NEWS POST: A Biodegradable Battery Fuelled By Bacteria Has Been Developed By Scientists

A biodegradable battery fuelled by bacteria has been developed by scientists. Microbes known as 'exoelectrogens' (shown in red in inset) power the device (main image shows artist impression) by transferring electrons outside of their cells to external electrodes

The device, which is activated using saliva and made by printing thin layers of metals on to a paper surface, is capable of powering a calculator or small light source. Scientists claim the technology could fuel disposable HIV tests, glucose sensors and other medical devices in poor countries where electrical sources are sparse.

It could also help cut electronic waste because it decomposes naturally, they said.

Researchers at the State University of New York, Binghamton, made the batteries using 'exoelectrogens' - bacteria that can transfer electrons outside of their cells. These microbes were freeze-dried and placed on a paper surface, which was then layered with strips of metals and other materials. To activate the battery, researchers added saliva or water, which awoke the bacteria from their dormant state. Electrons generated naturally by the microbes passed through their cell membrane and made contact with the battery's electrodes.

This allowed the scientists to create a small electrical circuit that generates enough charge to power small, portable devices while producing little electrical waste.

'There's been a dramatic increase in electronic waste and this may be an excellent way to start reducing that,' study coauthor Dr Seokheun Choi said.

A prototype created by the team is capable of powering a calculator or a light-emitting diode - a small semiconductor light source. The structures are lightweight, low-cost and flexible, and can be used once and then thrown away, with a shelf life of around four months. Researchers said the technology could one day power medical equipment in poorer countries.

●New battery is made by printing thin layers of metals on to a paper surface ●It is activated using saliva and can power a calculator or small light source ●Scientists created the device using specialized bacteria called 'exoelectrogens' ●They can transfer electrons outside of their cells to the battery's electrode

In remote areas of the world, everyday items like electrical outlets and batteries are luxuries, and health care workers often lack electricity to power diagnostic devices, while commercial batteries may be too expensive.

The prototype exhibited a much higher power-to-cost ratio than all previously reported paper-based microbial batteries, according to Dr Choi. His team investigated how oxygen affected the technology's performance.

The device (pictured) is activated using saliva and made by printing thin layers of metals on to a paper surface, and is capable of powering a calculator or small light source

In other batteries, the gas has reduced the movement of charge by absorbing electrons produced by bacteria before they reach the electrode. But the new device was only slightly impeded by oxygen because the bacteria are tightly attached to its paper fibres, meaning electrons are shifted to the anode before they can be absorbed by oxygen.

Dr Choi is now working on a way to improve the survival and shelf-life of the freeze dried bacteria. He said newer versions of the power source could be stacked and connected to boost power generation. 

The findings were presented at the National Meeting and Exposition of the American Chemical Society.

Originally published on DAILY MAIL SCIENCE & TECH