Microfluidic fuel cell is a promising power source in many applications, such as portable electronic devices. In this work, a novel and unique scale-up approach is developed to increase the capability of the microfluidic aluminum-air fuel cell, while maintaining the co-laminar flow characteristic at the same time. In the scaled-up cell, the crossover of different electrolyte streams was well controlled and a higher cell output was achieved. With a four-fold increase in the electrode area, the maximum current density could be maintained over 75%. Impedance spectroscopy study on full aluminum-air cells was conducted for the first time, and employed to analyze the cell properties during their scaling up process.