Hi, my name is Laura Segedin. And
today I'm going to be telling you about a microbial
fuel cell project that I completed in biotechnology. But
first, what is a microbial fuel cell? Well,
a fuel cell is a device that converts the
chemical energy of a fuel such as hydrogen into electricity.
In microbial fuel cell, the microbes will be
eating biomass and will be converting that their energy into
electricity. So the electrons they give off will be
uh creating electricity. What you see in the middle
is a very large microbial fuel cell which is used
in water treatment plant. And as you know,
a water treatment plant has lots of wonderful microbes that
eat the biomass. And in doing so, they
create electricity that can help to run the water treatment
plants and they also help to clean the water.
The problem scenario that we were given was to design
and build a prototype that uses microbes to generate a
portable power source, such as a very small fan
or an LED light. And in order to create
this device, we are going to be going through
the design process, the technology / engineering design process.
And so as we go through, I will
highlight all of these steps so that you can see
how they all come together. So the very first
step is to identify the problem and we have done
this right now. The second step is to brainstorm
some ideas. And in the beginning, I was very
limited on what I knew about microbial fuel cells.
So I basically read a little bit on it and drew
up what I thought would be an appropriate design.
As you can see. I didn't really get into
any sort of materials that I was thinking about.
I just was trying to wrap my brain around the
components of it and how it all worked together.
So in the beginning my brainstorming skills were very limited.
Uh after that I did a little bit more
research and I learned a lot. Um number one
was that microbes need to be electrochemically active and
what this means is when they are eating uh the
biomass they are giving off electrons and these electrons will
then attach to an electrode and that electrode will collect
the electron and then that electron can travel up uh
and to a load that we will attach to the
microbial fuel. So redox also known as reduction oxidation,
creates hydrogen protons which will travel through what is
called a P. M. A. proton exchange
memory and also free electrons which will travel up and
into our load. So that is where we are
going to measure our current at the load. Part
of my ideation was again, to just visualize how
this all worked. So I basically drew up what
I was reading. So on the right hand side
is the node and I put a big minus sign
because the negative electrons will be coming from the an
ode to the load and basically in the and it
is bacteria and organic matter and in my case it
would be mud and then the ease the green ease
signify the electrons moving the arrow shows direction is moving
to this middle part here is called the P.
M. Or the salt bridge. And again that's
the proton exchange membrane. And that is where the
protons, those free protons from the redox will travel
over to the cathode. And the cat is basically
made out of stream water and salt and I am
pumping oxygen into that solution so that it stays oxidized.
Whereas with the an ode there's no oxygen.
It is anaerobic. And finally you can see your
water out. One of the wonderful byproducts is clean
water that is produced through this whole process. So
one of the next steps in the design process is
to select an idea and to start building it.
So in order to get my microbes, I needed
to go collect them. And so I went to
my nearest creek called Tom's Creek and I got a
shovel in some waiters and collected Timlin with mike.
After that I began to build my prototype And as
you can see I used plastic containers for both the
cathode and the and let's see here that is what
they look like in real life. I and in
order to connect the PM I drilled a hole in
both of the chambers, the capital and the endo
chambers. And um after that I filled up this
PVC pipe which you can see right, a loner.
I filled it with nutrient agar and water and
salt and that formed a gel almost like a yellow.
And uh that was then attached to uh both
chambers using a plastic adhesive. And you'll also notice
there's holes in the very top lids for the wires
in both the catholic and the an ode. Um
the electrodes are attached to those wires so that the
electrons can flow through them. So we needed holes
in the top. And then also there is a
wire here so that oxygen can bubble in. So
that is what you're looking at right here. Here's
a close up of my proton exchange membrane and that's
the drilling. And then this is the final product
Testing it out. After the very first hour of
this being built and run, I got a measurement
of.5V which I was thrilled about. However,
after that things decreased a lot and then plateau for
a bit. Um however, as you can see
here after 171 hours, my reading was.17V which
is a drastic increase. And on the next slide
you'll see exactly what happened. You know what this
looks like. Please take note that. I know
it's a little bit hard to see here, but
the cathode chamber here has very clear water in it.
That is when it first started. And now
the water is blue and the blue color is from
the copper oxidizing because there's copper um on the electrode
wires and that turns the water blue, you'll also
notice a little bit of white um coming off.
I believe that salt that has formed on the outside
of that. And then um the mud here,
the water in the mud is very cloudy. However,
in the after picture, uh the water is
very clear and you can see that a lot better
in person. So my results graphed out, like
I said, I got a very big increase in
the beginning and then it started to decrease and then
plateau did. It stated about.1V for a few
days. And a funny thing happened when I was
testing out my voltage, um I would always connect
my two leads together before and after I tested,
so they would always be connected and then I would
take them apart test and then I would put them
back together and uh one day I forgot to put
them back together. And the next day my reading
Was very high. So you'll see here at our
152. Uh my reading increased drastically and I believe
that was due in part to the wires not being
connected. So that was my hypothesis. So I
left those wires unconnected for the next day just to
see what would happen. And in fact it kept
increasing. So in the last three days I've had
a good increase. If I were to redesign this
again, number one, I would definitely keep the
electrode buyers separated as I just mentioned. I believe
if I had done this from the start, I
would have had a much better voltage reading at this
point in time. Another idea would be to increase
the surface area of my P E. M.
I think the opening for it is pretty narrow and
I think by opening up that surface area I might
get better and quicker transfer of protons over. So
hopefully um that will encourage the electrons to travel faster
as well. I would also decrease the space between
the anodes and cathodes. A lot of the designs
that I saw had much shorter space in between the
two chambers. And so I think maybe an inch
or two inches would suffice rather than the 4.5 inches
of what I have. I would try a carbon
brush electrode instead of carbon cloth that I used um
simply because I read that carbon brushes were very effective
at attracting electrons free electrons and I would also obtain
a variety of blood samples even though I went to
Tom's Creek, which I heard was a very reliable
source. Um, I think even taking samples from
different parts of the creek would have been really nice
and also maybe trying one or two other locations.
Um, so that I could just compare and contrast
between the different samples. These are my resources and
I'm also going to fire up my MSC and you'll
notice the oxygen going in on the left hand side
and the catholic and my p e M and Maya
node. Currently, we can measure the voltage 176V,
which right now is the highest ever been.
Thank you for watching.