Using Shewanella Oneidensis MR1 as a Biocatalyst in a Microscale Microbial Fuel Cell

Microbial fuel cell (MFC) technology is a promising area in the field of renewable energy because of their capability to use the energy contained in wastewater, which has been previously an untapped source of power. Microscale MFCs are desirable for their small footprints, relatively high power density, fast start-up, and environmentally-friendly process. Microbial fuel cells employ microorganisms as the biocatalysts instead of metal catalysts, which are widely applied in conventional fuel cells. MFCs are capable of generating electricity as long as nutrition is provided. Miniature MFCs have faster power generation recovery than macroscale MFCs. Additionally, since power generation density is affected by the surface-to-volume ratio, miniature MFCs can facilitate higher power density. We have designed and fabricated a microscale microbial fuel cell with a volume of 4 μL in a polydimethylsiloxane (PDMS) chamber. The anode and cathode chambers were separated by a proton exchange membrane. Carbon cloth was used for both the anode and the cathode. Shewanella Oneidensis MR-1 was chosen to be the electrogenic bacteria and was inoculated into the anode chamber. We employed Ferricyanide as the catholyte and introduced it into the cathode chamber with a constant flow rate of approximately 50 μL/hr. We used trypticase soy broth as the bacterial nutrition and added it into the anode chamber approximately every 15 hours once current dropped to base current. Using our miniature MFC, we were able to generate a maximum current of 4.62 μA.