Proton transport is plausible, because MFCs work in a similar manner as hydrogen fuel cells. However, recent studies have found that cation transport may play a more important role than proton transport in the completion of cathodic reactions . The first experimental evidence of bioelectricity was found in the late eighteenth century by Luigi Galvani, who observed electric response by connecting frog legs to a metallic conductor . To further explore the potential of bioelectricity, Michael C. Potter built the first MFC in 1911. He demonstrated a current flow between two electrodes emerged in a bacterial culture and in sterile medium . In 1931, Barnett Cohen operated a potentiostat-poised half cell and obtained a current of 0.2 mA by applying þ0.5 V. He found that the capacity of this device could be improved by introducing potassium ferricyanide or benzoquinone as artificial electron mediators in the anode. During the 1960s, research on MFCs became popular due to the increased interest in converting organic waste into electric energy.