Picture of Microbial Fuel Cell Of Science!!!
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Fuel cell that harvests electrons from the bacteria in mud! And ELECTRons mean get me?

The cell also makes a great habitat for a beta fish... The bacteria decompose the fish poop adding to the cell's fuel and keeping the water clean!
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Step 1: Get Some MUCK!

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"MUCK" is actually the correct term for soil from Wetlands .... I LOVE WETLANDS!

Muck has all kinds of awesome bacteria, one of which is Geobacter, it produces electrons as part of its cellular digestion!

Step 2: Prepare The Proton Exchange Membrane

Picture of Prepare The Proton Exchange Membrane
75g salt. 200ml water. 5 grams agar or gelatin. Bring to boil. Petri dish. Fridge. Done.

The bacteria produce hydrogen IONS (an ion is an atom that has lost electrons)...a hydrogen ATOM is nothing but a proton and an electron buzzing around it...its like if the Earth was a proton and the moon was an electron...take away the I mean the electron and all you are left with is a single PROTON aka  a hydrogen ION

The PEM as they say  allows protons through it  and recombine with oxygen and the electrons to form a circuit and H20 as a byproduct.

Step 3: Make Electrodes

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Cut up strips of window screen and fold them into a square.

Google how to make "char cloth"....normally its made by survivalists to act as tinder for fire making but the high carbon content will make the bacteria grow and exchange their electrons to the window screen wire! Wrap the screen around a thick mat of carbon cloth. You can also just strip the insulation off the black wire and wrap the copper inner wires around a thick mat of char cloth if you don't have window screen or alligator clips. 


Strip the red wire's insulation back to expose the copper wire's "dendrites" or "feelers" as I like to call them. 

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drdan152 (author) 1 year ago
Voltage up to 725mV and counting!
abtahee161 month ago

great project could you bring it to 3 volts an power a led

R2D2J2B22 months ago
Thanks for the great instructions! I'm doing this for my science fair project, and the voltage from my first attempt is decreasing daily rather than increasing. Any suggestions?

What do you mean by "cover the anode from top and bottom".

gabedc1 year ago
Hey! I was looking at this and plan to wire up a bunch of them for higher voltages, but how does this beta fish survive? What does it feed off of?

Thanks for your help!
drdan152 (author)  gabedc12 months ago

The cell is a totally harmless (although small) aquarium.....totally PH balanced and the bacteria has nitrogen fixing bacteria that help keep the water clean! Just feed the fish like you normally would and water changes etc.

Beta pellets..... Duh..
What else?
What step does the Beta come in?
drdan152 (author)  goodiesohhi12 months ago

last step!

nashley11 year ago
How well would this work on a major aquarium scale (Georgia or Tennessee aquarium). You said in a comment that the more surface area you have the better it works and there are a ton of fish to poo all over the bacteria. This could help power the aquarium and clean the water. If someone was building a new aquarium this could be put in but how many volts and watts does it produce?
drdan152 (author)  nashley112 months ago

I have a feeling its exponential...imagine all the power we could harness from wetlands! Wetlands clean our water, prevent flooding, provide habitat for wildlife and in the future may be electrical powerplants as well...hey powerPLANTs haha get it?

thakku1 year ago
I am hoping to do this as my project in school. And i have a question, can we do this large-scale?
drdan152 (author)  thakku1 year ago
Hey! The best way to make it large scale is to make a bunch and wire them in series! Lemme know if u need anymore help.
Has anyone successfully done this? I am reading it doesn't work without using capacitors to catch the voltage.
drdan152 (author)  Chazman199212 months ago

It works! However you need a charge pump circuit with capacitors like you said if you want to power an LED....this is just a demo using a multimeter to show how much voltage little bacteria can make...which is cool.

yeah thats a good idea!
What has been the most efficient anode design? Screen mesh? Wires to the cloth? If so how? Flat? Rolled! Max surface area?
drdan152 (author)  Chazman199212 months ago

flat and max surface area!!!

eous1 year ago
hey, how did the poop go to the muck? isn't the PEM is in between them?
drdan152 (author)  eous12 months ago

Just dissolved into the solution!

mmolter1 year ago

We can't keep our PEM from dissolving as soon as we put it in the cell? We used 2.5% unflavored KNOX gelatin and 2.0M NaCl for the PEM. The recipe calls for about 6.5M NaCl, but when we tried that concentration, the gelatin completely salted out of solution.

drdan152 (author)  mmolter12 months ago

Try agar agar flakes from the natural or Asian makes really good solid gelly!

gadgadgad1 year ago
have you video for this article?? coz i need detail process
Paugambi1 year ago
I put fish oil and added light to my beaker and it momentarily increased the voltage!
drdan152 (author)  Paugambi1 year ago
Sooo cool! Keep up the experiments! I noticed too that if u take a straw and blow bubbles into the water it increases voltage... Prob due to more O2 available for the "redox" reaction
wow i wonder if you have enough milliamps to power a led to light up that fishy!
Paugambi1 year ago
Thank you so much for your fast response!
drdan152 (author)  Paugambi1 year ago
No problem! Let me know if you need any more help! Can't wait to see your finished fuel cell! I have all the parts for a charge pump circuit so hopefully i can get it up and running 3v for a clock or something...ill keep it updated!
Paugambi1 year ago
Is there a good substitute to window screen? Would any easily bendable metal be okay?
drdan152 (author)  Paugambi1 year ago
Actually I discovered a way way WAY better Anode/Cathode design that just uses the char cloth and the wire with insulation stripped off...I'm posting the updated info as we speak, the voltage went from 145mV to 585mV just by this simple change!
Orngrimm1 year ago
I wonder whats the wattage is of those setups? A few milliwatts at max i think. However, that would be more than enough for sensor-networks to run on.

Also as a sidenode: be sure you check also "Energy harvester"-Chips from Linear technologies like the LTC3108 or LTC3109 which start at a measly 0.02V and boost it up to 3.3V
Or go with a LTC3105 " Step-Up DC/DC Converter with Maximum Power Point Control and 250mV Start-Up" which sounds nicely!
See for a full list
drdan152 (author)  Orngrimm1 year ago
I'm Also experimenting a Joule thief circuit.. So well see how that goes.
If you want to use the classic JouleThief-Design, be sure you use a BJT (bipolar junction transistor) with a low VCE like the 2SD965, 2SD5041 or 2SC2500D.

Also be sure you check this topic here for some really good ideas and advices especially in the winding of the coils but also on "inverted" JouleThiefs and suggestions for Transis/FET's:
drdan152 (author)  Orngrimm1 year ago
Awesome thanks again! Ill Keep my Instructable up to date on my latest circuits.
drdan152 (author)  Orngrimm1 year ago
Swwwwwaweeet! Thanks for the info .. I have some ultra low voltage ICs comming from eBay but linear tech has their stuff together!
And yeah: linear knows their analog circuits :)
At work and also in hobby I often find what I need at LT.
Kdemon1 year ago
QUESTION: Does the metabolized waste fall to the bottom? If I wanted to build a fixed sized machine running on this type of fuel cell, how do you suggest removing used waste to make room for new organic fuel?
drdan152 (author)  Kdemon1 year ago
Yes it does, it takes a while and it actually increases the voltage as the bacteria eat the anode!
drdan152 (author)  Kdemon1 year ago
The waste in my experience stays in the layer of MUCK, and it will decompose it on ifs own due time. The more room for muck the more room for waste to be added.
Thanks for the fast response. I bet all the Phosphorus, magnesium, iron, and other elements are used to make more bacteria.
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