A domestic research team developed a transparent electrode that can deliver light to the brain while simultaneously reading neural signals and confirmed signals in animal tests similar to actual visual responses.
A joint team led by researchers Seong Hye-jeong and Im Mae-sun at the Brain Science Institute of the Korea Institute of Science and Technology (KIST) said on the 30th that they developed an ultrathin transparent neural electrode and succeeded in generating artificial visual signals in the brains of blind mice.
The technology targets diseases in which the retina's light-sensing cells are damaged, such as retinitis pigmentosa. In such cases, the eyes cannot properly receive light, but the brain regions that process visual information may retain function to some extent. Focusing on this point, the team tested a method of stimulating the brain's visual center with light without going through the eyes.
The core of the technology is an electrode that transmits light well while accurately reading brain signals. Conventional metal electrodes are advantageous for measuring neural signals but block light. Conversely, transparent electrodes let light through but have inferior performance in reading electrical signals.
The team reduced this limitation by applying a special coating to the electrode surface to deposit gold very thinly and uniformly. They reduced the gold film thickness to the 10-nanometer (nm, one-billionth of a meter) level and made the total electrode thickness as thin as about 4 micrometers (μm, one-millionth of a meter). It is much thinner than a hair, making it easy to conform to the brain surface.
The developed electrode transmitted more than 65% of light while maintaining conventional-level neural signal measurement performance. Electrical noise generated during light stimulation was reduced by up to 74%, and performance was maintained even after 20,000 crumpling-and-unfolding cycles.
The team placed the electrode on the brain surface of blind mice and stimulated neurons in the visual center with blue light. As a result, artificial visual signals appeared that were 78% similar to the brain signals of mice with normal vision. They confirmed that it is possible to generate signals in the brain close to visual responses without going through the retina.
However, the results are at the animal testing stage. To apply the technology to actual patients, further verification is needed on long-term safety, the precision of visual information, and human applicability. The team noted that the technology could be used not only for artificial vision in the future but also for restoring hearing and touch and for brain-computer interface (BCI) technology.
Im Mae-sun, principal researcher at KIST, said, "Because it can process light and signal technologies simultaneously, it lays the foundation to evolve into an advanced BCI system," adding, "We expect it will take us a step closer to improving the quality of life for people suffering from intractable neurological and sensory diseases."
The study was published as the cover article in the latest issue of the international journal Advanced Functional Materials.
References
Advanced Functional Materials (2026), DOI: https://doi.org/10.1002/adfm.202531459