A prosthetic controlled by signals form the spinal cord would have greater dexterity Anadolu Agency/Getty
A sensor that picks up nerve signals from the spinal cord could let people control a prosthetic arm by simply imagining the movement they want to make.
In tests using the sensor, which has to be surgically implanted, people were able to control a virtual arm on a screen with a larger range of movement聽than many existing prosthetics.
Prosthetic arms currently on the market are usually controlled by the user flexing聽muscles in their arm or chest. But there is a limit to how many commands can be mapped onto these muscle movements, which makes it difficult to do more intricate manoeuvres like pinching two fingers together.
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Greater dexterity
A team led by Dario Farina, then at University Medical Centre G枚ttingen, Germany, instead developed a technique that interprets signals directly from motor neurons in the spinal cord. 鈥淚n principal, we can reproduce all of the motion of a real limb this way, giving patients much greater dexterity,鈥 he says.
Six people who are amputees from above the elbow tested the new sensor. To make the nerve signals strong enough for the sensor to pick up, they had some nerves associated with hand and arm movements surgically rerouted to muscles in their chest. This effectively amplifies the nerve signals, making them easier for the sensor to read.
The researchers then mapped these nerve signals to corresponding arm movements in people who have both arms. 鈥淲e can use this to reconstruct the movement as if the arm were present,鈥 says Farina. Then, all the user has to do is try to move the prosthetic as if it is their arm.
痴颈谤迟耻补濒听辫谤辞蝉迟丑别迟颈肠蝉
At this early stage of the work, the participants controlled a virtual arm on a screen rather than a real prosthetic. They were able to move the virtual prosthetic with greater freedom than has been achieved with muscle-controlled prosthetics.
Farina says that people who use prosthetic limbs capable of movement may abandon them if they are too difficult to control or do not offer a useful range of movement. He believes that making prosthetics controlled by nerve signals could be a better option.
鈥淚t鈥檚 a nice piece of biomedical engineering that allows really natural movement,鈥 says at the Swiss Federal Institute of Technology (EPFL) in Lausanne, Switzerland. Now that they have聽tested the concept, he says, the researchers聽need to show it working in a bigger study and with an actual prosthetic.
Journal reference:
Read more: Man controls new prosthetic leg using thought alone
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