Now, a Melt-Into-The-Brain Silk Implant
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20 April 2010
Flexible Device’s Electrodes Can Help People With Spinal Injuries Move Their Arms And Legs
A brain implant made partly of silk can melt onto the surface of the brain, providing an “intimate” connection for recording signals, researchers reported.
Tests of their device showed the thin, flexible electrodes recorded signals from a cat’s brain more accurately than thicker, stiff devices.
Such devices might help people with epilepsy, spinal cord injuries and even help operate artificial arms and legs, the researchers report in the journal Nature Materials.
John Rogers of the University of Illinois, Urbana, and colleagues at the University of Pennsylvania and Tufts University in Boston made the electrode arrays using protein from silk and thin metal electrodes.
The silk is biocompatible and water-soluble, dissolving into the brain and leaving the electrodes draped over its contours, the experts reported.
They tested them on cats who were anesthetized but whose eyes were functioning. The electrodes recorded the signals from the eyes of the cats as they were shown visual images.
“These implants have the potential to maximize the contact between electrodes and brain tissue, while minimizing damage to the brain,” said Walter Koroshetz of the National Institute of Neurological Disorders and Stroke, part of the National Institutes of Health, which helped pay for the study.
“They could provide a platform for a range of devices with applications in epilepsy, spinal cord injuries and other neurological disorders.”
For instance, such a sensitive electrode could detect a seizure as it starts and deliver pulses to counter it. Brain signals might be routed to prosthetics for people with spinal cord and other injuries.
In people with epilepsy, the arrays could be used to detect when seizures first begin, and deliver pulses to shut the seizures down, while in case of spinal cord injuries, the technology could read complex signals in the brain that direct movement and routing those signals to healthy muscles or prosthetic devices.
The implants contain metal electrodes that are about five times the thickness of a human hair. The absence of sharp electrodes and rigid surfaces should minimize damage to brain tissue.
Also, the implants’ ability to mould to the brain’s surface could provide better stability; the brain sometimes shifts in the skull and the implant could move with it, said a University of Pennsylvania’s School of Medicine release. Finally, by spreading across the brain, the implants have the potential to capture the activity of large networks of brain cells.
Silk is also transparent, strong and flexible, and it is possible to control the rate at which it dissolves.