John Hopkins University

A revolutionary prosthetic hand that connects the directly to the brain has allowed a 28-year-old paralysed volunteer to "feel" physical sensations for the first time in a decade.

The prosthetic has been created as part of a project by Darpa, the US government's defence research agency, which is primarily famous for its work in military robotics. As well as building weaponised drones however, the agency also has a programme dedicated to revolutionising prosthetics through the introduction of feedback loops.


The whole premise for the project has been that people living with paralysis or missing limbs will only be able to manipulate objects by controlling their robotic prostheses directly from their brain, and are able to sense what they are touching.

Its latest breakthrough is subtle enough for the paralysed volunteer to identify exactly which mechanical finger has been touched -- even if two are touched at once. In order to achieve this, it was necessary to place electrode arrays onto the volunteer's sensory cortex -- the region of the brain that identifies tactile sensations and the motor cortex -- the region of the brain that directs body movements. Wires were then run from the motor cortex to the prosthesis.

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It's not the first time Darpa has implemented this technology, but it has broken new neurological ground by routing electrical signals from touch signals in the prosthesis back to the sensory cortex. "We've completed the circuit," said Justin Sanchez, who manages the Darpa programme. "Prosthetic limbs that can be controlled by thoughts are showing great promise, but without feedback from signals traveling back to the brain it can be difficult to achieve the level of control needed to perform precise movements. By wiring a sense of touch from a mechanical hand directly into the brain, this work shows the potential for seamless bio-technological restoration of near-natural function."

In tests, the volunteer could identify even the lightest touches to their finger with nearly 100 percent accuracy. "At one point, instead of pressing one finger, the team decided to press two without telling him," said Sanchez. "He responded in jest asking whether somebody was trying to play a trick on him. That is when we knew that the feelings he was perceiving through the robotic hand were near-natural."


Completing this "circuit" in the prosthetic hand is one of a series of breakthroughs in prosthetics that have occurred over the past few years marking a massive shift in the affordability and sophistication of a technology which has seen little innovation in decades. WIRED has been keeping a close eye on this innovation, which promises to eventually transform the lives of everyone across the world in need of prosthetic limbs.

The prosthetics revolution

Ossur -- brain-controlled prosthetics

In May this year, WIRED reported the story of Cathy Hutchinson, the first almost-fully paralysed person to be able to take a drink by controlling a robotic arm using her mind. Despite the fact that the technology, called myoelectric prostheses, that allowed her to do this has been in development for years, brain controlled prostheses are still far from commonplace.

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Shortly after WIRED published Hutchinson's story, Icelandic company Ossur announced that brain controlled prostheses would be widely available within a couple of years. The company's extensive work in revolutionary prosthetics were responsible for Oscar Pistorius' Flex-Foot Cheetah Blades and it even claims it has developed the first prosthetics that can even react to "subconscious" thoughts, rather than just conscious decisions to move.

Open bionics -- 3D printing affordable prosthetics

The prototype prosthetic hand can be manufactured in less than two days using a 3D-printer Open Bionics

WIRED first encountered Bristol-based Open Bionics at the final of Intel's Make It Wearable competition at the end of 2014. Only last month, the company, which 3D prints custom-made lightweight prosthetics that can cheaply and quickly be fitted to those with missing limbs, was announced as the winner of the 2015 James Dyson prize.

bebionic3 -- introducing extreme versatility

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The hand automatically senses when any held item is slipping and tightens its grip. It can grip with the force of 140 Newtons and each finger can lift up to 25kg. It takes just half a second to fully open or close the 500g bebionic3 Sun Lee

Speaking at WIRED Health this year, Nigel Ackland who lost his arm in an industrial accident told the story of how he came to wear one of the world's most advanced prosthetics.

The bebionic3 was developed by Leeds-based assistive living company RSLSteeper and can form multiple grips. Wearing the prosthetic has given Ackland back much of the independence and manoeuvrability that he lost when he had his accident, dramatically improving his quality of life. It's worth watching his WIRED Health talk to hear him tell his moving story in his own words.