  The emerging field of living technologies aims to create new functional
hybrid materials in which living systems interface with artificial 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 pico-Farads. 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.
