- Biodegradable battery invented by scientists in Switzerland
- Sponges, which are the building blocks of mushrooms, are the core material used
- The sponge-powered battery generates enough electricity to power sensors
Fungi have fascinated scientists for decades—probably centuries. There are about 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 have seen or played The last of us, you’ll know that the parasitic Cordyceps fungus infects its host by colonizing and consuming its body (granted, in the real world it takes over insects and won’t invade humans just yet).
Through a three-year project supported by the Gebert Rüf Stiftung’s microbial funding program, researchers at Empa (Swiss Federal Laboratories for Materials Science and Technology) have found a new use for fungi – as they have developed a 3D-printed, biodegradable fuel cell that requires feeding rather than charging.
Although the sponge battery (technically, it’s a microbial fuel cell rather than a battery per se) only produces modest amounts of electricity, Empa says it can sustain devices such as temperature sensors for days.
3D printed battery
Microbial fuel cells work by harnessing the metabolism of living organisms to produce electricity. Previously, it was done with bacteria. Empa’s breakthrough combines two fungal species: a yeast on the anode side, which releases electrons, and a white rot fungus on the cathode side, which produces an enzyme that captures and directs these electrons.
“For the first time, we have combined two types of fungi to create a functioning fuel cell,” explains Empa researcher Carolina Reyes.
Instead of adding fungi to a pre-assembled battery, researchers integrated fungal cells into the 3D-printed battery structure itself. Electrodes are carefully designed to provide nutrients to the fungi while remaining biodegradable and conductive.
Traditional battery disposal presents environmental challenges, as many contain toxic materials that can contaminate land and water if not handled properly. Empa’s living batteries do not have that problem, as they cleverly self-digest – by consuming the cellulose-based ink, the fungal cells are embedded in – when their purpose is fulfilled.
As the main source of nutrients, the researchers add simple sugars to the battery cells. “You can store the mushroom batteries in a dried state and activate them in situ by simply adding water and nutrients,” says Reyes.
Although a promising idea, the project faces challenges due to the complexity of working with living materials, mixing microbiology, materials science and electrical engineering. Empa plans to experiment with different types of mushrooms in the future in the hope of finding combinations that will make the mushroom battery more powerful and longer lasting.
