by Bennett Davis
A special strain of bacteria can generate electricity from air, scientists at the University of Massachusetts at Amherst have discovered.
It’s long been known that several kinds of bacteria can move electrons from their bodies to the ground, metal compounds, or other bacteria along protein filaments that stick out of their bodies. The filaments are about a tenth the diameter of a human hair.
Scientists aren’t sure how the bugs do it and have tried for years without success to devise a way to turn these short bursts of electricity into a steady current that could be collected and used.
Two years ago, the Amherst researchers noticed that the bugs’ “nanowires” were generating current spontaneously. They varied possible causes – temperature, light, and the kinds of metal making up the electrodes that the filaments were in contact with. Finally, they settled on water vapor in the air: the amount of electricity the bugs generated varied as the humidity changed.
The trick was to create a film of the protein nanowires sandwiched between metal electrodes. One electrode is shorter than the other and the ends of the filaments stick out past it and are exposed to air.
As the protein filaments absorb moisture, water droplets moving in and out of the filaments separate into hydrogen and oxygen ions – charged particles. The charge difference between the filament surfaces and the metal electrodes causes the charged particles to flow, making an electric current.
The self-recharging arrangement produces about half a volt of electricity per square centimeter of surface continuously for as long as 20 hours.
The scientists have named their device the Air-Gen and are mulling ways to scale it up to commercial size while further refining the technology.
Meanwhile, they’re working on a wearable Air-Gen patch to power implanted medical devices.
TRENDPOST: All living things generate electricity internally. Drawing that electricity out of a living organism and into a circuit is the ultimate form of clean, renewable power.
The Amherst lab has developed other applications for bio-generated electricity and will help to inaugurate a new research and development field of protein-based electronics.
