A microbial fuel cell uses anaerobic biological decomposition of organic matter to produce electricity.

The salt solution can also draw excess water from the anaerobic chamber, and controlling evaporation from the brine will control the moisture level of the decomposing material.

• It may be possible to use stainless steel for at least the anode.

Those 'breathable' produce bags may work. Natural rubber latex is a possibility. A toy balloon filled with air gradually loses its pressure as the gases diffuse out of it. (Mylar is now widely used for helium balloons because it holds helium better than natural rubber, and so is likely to hold hydrogen and hydronium longer, as well.)

It should be entirely possible to use an egg¹⁾ suspended in weak brine, so long as it (the egg) is vented.

• Sulfonated PTFE (Naflon) is often used as a proton diffusion membrane.
• Paraffin is rich in protons and parafilm may work well.
• Window glass blown thin should work very well.
• PVC might work if it has the right impurities. (inflatable pool toys)

It is possible to use a gel to integrate both chambers in what is essentially a thick membrane.

• Lime Jello, Yeast and Carbon Paper Fuel Cell
• Red cabbage in a gel medium may show the pH gradient. (Blend with an equal part of deionized water and use raw.)
• Pomegranate juice should also be an indicator and not smell as bad. (Steam-extracted red prickly pear fruit juice turned blue when fermented with something else.)
• Other indicators: red apple, blackberry, blueberry, red cabbage, cactus, cherry, cranberry, grape, loganberry, red onion, plum, pomegranate, raspberry, rhubarb, strawberry, and black tea.

Materials Needed

• Plastic Tray
• Plastic Produce Bag
• Scrap Paper
• Stubby Pencils
• Salt

• [http://microbialfuelcell.wordpress.com/2006/08/27/a-simple-description-of-the-biological-mechanism-that-takes-place-in-an-mfc/|A simple description…]]
• http://microbialfuelcell.org/