Researchers from Chalmers University of Technology in Sweden, University of Freiburg, and the Netherlands Institute for Neuroscience have developed a tiny implant with electrodes the size of a single neuron. This implant can also stay in the body for a long time, which is a unique feature. This combination shows potential for future vision implants for blind individuals.
When a person is blind, their eye or part of it may be damaged, but the visual cortex in the brain is still functioning and ready for input. In order to restore sight, thousands of electrodes would need to be implanted to provide enough information to create an image. By sending electrical impulses to the visual cortex, an image can be created, with each electrode representing a pixel.
It’s important to note that the image created by electrical impulses would not be the same as what someone with full vision would see. Instead, it would be a simplified representation.
According to Maria Asplund, a Professor of Bioelectronics at Chalmers University of Technology in Sweden, the trix board on a highway is a dark space with spots that light up based on the given information. The more electrodes that are connected to it, the better the image will be. The vision implant developed in this study can be compared to a ‘thread’ with multiple electrodes arranged in a row. In the future, multiple threads with thousands of electrodes connected to each one will be needed, and the findings of this study are an important step towards achieving this goal.
The future of vision implants is an electrical implant designed to improve vision in blind individuals. While the concept is not new, the current implant technology being explored in human patients dates back to the 1990s and has several limitations that need to be addressed. These include the bulky size of the implants, scarring in the brain due to their large size, corrosion of materials over time, and rigidity of the materials.
Researchers are now working on creating smaller electrodes, the size of a single neuron, which could potentially allow for more electrodes to be fitted onto a single implant. This would in turn provide a more detailed image for the user. The unique aspect of this new technology is its ability to overcome the limitations of previous vision implants and pave the way for significant advancements in the field.The use of pliable and non-corrosive materials makes this vision implant a durable solution in the long run.
“It is crucial to miniaturize the components of the vision implant, particularly the electrodes, in order to stimulate a large number of spots in the brain’s visual areas. The primary research inquiry for the team was whether we could fit numerous electrodes on an implant with the available materials, make it small enough, and still ensure its effectiveness. This study’s findings confirm that it is indeed achievable,” explained Professor Asplund.
As the size decreases, the risk of corrosion increases
Creating a small-scale electrical implant presents significant challenges, especially in a harsh environment like the human body. The main hurdle is not simply making the electrodes small, but ensuring that they can last a long time in a moist and humid environment. Corrosion of metals in surgical implants is a major issue, and since the metal is both the functional part and the part that corrodes, the amount of metal used is crucial. The electrical implant developed by Asplund and her team is incredibly small, measuring just 40 micrometers wide and 10 micrometers thick, similar to a split hair, with the metal parts being only a few hundred nanometers.< p >The vision electrode is incredibly small, measuring just a few millimeters in thickness. The tiny amount of metal in the electrode makes it essential that it does not corrode, as this would cause it to stop working.
In the past, solving this problem has been challenging. However, the research team has developed a special combination of materials that are layered together to prevent corrosion. This includes a conducting polymer that converts the electrical stimulation needed for the implant to function into electrical responses in the neurons. The polymer creates a protective layer on the metal, making the electrode much more resistant to corrosion. In essence, it acts as a protective layer of plastic. < /p>
The combination of conducting polymer and metal that we have used is groundbreaking for vision implants because it could potentially allow them to remain functional for the entire lifetime of the implant. We have discovered that it is feasible to create electrodes as small as a neuron (nerve cell) and maintain their effectiveness in the brain over long periods of time, which is a promising development that has been lacking until now. Our next objective is to develop an implant that can accommodate connections for thousands of electrodes,” explains Asplund. This is currently being investigated as part of a larger team effort in the ongoing EU project Neuraviper.
More about: the study method
The research method was utilized by the research partners at the Netherlands Institute for Neuroscience. They trained mice to respond to an electrical impulse to the visual cortex of the brain. The study revealed that the mice were able to learn to react to the stimulation from the electrodes in just a few sessions. Additionally, the minimal current threshold for which the mice reported a perception was lower than standard metal-based implants. The research team also observed that the functionality of the implant remained stable over time, with one mouse even retaining functionality until the end of its natural life.
