TECHNOLOGY FOCUS - BIOLOGY - Preferred Components: The biofilm comprises at least one of Methanogens, Enterobacter, Citrobacter, Eubacterium, Clostridium, sulfate reducing bacteria, nitrate reducing bacteria, nitrite reducing bacteria, Desulfobacterales, Syntrophobacterales, thiosulfate reducing anaerobes, tetracholoroethene degrading anaerobes, triethanolamine degrading bacteria, denitrifiers, xylan degrading bacteria, Nitrospirae, Halomonas, Idiomarina, Marinobacter aquaeolei, Thalassospira, Silicibacter, Chromohalobacter, Bacilli, Comamonas denitrificans, Methanobacteriales, Methanomicrobiales, or Methanosarcinales.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Device: In the device, the MFC is miniaturized in size; is calibrated to an electron carrier; and is produced with a microbial biofilm deposited upon an MFC anode.    TECHNOLOGY FOCUS - METALLURGY - Preferred Components: The sample is selected from metal or metal alloy.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The electron carrier is selected from riboflavin, flavin adenine dinucleotide (FAD), metalorganics, methylene blue (MB), thionine, meldola's blue (MelB), 2-hydroxy-l,4-naphthoquinone (HNQ), Fe(III)EDTA, humic acids, anthraquinone-2,6-disulfonate, safranine O, resazurin, viologens, cytochromes, nicotinamide adenine dinucleotide (NAD), nicotinamide adenine dinucleotide phosphate (NADP), ferrocyanide, ferrocene monocarboxylic acid, tetracyanoquino-dimethane, tetrathiafulvalene, bipyridine, 3,4-dihydroxybenzaldehyde, poly(vinylferrocene-co-hydroxyethyl methacrylate), poly(Nacryloylpyrrolidine-co-vinylferrocene), acryl amide copolymers, or poly(glycidyl methacrylate-co-vinylferrocene). The medium is selected from an aqueous solution, oil, and fuel. The aqueous solution is selected from a solution comprising of water and water soluble components, a biphasic mixture with oil and fuel, or an emulsification with oil and fuel. The aqueous solution comprises at least one of volatile fatty acids, salts of volatile fatty acids, alcohols, hexoses, or hydrogen. The volatile fatty acid is selected from acetic acid, propanoic acid, butyric acid, lactic acid, or fumaric acid. EXAMPLE - No suitable example given.