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Microbial Fuel Cell (MCF) Sonic Installation: ‘Oxidising the Spectrum’
Proposal to the Parks Department, Belfast City Council of Northern Ireland
Tropical Ravine
Technical aspects of the proposal to the Belfast City Council of Northern Ireland
additional webcam to map variations in colour of the
MCF during the process of oxidation.
‘Oxidising the spectrum’ is a sonic installation which
explores the possibilities of Microbial electrochemistry
in the compositional environment. This piece when
completed is planned to be exhibited and presented on a
Greenhouse environment. Hopefully the Tropical Ravine
at the Botanic Gardens and the paper diffused on major
Computer Music Conferences
Introduction to MCFs. Work in progress.
A microbial fuel cell (MCF) can be built with relatively
unsophisticated equipment and is capable of generating
electricity, which can be converted into data to control
several musical parameters.
Experiments have been carried out using a single MCF
to produce low voltage. This analog signal was sent to a
Javelin Stamp (parallax2001) micro-controller and monitored on a computer to study the behavior of the cell.
As the microorganisms oxidise the fuel (a carbohydrate),
they start a process of voltage charge and discharge
which repeats as long as they are constantly fed.
To make musical sense out of the data, the signal is sent
to Puredata software (1991, Miller Puckette) via the
COM port and from the micro-controller. This data updown movement in cycles of 18-20 minutes was the
starting point of the composition.
By using four cells it is possible to derive patterns and
musical ideas from the cycles. One of the main aims
from a compositional perspective was to find ways of
destabilising the optimal conditions of the living cell,
which could mean musically expressive variations of the
cycles and the patterns.
Although the microbial fuel cell works as itself as a live
form music generator, it was designed as an extended
version of the installation for a greenhouse environment.
Some research in progress is studying the possibility of
having the installation running at the the Tropical Ravine
at the Botanic Gardens. It incorporates additional ways of
collecting data and therefore new musical parameters,
from different sensors as photoresistors, a sonar mounted
on a servo, barometer, thermostat, rain detector, minisolar panel, all built around the Javelin Stamp and an
Fig 1. Research and development plan.
Producing electrical energy from organisms
as a vehicle of creative expression in the
compositional environment.
“In an anodic compartment of microbial fuel cells, microorganisms oxidise fuels such as carbohydrates to produce electrons. Electrons, in turn, are captured by the
oxidised mediator and transferred to the anode. At the
anode, the mediator is deoxidised by delivering electrons
and ready to take electrons from the microorganism.
This in combination with a suitable cathode, produces
electrical energy.” 1
____________________________________________
Development of Microbial Fuel Cells Using proteaus vulgaris by
Namjoon Kim, Youngjin Choi, Seunho Jung, and Sunghyun Kim.
Department of Microbial Engineering, Konkuk University, Seoul
Korea
voltage 0.7
0.6
These reaction processes can be sustained as long as the
substrate is supplied to the microorganisms.
0.5
0.4
0.3
0.2
0.1
5
10
15
20
25
30
minutes
Fig. 3 Process of charging-discharging an MCF
Ways to destabilise the optimal conditions of an MCF:
By manipulating the conditions of the cell it was possible to have a certain degree of control over the number
of electrons liberated and therefore control of the output
voltage. The manipulation of the musical parameters was
thus not created through software but by biological
means.
Fig. 2 microbial fuel cell circuit
The following experiments were carried out:

Varying the refueling time and amount of the carbon
source. This process can be automated by simply
stimulating the ‘appetite” (hunger sensing) and
swallowing. Appetite is a state when an MCF needs
more food to be added.

Changing the mediator’s concentration: the mediator
is an electron shuttle; by varying the concentration it
is possible to modify the transfer of electrons. The
mediator can also decompose reducing the transfer
of electrons.

Varying the substrate carbon sources injected: although not all aspects have been explored, it is possible to ‘feed’ the microorganisms with glucose, sucrose, maltose or trehalose among other possibilities.

Changing temperature: the electrocatalystic process
is not thermally stable. Optimal temperatures for the
MCF to work more efficiently are around 35 oC.

Modifying the anaerobic conditions in the anode
chamber, oxygen present will divert electrons away
from the external circuit

Corrosion can shorten the cell’s life.
An example of typical microbial fuel kit elements:

Microorganism: P. vulgaris.

Mediator: thionin

Substrate: various mono and disaccharides.(glucose,
sucrose, maltose, trehalose)
Cell body:

Methylmethacrylate with two body compartments
with a capacity of 45x45x15 mm3

Anode: RCV or Reticulated vitreous carbon

Membrane of separation: Nafion membrane and 1.5
mm thick silicon

Rubber gaskets
 Electrodes
Generally, when the substrate is added to the MCF, the
cell voltage increases quite rapidly until it reaches its
steady-state value.
After this, it slowly consumes the carbon sources and the
cell voltage starts dropping to a zero value. (Fig 3.)
This process of low voltage charging-discharging is one
of the principles of this music composition. Variations of
low voltage are converted into midi values, via A-192
CV to midi (Doepfer) and digital signals via ADCJavelin, to activate and modify different DSP music algorithms within a Real-Time environment. Current experiments include the implementation of a java midi
class in the javelin stamp environment to convert voltage
signals to midi directly from the PIC and avoid the use
of the A-192.
The use of more than one microbial fuel kits can create
more interesting structural patterns in time. Four units
were used for this particular musical work. By finding
different mechanisms to couple their behaviors one
could compare this process to the art of writing for an
instrumental improvisational ensemble. Furthermore, if
one can find ways of destabilising the optimal conditions
for fuel oxidation and can alter the cycles, one is starting
to build the foundations for the microorganisms’ musical
expression.
Threshold activating events: The microbes work as
switchers of events. Some of these events have musical
implications but others are simply mechanisms such as
messages to refuel the cells or manipulating the additional sensors or varying the behaviors of the events in
coming cycles.
Among the DSP events, the threshold triggers randomly
selected audio files, which are passed to a process of
analysis and resynthesis. Fig 5 shows the MCF emulator
designed on MaxMSP (Puckette, Zicarelli) to asses several compositional ideas.
voltage
0.7
Stable MCF
0.6
Destabilised
MCF
0.5
0.4
0.3
0.2
0.1
5
10
15
20
25
30
mi nutes
Fig. 4 Stable vs. unstable data from an MCF
Additionally, in a wider experimental environment, this
self-contained life form and musical mechanism could be
integrated for instance in a greenhouse, in order to increase the collection of data to interact with more musical parameters. All controlled by the PIC (Javelin
Stamp) and interacted by the MCF output in many different ways.
It is possible to control up to 6 MCFs with a single Javelin Stamp.
There are several ways in which the data from the microbial fuel cell are treated:

Continuous value reading from the MCFs

Threshold activating events from the MCFs
Fig. 5 An MCF Emulator written in MaxMSP (Puckette, Zicarelli)
Structure of the cycles: The cells start their cycles at
different times and once the loop is finished the thresholds change not only in time but also in behavior. Indications a,b,c,d …q showed below represent the threshold
events to activate DSP event or mechanical actions.
On top of that we have to add:
f
e

Additional data collected from other sensors in the
greenhouse.
digital
midi
255
127
g
h
voltage
0.7
0.6
0.5
i
j
d
k
l
m
n
o
p
q
c
Using software simulation the behavior of the four microbial fuel cells could be experimented to asses different compositional ideas. This helped to revise the compositional process and increase the degree of musical
expression without the need of having the installation
running.
Fig. 6 Threshold events planned on a single MCF.
Continuous value reading: this data was used for different arguments of several digital signal processes and
slow musical transitions since the cycle may last for 1820 minutes.
To implement and record multiple measures from more
than one cell it was used the following equipment: Minilab data logger / controller developed by Dr. Pei. An. It
is a universal solution for data collection and storage,
0.4
0.0
0.0
0.3
0.2
0.1
0.0
b
a
5
10
15
20
25
30 minutes
which also can control peripheral equipment like the
mechanical syringes.
Fig 7 represents the process of charging-discharging four
MCF running in parallel which cycles start at different
times.
digital
midi
255
127
voltage
0.7
0.6
0.5
0.4
0.0
0.0
0.3
0.2
0.1
0.0
5
10
15
20
25
30
35
40
45
50 minutes
Fig. 7 MCF patterns on a 4 Cell installation.
The Greenhouse installation and the MCF
demo.
Fig. 8 The polaroid Sonar mounted on a Javelin
Stamp.
The proposal consists of two different spaces:
A) The installation in the Campus greenhouse
B) A simplified version in the conference space
A) The installation in the Campus greenhouse, including
the use of four MCFs and the additional collection of
sensor to collect data.
This is the sensors’ collection experimented so far:
 Temperature sensors
 Photoresistors on a A179 doepfer Light to CV circuit,
(variable CV out, inv. CV out, offset and gate out)
 USB Webcam. for analysis of colour changes in the
microbial kit
 USB Webcam. for movement detection in the greenhouse on a grid.
 Mini solar panel
 ‘Rain detector’ circuit
 Barometer sensor
 Doepfer’s A190 CV Theremin
 Doepfer’s A192 CVM16 to midi interface
 Mildford’s Polaroid Ultrasonic Sonar (0.15m-2.6m
range, 10mm resolution, 180o sweep angle), mounted
on a servo to detect visitors movement. RS232 interface to the Javelin or CV (0-5DC voltage). Two servo
modes.
Fig. 9 Installation diagram of the Microbial Ensemble in the Greenhouse (Tropical Ravine)
B) The simplified version in the conference space consisting on a single MCF installation looks as follows.
similar way than a string quartet, although each MCF has
a distinctive musical voice in terms of timbre and gesture. The interaction among them goes further due to the
fact that the data provided by each MCF is not only converted into musical parameters but also into mechanical
instructions. For instance, one MCF should be able to
modify the anaerobic conditions in the anode chamber of
another MCF. It would be a similar effect to a violin
having control over the timbre of a viola.
The data tracked from the MCFs provide access to a
palette of musical sources and signal processes creating
multiple layers of sonic materials. The sonic soundworld
of the installation is still work in progress and the source
materials were collected from several contrasted sources;
among others, urban sounds from the streets and subway
of Seoul, and natural soundscapes from some locations
near
the
Mediterranean
coast.
With automated mechanical feeding of the MCFs the
installation can run for days if not longer.
Fig 10. Converting voltage signals into possible musical parameters
The desired dimensions of the space are 2x3 meters and
an upright panel to display two A0 size colour posters
explaining the principles of the MCF and how it manipulates the musical parameters in the Greenhouse installation.
Next figure shows a picture of the MCF used for testing
purposes and the Doepfer’s A192 Voltage to midi converter.
Solutions for travelling with microbes.
It is well know that travelling to countries carrying microbes and certain chemical products may result difficult
if not impossible for obvious safety reasons and traveling
to Canada will not be an exception.
There are several possible solutions to this potential
problem:
A) To obtain a special research travel-certificate authorization from the National Centre for Biotechnology Education, The University of Reading, providers of the MCF
kit and an authorization from the Canadian Government.
B) To travel with the MCF kit without the microbes and
chemical products and purchase them through the Chemical Engineering department at University of McGill and
coordinated by the Chemical engineering department at
Queen’s University of Belfast. This is probably the best
solution.
C) Instead of using the P. Vulgaris cultive which needs
more sophisticated laboratory equipment, it can simply
be used yeast microorganisms. Yeast is widely used in
school centres and Universities. The production of electrons is slightly lower therefore some parameters in the
software might need minor revisions.
Fig 11. The MCF and Dopefer’s A192
The microbial ensemble. How to organise a
soundworld of microbes.
It is difficult to imagine how an ensemble of microbes
may sound like, but not too difficult to understand that it
might have some degree of organization and structure. In
‘Oxidising the Spectrum’, the four MCFs work in a very
ACKNOWLEDGMENTS
Thanks to the Chemistry Engineering department at
Queen’s University of Belfast for their advise and
providing the cultures, labs and some technical equipment and support for the experiments. Thanks to the
SARC team for their contagious enthusiasm.
REFERENCES
[1] Bennetto, H.P. 1990. Electricity generation by microorganisms. Biotechnology education, 1(4):163168
[2] Wilkinson, Stuart. 2000. ‘Gatrobots’ Benefits and
Challenges of Microbial Fuel Cell in Food Powered
Robots Applications. Autonomous Robots 9,99-111
[3] MCF @ National Centre for Biotechnology Education, The University of Reading.
http://www.ncbe.reading.ac.uk
[4] Namjoon Kim, Youngjin Choi, Seunho Jung, and
Sunghyun Kim. Development of Microbial Fuel
Cells Using proteaus vulgaris. Department of Microbial Engineering, Konkuk University, Seoul Korea
[5] An, Pei. Centronics Mini-lab data logger / controller. A universal solution to allow your computer to
collect data and control electrical systems.
[6] Madden, Dean and Schollar, John. The microbial
fuel cell, Electricity for yeast cells. University of
Reading. Bioscience explained. Vol 1, num.1. 2001
[7] Milford Instruments, Milford House. Leeds. UK.
Javelin Stamp and PCB kit, Ultrasound module,
http://www.mildinst.com
[8] Microsystems Engineering. Bilbao, Spain.
http://www.microntroladores.com
[9] Parallax inc. http://www.parallaxinc.com
[10] PD, http://www.pure-data.org
[11] MaxMsp http://www.cycling74.com