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Journal of Bioresources and Bioproducts xxx (xxxx) xxx
Contents lists available at ScienceDirect
Journal of Bioresources and Bioproducts
journal homepage: http://www.keaipublishing.com/en/journals/journal-of-
bioresources-and-bioproducts/
Living mycelium composites discern weights via patterns of
electrical activity
Andrew Adamatzky
a , ∗
, Antoni Gandia
b , 1
a
Unconventional Computing Laboratory, University of the West of England, Bristol, UK
b
Institute for Plant Molecular and Cell Biology, CSIC-UPV, Valencia, Spain
Keywords:
Fungi
Unconventional materials
Electrical activity
Bionics
Fungal construction materials —substrates colonised by mycelium —are getting increased recog-
nition as viable ecologically friendly alternatives to conventional building materials. A function-
ality of the constructions made from fungal materials would be enriched if blocks with living
mycelium, known for their ability to respond to chemical, optical and tactile stimuli, were in-
serted. We investigated how large blocks of substrates colonised with mycelium of Ganoderma
resinaceum responded to stimulation with heavy weights. We analysed details of the electrical re-
sponses to the stimulation with weights and show that ON and OFF stimuli can be discriminated
by the living mycelium composites and that a habituation to the stimulation occurs. Novelty
of the results cast in the reporting on changes in electrical spiking activity of mycelium bound
composites in response to a heavy loads.
1. Introduction
Current practices in the construction industry make a substantial contribution to global climate change with potential damages
to natural environment, natural resources supplies, agriculture, and human health ( Omer, 2008 ; Schwartz et al., 2018 ; Onat and
Kucukvar, 2020 ). Therefore recyclable biomaterials are emerging as potential key players in the alternative construction industry
( Zeller and Zocher, 2012 ; Williams, 2014 ; Pellicer et al., 2017 ). Materials produced from and with fungi are amongst most promising
candidates.
Mycelium bound composites —masses of organic substrates colonised by fungi —are considered to be future environmentally sus-
tainable growing bio-materials ( Karana et al., 2018 ; Cerimi et al., 2019 ; Jones et al., 2020 ). The fungal materials are used in acoustic
insulation panels ( Pelletier et al., 2013 ; Elsacker et al., 2020 ; Robertson et al., 2020 ), thermal insulation wall cladding ( Wang et al.,
2016 ; Yang et al., 2017 ; Xing et al., 2018 ; Girometta et al., 2019 ; Cárdenas-R, 2020 ; Dias et al., 2021 ), packaging materials ( Holt et
al., 2012 ; Mojumdar et al., 2021 ; Sivaprasad et al., 2021 ) and wearables ( Karana et al., 2018 ; Silverman et al., 2020 ; Appels, 2020 ;
Jones et al., 2021 ; Adamatzky et al., 2021c ). In Adamatzky et al. (2019) , we proposed to develop a structural substrate by using
live fungal mycelium, functionalise the substrate with nanoparticles and polymers to make mycelium-based electronics ( Beasley et
al., 2020a ; 2020b ; 2020c ), implement sensorial fusion and decision making in the mycelium networks ( Adamatzky et al., 2020 ).
The structural substrate —the mycelium bound composites —will be used to grow monolithic buildings from the functionalised fungal
substrate ( Adamatzky et al., 2021a ). Fungal buildings would self-grow, build, and repair themselves subject to substrate supplied,
use natural adaptation to the environment, sense all that humans can sense. Whilst major parts of a building will be made from dried
∗ Corresponding author:
E-mail address: andrew.adamatzky@uwe.ac.uk (A. Adamatzky).
1 At the time of experiments AG was aliated with Mogu S.r.l., Inarzo, Italy. doi: 10.1016/j.jobab.2021.09.000
https://doi.org/10.1016/j.jobab.2021.09.003
Received 4 August 2021; Received in revised form 2 September 2021; Accepted 6 September 2021
Available online xxx
2369-9698/© 2021 The Authors. Published by Nanjing Forestry University. This is an open access article under the CC BY-NC-ND license
( http://creativecommons.org/licenses/by-nc-nd/4.0/ )
Please cite this article as: A. Adamatzky and A. Gandia, Living mycelium composites discern weights via patterns of electrical
activity, Journal of Bioresources and Bioproducts, https://doi.org/10.1016/j.jobab.2021.09.003
A. Adamatzky and A. Gandia Journal of Bioresources and Bioproducts xxx (xxxx) xxx
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Fig. 1. Experimental setup. a, scheme of recording. b, c, position of electrodes in fungal blocks: (b) top view and (c) side view; d, pairs of dierential
electrodes inserted in a fungal block and 16 kg kettle bell placed on top of the fungal block. Channels are from the top right clockwise (1–2), (3–5),
…, (15–16)
and cured mycelium composites there is an opportunity to use blocks with living mycelium as embedded sensorial elements. On our
venture to investigate sensing properties of the mycelium composite blocks, called ‘fungal blocks’ further, we decided to study how
large fungal blocks respond to pressure via changes in their electrical activity. The electrical activity has been chosen as indicator
because fungi are known to respond to chemical and physical stimuli by changing patterns of their electrical activity ( Olsson and
Hansson, 1995 ; Adamatzky, 2018a ; 2018b ) and electrical properties ( Beasley et al., 2020a ).
In Section 2 , we describe experimental setup used to record electrical activity of mycelium bound composites and to stimulate the
fungal blocks. Electrical responses of the fungal blocks to stimulation with weights are analysed and discussed in Section 3 . Section
4 summarises the outcomes of the research.
2. Methods and materials
Mycelium bound composites have been prepared as follows. A pre-selected strain of the lamentous polypore fungus Ganoderma
resinaceum (stock culture #19-18, Mogu S.r.l., Italy) was cultured on a block shaped substrate based of hemp shives and soybean hulls
(mixture ratio 3 1, moisture content 65%) in plastic lter-patch microboxes in total darkness and at ambient room temperature of
22 °C. After seven days of incubation, the colonised substrate produced living blocks 20 cm ×20 cm ×10 cm that were immediately
used for the experiments.
Electrical activity of the colonised fungal blocks was recorded using pairs of iridium-coated stainless steel sub-dermal needle
electrodes (Spes Medica S.r.l., Italy), with twisted cables and ADC-24 (Pico Technology, UK) high-resolution data logger with a 24-bit
A/D converter, galvanic isolation and software-selectable sample rates all contribute to a superior noise-free resolution. An overall
scheme of recording is shown in Fig. 1 a. The pairs of electrodes were pierced, 5 mm deep, into sides of the blocks as shown in Fig. 1 b
and Fig. 1 c, two pairs per side. Distance between electrodes was 1–2 cm. In each trial, we recorded eight electrode pairs, channels,
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Fig. 2. Electrical activity of the fungal blocks, stimulated with heavy loads. a, the activity of the block stimulated with 8 kg load; b, the activity
of the block stimulated with 16 kg load. Moments of the loads applications are labelled by ‘ON’ and lifting the loads by ‘OFF’. Channels are colour
coded as (1–2)-black, (3–4)-red, (5–6)-blue, (7–8)-green, (9–10)-magenta, (11–12)-orange, (13–14)-yellow.
simultaneously. We recorded electrical activity one sample per second. During the recording, the logger has been doing as many
measurements as possible (typically up to 600 per second) and saving the average value. The humidity of the fungal blocks was
70%–80% (MerlinLaser Protimeter, UK). The experiments were conducted in a growing tent with constant ambient temperature at
21 °C in absence of light.
We stimulated the fungal blocks by placing a 8 kg and 16 kg cast iron weights on the tops of the blocks ( Fig. 1 d). The surface of
the fungal blocks was insulated from the cast iron weight by a polyethylene lm.
3. Results and discussion
An example of fungal block’s electrical responses to 8 kg load is shown in Fig. 2 a. The responses are characterised by an immediate
response, i.e., occurring in 10–20 min of the stimulation, and a delayed, in 1–4 h after beginning of the stimulation response. The
immediate responses were manifested in spikes of electrical potential recorded on the electrodes. Average amplitude of an immediate
response to the loading with 8 kg was 3.05 mV, 𝜎= 2.5 and the spikes’ average duration of 489 s, 𝜎= 273. Average amplitude of the
immediate response to lifting the weight was 4 mV, 𝜎= 4.4 and average duration of 217 s, 𝜎= 232. Delayed responses were manifested
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Fig. 3. Recording of electrical activity of the dry block of mycelium bound composite stimulated with 16 kg load. Moments of the loads applications
are labelled by ‘ON’ and lifting the loads by ‘OFF’. Channels are colour coded as (1–2)-black, (3–4)-red, (5–6)-blue, (7–8)-green, (9–10)-magenta,
(11–12)-orange, (13–14)-yellow.
in trains of spikes with average amplitude of 1.7 mV, 𝜎= 1, average duration of 161 s, 𝜎= 74 and distance between spikes of 125
s, 𝜎= 34. The responses are clearly attributed to the electrical activity of the living mycelium. The recording of electrical activity of
the dried mycelium bound composite block (with dead mycelium) is shown in Fig. 3 . The electrical activity of the dry block does
not exceed a level of noise [–0.002, 0.002] mV. When a load is applied an amplitude of the noise slightly decreases and stays in the
interval [–0.0015, 0.0015] mV.
Fungal blocks shown responses, with patterns of electrical activity dierent in amplitude and frequency of oscillations from that
observed in the non-stimulated blocks, to the 8 kg loads only for 1–2 cycles of loading and unloading, no signicant responses to
further cycles of the stimulation have been observed. The fungal blocks responded to stimulation with 16 kg weight for at least 8
cycles of loading and unloading. Let us discuss these responses in details.
An example of electrical activity recorded on 8 channels, during the stimulation with 16 kg weight, is shown in Fig. 2 b. Distri-
butions of ‘spikes amplitudes versus spikes duration for spike-responses to application of the weight (ON spikes) and lifting of the
weight (OFF spikes) are shown in Fig. 4 . In response to application of 16 kg weight the fungal blocks produced spikes with median
amplitude of 1.4 mV and median duration of 456 s; average amplitude of ON spikes was 2.9 mV, 𝜎= 4.9 and average duration of 880
s, 𝜎= 1379. The OFF spikes were characterised by median amplitude 1 mV and median duration of 216 s; average amplitude of 2.1
mV, 𝜎= 4.6, and average duration of 453 s, 𝜎= 559. The ON spikes are 1.4 higher than and twice as longer as OFF spikes. Based on
this comparison of the response spikes we can claim that fungal blocks recognise when a weight was applied or removed.
Would living fungal material habituate to the stimulation with weight? Yes, as evidenced in Fig. 5 . Amplitudes of ON and OFF
spikes decline with iterations of stimulation as shown in Fig. 5 a. The duration of spikes also decreases, in overall, with iterations of
stimulation, Fig. 5 b, albeit not monotonously.
As previously demonstrated in Olsson and Hansson (1995) , Adamatzky (2018a) , Adamatzky (2018b) , mycelium networks exhibit
action- potential like spikes. An example of spiking activity recorded in present experiments is shown in Fig. 6 , where spikes are shown
by arrows. The plot demonstrates an extent of the variability of the spike in amplitude and duration. The spikes have an average
amplitude of 0.02 mV, 𝜎= 0.01. The amplitudes of spikes depend on a distance of an excitation wave-front from the electrodes and
therefore will be ignored here, and we will focus only on frequencies of spiking. We found that median frequency of spiking of the
non-stimulated fungal blocks is 1/702 Hz, while the fungal blocks loaded with the weights spike with a median frequency is 1/958
Hz. Average spiking frequency of the unloaded fungal blocks is 1/793 Hz and of the loaded blocks of 1/1031 Hz. Thus, we can
speculate that fungal blocks loaded with weights spike 1.4 times more frequently than unloaded blocks.
Let us overview the ndings presented. We applied heavy weights to large blocks of mycelium bound composites, fungal blocks, and
recorded electrical activity of the fungal blocks. We found that the fungal block respond to application and removal of the weights
with spikes of electrical potential. The results complement our studies on tactile stimulation of fungal skin (mycelium sheet with
no substrate) ( Adamatzky et al., 2021b ): the fungal skin responds to application and removal of pressure with spikes of electrical
potential. The fungal blocks can discern whether a weight was applied or removed because the blocks react to application of the
weights with higher amplitude and longer duration spikes than the spikes responding to the removal of the weights. The fungal
responses to stimulation show habituation. This is in accordance with previous studies on stimulation of plants, fungi, bacteria, and
protists (Yokochi et al., 1926 ; Applewhite, 1975 ; Boussard et al., 2019 ; Fukasawa et al., 2020 ; Ginsburg and Jablonka, 2021 ). An
additional nding was that loading of the fungal blocks with weights increase frequency of electrical potential spiking. This increase
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Fig. 4. Distribution of spike-response amplitude versus duration in response to (a) application of the 16 kg weight and (b) removal of the 16 kg
weight
in the spiking frequency might be due to physiological responses to a mild mechanical damage caused by heavy loads; the responses
involve calcium waves and lead to regeneration processes and sprouting ( Hernández-Oñate and Herrera-Estrella, 2015 ).
Further studies in stimulation of living mycelium bound composites with weights could focus on studying whether shapes of the
weights could be recognised by mycelium networks. A possible scenario would be to map a set of basic shapes into sets of electrical
responses recorded on pairs of dierential electrodes inserted into sides of the fungal blocks. Another promising direction of the
research will be to study electrical responses of the fungal blocks to changes in ambient temperature.
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Fig. 5. Responses of living fungal blocks to stimulation as functions of iterations of stimulation. Median amplitude (a) and median duration (b) of
ON (circles) and OFF (discs) spikes.
Fig. 6. Example of spiking activity of living mycelium composite. The spikes of electrical potential are shown by arrows.
4. Conclusions
Live mycelium composites exhibit a range of electrical activity. The patterns of their electrical activity change when a pressure
(in the form of a weight) is applied to the composites. Whilst it is still unknown if the composites can accurately reect an amount
of pressure developed via their electrical activity patterns, it is proved that they can act as ON/OFF sensors. The ndings open new
horizons into reactive biomaterials.
Declaration of Competing Interest
There are no conicts to declare.
Acknowledgements
This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme FET OPEN
“Challenging Current Thinking ”(Grant Agreement No. 858132 ). The authors would like to acknowledge the collaboration of Mogu
S.r.l. providing the living materials used in the experiments.
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