Scientists have developed a stretchable battery to be used for robotic skins, bionic eyeballs and brain-wave monitoring devices.

The battery was demonstrated by Yonggang Huang of Northwestern University and John A. Rogers of the University of Illinois. Because of its unique design and the fact that it doesn't need to be plugged into an electrical outlet, the battery is quite versatile in its use and could even be used in humans.

 The new device is essentially a silicone sheet comprised of small lithium-based batteries. It can stretch up to three times its original length.

Stretchy, thin batteries have been created before, but performance for these devices has tended to be poor. Unlike the new battery, they also did not have the ability to charge wirelessly. In creating their new device, Huang and fellow researchers embedded the smaller lithium-based batteries into an S-shaped framework of conducting wires.

"We start with a lot of battery components side by side in a very small space, and we connect them with tightly packed, long wavy lines," Huang said. "These wires provide the flexibility. When we stretch the battery, the wavy interconnecting lines unfurl, much like yarn unspooling. And we can stretch the device a great deal and still have a working battery."

In order to demonstrate the battery, the researchers stretched and twisted it while powering a red light-emitting diode (LED). These types of batteries are so innovative that the market has hardly any space for them at this time.

"Batteries are particularly challenging because, unlike electronics, it's difficult to scale down their dimensions without significantly reducing performance," Rogers said.

Despite the remarkable innovation of the battery, the power it produces is not enough to keep a laptop or large light bulb running. This narrows its use down to sources that require little power, such as biological implants.

"It's for a niche market," says Lawrence Berkeley National Laboratory chemist Gao Liu. "You really need to find a market where you don't really need much energy, but you need to deliver the energy on the spot, where you couldn't use a wire."

The battery was featured on Tuesday Feb. 26 in the journal Nature Communications.