Why it’s Breakthrough: It’s an artificial robotic hand with built-in sensors that can actually enable the user to “feel” objects and sensations.

The Story: Motorized prosthetic hands are not brand new, though they’re still breakthrough. However, the next step in this evolution is focused on creating a hand that gives the user unprecedented sensory feedback, according to researchers of the SmartHand Project, a collaboration between researchers from across Europe.

Fredrik Sebelius, of Lund University, in Sweden, says the SmartHand actually addresses this notion of the “phantom hand.” Sebelius says: ”If you push the skin on an amputee’s forearm, they feel like you are pushing on their phantom fingers.” That’s because the nerve fibers in the forearm still send myolelectric signals to what would have been the hand and fingers, and the messages traveling down those pathways don’t end where the limb was cut off – at least it doesn’t feel like they end, according to amputees. The SmartHand takes advantage of that sensation, and not only uses the information to power the hand, but in turn from the SmartHand itself, to relay messages back from the hand, reconnecting with those pathways and carrying the message to the user’s brain, where he or she can interpret the signal as something coming from or to the hand.

According to Dr. Sebelius, this “connection” gives the SmartHand not only more control than competing systems, but this ability to incorporate sensation. The SmartHand has dozens of sensors in each prosthetic finger, so “feeling” an object as it’s in hand is now possible. Though this idea seems more like science fiction, these researchers believe it’s going to become a reality. Sebalius adds, “Sensors in the prosthesis pick up tactile information, which is relayed to actuators on the arm that pass on the sensory feedback, and this hasn’t been done before.”

Sebelius sites an the example of a pressure sensor on the artificial index finger sending a signal to forearm. By zeroing in on the part of the brain that responds to index finger sensitivity, and having signals from that index finger “plug into” the forearm that transmits that signal to the pathway that alerts the brain to activity at the tip of the index finger, the brain senses that there is some sort of stimulus taking place at the tip of the index finger. Rather than having that signal hard-wired from a real index finger all the way to that specific part of the brain, the signal is now, in effect, sent wirelessly.

And it’s working.

Dr. Sebelius says the prosthesis could be commercially available within two years, but that the current technology is only suitable for amputations below the elbow. Upper arm amputees don’t have enough muscles associated with hand movement to control the SmartHand.

Martin Twiste, senior lecturer of prosthetics and orthotics at the University of Salford, in England, said he did not know of any commercially available prosthetic hands that gave this kind of sensory feedback. But he said the challenge with relaying sensory information from a prosthetic hand is sending the signals to the right place.

“Any sensory information from the prosthetic hand has to be fed back to the residuum (remainder of the amputated arm) and then to the brain,” he said. “The difficulty is where do you feed it back to?”

“If you have several electrodes on the residuum it’s very difficult to place the electrodes accurately enough for the amputee to distinguish, say, the index finger from the middle finger.”

One potential solution for upper arm amputees being explored by U.S. firm Deka Research and Development is to control an artificial arm using foot pedals.

Another method uses “Targeted Muscle Reinnervation,” a technique developed by Dr Todd Kuiken at the Rehabilitation Institute of Chicago. This involves transferring the remaining nerves from an amputated limb to other muscles — for example the pectoral muscle in the chest.

That means that when someone thinks about moving their amputated hand, they activate the muscle in their chest, and the myolelectric signals from that muscle can be used to control a prosthetic hand.

Researchers from the Johns Hopkins University Applied Physics Laboratory have developed a prototype prosthetic limb that uses this technique as part of a U.S. Defense Advanced Research Projects Agency-sponsored project.

But another solution is to directly attach electrodes to nerve bundles in the remaining part of the amputated arm, recording signals from the nerves, rather than from muscles.

Some of the SmartHand researchers have been working on this technology and Sebelius says developing this kind of “neural interface” is the long-term goal of the project.

Although neural interfaces have been tested in animals, Sebelius says there are a number of problems that have to be overcome before the technology can be made commercially available for humans.

“The neural interface has to be implanted in the body, which brings problems of biocompatibility,” Sebelius said.

“A common problem is for the interface to be rejected by the body, then you get a lot of tissue forming around the interface and it doesn’t function correctly,” he concluded.

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Story courtesy of CNN