Researchers develop 'jelly-like' batteries to power wearable devices, brain implants - UPI.com (2025)

Researchers at Britain's Cambridge University have successfully developed soft, stretchable "jelly batteries" that could be used for wearable devices and soft robotics, or even implanted in the brain to deliver drugs or treat conditions such as epilepsy. Photo courtesy of Cambridge University.

The self-healing batteries can stretch 10-fold without any reduction in their conductivity, the first time a single material has combined the two properties, according to the research published in the peer-reviewed U.S. journal Science Advances.

The batteries are made of 3D networks of polymers, or hydrogels, that contain more than 60% water and are bonded in place by on-off interactions that precisely control the jelly's mechanical properties to mimic the characteristics of human tissue.

That characteristic makes hydrogels a perfect fit for soft robotics and bioelectronics, provided they also offer the conductivity and ability to flex lengthways.

"It's difficult to design a material that is both highly stretchable and highly conductive, since those two properties are normally at odds with one another," said first author Stephen O'Neill from Cambridge's Yusuf Hamied Department of Chemistry.

"Typically, conductivity decreases when a material is stretched."

The team were able to overcome the issue by charging the normally neutrally charged polymers of the hydrogels to make them conductive, said co-author Dr. Jade McCune, who works in the same lab as O'Neill.

"By changing the salt component of each gel, we can make them sticky and squish them together in multiple layers, so we can build up a larger energy potential.

"Conventional electronics use rigid metallic materials with electrons as charge carriers, while the jelly batteries use ions to carry charge, like electric eels. The hydrogels stick strongly to each other because of reversible bonds that can form between the different layers, using barrel-shaped molecules called cucurbiturils that are like molecular handcuffs," McCune said.

These strong bonds are what allow the jelly batteries to be stretched without the layers detaching from each other and critically, without any loss of conductivity.

The team believe the unique properties of the jelly batteries, particularly their softness and ability to mold to human tissue, mean they hold great promise for future use in biomedical implants.

"We can customize the mechanical properties of the hydrogels so they match human tissue," said research lead Professor Oren Scherman, director of Cambridge's Melville Laboratory for Polymer Synthesis.

"Since they contain no rigid components such as metal, a hydrogel implant would be much less likely to be rejected by the body or cause the build-up of scar tissue."

Scherman noted that the hydrogels also are incredibly durable polymers that, in addition to withstanding being squashed without permanently losing their original shape, could repair themselves after sustaining damage.

The researchers next plan to evaluate the hydrogels' suitability for use in a range of medical applications by conducting experiments using them in live organisms.

The project was conducted with funding from the European Research Council and the Engineering and Physical Sciences Research Council, part of UK Research and Innovation.