In an attempt to improve upon conventional flow fields (e.g., serpentine flow field), Murray's Law was applied to design two different bio-inspired, leaf-shaped flow fields. This law governs the dimensions of natural networks, such as: the veins within plant leaves and human lungs. In this study, the serpentine, the lung, and the two leaf-shaped flow fields were used to form seven different anode cathode combinations. The experiments focused on the effects of methanol concentration (0.50 M, 0.75 M, and 1.00 M) and the combined effect of methanol and oxygen flow rates (1.3 ml/min methanol and 400 ml/min oxygen, as well as 2 and 3 times both of these flow rates). An analytical model was also developed to help understand the experimental results. The results show that the highest performance could be achieved when the bio-inspired configurations were used on the cathode. The best configuration was the serpentine (anode) second leaf design (cathode), with a peak power density of 888 W/m(2). For comparison, a peak power density of 824 W/m(2) was achieved when the serpentine flow field was used on the anode and cathode. Furthermore, of all the tested configurations, the lung-based flow field provided the lowest performance in all tests. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.