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Absorbent film could lead to sweat-powered wearables

Out There | January 25, 2021 | By:

Shoe insoles made with the sweat-absorbing film change color from blue to pink as they absorb moisture. Photo: National University of Singapore

Researchers at the National University of Singapore (NUS) have developed a new film that can absorb sweat and potentially use the moisture to power wearable electronics. For sweat to cool us down properly, it needs to evaporate, which carries the heat away. The new film is designed to speed that process up, with the research team claiming it works six times faster and absorbs 15 times more moisture than existing materials.

The film is made from two key chemicals, cobalt chloride and ethanolamine, which are effective water absorbents. These are set into PTFE (polytetrafluoroethylene) membranes, which are waterproof, breathable and flexible. The researchers believe that if the resulting material was incorporated into shoe insoles or underarm pads, it could keep wearers drier and more comfortable, particularly in hot weather or while exercising.

Additionally, the film changes color as it absorbs moisture, starting off blue, then turning purple and eventually pink, which can show the wearer how “full” it is. The material will also release the trapped water when placed in sunlight, so it is believed that it can be reused over 100 times.

In another test, the team created a material that generates energy by absorbing moisture, using the new film as an electrolyte. This is sandwiched between eight electrochemical cells, each generating about half a volt, which together is enough to power an LED. Although that’s a very small amount of power, as a proof of concept it suggests that low-power wearable electronic devices could one day be powered by sweat.

The research was published in the journal Nano Energy.

Source information was provided by the National University of Singapore and reported on

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