. Empa plans to experiment with different forms of fungi going forward in the hope of finding combinations that will make the fungal battery more powerful and longer-lasting.

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