Neural implants have the potential to treat disorders and diseases that typically require long-term treatment, such as blindness, deafness, epilepsy, spinal cord injury, and Alzheimer’s and Parkinson’s. However, implantable devices have been problematic in clinical applications because of bodily reactions that limit device functioning time. Graphene neural implants could be made to last longer (perhaps 5 years) and could be smaller than current implants.
Mark Ming-Cheng Chen (Wayne State has an NSF grant) is studying the potential of graphene, a novel carbon material, in the development of a reliable, high-performance, long-term implantable electrode system to improve quality of life using nanotechnology
Cheng hypothesizes that graphene might be better suited to long-term treatment than platinum and iridium oxide, two of the most popular materials now used to make implantable electrodes. Making platinum and iridium oxide electrodes small enough to be implanted reduces the amount of charge they can carry and therefore limits their ability to stimulate neural connections. Additionally, Cheng said, signals from these electrodes to machines that record neural activity often contain a lot “noise” because of the impedance levels of the materials.
Graphene, he said, enables a larger electrical charge and can be made smaller than previous electrodes, yet still big enough to do the job. The smaller size and higher conductivity also decreases impedance, enabling clearer readings of neural activity, Cheng said.
Using graphene electrodes poses a challenge, however, because its flexibility makes it difficult to insert into tissue. In order to overcome that issue, Cheng plans to use a porous silicone “backbone” that slowly and safely biodegrades into brain tissue while releasing anti-inflammatory medication, thus limiting the formation of scar tissue.
Though it’s too early to tell how long a graphene electrode will hold up after implantation, Cheng said a five-year lifespan would yield a “huge” number of potential applications in areas like neuroscience, drug delivery, bioelectronics, biosensors and security.