A glucose-powered biofuel cell equipped with cotton fiber-based electrodes is under development as a power source for pacemakers and other implantable medical devices. Researchers from the U.S. and South Korea envision pairing the fuel cell, which provides twice as much power as conventional biofuel cells, with batteries or supercapacitors to provide a hybrid power source for medical devices.

The addition of gold nanoparticles to cotton yields high-conductivity electrodes that improve fuel cell efficiency. The structure facilitates connecting the enzyme used to oxidize glucose with an electrode. A layer-by-layer assembly technique used to fabricate the gold electrodes boosted power capacity to as much as 3.7 milliwatts per square centimeter. The assembly method precisely controls deposition of both the gold Plain cotton fibers and metallic cotton fibers are used as electrodes in a new biofuel cell. Source: Georgia Institute of Technology/Korea UniversityPlain cotton fibers and metallic cotton fibers are used as electrodes in a new biofuel cell. Source: Georgia Institute of Technology/Korea Universitynanoparticle and enzyme, which in turn increases fuel cell power density.

Gold nanoparticles about 8 nm in diameter are assembled onto porous cotton fiber composed of multiple hydrophilic microfibrils using organic linker materials. Glucose oxidase enzyme is applied in layers alternating with an amine-functionalized small molecule - tris-(2-aminoethyl)amine - to form the anode for oxidizing glucose. The cathode, where the oxygen reduction reaction takes place, uses the gold-covered electrodes which have electrocatalytic capabilities.

The porosity of the hydrophilic cotton supports an increase in the number of gold layers compared to a nylon fiber. The material also enhances the biocompatibility of the device, which is designed to operate at low temperature for use inside the body.

Implantable devices are currently powered by batteries that require replacement via surgical procedures. The biofuel cell could provide a continuous charge for those batteries, potentially extending the time that devices may operate without battery replacement, and could be used to power devices intended for temporary use. These might be implanted to provide timed release of a drug, but would biodegrade over time without requiring surgical removal. For such applications, no battery would be included, and the limited power needed could be provided by the biofuel cell.

Scientists from Georgia Institute of Technology, Korea University and Sungkyunkwan University contributed to this research, which is published in Nature Communications.

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