A bionic spinal cord for paralysis patients
Electrode could help steer bionic limbs or exoskeletons. Vivian Richter explains.
Paralysis patients may soon be back on their feet without risky open-brain surgery, thanks to a team of Melbourne medical researchers.
They developed a device that measures brain activity from inside a blood vessel and transmits signals that could steer bionic limbs or exoskeletons.
The revolutionary DARPA-funded brain-machine interface consists of an electrode attached to a matchstick-sized stent, similar to those used to keep arteries of heart disease patients open. The stent is made of nickel titanium, which can be tightly compressed, allowing the device to fit inside a narrow catheter.
This “stentrode” is fed through the jugular vein in the neck into a blood vessel in the brain’s motor cortex, the region that directs voluntary muscle movement. Once inserted, it expands and sticks to the inner wall of the vein, where it records electrical frequencies emitted by the surrounding nerves and transmits the signals to a computer.
Implanted in living, freely moving sheep, the device transmitted nerve activity for up to six months.
These signals, the authors say, could be used to control wheelchairs, exoskeletons, prosthetic limbs or computers.
“In essence this a bionic spinal cord,” first author Thomas Oxley explained. For now, the electrode transmits through a wire but eventually, the scientists say, the recordings will become wireless.
The device is intended for patients with spinal cord injuries, of which there are 20,000 in Australia alone. But the team says the stentrode could have application in other neurological diseases, such as epilepsy and Parkinson’s.
Where electrodes implanted directly on to the brain through invasive open-brain surgery can cause infections, senior author Terry O’Brien said the development of the stentrode has been the “holy grail” for research in bionics.
“To be able to create a device that can record brainwave activity over long periods of time, without damaging the brain is an amazing development in modern medicine,” he said.
In late 2017 paralysed human subjects will be selected from the Royal Melbourne and Austin Hospitals for the device’s first in-human trial. If successful, the researchers hope the device will reach the market by 2022.
The scientists published the device’s performance in Nature Biotechnology.