Researchers at the University of British Columbia have invented a thin, flexible battery that can be tossed into a load of laundry and survive.

The washable works when twisted and stretched to twice its normal length and could be a boon for the wearable electronics industry, which includes both smart clothes and smart accessories, like watches.

“Wearable electronics are a big market and stretchable batteries are essential to their development,” said Ngoc Tan Nguyen, a postdoctoral fellow at UBC’s faculty of applied science, in a news release.

“However, up until now, stretchable batteries have not been washable. This is a critical addition if they are to withstand the demands of everyday use.”

According to the release, Nguyen and his colleagues averted the need for hard battery casing by grinding the compounds — zinc and manganese dioxide — into small pieces and embedding them in rubbery plastic.

There are several “ultra-thin” layers of these polymers wrapped in a casing of the polymer, creating a waterproof seal that has so far, withstood 39 wash cycles.

Zinc and manganese are safer when worn next to the skin than typical lithium-ion batteries, which can produce toxic compounds if they break, Nguyen added.

According to UBC, the invention has already attracted commercial interest.

By the time the battery is ready for the market, it could cost the same amount as an ordinary, rechargeable battery.

“The materials used are incredibly low-cost, so if this is made in large numbers, it will be cheap,” said electrical and computer engineering professor Dr. John Madden, director of UBC’s Advanced Materials and Process Engineering Lab.

“In addition to watches and patches for measuring vital signs, the battery might also be integrated with clothing that can actively change colour or temperature.”

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