A mixed media fuel-flexible direct alcohol microfluidic fuel cell (mu DAFC) with flow-through configuration is introduced. The anode of the fuel-flexible mu DAFC can interchangeably use methanol, ethylene glycol or glycerol in alkaline media, while saturated oxygen in acidic media feeds the cathode to generate similar to 30-40 mW cm(-2) of maximum power density. The performance in terms of output power density of the mu DAFC is highly dependent on the fuel concentration in each case. The output power is proportional to the fuel concentration for ethylene glycol and methanol. Contrarily, glycerol shows higher power at low concentrations and vice-versa, which is rationalized as a consequence of the poisoning effect due to the limited glycerol catalysis on Pt at high concentration cases. The fuel-flexible mu DAFC with consistently high power density is achieved by balancing the number of carbons participating in the ethylene glycol and methanol oxidation reactions, while glycerol must be administered in low concentrations. This concept therefore shows promise as a practical and cost-effective fuel cell solution that can operate on a range of organic, biomass-derived fuels without sacrificing power density at room temperature. (C) 2018 Elsevier Ltd. All rights reserved.