Enhanced current and power density of micro-scale microbial fuel cells with ultramicroelectrode anodes

Hao Ren, Sriram Rangaswami, Hyung Sool Lee, Junseok Chae

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


We present a micro-scale microbial fuel cell (MFC) with an ultramicroelectrode (UME) anode, with the aim of creating a miniaturized high-current/power-density converter using carbon-neutral and renewable energy sources. Micro-scale MFCs have been studied for more than a decade, yet their current and power densities are still an order of magnitude lower than those of their macro-scale counterparts. In order to enhance the current/power densities, we engineer a concentric ring-shaped UME, with a width of 20 μm, to facilitate the diffusion of ions in the vicinity of the micro-organisms that form biofilm on the UME. The biofilm extends approximately 15 μm from the edge of the UME, suggesting the effective biofilm area increases. Measured current/power densities per the effective area and the original anode area are 7.08 0.01 A m-2 & 3.09 0.04 W m-2 and 17.7 0.03 A m-2 & 7.72 0.09 W m-2, respectively. This is substantially higher than any prior work in micro-scale MFCs, and very close, or even higher, to that of macro-scale MFCs. A Coulombic efficiency, a measure of how efficiently an MFC harvests electrons from donor substrate, of 70%, and an energy conversion efficiency of 17% are marked, highlighting the micro-scale MFC as an attractive alternative within the existing energy conversion portfolio.

Original languageEnglish (US)
Article number095016
JournalJournal of Micromechanics and Microengineering
Issue number9
StatePublished - Jul 25 2016


  • carbon-neutral
  • energy harvesting
  • micro-scale
  • microbial fuel cell (MFC)
  • microfabrication
  • ultramicroelectrode (UME)

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Mechanics of Materials
  • Mechanical Engineering
  • Electrical and Electronic Engineering


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