Are fungi capacitors?

The emerging field of living technologies aims to create new functional hybrid materials in which living systems interface and interact with inanimate ones. Combining research into living technologies with emerging developments in computing architecture has enabled the generation of organic electronics from plants and slime mould. Here, we expand on this work by studying capacitive properties of a substrate colonised by mycelium of grey oyster fungi, Pleurotus ostreatus. Capacitors play a fundamental role in traditional analogue and digital electronic systems and have a range of uses including sensing, energy storage and filter circuits. Mycelium has the potential to be used as an organic replacement for traditional capacitor technology. Here, were show that the capacitance of mycelium is in the order of hundreds of picofarads and at the same time a voltage-dependent pseudocapacitance of the order of hundreds of microfarads. We also demonstrate that the charge density of the mycelium dielectric decays rapidly with increasing distance from the source probes. This is important as it indicates that small cells of mycelium could be used as a charge carrier or storage medium, when employed as part of an array with reasonable density.