| Researchers are working on a breakthrough in | | | | But he said the challenge with relaying sensory |
| artificial limb technology -- a prosthetic hand that can | | | | information from a prosthetic hand is sending the |
| actually feel. | | | | signals to the right place. |
| The SmartHand project is funded by the European | | | | "Any sensory information from the prosthetic hand |
| Union and is a collaboration between researchers | | | | has to be fed back to the residuum (remainder of |
| from across the continent. It has produced a | | | | the amputated arm) and then to the brain," he told |
| prototype motorized prosthetic hand that | | | | CNN. "The difficulty is where do you feed it back |
| researchers say gives unprecedented sensory | | | | to?" |
| feedback. | | | | "If you have several electrodes on the residuum it's |
| Fredrik Sebelius, of Lund University, in Sweden, is one | | | | very difficult to place the electrodes accurately |
| of those working on the project. He told CNN that | | | | enough for the amputee to distinguish, say, the index |
| the SmartHand is able to exploit the fact that many | | | | finger from the middle finger." |
| amputees experience what he terms a "phantom | | | | One potential solution for upper arm amputees being |
| hand." | | | | explored by U.S. firm Deka Research and |
| "If you push the skin on an amputee's forearm, they | | | | Development is to control an artificial arm using foot |
| feel like you are pushing on their phantom fingers," | | | | pedals. |
| Sebelius told CNN. | | | | Another method uses "Targeted Muscle |
| When an amputee imagines moving a "phantom | | | | Reinnervation," a technique developed by Dr Todd |
| hand," signals are sent down nerve fibres in the | | | | Kuiken at the Rehabilitation Institute of Chicago. This |
| remaining part of the amputated arm to activate | | | | involves transferring the remaining nerves from an |
| muscles that would have moved the fingers. | | | | amputated limb to other muscles -- for example the |
| Myolelectric signals from those muscles are recorded | | | | pectoral muscle in the chest. |
| by electrodes applied to the forearm and then | | | | That means that when someone thinks about |
| transmitted to motors in the artificial hand. | | | | moving their amputated hand, they activate the |
| It's a technique that has been used in prosthetic limbs | | | | muscle in their chest, and the myolelectric signals |
| for decades, but Sebelius says the SmartHand gives | | | | from that muscle can be used to control a prosthetic |
| much more control than other systems. | | | | hand. |
| It also allows sensory information to be detected and | | | | Researchers from the Johns Hopkins University |
| transmitted from several sensors in each prosthetic | | | | Applied Physics Laboratory have developed a |
| finger, meaning users can actually "feel" objects they | | | | prototype prosthetic limb that uses this technique as |
| hold in the SmartHand. | | | | part of a U.S. Defense Advanced Research Projects |
| "The big difference between our system and others | | | | Agency-sponsored project. |
| is the sensory feedback", Sebelius told CNN. | | | | But another solution is to directly attach electrodes |
| "Sensors in the prosthesis pick up tactile information, | | | | to nerve bundles in the remaining part of the |
| which is relayed to actuators on the arm that pass | | | | amputated arm, recording signals from the nerves, |
| on the sensory feedback, and this hasn't been done | | | | rather than from muscles. |
| before," | | | | Some of the SmartHand researchers have been |
| Sebelius gives the example of a pressure sensor on | | | | working on this technology and Sebelius says |
| the artificial index finger sending a signal to forearm. | | | | developing this kind of "neural interface" is the |
| By targeting the area of the forearm that activates | | | | long-term goal of the project. |
| the part of the brain associated with the index finger, | | | | Although neural interfaces have been trialled in |
| the signal from the finger is "felt" by the brain. | | | | animals, Sebelius says there are a number of |
| He says the prosthesis could be commercially | | | | problems that have to be overcome before the |
| available within two years, but that the current | | | | technology can be made commercially available for |
| technology is only suitable for amputations below the | | | | humans. |
| elbow. Upper arm amputees don't have enough | | | | "The neural interface has to be implanted in the |
| muscles associated with hand movement to control | | | | body, which brings problems of biocompatibility," |
| the SmartHand. | | | | Sebelius told CNN. |
| Martin Twiste, senior lecturer of prosthetics and | | | | "A common problem is for the interface to be |
| orthotics at the University of Salford, in England, told | | | | rejected by the body, then you get a lot of tissue |
| CNN that he did not know of any commercially | | | | forming around the interface and it doesn't function |
| available prosthetic hands that gave this kind of | | | | correctly. |
| sensory feedback. | | | | |