A stick-on microbial 'battery' uses the evaporation of moisture from the skin to generate electricity and power wearable devices.
Biologists from the University of Massachusetts at Amherst (USA) have presented a technology for producing persistent biofilms based on the bacteria Geobacter sulfurreducens. These unusual microbes generate and conduct electricity, and scientists are trying to harness their abilities to create new devices - such as an unusual 'semi-liveable computer' made from metal electrodes and bacterial proteins. G. sulfurreducens have now become the basis of unusual and promising power sources. This is reported in an article published in the journal Nature Communications.
Similar ideas have been heard before, but the problem was the power of bacterial cells-"electrogenerators". Therefore, Derek Lovley (Derek Lovley) and his colleagues went the other way. They took advantage of the ability of G. sulfurreducens to form biofilms - persistent dense conglomerates attached to the surface of the substrate. The cells in them are connected to each other to form structures capable of conducting electricity.
Scientists grew these biofilms by laser "engraving" them with an electrical circuit then placing them between a pair of thin and flat metal electrodes before finally encasing them in a soft, sticky polymer. The cells inside died, but the electrical circuit was not affected. Such a device is enough to put on the skin and it will generate electricity by harnessing the energy of sweat that continuously evaporates from its surface.
The developers estimate that a biofilm just 40 micrometres thick will produce a battery with an energy density of about one microwatt per square centimetre, surpassing traditional sources of similar geometry. In in vitro experiments, scientists chained together several of these devices and successfully powered small electronic gadgets. Now they plan to scale the system to learn how to get more powerful generators capable of powering more complex devices, using "energy of sweat".
Such an option, however, is far from the only possibility of using biofilms of "electric" microbes. Evaporation is everywhere, and about half of all solar energy on Earth is used to evaporate moisture. "This is a huge and completely untapped source of energy," said Professor Jun Yao, one of the authors of the new work.
