Continuous power generation from glucose with two different miniature flow-through enzymatic biofuel cells

Enzymatic biofuel cells (EBFCs) can generate energy from metabolites present in physiological fluids. They represent an attractive alternative to lithium batteries to power implantable devices, as they work at body temperature, are light and easy-to-miniaturise. To be implantable in blood vessels, EBFCs should not only be made of non-toxic and biocompatible compounds but should also be able to operate in continuous flow-through mode. The EBFC devices reported so far, however, implement carbon-based materials of questionable toxicity and stability, such as carbon nanotubes, and rely on the use of external redox mediators for the electrical connection between the enzyme and the electrode. With this study, we demonstrate for the first time continuous power generation by flow through miniature enzymatic biofuel cells fed with an aerated solution of glucose and no redox mediators. Non-toxic highly porous gold was used as the electrode material and the immobilisation of the enzymes onto the electrodes surface was performed via cost-effective and easy-to-reproduce methodologies. The results presented here are a significant step towards the development of revolutionary implantable medical devices that extract the power they require from metabolites in the body.