January 21, 2025
Swiss scientists have developed a biodegradable living battery capable of powering environmental sensors. Environmental sensors are useful for collecting data, but they often experience power supply issues. The Swiss researchers' solution is a 3D printed biologically degradable battery.
This battery uses the metabolism of two different types of fungi to produce energy, acting like a microbial fuel cell. Between 300 and 600 millivolts, as reported in the paper ACS Sustainable Chemistry & Engineering, the efficiency is not particularly high, but it is enough to run a four-cell temperature sensor for two and a half days. Usually, environmental studies and agriculture use these sensors.
Since these fuel cells historically use bacteria, the technique isn't exactly new. But this invention, made by the team at Empa's Cellulose and Wood Materials Laboratory, is the first time that two separate fungi have been used to produce a functional fuel cell. While the cathode uses a white rot fungus that produces an enzyme to transport electrons, the anode releases electrons using regular baker's yeast.
The creation procedure involves 3D printing an ink composed of cellulose and fungal cells, to which graphite flakes and carbon black are added for conductivity. To keep the material electrically conductive and biodegradable, this ink is designed to promote fungal growth and preserve cell viability.
By eating the extra sugar molecules and, once the sugar is depleted, the cellulose itself, mushrooms also contribute to battery breakdown. When water and nutrients are added, the cells wrapped in beeswax, which can be kept dry, become active.
In the future, the Empa team intends to study more species of fungi that may be suitable for this technology and improve the functionality and durability of their fungal battery. According to them, fungi have untapped potential in materials science that deserves to be studied in more depth.
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