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Step 2Create the salt bridge
The heart, so to speak, of a two chamber MFC lies in the salt bridge or membrane that seperates the cells. Agar is most commonly used but isn't necessarily readily available. However since Agar is a gelatin I thought conventional unflavored gelatin might make a substitute.
This is my least favorite component in this design, although I like its novelty. I would really like to have something at the ends to provide mechanical stability.
To create the salt bridge we will use Knox Unflavored gelatin in place of the more common agar. I have some reservations about the stability of this innovation. My next round will focus on the use of hide glue (dry not liquid) as the binding agent. This will not substantially alter the bridge process.
Start some water to boil, you don't need and actually won't use more than a couple of tablespoons.
Take one of the coupler sections. Place the plastic wrap firmly over one end and secure with a rubber band to form a tight seal. Place the coupler open end up in a bowl.
Take one packet of Knox unflavored gelatin and pour it into the coupling. Fill the rest of the way with salt. Pour this mixture into a dry measuring cup and pour back into the coupling. You'll notice that settling left a little more room. Top off with salt, pour back into the measuring cup and add an extra tablespoon. Mix the dry ingredients thoroughly and pour back into the upright coupler.
When the water is at a strong boil pour a bit into the measuring cup and use this to gently fill the salt bridge. Pour carefully so you don't flush the tube but be generous. The mixture will settle and allow you to "top off" the water, this will disclose air bubbles flushed out and help judge when the bridge is full. Carefully picking it up and examining the bottom can also help make sure that the entire column is saturated.
Allow to stand for a few minutes and pour off any tiny bit of standing water on the top. Then place the bowl in the refrigerator for 3-4 hours.
This is the salt bridge, it should be left in the refrigerator until final assembly.
This is my least favorite component in this design, although I like its novelty. I would really like to have something at the ends to provide mechanical stability.
To create the salt bridge we will use Knox Unflavored gelatin in place of the more common agar. I have some reservations about the stability of this innovation. My next round will focus on the use of hide glue (dry not liquid) as the binding agent. This will not substantially alter the bridge process.
Start some water to boil, you don't need and actually won't use more than a couple of tablespoons.
Take one of the coupler sections. Place the plastic wrap firmly over one end and secure with a rubber band to form a tight seal. Place the coupler open end up in a bowl.
Take one packet of Knox unflavored gelatin and pour it into the coupling. Fill the rest of the way with salt. Pour this mixture into a dry measuring cup and pour back into the coupling. You'll notice that settling left a little more room. Top off with salt, pour back into the measuring cup and add an extra tablespoon. Mix the dry ingredients thoroughly and pour back into the upright coupler.
When the water is at a strong boil pour a bit into the measuring cup and use this to gently fill the salt bridge. Pour carefully so you don't flush the tube but be generous. The mixture will settle and allow you to "top off" the water, this will disclose air bubbles flushed out and help judge when the bridge is full. Carefully picking it up and examining the bottom can also help make sure that the entire column is saturated.
Allow to stand for a few minutes and pour off any tiny bit of standing water on the top. Then place the bowl in the refrigerator for 3-4 hours.
This is the salt bridge, it should be left in the refrigerator until final assembly.
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