Researchers at Sandia National Laboratories are using off-the-shelf equipment to improve amputees' control over prosthetics with direct help from their own nervous systems. The goal is improved prosthetics with 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 connected to separate, implanted electronics.

Sandia's research focuses on biomaterials and peripheral nerves at the interface site. The idea is to match material properties to nerve fibers with flexible, conductive materials that are biocompatible so they can integrate with nerve bundles. Researchers are looking at flexible conducting electrode materials using thin evaporated metal or patterned multiwalled carbon nanotubes.

They began with a technique first patented in 1902 called electrospinning, which produces nonwoven fiber mats by applying a high-voltage field between the tip of a syringe filled with a polymer solution and a collection mat. Tip diameter and solution viscosity control fiber size. In collaboration with University of New Mexico's Center for Biomedical Engineering and department of chemical engineering, Sandia researchers worked with polymers that are liquid at room temperature. They were able to tune the conductivity of the final composite with the addition of multiwalled carbon nanotubes.

They are now seeking a way to fabricate more porous substrates through projection microstereolithography, which is being used to create biocompatible photo crosslinkable polymers. The technique is allowing the researchers to create a regular array of holes and to pattern holes as small as 70 microns. Now, researchers are using other equipment to create more controlled features.

Also: A portable, wearable system improves prosthesis fitting.