A team of Swedish and Israeli scientists has unveiled the world’s thinnest retinal implant, crafted from layers of gold and organic tattoo ink. The device is wireless, silicone-free, and 500 times slimmer than existing retinal implants, the researchers reported May 2 in the journal Advanced Materials.

If the implant performs as well in humans as it has in animal models, it could someday restore light perception to millions of people with degenerative eye conditions such as retinitis pigmentosa or macular degeneration. The device also holds promise for treating traumatic injury.

The platform is the latest effort to create a wireless workaround for faulty photoreceptors. Earlier this year, Chinese researchers fashioned artificial photoreceptors from an array of gold-flecked nanowires and used their prosthesis to restore the light response in a mouse model of degenerative blindness.

Rather than swapping out faulty photoreceptors for artificial ones, the new device bypasses photoreceptors entirely and acts directly on retinal ganglion cells. The team built the device by painting 2 layers of organic pigment on a base layer of gold. They immersed this superconductor sandwich in a saltwater solution to mimic the ocular environment. Upon exposure to light, they report, the device becomes charged and generates an electric field that stimulates nearby neurons.

The researchers tested the system in cultured neurons and in retinas from chicken embryos that had not yet developed photoreceptors. In both cases, the device generated enough electricity to power surrounding retinal neurons.

“That was the crowning achievement,” senior author Eric Glowacki, a principle investigator at Linköping University in Sweden, told Live Science. The device is the first non-silicone free-standing optoelectronic system capable of generating such power, he says. Unlike some commercially available implants, the new device accomplishes this feat without help from an external battery pack or other hardware. And the use of organic material may reduce the risk of rejection posed by silicone-based implants.

The team is now testing the device in live rabbits to see if it can confer a response to red light, which the animals normally cannot detect.