Micro Biofuel Cells Research Articles

Graphene/enzyme-encrusted three-dimensional carbon micropillar arrays for mediatorless micro-biofuel cells.

Two-dimensional graphene is a promising candidate material for use in high-performance enzymatic biofuel cells (EBFCs). In this work, graphene/enzyme has been integrated onto three-dimensional (3D) micropillar arrays in order to obtain efficient enzyme immobilisation and enhanced enzyme loading and facilitate direct electron transfer. The fabrication process of this system combines top-down carbon microelectromechanical systems (C-MEMS) to fabricate the 3D micropillar array platform and bottom-up electrophoretic deposition (EPD) to deposit the graphene/enzyme onto the electrode surface. The amperometric response of the graphene-based bioelectrode exhibited excellent electrochemical activity, which indicated the successful co-deposition of graphene with the enzymes. The developed 3D graphene/enzyme network-based EBFC generated a maximum power density of 136.3 μW cm(-2) at 0.59 V, which is almost seven times the maximum power density of the bare 3D carbon micropillar array-based EBFC.

Microbiofuel cell powered by glucose/O2 based on electrodeposition of enzyme, conducting polymer and redox mediators. Part II: Influence of the electropolymerized monomer on the output power density and stability

In this study, we investigated the influence of nature of the electropolymerized monomer on the resulting power output and stability of a glucose/O2 powered biofuel cells (BFCs). The bioanode was prepared from a mixture of glucose oxidase-polymeric monomer-ferrocenium hexafluorophosphate-pyrroloquinoline quinone (abbreviated as, GOx-monomer-FHFP-PQQ) and the biocathode from laccase enzyme-polymeric monomer-4,4-sulfonyldiphenol-Bis-(bipyridine)-(5-aminophenanthroline) ruthenium bis (hexafluorophosphate) (abbreviated as, LAc-monomer-SDP-RuPy) electrodeposited from low conductivity solutions using pulsed square wave potentials (10 s at 4V, then 3 s at 0.5V) for 180 cycles. Three different monomers were investigated: aniline, phenol and pyridine. The power output of the aniline based BFCs reached 5.97μW.mm−2 which is higher than the pyrrole based BFCs reported previously (3.17μW.mm−2). With phenol monomer, the estimated maximum power density was only 0.276μW.mm−2. The pyridine based BFCs showed the lowest power density (0.046μW.mm−2) of all, even lower than the monomer-free BFC (0.124μW.mm−2). The evaluation of the BFCs in buffer solution pH 7.4 under air at 37°C for 3 days of continuous operation showed that pyrrole and aniline based BFCs are the most stable followed by phenol based BFCs. Pyridine and monomer-free BFCs undergo significant deterioration with up to 75% loss in power density.

An intravenous implantable glucose/dioxygen biofuel cell with modified flexible carbon fiber electrodes

An intravenous implantable glucose/dioxygen hybrid enzyme-Pt micro-biofuel cell (BFC) was investigated. In this miniaturized BFC, a flexible carbon fiber (FCF) microelectrode modified with neutral red redox mediator and glucose oxidase was used as the bioanode, and an FCF modified with platinum nanoparticles stabilized on PAMAM-G4 dendrimer was used as the cathode. In vitro experiments conducted using the BFC in a phosphate buffer solution (50 mmol L(-1), pH = 7.2) and glucose (47 mmol L(-1)) showed high electrocatalytic performance with an open circuit voltage (OCV) of 400 mV, a maximum current density of 2700 μA cm(-2) at 0.0 V and a maximum output power of 200 μW cm(-2) at 250 mV. Under physiological conditions, glucose from rat blood is used as a fuel in anodic reactions and dissolved molecular oxygen is used as the oxidizing agent on the cathode. For in vivo experiments, the BFC was inserted into the jugular vein of a living rat (Rattus novergicus) using a catheter (internal diameter 0.5 mm). The power density of the implantable BFC was evaluated over a period of 24 h, and an OCV of 125 mV with a maximum power density of 95 μW cm(-2) was obtained at 80 mV.

Single-walled carbon nanotube ensembles modified gold ultramicroelectrodes prepared by self-assembly deposition method with 1-(1-pyrenyl)-1-methanethiol monolayer as an adhesion layer

Single-walled carbon nanotubes (SWNTs) modified ultramicroelectrodes (UMEs) have potential in many fields, such as electrochemical microsensors, microbiofuel cells, and in vivo biology. This study describes a new and facile self-assembly method for fabricating SWNT ensembles modified UMEs. In this method, bare gold UMEs were modified with 1-(1-Pyrenyl)-1-methanethiol (PyMT) monolayer as an adhesion layer, followed by self-assembly deposition of SWNTs to obtain the SWNTs/PyMT/gold UMEs. The electrochemical properties, such as electrode reactivity and interfacial capacitance, of the fabricated SWNTs/PyMT/gold UMEs were investigated by using cyclic voltammetry. Furthermore, the fabricated SWNTs/PyMT/gold UME was used as a microscaffold exhibiting the SWNT properties for immobilization of organic redox dye methylene blue (MB).

Micro-biofuel cell powered by glucose/O 2 based on electro-deposition of enzyme, conducting polymer and redox mediators: Preparation, characterization and performance in human serum

In this study we report a new simple process to manufacture a biofuel cell consisting of a glucose oxidase (GOx) based anode and a laccase (LAc) based cathode. The process is based on the electro-deposition of the enzymes, conducting polymer and redox mediators from ultrapure water at a potential of 4 V vs. AgCl/Ag. Contrary to the conventional electro-deposition from high ionic strength (buffer solution) at low applied potential (1 V vs. AgCl/Ag) where only thin films could be deposited, leading to BFC with moderate power, the electro-deposition from ultrapure water at 4 V allows the growth of thick films leading to BFC with high power output. It was observed that the combination of polypyrrole (PPy), with ferrocenium hexafluorophosphate (FHFP) and pyrroloquinoline quinone (PQQ) to be appropriate for the electron transfer at the GOx bioanode, while the combination of polypyrrole with bis-(bipyridine)-(5-amino-phenanthroline) ruthenium bis (hexafluorophosphate)(RuPy) and 4,4-sulfonyldiphenol (SDP) to be effective for the electron transfer at the LAc biocathode. The working biofuel cell was studied at 37 °C in phosphate buffer solution at pH 7.4 containing 10 mM glucose and in human serum. Under these conditions, the maximum power density reached 3.1 μW mm −2 at a cell voltage of 0.28 V in buffer solution and 1.6 μW mm −2 at a cell voltage of 0.21 V in human serum. This study offers a new route to the development of enzymatic BFCs with high performance and provides information on enzymatic BFCs as in vivo power sources.

Towards Alcohol Microbiobatteries and Microbiofuel Cells

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Evaluation of bacteria compatible microporous surfaces for biofuel cells

Prototypes of photosynthetic-bacterium micro-biofuel cells have been developed in our laboratory, in which electrons are extracted from bacterial cells while they are in contact with an electrode. The material and shape of the electrode should be electroconductive and biocompatible with a low electrical resistance and a high-specific surface area, therefore, pyrolyzed carbon was fabricated either to a flat or porous surface electrode using carbon microelectromechanical systems (C-MEMS). The developed electrodes were applied in micro-biofuel cells, and the porous electrode showed a fourfold higher performance than the flat one.

Mediatorless catalytic oxygen reduction at boron-doped diamond electrodes

Most approaches to electron conduction from electrode to the enzyme requires the use of mediators – molecular relays which can take electrons from the electrode and deliver them to the redox sites of the enzyme. In the present paper, the biocatalytic reduction of oxygen to water in the presence of laccase is shown to proceed on the boron-doped diamond at highly positive potentials and without any additional mediator. The onset of catalytic reduction current appears at 0.805 V vs. NHE in solutions of pH 5.2. Laccase is either dissolved in the solution or trapped on the BDD electrode in a thin film of lipidic cubic phase. The remarkable stability of the modified electrode, avoiding the use of mediators and positive potential of the dioxygen reduction process make the BDD–laccase system especially interesting for applications in electrochemical sensing and microbiofuel cells.