Microfabricated microfluidic fuel cells

We demonstrate high performance microfuel cells (μFC) operating at room temperature. The smallest μFC has a reaction surface of 0.11 cm2 and has an output power density equal to 22.9 mW cm−2. Methanol and air are supplied using microchannels etched into silicon wafers using microfabrication techniques which can accurately determine the μFC surface and the microchannel dimensions. The insertion of a novel hydrophilic fibrous layer into the anode diffusion layer stack produces 9.25 mW cm−2 for an input fuel flow rate of 550 nL min−1. The benefits of size-scaling and architecture optimization in μFC are demonstrated. Our observations and conclusions are by no means unique to methanol μFC but could be applied to other microfluidic liquid fuel μFC based on, e.g. microbial fuel cells, bio-ethanol and glucose solution.