Computational Analysis of Microfluidic Biofuel Cells

Biofuel cells are devices that convert biochemical energy directly into electrical energy. They are distinguished from conventional fuel cells by the use of biocatalysts (enzymes/microbes) to generate electricity from organic substrates such as carbohydrates. Microfluidic biofuel cells exploit the difficulty of mixing at low Reynolds number to eliminate the use of membranes, which are commonly used in conventional fuel cell systems. Simulation of the microfluidic fuel cell by solution of the governing 3-D conservation equations (flow, species transport) reveals that the oxygen transport limits the performance of the cathode compartment. An exponential decay in the availability of oxygen at the cathode is also observed, indicating that increasing the number of electrode pairs reduces the overall current density. This conclusion is consistent with experimental observations. Increasing electrolyte flow rates can reduce the mass transport limitations by decreasing the diffusion thickness, but disparity between the anolyte and catholyte flow rates can induce wastage of dissolved oxygen.