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Step 3Assemble the electrodes
It seems the biggest challenge facing the amateur microbiologist or energy researcher...er, among the challenges facing the amateur microbiologist or energy researcher is the elusive carbon electrode.
Okay, first you will need to use one wire and one carbon brush to make a carbon electrode according to my other instructable Easy Carbon Electrode.
Now taking the DRY sponge cut a strip 3/4" wide and about an inch long. This piece should fit smoothly into the neck opening of the screw top. Now take it back out and using a skewer, nail or other suitable object punch a hole big enough for the wire to pass through.
Using the smallest drill bit you have equal to or greater than the size of the wire drill a small hole in the center of the screw cap. Thread the electrode lead through the sponge and slide the sponge into the the neck of the screw top. Thread the wire through the cap, it should pass more or less freely. Screw the top down lightly and add water to the sponge. It will expand to fill the neck and provide a slight overcover at the base.
This is the anode assembly. It is used for the anaerobic (microbe cell). The small gap will allow the decomposition gasses to escape while the sponge will inhibit the passage of air into the chamber. To add nutrients to the anode chamber simply unscrew the top and gently pour the nutrient medium through the sponge.
For the cathode we are using a different approach. The cathode is inserted into the sponge (actually placed between two pieces of sponge) where air can circulate freely.
To make the cathode assembly remove the coil wire from the remaining brush. Because the brush lead will be fully exposed I did not add a secondary lead or connector although it would certainly do no harm.
From the remaining section of the sponge cut a strip 1" wide by 4" inches long, then cut this into two strips. Please the remaining carbon brush between the two strips so that only the top is exposed. Insert this into one of the 1" connectors. Wet the sponge and it will expand to hold the electrode in place.
Okay, first you will need to use one wire and one carbon brush to make a carbon electrode according to my other instructable Easy Carbon Electrode.
Now taking the DRY sponge cut a strip 3/4" wide and about an inch long. This piece should fit smoothly into the neck opening of the screw top. Now take it back out and using a skewer, nail or other suitable object punch a hole big enough for the wire to pass through.
Using the smallest drill bit you have equal to or greater than the size of the wire drill a small hole in the center of the screw cap. Thread the electrode lead through the sponge and slide the sponge into the the neck of the screw top. Thread the wire through the cap, it should pass more or less freely. Screw the top down lightly and add water to the sponge. It will expand to fill the neck and provide a slight overcover at the base.
This is the anode assembly. It is used for the anaerobic (microbe cell). The small gap will allow the decomposition gasses to escape while the sponge will inhibit the passage of air into the chamber. To add nutrients to the anode chamber simply unscrew the top and gently pour the nutrient medium through the sponge.
For the cathode we are using a different approach. The cathode is inserted into the sponge (actually placed between two pieces of sponge) where air can circulate freely.
To make the cathode assembly remove the coil wire from the remaining brush. Because the brush lead will be fully exposed I did not add a secondary lead or connector although it would certainly do no harm.
From the remaining section of the sponge cut a strip 1" wide by 4" inches long, then cut this into two strips. Please the remaining carbon brush between the two strips so that only the top is exposed. Insert this into one of the 1" connectors. Wet the sponge and it will expand to hold the electrode in place.
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Aug 31, 2009. 4:43 PMlendogg
says:
I am working on a similar project and have used carbon fibre electrodes c/f is available from ebay, as the fabric. and has a very large surface area for its size. as I understand it one cell will only ever give around 0.5 volts but the current is related to the surface area of the electrodes
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Sep 2, 2009. 5:48 AM
egbertfitzwilly (author)
says:
egbertfitzwilly (author)
says:
You are current that the current is directly related to the surface area of the electrodes. I have heard numbers for max cell voltage up to around 2 volts. Logan at Penn State holds that peak voltage is about 1.4. However there is a great deal which is not understood about this and higher voltages may be possible.
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