A bioanode was constructed using glucose oxidase enzyme (GOx) supported on multi walled -carbon nanotubes (MWCNTs) in the presence of glutaraldehyde (GA) (GOx/MWCNTs-GA) and evaluated in an air-breathing hybrid glucose microfluidic fuel cell (HG-mu FC). The air-breathing HG-mu FC operated under physiological conditions (5 mM glucose at pH 7 with an air-exposed cathode) delivers an open circuit value of 0.72 V with 610 W cm(-2) of maximum power density, and shows potential possibilities to develop future implantable applications. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.