Integration of cantilevered porous electrodes into microfluidic co-laminar enzymatic biofuel cells: Toward higher enzyme loadings for enhanced performance

Abstract

This paper introduces a novel design of co-laminar microfluidic biofuel cell that incorporates three-dimensional (3D) porous electrodes containing immobilized enzymes. An innovative characteristic of the microfluidic configuration presented here is the presence of cantilevered bioelectrodes protruding along the internal walls of the miniature electrochemical chamber. Such suspended-like electrodes can maximize the penetration depth of the reactants inside the porous medium. As a first proof-of-concept, we demonstrate the integration of a bioanode and a biocathode into a lamination-based ethanol/O2 microfluidic biofuel cell fabricated via rapid prototyping. With enzymes deposited into the 3D fibrous structure of 25mm long, 1mm wide and 0.11mm thick carbon paper electrodes, the volumetric current density reached ≈2.9mAcm−3 at 0.43V under a flow rate of 50μLmin−1. A major advantage of the presented microfluidic cell is that it can be adapted to include a larger active electrode volume via the vertical stacking of multiple thin bioelectrodes. We therefore envision that our design would be amenable to reach the level of net power required to supply energy to a plurality of low-consumption electronic devices.