Structural optimization of contact electrodes in microbial fuel cells for current density enhancements

More than 200% current density enhancement in miniaturized microbial fuel cells (MFCs) has been successfully demonstrated by optimizing the contact electrode structure using micro and nano features. Two fundamental issues are addressed in this work: (1) a methodology to enhance current/power density of MFCs by changing micro and nano structural configurations of contact electrodes and (2) a study on the effectiveness of charge transfer between living cells with organic nanowire-pili and micro/nano interfacial electrodes. This paper details the fabrication and characterization processes of miniaturized MFCs with experimental results, and discusses the prospective power density of MFCs using micro/nano processes. Moreover, a hypothesis for the direct electron transport mechanism from living cells to electrodes is experimentally corroborated. As such, this work represents a step toward higher energy conversion efficiency as well as practical applications of MFCs.