With rare exceptions, the major shortcoming of wearable technology is its lack of energy autonomy. Human perspiration may hold the key to this problem’s solution. Recently, scientists created a biofilm that can capture the energy of evaporation and transform it into electricity.
A Chip that converts sweat into electricity.
This foil, created by researchers at the University of Massachusetts Amherst, has the potential to change the world of wearable electronics by providing power for a wide range of devices, from personal medical sensors to consumer electronics.
The project’s lead researcher, Xiaomeng Liu, describes this solution as “truly green energy and, unlike other so-called ‘green energy sources, its production is completely green.”
This biofilm is made naturally by a modified strain of the bacterium Geobacter sulfurreducens. It is composed of a thin layer of bacterial cells roughly the thickness of a sheet of paper. It has been investigated how to use this bacterium, which is known to create electricity, to electrical power equipment using “microbial batteries.”
Because they require G. sulfurreducens to be adequately cared for and fed a consistent diet, microbial batteries did not succeed as a solution. This novel biofilm is an exception; because it is dead and cannot be powered, it can continually produce as much energy, if not more, than a battery of comparable size.
Distinguished Professor of Microbiology at the University of Massachusetts Amherst and one of the paper’s lead authors, Derek Lovley, thinks it is “far more effective.” We have streamlined the electricity generation process by drastically lowering the amount necessary for processing. We use the clump of cells after they have grown sustainably in a biofilm. This streamlines operations, lower energy requirements and increases the range of possible uses.
This novel biofilm’s ability to produce energy from skin moisture is its secret. Even though we frequently read articles on solar energy, at least half of the solar energy that reaches the Earth is used to evaporate water. Jun Yao, a professor of electrical and computer engineering at UMass and the other paper’s lead author, asserts that “this is a major untapped energy source.” Since perspiration constantly dampens the surface of our skin, the biofilm can “plugin” and transform the energy locked in evaporation into sufficient energy to run small gadgets.
The key to how this all works is that G. sulfurreducens grows in colonies that resemble thin mats, with each bacterium interacting with its neighbours via a network of natural nanowires, as described in this research paper in Nature Communications. After gathering these mats, the team uses a laser to etch tiny circuits onto the films. The films are recorded, sandwiched between electrodes, and then encapsulated in a flexible, tacky, breathable polymer that may be applied directly to the skin afterwards. This tiny battery can power small devices once it has been “plugged in” to your body.
According to Yao and Liu, one objective is to power complete electronic systems rather than individual gadgets. “Our next step is to increase the size of our films to power more complex electronic devices that can be worn on the skin,” Yao says.