H612 Journal of The Electrochemical Society, 160 (9) H612-H619 (2013) 0013-4651/2013/160(9)/H612/8/$31.00 © The Electrochemical Society

This paper describes the design and testing of a microfluidic biofuel cell that uses a flow-through bioanode and an air-breathing cathode. The bioanode is Toray carbon paper with glucose dehydrogenase (GDH), multi-walled carbon nanotubes (MWCNTs), and methylene green immobilized within a hydrogel. The cathode consists of a commercially available air-breathing platinum cathode hot pressed to a Nafion membrane. All remaining biofuel cell components were laser-cut from poly(methyl methacrylate) (PMMA) and silicone sheets. Half-cell experiments indicate that cathode variability limits the biofuel cell. An examination of flow rate effects on the biofuel cell showed that the current density increased sharply up to about 1 mL/min. Tested at this flow rate, the flow-through biofuel cell achieved a maximum current and power density of 705 μA/cm2 and 146 μW/cm2. This was a 6 % and 29 % improvement in the current and power density, respectively, compared to the previously demonstrated bioanode without flow. Fuel utilization was calculated based on the measured current and by measuring UV-Vis absorbance of the reduced form of hydroxybenzhydrazide. The maximum fuel utilization was 5.8 % at a flow rate of 0.05 mL/min. Finally, a numerical model of the biofuel cell was designed and its results compare favorably to actual data