Microbial Fuel Cell Science Fair Project by Aurora Garza

Hello, I am her father and I helped her make this. I want to apologize for what appears to be missing from this video because we started making the video after a couple steps were already completed so I will explain below.

WHAT IS NEEDED:
- Microbe rich sludge (mud. swamp mud, gross river mud, smelly beach mud, you get the idea). We used mud from an ocean inlet that rises and falls with the ocean tide. It smelled like fish and the ocean. The worse it smells the better it will be. Don't use fecal matter.
- 2x containers with lids. We got ours at the dollar store 4 for $1
- 2 feet of thick clear tubing. You won't use 2 feet but get more than you need. Our tubing was maybe 3/4 inch thick inside.
- Aluminum Mesh. We used metal screen from Home Depot.
- 12 gauge wire. Any thickness wire should work because the voltage is really low.
- Cotton Rope for the salt bridge. We used a cotton dog toy that had knots on each end for tug-of-war, also found at the dollar store for $1. We untied the knots.
- Salt
- Water
- Waterproof sealant. We used caulking for the bathtub.
- smaller tubing. Even a straw will work.

INSTRUCTIONS:
- Drill holes in your 2 containers large enough for your clear tubing to snugly fit through. Don't make them too big. The holes should be equal distance from the bottom so that the salt bridge is level and your clear tubing needs to fit firmly in the holes because you need to seal this with waterproof sealant or caulking.
- SALT BRIDGE: boil your cotton rope in super salty water for 20 minutes. Then let the cotton rope dry naturally with all the salt in it.
- Put the salt bridge (rope) inside the clear tubing (it's best if the rope barely fits in the tubing so that there is no extra space in the tube).
- Epoxy (with waterproof sealant) the clear tube in the holes that you drilled in your containers as shown in the video so that the tube (salt bridge) connects both containers with the salt bridge. The salty cotton rope should stick out into both containers to mix with the water that will be in one and the mud in the other. We used black electrical tape on the ends of the cotton rope so that it wouldn't unravel. I think this also helped lock in some of the salt.
- Take your aluminum mesh and put your wire leads (as shown in the video) inside the folded mesh with the wire coming out from one end. The copper wire needs to stay in the mesh and touch the mesh as much as possible. We fanned out the copper braiding from the wire so that as much of the wire as possible was touching the mesh (as shown in the video). With the wire attached to the mesh put one in each container with the wires coming out from the top. Poke a small hole in the lid for the wire to stick out of.
- Fill one container with your microbe mud. Fill the other container with DISTILLED water. It must be distilled (found at any grocery store). Make sure your mesh is deep in the mud.
- Drill a small hole in the water container lid just big enough for your small tubing to fit through into the water.
- The positive wire is in the WATER.
- The negative wire is on the MUD.
- Use a volt meter to test your voltage. We set ours to 200 millivolts and sometimes the 2 volts setting.

By the video and these instructions you should be able to make your own microbial fuel cell!

HAVE FUN!!!!