Concurrent optical and electric stimulation of spinal cord via rubbery fibers

Implantable fibers are one of the major breakthroughs in the field of brain research. It has enabled researchers to stimulate particular targets in the brain and assess the electric responses. However, similar trials in the spinal cord nerves, which can eventually result in treatments that can improve the injuries of the spinal cord, are critical to conduct. This is because the spine stretches and flexes with the movement of the body. And also the comparatively stiff, fragile fibers utilized at present can injury the frail tissues of the spinal cord.

The traditional optic fibers that are utilized in optogenetics studies do twist fairly but do not compress or stretch. Recently, a research team has designed a rubber-like fiber that can stretch and flex while at the same time deliver optical impulses as well as electric connections for optoelectronic stimulation and monitoring & stimulation, respectively.

The researchers merged coating made up of silver nanowires mesh that generates a conductive sheet for electrical signals and a newly designed translucent elastomer that functions as a waveguide for the optical impulses. In order to process this translucent elastomer, the substance was implanted in a polymer covering that made it possible to frame it into a fiber, which was validated to be flexible as well as stretchable according to the team. After the drawing procedure, the cladding was dissolved.

After the complete fabrication procedure, what remains is the translucent fiber with electrically conductive, flexible nanowire coverings. As stated by a team member, Professor Polina Anikeeva, “It is actually just a part of rubber, but what makes the difference is that it is conductive. The fiber can extend by at least 20–30% without influencing its properties.” The fibers are not only flexible but also very stretchable.

The team successfully utilized these new fibers in liberally moving mice demonstrating that they were able to read the electrical impulses from the spinal cord and also excite it with the use of light and electricity.

Chi Lu said, “We are the first to design something that makes it possible to concurrently do optical stimulation and electrical recording in the freely moving mice’s spinal cords. So, we expect our study comes up new opportunities for neuroscience research.”