A paper battery powered by electron-harvesting bacteria could one day power environmentally friendly disposable devices.
Researchers have been working on paper sensors and circuit boards for years, but they have mostly been powered by traditional batteries or simple chemical reactions. Yang Gao and Seokheun Choi at the State University of New York-Binghamton created a paper battery powered by bacteria to do the job instead.
The battery is made of waxed paper, with thin layers of metals and polymers printed on top to hold bacteria and harvest electrons. The type of bacteria used are called exoelectrogens, which pull electrons from the molecules that they eat and transfer them to outside of their cells.
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The battery is freeze-dried to place the bacteria in a dormant state, and it鈥檚 packaged with a small pouch of liquid bacteria food. When the device is squeezed, the liquid revives the bacteria and they start eating the organic material from the pouch.
Read more: Pencil sketches turn paper into a sensor
Through a series of reactions, electrons from the food are moved through the bacteria, eventually being absorbed into the battery, where they can be used to power small devices.
The team presented their work on 19 August at a meeting of the American Chemical Society in Boston.
For now, Gao says, it can only be used to fuel fairly low-power devices, like a small calculator or an LED light. But he and Choi hope that it will someday be used in medical technologies, like pregnancy tests, that currently require traditional batteries and can be hard to dispose of in an environmentally friendly way.
鈥淚f we can provide power without using conventional batteries, those devices could be cheaper and more disposable and environmentally friendly,鈥� Gao says.
The batteries have a shelf-life of about four months and can provide power for up to two days. They are not quite ready for use yet 鈥� for most practical applications, Gao says that they鈥檒l need to provide much more power, a problem he and his colleagues are working on now. Connecting several paper batteries by stacking and folding them may help, he says.
