Investigation of electrode scaling-up strategies for paper-based microfluidic fuel cells

Paper-based microfluidic fuel cells (PMFCs) are attracting extensive attention for their low cost, simple structure and environmental friendliness, making them suitable for wearable devices and micro-detection instruments. However, the small electrode area limits their power output. To date, researchers try to tackle this issue by developing complex PMFC stacks, but the research on direct expansion of single-cell's electrode area is still missing. This study explores three strategies to expand PMFC's electrode, namely the vertical scaling-up, the horizontal scaling-up and the horizontal scaling-up with additional wires. Results show that the vertical scaling-up increases ionic resistance while the horizontal scaling-up increases electrical resistance significantly, leading to limited scaling-up efficiency of 20.9 % and 37.5 %, respectively, when the electrode area is expanded for 5 times. On the contrary, the horizontal scaling-up with additional wires can reduce the ionic and electric resistances concurrently, achieving a much higher scaling-up efficiency of 64.3 %. Furthermore, rolling up the scaled-up PMFC can reduce device footprint with negligible performance loss, showcasing its excellent flexibility and high potential for practical applications.