A team of scientists at the University of California San Diego has designed a new device that uses sweat from your fingertips to generate energy. Similar in appearance to a Band-Aid, a user can wrap this flexible, thin strip around their fingertips, and the wearable starts converting human sweat into electrical energy that can then be utilised to charge gadgets such as a smartwatch. Scientists say that a harvester that is independent from external environment for sedentary states had not been developed before their discovery. Since the fingers continuously produce sweat, the device doesn’t need the human to move excessively to power it, which is very common with conventional self-powered wearable systems.

The team says that their bioenergy-harvesting process can continuously collect “hundreds of millijoules (mJ) of energy” during sleep without movements. It represents the most efficient approach compared to any reported on-body harvesters. This bioenergy harvester constantly scavenges energy from human passive sweat, they added.

Such an energy harvester has great implications for future high-efficiency practical energy sources for wearable electronics, they said. The paper, “A passive perspiration biofuel cell: High energy return on investment,” has been published in the journal Joule.

According to a report by CNET, Joseph Wang, a professor at UC San Diego and co-author of the paper, said that the technology provides a net gain in energy with no effort from the user. He adds that the device uses sweat on the fingertip, which flows naturally irrespective of where you are or what you are doing.

Lu Yin, a PhD student and co-author of the paper, says that their work was a step towards making wearables more practical, convenient and accessible for everyone. Unlike other sweat-powered wearables, this one requires no exercise, no physical input from the wearer to be useful, Yin added.

In terms of energy generated by the device, with 10 hours of sleep the strip could collect about 400mJ of energy — enough to keep an electronic wristwatch running for 24 hours. Casual typing and clicking on the mouse for an hour resulted in the device collecting 30mJ, reported Mirror.

Yin said that their objective was to prove that this was not just another device and that they intend to put it to practical use such as making the energy to power sensors and displays.