Enhancing fuel transport and cell performance by an anodic wedge-shaped channel in a paper-based microfluidic fuel cell

Paper-based self-pumping microfluidic fuel cells (PMFCs) typically exploit the wicking effects in porous papers to enable passive reactant delivery and co-laminar flow, eliminating micro pumps and physical membranes. PMFCs have been regarded as promising micro-power sources for next-generation paper-based electrochemical microfluidic assays for biomedical applications. However, the PMFC performance is fundamentally limited by the low capillary flow velocity and ineffective diffusive fuel transport. In this study, a novel PMFC with an anodic wedge-shaped channel is developed. The anodic wedge-shaped channel enables reactant convection at improved fuel flow velocity. Visualization experiments suggest that the fuel flow velocity can be improved by about 23 times in this anodic wedge-shaped channel configuration as compared to that in conventional single-layer paper-based flow channel. In addition, favorable features like localized enhancement of fuel transport and reduced fuel crossover are also observed in this novel configuration. Due to enhanced convective-diffusive fuel transport, the cell performance can be improved 245.8 % as compared to the single-layer case. The peak power density reaches 59.9 mW cm−2 and the limiting current density achieves 305.9 mA cm−2, outperforming most of the previous PMFCs. This anodic wedge-shaped channel configuration can also be potentially used in paper-based assays to enhance reactant delivery.