Professor Michael Cima and his colleagues are now designing brain implants that can not only deliver electrical stimulation but also record brain activity or deliver drugs to very targeted locations. Image: Christine Daniloff/MIT
By making a brain implant smaller, researchers believe they can effectively fight several diseases including Parkinson’s disease and other neurological disorders.
Researchers from the Massachusetts Institute of Technology have made electrodes as small as 30-microns to eliminate brain scarring that diminishes the effectiveness of the implants and possibly require replacement surgeries as about half of implants stop working within the first six months.
“What we’re doing is changing the scale and making the procedure less invasive,” Michael Cima, the David H. Koch Professor of Engineering in the Department of Materials Science and Engineering and senior author of the study, said in a statement.
The implants could remain in the patient much longer than current implants being used.
Brain scarring, which contributes to the high failure rate of implants is caused by the electrodes constantly rubbing against the surrounding brain tissue.
Parkinson’s disease is often treated with low-frequency electrical current delivered to the part of the brain involved in movement control.
The implants also not only deliver electrical stimulation but also record brain activity or deliver drugs to a more targeted location. They are also coated with a soft polyethylene glycol (PEG) hydrogel which is expected to reduce scarring.
The coating has an elasticity similar to that of the brain. The researchers were able to dry the hydrogel after applying it to the electrode to prevent it from falling off once it is pushed into the brain. After it is dried the coating becomes a hard, thin film that soaks up water and becomes soft again.
The researchers tested the electrode in mice with both coated and uncoated glass fibers with varying diameters. They found that coated fibers produced significantly less scarring than the uncoated fibers but as the electrode fibers became smaller—down to about 30 microns in diameter—the uncoated versions produced less scaring.
“Before this paper, no one really knew the effects of size,” Cima said. “Softer is better but not if it makes the electrode larger.”
Cima and the researchers have had some success developing fibers that are only 30 microns in diameter and will continue to examine whether they can be adapted for electrical stimulation, drug delivery and recording electrical activity in the brain.
“It’s one of those things that at first glance seems impossible. If you have 30-micron glass fibers, that’s slightly thicker than a piece of hair. But it is possible to do,” Cima said.
