Most smartwatches and fitness wearables need to be designed in a certain way because they need to house a rigid battery. However, a team at Stanford has a good idea for how to fix that: what if you had a stretchable battery that could move with your body?

As first shown off on the Stanford engineering site, the stretchable battery prototype can move, bend, and stretch in all manners of ways. While that’s happening, the current created by the battery is unaffected.

In the video above, you can see how the battery (the goopy-looking white thing) powers a small LED light. Notice that as the person stretches and moves the battery around, the light doesn’t even so much as flicker.

The team at Stanford created this prototype based on previous technology. In many lithium-ion batteries (such as the one in your smartphone), there’s a polymer gel that moves negative ions to the battery’s positive pole, which creates energy. The Stanford team figured out a way to make that liquid polymer into a more solid material, which you see in the video.

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Not only does this make the battery easier to handle and less prone to leakage, but it also reduces the risk of the battery catching fire.

As one would expect, this prototype is not at all ready for any kind of commercial application. As of now, it stores about half as much energy, ounce-for-ounce, as a “normal” Li-ion battery. The team is hard at work though, making the battery stronger, able to hold more energy, and larger.

If this stretchable battery does become a commercial product, it could radically change the way wearable technology is designed. Imagine a wearable that wraps around your wrist in a consistent manner, rather than a band with a large protruding chassis holding a display and the battery. Sounds nice to us!