Researchers develop foil that can convert sweat into electricity
The devices wearablesWith few exceptions, their main weakness is their energy autonomy. A solution for this could come from human sweat.
Researchers recently designed a biofilm that is capable of harvesting the energy of evaporation and converting it into electricity.
A film that transforms sweat into electrical energy
This foil, developed by researchers at the University of Massachusetts Amherst, has the potential to revolutionize the world of wearable electronics, providing power for a wide variety of devices, from personal medical sensors to consumer electronics.
Xiaomeng Liu, principal investigator of the project, defines this solution as “real green energy and, unlike other sources called ‘green energy’, its production is totally green«.
This biofilm consists of a thin sheet of bacterial cells, about the thickness of a sheet of paper, that is produced naturally by a modified version of the bacteria Geobacter sulfurreducens. This bacterium is known to produce electricity and its use in ‘microbial batteries’, to power electrical devices, has been previously explored.
Microbial batteries have not prospered as a solution, because they require that G. sulfurreducens properly cared for and fed a consistent diet. A different case is that of this new biofilm, which can provide as much energy, if not more, than a battery of similar size and continuously, because it is dead, which is why it does not need to be powered.
“It is much more efficient”says Derek Lovley, Distinguished Professor of Microbiology at the University of Massachusetts Amherst and one of the paper’s lead authors. «We’ve simplified the process of generating electricity by radically reducing the amount of processing required. We sustainably grow cells in a biofilm and then use that clump of cells. This reduces energy inputs, makes everything simpler and broadens its potential applications”.
The secret behind this new biofilm is that it generates energy from the moisture in the skin. Although we read stories about solar energy every day, at least 50% of the solar energy that reaches the Earth goes to the evaporation of water. “This is a huge untapped source of energy,” says Jun Yao, a professor of electrical and computer engineering at UMass, and the paper’s other lead author. Since the surface of our skin is constantly moistened with sweat, the biofilm can “plug in” and convert the energy trapped in evaporation into enough energy to power small devices.
What makes all of this work, as detailed in this research paper in Nature Communications, is that G. sulfurreducens it grows in colonies that look like thin mats, each of the individual microbes connecting with its neighbors through a series of natural nanowires. The team then collects these mats and uses a laser to etch small circuits onto the films. Once the films are recorded, they are sandwiched between the electrodes and finally sealed in a soft, sticky, breathable polymer that can be applied directly to the skin. Once this small battery is “plugged in” by applying it to your body, it can power small devices.
“Our next step is to increase the size of our films to power more sophisticated electronic devices that can be worn on the skin”Yao says, and Liu notes that one goal is to power entire electronic systems, rather than individual devices.
Apart from the future progress of this project in the improvement of the offered product, the adoption of this alternative as a solution to supply certain devices with energy will depend on the industry. A small, thin and flexible transparent biofilm that produces a continuous and constant supply of electricity and that can be used, like a band-aid, like a patch applied directly to the skin, at least initially, is emerging as a solution for all these problems.
