Better Implants to Treat Diseases

Photo: neurons

Microelectrodes can communicate
with individual neurons;
© University of Michigan (U-M)

The coating helps the devices operate longer and could improve treatment for deafness, paralysis, blindness, epilepsy and Parkinson's disease.

Brain implants operate in one of two ways. Either they stimulate neurons with electrical impulses to override the brain's own signals, or they record what working neurons are transmitting to non-working parts of the brain and reroute that signal.

On-scalp and brain-surface electrodes are giving way to brain-penetrating microelectrodes that can communicate with individual neurons, offering hope for more precise control of signals.

In recent years, it was demonstrated that these implanted microelectrodes can let a paralysed person use thought to control a computer mouse and move a wheelchair. The researchers say their new coating can most immediately improve this type of microelectrode.

The new coating is made of three components that together allow electrodes to interface more smoothly with the brain. The coating is made of a special electrically-conductive nanoscale polymer called PEDOT; a natural, gel-like buffer called alginate hydrogel; and biodegradable nanofibers loaded with a controlled-release anti-inflammatory drug.

The PEDOT in the coating enables the electrodes to operate with less electrical resistance than current models, which means they can communicate more clearly with individual neurons.

The alginate hydrogel, partially derived from algae, gives the electrodes mechanical properties more similar to actual brain tissue than the current technology. That means coated neural electrodes would cause less tissue damage.

The biodegradable, drug-loaded nanofibers fight the "encapsulation" that occurs when the immune system tells the body to envelop foreign materials. Encapsulation is another reason these electrodes can stop functioning properly. The nanofibers fight this response well because they work with the alginate hydrogel to release the anti-inflammatory drugs in a controlled, sustained fashion as the nanofibers themselves break down.

MEDICA.de; Source: University of Michigan