A μL-scale micromachined microbial fuel cell having high power density

Area of Science:

• Microbiology
• Electrochemistry
• Materials Science

Background:

• Microbial fuel cells (MFCs) offer a sustainable energy source.
• Previous MEMS-based MFCs have faced limitations in power density and efficiency.
• Anode-respiring bacteria (ARB) are crucial for efficient microbial fuel cell operation.

Purpose of the Study:

• To develop a high-performance Micro-Electro-Mechanical Systems (MEMS)-based microbial fuel cell (MFC).
• To investigate the impact of optimized chamber design and efficient ARB on MFC performance.
• To achieve substantial improvements in power density and coulombic efficiency compared to existing MEMS MFCs.

Main Methods:

• Fabrication of a MEMS-based MFC with 4.5-μL anode/cathode chambers using photo-definable polydimethylsiloxane (PDMS) films.
• Utilizing a Geobacter-enriched mixed bacterial culture as the anode-respiring bacteria (ARB) for biofilm formation.
• Minimizing oxygen intrusion into the anode chamber through optimized design.

Main Results:

• The MEMS MFC achieved a maximum current density of 16,000 μA cm⁻³ (33 μA cm⁻²) and power density of 2300 μW cm⁻³ (4.7 μW cm⁻²).
• Coulombic efficiency reached at least 31%, the highest reported for MEMS MFCs.
• Performance gains attributed to efficient ARB, reduced oxygen intrusion, and large specific surface area leading to low internal resistance.

Conclusions:

• The developed MEMS MFC demonstrates a significant advancement in microbial fuel cell technology.
• The design innovations enable higher power and current densities, making MFCs more viable for energy applications.
• This work highlights the potential of MEMS technology for creating efficient and scalable microbial energy harvesting devices.