University of Melbourne medical researchers have created a new minimally invasive brain-machine interface, giving people with spinal cord injuries hope to walk again with the power of thought.

The brain-machine interface consists of a stent-based electrode ("stentrode") that is implanted within a blood vessel next to the brain and records the type of neural activity that has been shown in pre-clinical trials to move limbs through an exoskeleton or to control bionic limbs. The new device is the size of a small paperclip and is capable of recording high-quality signals emitted from the brain’s motor cortex without the need for open-brain surgery.

This tiny device can read signals from the brain's motor cortex. Image credit: University of Melbourne.“We have been able to create the world’s only minimally invasive device that is implanted into a blood vessel in the brain via a simple day procedure, avoiding the need for high-risk open-brain surgery," says Dr. Thomas Oxley, neurologist at the Royal Melbourne Hospital and research fellow at the University of Melbourne.

“Our vision, through this device, is to return function and mobility to patients with complete paralysis by recording brain activity and converting the acquired signals into electrical commands, which in turn would lead to movement of the limbs through a mobility-assist device like an exoskeleton. In essence this a bionic spinal cord,” he adds.

Dr. Nicholas Opie, co-principal investigator and biomedical engineer at the University of Melbourne, says the concept is similar to an implantable cardiac pacemaker—electrical interaction with tissue using sensors inserted into a vein—but inside the brain.

“Utilizing stent technology, our electrode array self-expands to stick to the inside wall of a vein, enabling us to record local brain activity. By extracting the recorded neural signals, we can use these as commands to control wheelchairs, exoskeletons, prosthetic limbs or computers,” he says.

In in-human trials, which will begin in 2017, the researchers aim to achieve direct brain control of an exoskeleton for three people suffering from paralysis.

“Currently, exoskeletons are controlled by manual manipulation of a joystick to switch between the various elements of walking—stand, start, stop, turn. The stentrode will be the first device that enables direct thought control of these devices,” Opie says.

In addition to spinal cord injury and stroke victims, the researchers say the device can also be used in people with a range of other conditions, including epilepsy and Parkinson's disease.