The idea is to match material properties of prosthetics to nerve fibers, using conductive materials that are biocompatible so they can integrate with nerve bundles.
The prosthetics will have flexible nerve-to-nerve or nerve-to-muscle interfaces through which transected nerves can grow, putting small groups of nerve fibers in close contact to electrode sites,which are connected to separate, implanted electronics.
These interfaces operate where the nervous system and an artificial device intersect. Interfaces can monitor nerve signals or provide inputs that let amputees control prosthetic devices by direct neural signals, the same way they would control parts of their own bodies.
The researchers are looking at flexible conducting electrode materials using thin evaporated metal or patterned multiwalled carbon nanotubes.
The Amputee Coalition estimates 2 million people in the United States are living with limb loss. The Congressional Research Service reports more than 1,600 amputations involving U.S. troops between 2001 and 2010, more than 1,400 of those associated with the fighting in Iraq and Afghanistan. Most were major limb amputations.
Interfaces must be structured so nerve fibers can grow through. They must be mechanically compatible so they don’t harm the nervous system or surrounding tissues, and biocompatible to integrate with tissue and promote nerve fiber growth. They also must incorporate conductivity to allow electrode sites to connect with external circuitry, and electrical properties must be tuned to transmit neural signals.