Swiss engineers have unveiled a lightweight and portable hand exoskeleton that can be controlled by the brain.
The exoskeleton is designed to be operated by people who cannot otherwise move their hands due to injury or other disabilities.
Metal cables act as soft tendons along the back-side of each finger, leaving the palm free in order to maximise sensations felt by the hand.
A chest-pack contains motors that can push and pull on the different cables, flexing the fingers when the cables are pushed and extending them when pulled.
The control interface can be anything from eye-movement monitoring for the severely paralysed, to smartphone-based voice interfaces, residual muscular activity of the damaged limb, all the way to reading brainwave activity with a headset.
Scientists at Switzerland’s EPFL labs have been able to demonstrate brainwave-control of the exoskeleton via an EEG headset that measures the users' brainwaves as they used the exoskeleton.
They found that the hand motions induced by the device elicit brain patterns typical of healthy hand motions, but they also discovered that exoskeleton-induced hand motions combined with a user-driven brain-machine interface lead to peculiar brain patterns that could actually facilitate control of the device.
The part of the brain that controls body movement is called the motor cortex, which in fact is divided into a left- and a right-hand side. The right motor cortex is mostly active during control of the left hand, and vice versa, a property of the nervous system called contralateral control.
As expected, the scientists observed this contralateral brainwave activity in people who passively received hand motion by the exoskeleton. They also noticed that, when the subjects were asked to control the hand-exoskeleton with their brainwaves, consistent same-side patterns also emerged in the brainwave data.
In other words, when these people were asked to actively think about moving the exoskeleton, the part of the brain that normally thinks about controlling the opposite hand was also being solicited in the brain.
The scientists believe that this brain activity emerging from the combination of voluntary control and coherent feedback provided by the device could be exploited for improving brain control of these devices.
“This enhanced control of the hand-exoskeleton with brainwave activity is most likely due to higher engagement of subjects facilitated by rich sensory feedback provided by the nature of our exoskeleton,” says lead researcher José del R Millán.
“Feedback is provided by the user's perception of position and movement of the hand, and this proprioception is essential.”
So far, the hand-exoskeleton has been tested with patients with disabilities due to strokes and spinal cord injuries. The next steps involve improving the system both for assistive purposes, for performing tasks at home, or even as a tool for rehabilitation.
