A Battery Powered by Breaking a Sweat

As wearables become a common sight in our daily life, whether through smartwatches or fitness tracking devices, the need for new sources of electricity to power them is driving the research of innovative technologies. If some time ago we explored the potential of the human body as a source of renewable energy, by leveraging kinetic energy or emitted heat, now we will be focusing on the possibilities afforded by a substance like sweat. Jointly with the University of San Diego, the University of Grenoble Alpes has developed a foldable and stretchable device that can be placed on the skin and is able to produce electric power through one of the most common “biofuels” — human sweat.  

This innovative technology project is the outcome of bringing together the expertise of the bioelectrochemistry team from the University of Grenoble Alpes and the knowledge of their American counterparts regarding nanomachines, biosensors, and nanobioelectronics. The basic principle is the reduction of oxygen and the oxidation of the lactate present in perspiration. As to the type of materials they have used for the device, the developers of this technology project have worked with a mesh of nanotubes, polymers, and enzymes that carry a set of flexible connectors printed straight on the surface. The anode is an enzyme that obtains electrons from the lactate and transfers them to a molecule that works as a cathode.

While they have ended up creating a biobattery, the initial goal for the technology project was to develop a lactate sensor that would enable real-time measurement of physical effort. Ironically, they soon discovered that the less fit volunteers produced much more electricity. This is due to the fact that, when working out, sedentary people release much more lactate, the compound behind the muscular pain experienced in these situations.

The new biobattery, however, will not be replacing nuclear power plants for the time being, as it only generates enough electricity to power a small LED diode. According to its creators, they are currently able to produce only 70 microwatts worth of power per square centimeter. Nevertheless, this battery is a simple-manufacturing and low-cost technology that the researchers hope to optimize in the future so it can power more demanding devices.

Bacterial batteries

The battery developed by the University of Grenoble Alpes is far from being the only example of a technology tapping on the potential of perspiration to generate electricity. Two years ago, researchers from the University of Binghamton in New York announced another battery model based on a stretchable material that carries bacteria able to produce electricity by feeding on sweat. Under this approach, the material would be embedded into sportswear in order to power IoT devices. The developers of this new technology are also exploring the potential applications of the electric charge found in the millions of bacteria inhabiting the human body.

Source: Science Daily, Fast Company