Scientists in the US have developed a new brain implant that can be used to record information from nerve cells, and also to transmit signals into the nervous system, to stimulate parts of the brain.
Unlike existing electrode devices, which can trigger a scar to form around the implant that eventually prevents it from working, the new device, developed by Harvard’s Charles Lieber, is made from a polymer-coated conductive nickel mesh that is very well tolerated by the host tissue.
The springy nature of the mesh means that it is very simple to deploy and can be rolled up and drawn inside a needle measuring less than a tenth of a millimetre across.
This permits injection into the brain with minimal harm and high precision. A small section of the mesh assembly is left projecting above the brain surface to act as a connector so that signals can be read off, or transmitted into the underlying brain tissue.
"Unlike conventional implants used for things like deep brain stimulation in Parkinson's disease, these electrodes are very well tolerated," explains Lieber. "We see no inflammatory reaction or 'gliosis' as you do with other devices, and they keep working for extended periods."
The key to the breakthrough appears to be the spring-like, open structure of the meshwork, and the sticky polymer coating that covers the nickel. Lieber likens the structure to the chicken wire you might use to enclose a vegetable patch. "Plants like a chicken wire enclosure because they can grow through it and light can also get through. It's the same with these implants. The nerve cells can grow up to and through the mesh, and even make connections to the mesh."
At the moment the Harvard team have tested the device, details of which they published this week in Nature Nanotechnology, only in rats and mice. "Regulations are a bit more difficult for humans," laughs Lieber. But they are confident that their device has the potential to be a neurological game-changer that can improve substantially on the present generation of implants used for Parkinson's Disease and even help patients with more severe disabilities resulting from strokes and trauma. "We're scientists, so we like to dream about the future," says Lieber. Who knows, equipped with one of his own implants, we might even be able to decode those dreams one day...