| Work Detail |
A team from the Swiss Federal Laboratories for Materials Science and Technology (Empa) has developed a 3D-printed battery. Fungi are used as both anode and cathode: one releases electrons during metabolism and the other is able to absorb them. Swiss researchers have developed a biodegradable battery made from fungi. At Empa, a 3D printer has combined two types of fungi to create a tiny living cell that generates electricity. The researchers report a potential application for non-toxic power supply in simple measuring devices, such as temperature sensors used in agriculture or environmental research. After supplying power to the temperature sensors for a few days, the organic batteries would decompose. Strictly speaking, the battery is a microbial fuel cell. The two types of fungi produce different enzymes and degradation products during metabolism. At the anode is a yeast fungus whose metabolism releases electrons. The cathode is made up of white rot fungi – velvet trametes. The latter produces an enzyme that can capture electrons from the yeast metabolism, the researchers say. The battery is manufactured using 3D printing with the fungi mixed into the printers ink. The active components of the battery are therefore structural. Finding a material on which the fungi grow well is already a challenge, explains Gustav Nyström, head of Empas Cellulose and Wood Materials Laboratory. But the ink must also be easy to extrude without killing the fungal cells, and of course it must be electrically conductive and biodegradable. A cellulose-based ink fulfilled the requirements by providing nutrients to the fungi, making the device biodegradable. To prevent the battery from degrading too quickly, the researchers added sugar molecules. The fungi break these down before metabolizing the ink. The cellulose structure, with the fungi and sugar molecules, is coated with beeswax and equipped with two copper contacts. In order for the battery to start generating electricity, the fungi need water. This means that the device can be stored in a dry state without the fungus metabolising the sugar or ink. The battery is activated by adding water, explains Nyström. Empas team now wants to identify new fungi, materials and inks to make the battery more compact and powerful, potentially expanding its application. |
