A laminar flow-based single stack of flow-over planar microfluidic fuel cells

Power densities of microfluidic fuel cells are still not high enough for power source applications. In this study, we propose a novel planar stack to increase the total power of a microfluidic fuel cell. Electrical connections in serial or parallel are made within one channel by using multiple laminar flow. A planar structure with flow-over electrodes of platinum are adopted for easy integration with other planar micro devices. These structures are made by micromachining with a thin film process. Fuel cell performance and total ohmic resistances are measured experimentally with a formic acid-based fuel. The results show that the proposed single stacks provide more power density with a comparatively small total ohmic resistance and require less space than that of the fuel cell arrays. The peak volumetric power density improves by 97.5% and 39.3% using parallel and serial electrical connections, respectively, at a 300 μL min⁻¹ flow rate. Utilizing this single stack, we believe that microfluidic fuel cells can be integrated into a compact planar configuration to achieve a power high enough for energy source applications.