The Battery that can Stretch

Batteries that can stretch to up to 150% of their original size could revolutionise the design of wearable technologies...

"The design of wearable technology is currently limited by the energy source, our invention allows for the whole system to be stretchable," says Hanqing Jiang, lead author of the study. 

The stretchable batteries, designed by researchers at Arizona State University, are an ingenius invention combining engineering with the Japanese art form of Kirigami, which literally translates as 'paper-cutting'.

Not to be confused with the more popular origami, the art of paper folding, kirigami uses both folding and cutting to create more complex designs. It is the aspect of cutting that has allowed the idea of a stretchable battery to develop. As Hanqing explains, "origami relies on folding which changes the height of the battery. With kirigami, the height stays the same, so it is more versatile."

Their work, published in Scientific Reports this week, demonstrates how the design can successfully be used to power a Samsung Gear 2 smart watch whilst being subjected to movements that result in stretching. The battery was implanted in a stretchable wristband, which was then moved up the arm and onto the bicep, where it continued to power the watch even whilst the bicep was moving.

Using only the industry standard materials for battery production, they were able to achieve a level of performance comparable with that of a standard lithium-ion battery, but with a much more flexible device. "The batteries can stretch, twist and move with your body, they adapt to their physical environment" says Hanqing.

Current smart watches are approximately 1cm in thickness, with up to 70% of this being caused by the battery. Hanqing envisions "an entire strap containing the battery," which, when compared with current devices, could lead to "doubled energy capacity". So not only would your watch be thinner, it would also have twice the battery life.

With the recent launch of the Apple smart watch, the field of wearable technology is certain to be one of major growth over the coming years and the flexibility of this stretchable battery could give rise to even more wearable products in the form of headbands, wristbands and maybe even 'smart-clothes'.

"One of the most important aspects of wearable technology is how it looks, our batteries can be embedded in the fabric and become almost invisible", says Hanqing, "it will be much more stylish than a battery the size of a button."