Could this new technology let you charge your fitness tracker by sweating?

Using this sweaty solution, perhaps one day you could charge up your wearable without even having to take it off your wrist.

After a long day, it can be difficult to remember to slip your wearable off your wrist and put it on the charging stand so it’s ready for the next one; however, if this game-changing new technology is employed to the max then perhaps that niggling worry could become a thing of the past.

Ars Technica reports that a team of engineers at the University of California San Diego has designed a “biofuel cell” that can generate energy from the sweat on the tips of your fingers.

This ingenious idea is based on the fact that human fingertips proportionately produce a lot of sweat, most of which immediately evaporates and therefore goes unnoticed. With this biofuel cell however, sweat is absorbed by a hydrogel and enzymes from the electrodes then trigger a reaction between lactate and oxygen to produce electricity.

When applied to a test subject for 10 hours, the team found that this process had produces 400 millijoules of energy per square centimetre, which could power a simply electric wristwatch for 24 hours.

Evidently there’s going to be more work needed until it can power a demanding fitness tracker or smartwatch, but it’s a promising prototype that seems to only require a small strip about the size of a sticking plaster to be applied to the end of a finger. The idea of being able to charge up your device passively without relying on any external electricity is also potentially an attractive one as it would reduce reliance on the national grid. However, some people might be put off by the association with sweat, or just the nuisance of having something attached to your finger while you sleep.