Conductive polymer coatings that weave their way into implanted tissue might one day improve the performance of medical implants, such as cochlear implants and brain stimulators used to treat Parkinson’s disease. In early studies, neural interfaces coated with an electrically conductive polymer outperformed conventional metal counterparts. Scientists at the University of Michigan hope that the material’s novel properties will help lessen the tissue damage caused by medical implants and boost long-term function.
Use of devices that are surgically implanted into the brain or other parts of the nervous system is growing rapidly. Cochlear implants, which help deaf people hear, and deep brain stimulation, which relieves symptoms of Parkinson’s disease, for example, are approved by the Food and Drug Administration. Both work by stimulating nerve cells via an implanted electrode. Devices that record and translate neural activity are also under development for people with severe paralysis.
But as use of neural implants grows, so does concern over the damage that those devices can impose on neural tissue. Insertion of the rigid metal electrode into soft tissue triggers a cascade of inflammatory signals, damaging or killing neurons and triggering a scar to form around the metal. “We hope to come up with a way to communicate across the scar layer and send information to and from the device in a way that is as friendly as possible,” says David Martin, a materials scientists at the University of Michigan, in Ann Arbor, who is leading the research into the polymer coatings.