Eel-inspired hydrogel battery delivers record power without toxic materials

Electric eels can unleash 600 volts from cells thinner than a human hair, and now scientists at Penn State have borrowed that biological blueprint to create flexible batteries that could revolutionize medical implants and wearable technology. The researchers layered water-rich hydrogels just 20 micrometers thin, mimicking the ionic processes that give eels their shocking power.

"The electrocytes in electric eels are ultra-thin biological cells, capable of generating over 600 volts of electricity in a brief burst," says Joseph Najem, assistant professor of mechanical engineering. "These cells achieve very high-power densities, meaning they can produce a lot of power from small volumes."

Unlike previous eel-inspired devices that required rigid supports, these hydrogel batteries remain completely flexible while surviving extreme temperatures from minus 112 to 80 degrees Fahrenheit. The breakthrough came from perfecting the spin-coating process that creates ultra-thin layers without them flying off the spinning surface.

The batteries achieve power densities of 44 kilowatts per cubic meter while remaining non-toxic and water-retaining for days, opening possibilities for implanted sensors and soft robotics that need safe, flexible power sources.