A “Press and Go” Thin Biofuel Cell Patch for Power Generation

Biofuel cells are devices that generate portable electrical power, typically from glucose, alcohols or related biofuels, by using enzymatic anodes and cathodes. We report on the performance of membrane- and mediator-free enzymatic glucose biofuel cells (BFCs) fabricated in a sandwiched, patch geometry with carbon nanotube nanopaper bio-electrodes prepared using a compression technique to immobilize the enzymes. A gel electrolyte comprised of agar mixed with glucose is sandwiched between the two bio-electrodes to form a patch. Power densities up to 111.90 μW/cm² at a current density of 334.50 μA/cm² at a voltage of 0.335 V were obtained for a typical single cell BFC of this design. The sandwich BFC also showed good stability with a half-life of about 1.5 days under continuous operation. The relatively high power density for this new design is attributed to the compression-induced immobilization of the enzymes by the nanotubes as indicated by scanning electron microscope images. This compression-induced immobilization of enzymes provides improved direct electron transfer at the carbon nanotube electrodes.