Researchers in China have reported a nanowire-based biofuel cell (NBFC) based on a single proton conductive polymer nanowire for converting chemical energy from biofluids into electricity, using glucose oxidase and laccase as catalyst.
Principle
The biofuel cell has been integrated with a set of nanowire based sensors for performing self-powered sensing. The nanowire lies on a substrate (of any kind), with both ends tightly bonded to the substrate and outlet interconnects. GOx and laccase are used as catalysts in the anode and cathode regions respectively. The NBFC is immersed into a biofuel solution; two chemical reactions occur in the anode and cathode regions, creating a corresponding chemical potential drop along the nanowire which drives the flow of protons in the nanowire and electrons through the external load which is electricity.
Nafion nanowires
The proton exchange membrane is the key component in many of today's fuel cells and it is also a big obstacle to shrink the size of a fuel cell. Nafion nanowires have an enhanced performance of proton conductivity compared with Nafion film. The Nafion nanowires have a diameter about 100 nm to 1 µm and a length of about 20 µm. However, it turns out to be very difficult to build a platinum catalyzed fuel cell on such a small nanowire as the anode and cathode reacting area needs to be strictly separated. The scientists introduced a new method using electro spinning to fabricate nafion nanowires. Electro spinning is a very powerful method to produce nafion nanowires as long as few centimeters. This solves the miniaturization problem of the fuel cell, since the anode and cathode area need not to be separated again as enzymes are very selective to the reactants.
Output
This biofuel cell of a single nanowire generates an output power as high as 0.5-3 µW in glucose solution, in human blood and the juice of a watermelon.
Uses
Nano biofuel cell can be directly integrated to self-power chemical or biosensor such as pH sensor or glucose sensor, photon sensors, electrical measurement system, data processing logic system, and possibly wireless communication unit (RF technology) and even to power a heart cardiac pacemaker by generating power from human blood.