A brain implant the size of a paper-clip might one day help paralyzed people regain the ability to use their arms and legs via a wireless connection that will transmit their thoughts to an exoskeleton.

It's not the first technology to allow paralyzed people to operate mechanical limbs with signals from their brain, but it has the potential to revolutionize the field because it's minimally invasive and totally wireless. 

It's made possible because of a matchstick-sized implant called a stentrode, crafted from nitinol, an alloy that  is commonly used  in brassiere underwires and eyeglass frames, according to a study published in the journal Nature Biotechnology

​"It's really a new method for getting brain data out of the brain without performing brain surgery," Thomas Oxley, a neurologist at the University of Melbourne who designed the device, told CBC News.

"Part of the reason that brain-machine interfaces have not been successful to this point is because they get rejected by the body, and the reason they get rejected is because they all require direct implantation into the brain. And to do that you have to take off the skull — you have to perform a craniotomy."

exoskeleton

A stentrode will transmit signals from a paralyzed person's brain to an exoskeleton like this one. (Rex Bionics)

The new technology —  developed by a team scientists from the University of Melbourne's medicine, science, veterinary science and engineering faculties — is implanted in a blood vessel next to the motor cortex, the region of the cerebral cortex involved in the planning, control and execution of voluntary movements. The stentrode eliminates the need for complex surgery.

The researchers were inspired by advancements in cardiac medicine that allow pacemakers to be inserted via blood vessels, rather than through open-heart surgery.

"We had the same idea. You go up through the arteries, or through the blood vessels, up into the brain, choose the part of the brain you want, and then deposit the electrodes inside the blood vessels right next to the brain, but never go actually into the brain," Oxley said.

Once the implant is safely nestled near the motor cortex, it will theoretically be able to pick up signals from the brain and transmit them to an exoskeleton — allowing a patient to move their limbs with the power of their own thoughts.

stentrode

The stentrode can record brain signals from within a blood vessel next to the brain and pass them wirelessly through the skin to enable control of an exoskeleton. (University of Melbourne)

The stentrode has already proven safe and painless in tests on sheep. The researchers hope to begin human trials in 2017 on a select group of people who have been left paralyzed by spinal cord injuries.

However, it won't be quick or easy, Oxey said. 

"The trial is going to involve a learning period where the patients have to learn how to activate the device in their brain," Oxley said. "It's kind of like learning how to play a new sport or learning how to play the piano — it takes time."

The stentrode could have implications for a wide range of neurological disorders if it works, he said. 

For example, an implant in people with epilepsy could record brain activity and potentially predict an oncoming seizure, he said. 

Or it could provide a less-invasive alternative to deep brain stimulation, a process wherein doctors implant electrodes deep inside the brain to treat a range of disorders including Parkinson's disease, severe depression and obsessive-compulsive disorder. 

If tests prove successful, the researchers hope to bring the device to market by 2022.