A 1.5 mu L microbial fuel cell for on-chip bioelectricity generation

We have developed a dual-chamber microfluidic microbial fuel cell (MFC) system that allows on-chip bacterial culture and conversion of bacterial metabolism into electricity. The micro-MFC contains a vertically stacked 1.5 mu L anode chamber and 4 mu L cathode chamber, and represents the smallest MFC device to our knowledge. Microfluidic deliveries of growth medium and catholyte were achieved in separate flow channels without cross-channel mass exchange. After inoculation of electrogenic Shewanella oneidensis strain MR-1, current generation was observed on an external load for up to two weeks. Current production was repeatable with replenishment of organic substrates. A maximum current density of 1300 A/m(3) and power density of 15 W/m(3) were achieved. Electron microscopic studies confirmed large-scale, uniform biofilm growth on the gold anode, and suggested that the enhanced cell/ anode interaction in the small volume may accelerate start-up. Our result demonstrates a versatile platform for studying the fundamental issues in MFCs on the micro-scale, and suggests the possibility of powering nanodevices using on-chip bioenergy.