The UK’s first mind-controlled robotic arm has been implanted in a soldier who lost his limb in Afghanistan.
The technology relies on a medical technique that rewires a patient’s nervous system so that nerves from the shoulder – that would have controlled the hand – are wired into the chest muscle instead.
Previous robotic prostheses have picked up individual signals created by muscle movement, which controlled separate arm functions such as lifting or turning. The new arm simultaneously gathers up to six signals directly from the nerves, enabling it to replicate much more lifelike motion from the user’s thoughts.
Ken Hurst, who manages the UK training academy for the company behind the robotic arm, Otto Bock, said that once patients had learnt how to use the arm they could operate it with more intuitive, sub-conscious movements rather than conscious effort.
‘We’ve had a powered elbow, we’ve had the wrist rotation, but the clever thing now is the new processor unit that brings in more signals,’ he told The Engineer.
‘It’s still the same functions but what [the new technology] allows you to do is lift the arm, rotate the wrist and open and close the hand simultaneously. It’s a more natural process, whereas before each function was separately controlled.’
The arm, which was implanted in Corporal Andrew Garthwaite at the Medical University of Vienna in 2011, relies on a six-hour surgical procedure known as targeted muscle reinnervation (TMR).
Once this is complete, the arms collects signals from six electrodes in the chest, digitises and amplifies them before transmitting them to a central processing unit (CPU) that converts them into physical movement in the arm.
Garthwaite had to undergo 18 months of therapy to learn how to use the device. ‘The surgery has made a massive improvement to my life,’ he said in a statement.
‘I have become a lot more independent and all the normal things I was struggling with have become so much easier. I am now able to participate more in the kitchen – simple tasks like making a coffee, baking cakes and opening jars have made a real difference.’
Hurst said the challenge had been developing the software and hardware to manage the different signals and integrate the movement of the different elements of the prosthesis.
He added that smaller, more specified electrodes and more advanced motorised and electronic systems would create even more capable prostheses but that a different breakthrough would needed to make the technology easier to use.
‘The person that has to work the hardest is still the person wearing it,’ he said.‘It has to be a motivated person with good cognitive ability.’