Diamond implants inside the body can cure paralysis.
Two Case Western Reserve University researchers are building implants made of diamond and flexible polymer that are designed to identify chemical and electrical changes in the brain of patients suffering from neural disease, or to stimulate nerves and restore movement in the paralyzed.
AdvertisementThe work of Heidi Martin, a professor of chemical engineering, and Christian Zorman, a professor of electrical engineering and computer science, is years from human trials but their early success has drawn interest worldwide.
"Right now, we're trying to develop diamond-coated electrodes for implantable devices which last a lifetime. A patient would have one surgery and that's it," said Martin.
Unlike standard electrodes, diamonds won't corrode, said Martin.
Diamond is so hard and rigid, however, that an entire implant made of the stuff would quickly damage surrounding tissue and the body would seal off the implant as if it were a splinter, said Zorman.
The key is to use just enough diamond.
"We only need diamond at the biological interface - where the device connects with a nerve," said Zorman.
Martin's lab grows diamond film - real diamond - under high temperature, in a vacuum. By adding impurities they change the diamond's properties.
For electrodes, the team adds boron, turning the diamond blue. Blue diamonds, including the famous Hope Diamond at the Smithsonian, conduct electricity.
Because diamond is made at 800 to 900 degrees Celsius, a temperature that would melt the polymer base, Martin first selectively grows a series of tiny squares of diamond film on silicon dioxide, the stuff of sand and quartz.
Zorman's group then lays down a thin flexible polymer that fills in the gaps between diamonds, followed by a layer of metal that connects to the back of the diamonds and will conduct electricity.
Lastly, he adds a thick layer of flexible polymer base. They then dip the device in hydrofluoric acid, which eats away the silicon dioxide and frees the probe.
Small, cortical probes that measure chemical changes at a location in the brain or along a nerve have two diamond contacts affixed.
These probes are designed to assist health researchers who are trying to understand the role of chemicals in stimulating nerves or communicating within the brain.
Recent research has found, for example, a link between a deficiency in the neurotransmitter dopamine and Parkinson's disease.
Martin and Zorman also build electrodes with arrays of eight or more electrically-connected diamond segments.
These are designed for neruoprostheses, to stimulate nerves, enabling a paralysed patient to stand or a blind patient to see.
Lab tests show one diamond-coated electrode can monitor chemical and electrical signals as well as stimulate nerves. (