Optimal biofilm formation and power generation in a micro-sized microbial fuel cell (MFC)

Microbial fuel cells (MFCs) represent an emerging technology for generating electricity from renewable biomass. Micro-sized MFCs show promising applications in certain niche applications. However, existing micro-sized MFCs are generally limited by their low power density, rendering them insufficient for practical applications. Here, we report a micro-sized MFC having optimal biofilm formation and minimal oxygen invasion into its anode chamber to generate high power density. The biofilm formed by exo-electrogen, Geobacter sulfurreducens, was studied by using four different thicknesses of photo-definable polydimethylsiloxane (PDMS) spacer; 10, 20, 55, and 155 mu m. Both current and power densities were significantly limited when the PDMS spacer was less than 55 mu m thick. The maximum power density of our MFC was 95 mu W/cm(2), the highest value among previously reported micro-sized MFCs and even comparable to that of macro-scale counterparts. (C) 2012 Elsevier B.V. All rights reserved.