High-power biofuel cells based on three-dimensional reduced graphene oxide/carbon nanotube micro-arrays

Abstract

Miniaturized enzymatic biofuel cells (EBFCs) with high cell performance are promising candidates for powering next-generation implantable medical devices. Here, we report a closed-loop theoretical and experimental study on a micro EBFC system based on three-dimensional (3D) carbon micropillar arrays coated with reduced graphene oxide (rGO), carbon nanotubes (CNTs), and a biocatalyst composite. The fabrication process of this system combines the top–down carbon microelectromechanical systems (C-MEMS) technique to fabricate the 3D micropillar array platform and bottom–up electrophoretic deposition (EPD) to deposit the reduced rGO/CNTs/enzyme onto the electrode surface. The Michaelis–Menten constant K _M of 2.1 mM for glucose oxidase (GOx) on the rGO/CNTs/GOx bioanode was obtained, which is close to the K _M for free GOx. Theoretical modelling of the rGO/CNT-based EBFC system via finite element analysis was conducted to predict the cell performance and efficiency. The experimental results from the developed rGO/CNT-based EBFC showed a maximum power density of 196.04 µW cm ⁻² at 0.61 V, which is approximately twice the maximum power density obtained from the rGO-based EBFC. The experimental power density is noted to be 71.1% of the theoretical value.

Enzymatic biofuel cells: power for medical devices

A two-step process enables the fabrication of miniaturized enzymatic biofuel cells composed of nanomaterials for possible use as power sources in implantable devices. There is growing need for self-powered implanted medical devices. Enzymatic biofuel cells are attractive for this since they rely on bio-compatible and non-toxic materials. However, improvements in power cell density are needed, and agglomeration of nanomaterials on existing devices limits performance. Now, Yin Song and Chunlei Wang from Florida International University report a new process: top–down photolithography creates a high surface area micropillar array, followed by deposition of reduced graphene oxide, carbon nanotubes and enzymes onto the pillars. A maximum power density of 196.04 µW cm ⁻² at 0.61 V is achieved in the resulting devices, attributed to the combination of nanomaterials and conformal coating of the micropillars.

Abstract