Robotic Arms Controlled by Simply Thinking

A Colorado man made history at the Johns Hopkins University Applied Physics Laboratory (APL) this summer when he became the first bilateral shoulder-level amputee to wear and simultaneously control two of the Laboratory’s Modular Prosthetic Limbs (MPL). Most importantly, Les Baugh, who lost both arms in an electrical accident 40 years ago, was able to operate the system by simply thinking about moving his limbs, performing a variety of tasks during a short training period.

Baugh was in town for two weeks in June as part of an APL-funded research effort to further assess the usability of the MPL, developed over the past decade as part of the Revolutionizing Prosthetics Program. Before putting the limb system through the paces, Baugh had to undergo a surgery at Johns Hopkins Hospital known as targeted muscle reinnervation.

It’s a relatively new surgical procedure that reassigns nerves that once controlled the arm and the hand,” explained Johns Hopkins Trauma Surgeon Albert Chi, M.D. “By reassigning existing nerves, we can make it possible for people who have had upper-arm amputations to control their prosthetic devices by merely thinking about the action they want to perform.”

After recovery, Baugh visited the Laboratory for training on the use of the MPLs. First, he worked with researchers on the pattern recognition system.

We use pattern recognition algorithms to identify individual muscles that are contracting, how well they communicate with each other, and their amplitude and frequency,” Chi explained. “We take that information and translate that into actual movements within a prosthetic.”

Then Baugh was fitted for a custom socket for his torso and shoulders that supports the prosthetic limbs and also makes the neurological connections with the reinnervated nerves. , Advanced Arm Dynamics, the nation’s preeminent provider of comprehensive upper-limb prosthetic rehabilitation, designed and fit Baugh’s custom prosthetic socket. While the socket got its finishing touches, the team had him work with the limb system through a Virtual Integration Environment (VIE), a virtual-reality version of the MPL.

The VIE is completely interchangeable with the prosthetic limbs and through APL’s licensing process currently provides 19 groups in the research community with a low-cost means of testing brain-computer interfaces. It’s being used to test novel neural interface methods and study phantom limb pain, and serves as a portable training system.

By the time the socket was finished, Baugh said he was more than ready to get started. When he was fitted with the socket, and the prosthetic limbs were attached, he said “I just went into a whole different world.” He moved several objects, including an empty cup from a counter-shelf height to a higher shelf, a task that required him to coordinate the control of eight separate motions to complete.

This task simulated activities that may commonly be faced in a day-to-day environment at home,” said APL’s Courtney Moran, a prosthetist working with Baugh. “This was significant because this is not possible with currently available prostheses. He was able to do this with only 10 days of training, which demonstrates the intuitive nature of the control.

Source: https://www.jhuapl.edu/

Artificial Skin Opens SuperHuman Perception

A new type of sensor could lead to artificial skin that someday helps burn victimsfeel’ and safeguards the rest of us, University of Connecticut (UConn)  researchers suggest in a paper in Advanced Materials.

Our skin’s ability to perceive pressure, heat, cold, and vibration is a critical safety function that most people take for granted. But burn victims, those with prosthetic limbs, and others who have lost skin sensitivity for one reason or another, can’t take it for granted, and often injure themselves unintentionally. Chemists Islam Mosa from UConn, and James Rusling from UConn and UConn Health, along with University of Toronto engineer Abdelsalam Ahmed, wanted to create a sensor that can mimic the sensing properties of skin. Such a sensor would need to be able to detect pressure, temperature, and vibration. But perhaps it could do other things too, the researchers thought.

It would be very cool if it had abilities human skin does not; for example, the ability to detect magnetic fields, sound waves, and abnormal behaviors,” said Mosa.

Mosa and his colleagues created such a sensor with a silicone tube wrapped in a copper wire and filled with a special fluid made of tiny particles of iron oxide just one billionth of a meter long, called nanoparticles. The nanoparticles rub around the inside of the silicone tube and create an electric current. The copper wire surrounding the silicone tube picks up the current as a signal. When this tube is bumped by something experiencing pressure, the nanoparticles move and the electric signal changes. Sound waves also create waves in the nanoparticle fluid, and the electric signal changes in a different way than when the tube is bumped.

The researchers found that magnetic fields alter the signal too, in a way distinct from pressure or sound waves. Even a person moving around while carrying the sensor changes the electrical current, and the team found they could distinguish between the electrical signals caused by walking, running, jumping, and swimming.

Metal skin might sound like a superhero power, but this skin wouldn’t make the wearer Colossus from the X-men. Rather, Mosa and his colleagues hope it could help burn victimsfeelagain, and perhaps act as an early warning for workers exposed to dangerously high magnetic fields. Because the rubber exterior is completely sealed and waterproof, it could also serve as a wearable monitor to alert parents if their child fell into deep water in a pool, for example.

Source: https://today.uconn.edu/

Electronic Skin To Restore Sense Of Pain

Amputees often experience the sensation of a “phantom limb”—a feeling that a missing body part is still there. That sensory illusion is closer to becoming a reality thanks to a team of engineers at the Johns Hopkins University that has created an electronic skin. When layered on top of prosthetic hands, this e-dermis brings back a real sense of touch through the fingertips.

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After many years, I felt my hand, as if a hollow shell got filled with life again,” says the anonymous amputee who served as the team’s principal volunteer tester.

Made of fabric and rubber laced with sensors to mimic nerve endings, e-dermis recreates a sense of touch as well as pain by sensing stimuli and relaying the impulses back to the peripheral nerves.

We’ve made a sensor that goes over the fingertips of a prosthetic hand and acts like your own skin would,” explains Luke Osborn, a graduate student in biomedical engineering. “It’s inspired by what is happening in human biology, with receptors for both touch and pain“This is interesting and new,” Osborn adds, “because now we can have a prosthetic hand that is already on the market and fit it with an e-dermis that can tell the wearer whether he or she is picking up something that is round or whether it has sharp points.”

The work in the journal Science Robotics – shows it is possible to restore a range of natural, touch-based feelings to amputees who use prosthetic limbs. The ability to detect pain could be useful, for instance, not only in prosthetic hands but also in lower limb prostheses, alerting the user to potential damage to the device.

Human skin contains a complex network of receptors that relay a variety of sensations to the brain. This network provided a biological template for the research team, which includes members from the Johns Hopkins departments of Biomedical Engineering, Electrical and Computer Engineering, and Neurology, and from the Singapore Institute of Neurotechnology.

Bringing a more human touch to modern prosthetic designs is critical, especially when it comes to incorporating the ability to feel pain, Osborn states. “Pain is, of course, unpleasant, but it’s also an essential, protective sense of touch that is lacking in the prostheses that are currently available to amputees,” he says. “Advances in prosthesis designs and control mechanisms can aid an amputee’s ability to regain lost function, but they often lack meaningful, tactile feedback or perception.

Source: http://releases.jhu.edu/