Existing prosthetic arms rely on the user twitching the remnant muscles in their shoulder or arm, which are often damaged. This technology is fairly basic in its functionality and has limited range of movements, such as one or two grasping actions. This drawback could be the reason for around 40-50 per cent of users discarding this type of robotic prosthetic.
However, a new technology has been developed by Professor Dario Farina and colleagues on the Department of Bioengineering and Institute of Biomedical Engineering, Imperial College London: the world's first prosthetic arm controlled by spinal nerve signals.
This prosthetic have a wider range of movement and is functional. Users can even move their elbow joint and do radial movements moving the wrist from side to side, as well as opening and closing the hand. This is attained through re-routing parts of the users Peripheral Nervous System (PNS), connected with hand and arm movements, to healthy muscles in their body.
This allows detection of signals from spinal motor neurons in any intact or undamaged piece of muscle like chest or biceps, resulting to more commands programmed in such technology. It is operated just by thinking about what exactly it is that the user wants the arm to do. Signals are then detected by the sensors on the skin, consequently allowing movements of the robotic arm.
““When an arm is amputated the nerve fibres and muscles are also
severed, which means that it is very difficult to get meaningful signals from them to operate a prosthetic. We’ve tried a new approach, moving the focus from muscles to the nervous system. This means that our technology can detect and decode signals more clearly, opening up the possibility of robotic prosthetics that could be far more intuitive and useful for patients. It is a very exciting time to be in this field of research,” says Prof. Farina.
Further improvements and refinements are needed, but the researchers hope to have this prosthetic available on the market in the next three years.
Farina, D. et al.
Man/machine interface based on the discharge timings of spinal motor neurons after targeted muscle reinnervation. Nat. Biomed. Eng
, 0025 (2017).