Mainstreaming microfluidic microbial fuel cells: a biocompatible membrane grown in situ improves performance and...

Area of Science:

• Electrochemistry
• Microfluidics
• Biotechnology

Background:

• Microfluidic microbial fuel cells (MFCs) often omit membranes, relying on laminar flow for compartment isolation.
• Large inter-electrode distances (several millimeters) in membraneless MFCs increase internal resistance, negating microscale advantages.
• Current designs face challenges in maintaining efficiency and power output due to physical limitations.

Purpose of the Study:

• To develop a facile method for in situ micromembrane synthesis in MFCs.
• To enable sub-millimeter electrode spacing, reducing internal resistance and improving performance.
• To enhance power density, current density, and acetate conversion efficiency in microfluidic MFCs.

Main Methods:

• In situ synthesis of a micromembrane within the microfluidic device.
• Fabrication of MFCs with sub-millimeter electrode spacing using the synthesized membrane.
• Comparative analysis of the new membrane MFC against state-of-the-art membraneless MFCs.

Main Results:

• The sub-millimeter membrane MFC exhibited 60% lower internal resistance compared to membraneless designs with 6 mm spacing.
• Power and current densities were 45% and 290% higher, respectively.
• Acetate conversion efficiencies were 8 times higher, with maximum outputs of 660 mW m⁻¹ and 3.5 A m⁻¹.

Conclusions:

• In situ micromembrane synthesis is a viable and effective strategy for improving MFC performance.
• The proposed design overcomes limitations of membraneless MFCs, achieving record outputs for pure culture systems.
• This advancement facilitates the competitiveness of microfluidic MFCs with mainstream MFC technologies.