Researchers from Chalmers University of Technology, the University of Freiburg, and the Netherlands Institute for Neuroscience have created a tiny vision implant that stimulates the brain’s visual cortex with electrical impulses, similar to pixels on a screen.
The implant’s electrodes, the size of a neuron, are intricately placed on threads as thin as half a strand of hair. Crafted from non-corrosive material, this implant offers a permanent, more efficient solution for blindness.
When someone is blind, their eyes may be damaged, but their brain’s visual cortex still works. To restore sight, thousands of electrodes are needed to stimulate the brain. Each electrode represents a pixel in the image created by electrical impulses.
Maria Asplund, a professor at Chalmers University, compares this image to a highway matrix board, with dark spaces and lit spots based on the given information. The more electrodes used, the more precise the image. The vision implant in this study is like a thread with many electrodes in a row. This research is a step toward implants with thousands of electrodes for better vision restoration.
While electrical vision implants have existed since the 1990s, current technology has limitations, such as bulky size, brain scarring, and material corrosion. Researchers aim to solve these issues by creating tiny electrodes the size of neurons, allowing for more detailed images.
Flexible, non-corrosive materials promise long-term solutions. Professor Asplund states that the main question was whether they could fit many electrodes onto a small, effective implant. This study shows it’s possible.
Creating a small-scale electrical implant poses challenges, especially in the human body’s harsh conditions. The main obstacle is ensuring longevity in a moist environment. Traditional implants corrode due to metal parts, which are both functional and prone to corrosion.
Asplund’s team developed an implant 40 micrometers wide and 10 micrometers thick, with metal parts only a few hundred nanometers thick. To prevent corrosion, they layered materials, including a conducting polymer that protects the metal and ensures durability. This polymer acts as a shield, preventing corrosion and maintaining functionality.
Maria Asplund, who led the technology development part of the project and is a Professor of Bioelectronics at the Chalmers University of Technology in Sweden, said, “The conducting polymer-metal combination we have implemented is revolutionary for vision implants as it would mean they hopefully could remain functional for the entire implant lifetime. We now know it is possible to make electrodes as small as a neuron (nerve cell) and keep this electrode effectively working in the brain over very long timespans, which is promising since it has been missing. The next step will be to create an implant with connections for 1000s of electrodes.
Journal reference:
- Corinne Orlemann, Christian Boehler, et al., Flexible Polymer Electrodes for Stable Prosthetic Visual Perception in Mice. Advanced Healthcare Materials. DOI: 10.1002/adhm.202304169.