Mind-controlled artificial limb gives patients sense of touch again

Artificial limbs and prosthetics have come a long way from the 1963 CO2 gas-powered artificial arms exhibited at the Wellcome Trust in 2012.

In the 21st century, the Pentagon’s research division, Darpa, has been at the cutting edge of prosthetics development, in no small part due to the wars in Iraq and Afghanistan.

Darpa’s touch-sensitive artificial prosthetic, described in a statement on 30 May, interfaces directly with the wearer’s neural system and shows just how far we’ve come.

Unlike direct brain neural interfaces, the prosthetic connects with nerves in the patient’s limb, therefore requiring less serious and less risky surgery.

It doesn’t require any visual information to operate, allowing the wearer to control it without maintaining visual contact. This makes “blind” tasks, like rummaging through a bag, much easier.

A flat interface nerve electrode (Fine) provides direct sensory feedback to the patient. Fine is a way of hacking into the body’s nervous system by flattening a nerve. This exposes more of the nerve to electrical contact, making it easier to interface with it. Researchers at Case Western Reserve University, involved with the touch-sensitive prosthetic, previously used Fine to reactivate paralysed limbs.

In the video, the wearer of the prosthetic hand is able to identify which finger researchers at Case Western Reserve University are touching without looking.

Groups across the world are engaged in similar research, including a team at the École Polytechnique Fédérale de Lausanne in France which announced in February that it would be trialling a touch-sensitive prosthetic this year.

Startlingly natural prosthetic movement, including bouncing and catching a tennis ball with a fully artificial arm and hand, is also described in Darpa’s 30 May statement.

Using a type of neural connection called targeted muscle re-innervation (TMR), researchers at the Rehabilitation Institute of Chicago (RIC) were able to achieve simultaneous control of the shoulder, elbow and wrist.

TMR involves re-wiring nerves from amputated limbs so that existing muscles, like those in the shoulder, for example, can be used to control the prosthetic arm.

Last year, Zac Vawter climbed the 442m Willis Tower in Chicago with an artificial leg that used TMR. He was fundraising for the RIC.

This video shows former Army Staff Sgt Glen Lehman, injured in Iraq, demonstrating the full range of fluid motions enabled by the TMR prosthetic arm.

State science fair winner creates robot

The winner of this year’s State Science and Engineering Fair is from South Florida, and her project can someday make life easier for the physically challenged.

"It captures the brain waves of electrochemical activity. Basically, the nerve impulse produced by the brain, and it sends it over to the robot," said Daniela Rodriguez.

Steve is an award winning robot controlled by brain waves. He was invented by 13-year-old Daniela Rodriguez, who loves math and science. “I’ve always been interested in robotics; it’s my passion,” she said.

This year, Rodriguez won first place in the Annual State Science and Engineering Fair against 900 other finalists.

Rodriguez’ goal is to help people. “If the person is disabled, they can sit in their wheelchair, and they can use their thoughts and brain waves to control its movements, so they don’t have to move,” she said.

Her science project comes from the heart. Her mother was diagnosed with multiple sclerosis in 1996, and she is trying to find a way to keep her mom independent. “I work really hard to try to stay mobile, but the fact that she wants to help patients dealing with this illness is just a Godsend” said Rodriguez’ mom Jeannie.

Rodriguez’ wants to one day use her technology to help paralyzed people. Steve’s technology can even give wounded veterans the ability to use their brains to move the robot. “To help them move around in their wheelchairs or move their prosthetics because usually prosthetics now is just the muscle movement, but now it can be used and be more natural. It’s moving by your brain,” said Rodriguez.

Not only is Rodriguez winning awards, prosthetic companies have expressed interest in her program.

Improved Hearing Anticipated for Implant Recipients

The cochlear implant is widely considered to be the most successful neural prosthetic on the market. The implant, which helps deaf individuals perceive sound, translates auditory information into electrical signals that go directly to the brain, bypassing cells that don’t serve this function as they should because they are damaged.

According to the National Institute on Deafness and Other Communication Disorders, approximately 188,000 people worldwide have received cochlear implants since these devices were introduced in the early 1980s, including roughly 41,500 adults and 25,500 children in the United States.

Despite their prevalence, cochlear implants have a long way to go before their performance is comparable to that of the intact human ear. Led by Pamela Bhatti, Ph.D., a team of researchers at the Georgia Institute of Technology has developed a new type of interface between the device and the brain that could dramatically improve the sound quality of the next generation of implants.

A normal ear processes sound the way a Rube Goldberg machine flips a light switch — via a perfectly-timed chain reaction involving a number of pieces and parts. First, sound travels down the canal of the outer ear, striking the eardrum and causing it to vibrate. The vibration of the eardrum causes small bones in the middle ear to vibrate, which in turn, creates movement in the fluid of the inner ear, or cochlea. This causes movement in tiny structures called hair cells, which translate the movement into electrical signals that travel to the brain via the auditory nerve.

Dysfunctional hair cells are the most common culprit in a type of hearing loss called sensorineural deafness, named for the resulting breakdown in communication between the ear and the brain. Sometimes the hair cells don’t function properly from birth, but severe trauma or a bad infection can cause irreparable damage to these delicate structures as well.

Contemporary cochlear implants

Traditional hearing aids, which work by amplifying sound, rely on the presence of some functioning hair cells. A cochlear implant, on the other hand, bypasses the hair cells completely. Rather than restoring function, it works by translating sound vibrations captured by a microphone outside the ear into electrical signals. These signals are transmitted to the brain by the auditory nerve, which interprets them as sound.

Cochlear implants are only recommended for individuals with severe to profound sensorineural hearing loss, meaning those who aren’t able to hear sounds below 70 decibels. (Conversational speech typically occurs between 20 and 60 decibels.)

The device itself consists of an external component that attaches via a magnetic disk to an internal component, implanted under the skin behind the ear. The external component detects sounds and selectively amplifies speech. The internal component converts this information into electrical impulses, which are sent to a bundle of thin wire electrodes threaded through the cochlea.

Improving the interface

As an electrical engineer, Bhatti sees the current electrode configuration as a significant barrier to clear sound transmission in the current device.

"In an intact ear, the hair cells are plentiful, and are in close contact with the nerves that transmit sound information to the brain," says Bhatti. "The challenge with the implant is getting efficient coupling between the electrodes and the nerves."

Contemporary implants contain between 12 and 22 wire electrodes, each of which conveys a signal for a different pitch. The idea is the more electrodes, the clearer the message.

So why not add more wire electrodes to the current design and call it a day?

Much like house-hunting in New York City, the problem comes down to a serious lack of available real estate. At its widest, the cochlea is 2 millimeters in diameter, or about the thickness of a nickel. As it coils, it tapers down to a mere 200 micrometers, about the width of a human hair.

"While we’d like to be able to increase the number of electrodes, the space issue is a major challenge from an engineering perspective," says Bhatti.

With funding from the National Science Foundation, Bhatti and her team have developed a new, thin-film, electrode array that is up to three times more sensitive than traditional wire electrodes, without adding bulk.

Unlike wire electrodes, the new array is also flexible, meaning it can get closer to the inner wall of the cochlea. The researchers believe this will create better coupling between the array and the nervous system, leading to a crisper signal.

According to Bhatti, one of the biggest challenges is actually implanting the device into the spiral-shaped cochlea:

"We could have created the best array in the world, but it wouldn’t have mattered if the surgeon couldn’t get it in the right spot," says Bhatti.

To combat this problem, the team has invented an insertion device that protects the array and serves as a guide for surgeons to ensure proper placement.

Before it’s approved for use in humans, it will need to undergo rigorous testing to ensure that it is both safe and effective; however, Bhatti is already thinking about what’s next. She envisions that one day, the electrodes won’t need to be attached to an array at all. Instead, they will be anchored directly to the cochlea with a biocompatible material that will allow them to more seamlessly integrate with the brain.

The most important thing, according to Bhatti, is not to lose sight of the big picture.

"We are always designing with the end-user in mind," says Bhatti. "The human component is the most important one to consider when we translate science into practice."

Farsighted engineer invents bionic eye to help the blind

For UCLA bioengineering professor Wentai Liu, more than two decades of visionary research burst into the headlines last month when the FDA approved what it called “the first bionic eye for the blind.”

The Argus II Retinal Prosthesis System — developed by a team of physicians and engineers from around the country — aids adults who have lost their eyesight due to retinitis pigmentosa (RP), age-related macular degeneration or other eye diseases that destroy the retina’s light-sensitive photoreceptors.

At the heart of the device is a tiny yet powerful computer chip developed by Liu that, when implanted in the retina, effectively sidesteps the damaged photoreceptors to “trick” the eye into seeing. The Argus II operates with a miniature video camera mounted on a pair of eyeglasses that sends information about images it detects to a microprocessor worn on the user’s waistband. The microprocessor wirelessly transmits electronic signals to the computer chip, a fingernail-size grid made up of 60 circuits. These chips stimulate the retina’s nerve cells with electronic impulses which head up the optic nerve to the brain’s visual cortex. There, the brain assembles them into a composite image.

Recipients of the retinal implant can read oversized letters of the alphabet, discern objects and movement, and even see the outlines and some details of faces. And while the picture is far from perfect — the healthy human eye sees at a much higher resolution — it’s a breakthrough for people like the first patient, a man in his 70s who was blinded at age 20 by RP, to receive the implant in clinical trials. “It was the first time he’d seen light in a half-century,” said Liu, adding that “it feels good as the engineer” to have helped make this possible.

Liu joined the Artificial Retina Project in 1988 as a professor of computer and electrical engineering at North Carolina State University. The multidisciplinary research project was funded by the U.S. Department of Energy’s Office of Science because it envisioned a potential pandemic of eyesight loss in America’s aging population. Leading the project was Duke University ophthalmologist and neurosurgeon Dr. Mark Humayun, now on faculty at USC. He tapped Liu to engineer the artificial retina.

“I thought it was a great idea,” Liu said. “But I asked, ‘What can I do?’ because I didn’t know much about biology.” Humayun handed him a six-inch-thick medical manual on the retina. “The learning curve was very steep,” Liu recalled with a laugh.

However, Liu’s fellow engineers questioned his sanity. “I was working on integrated chip design and had just gotten tenure when I signed on to this project. They said, ‘You’re crazy!’ But I’m glad I made that choice, getting into this new field.”

How the bionic eye works

Wireless, implanted sensor broadens range of brain research

A compact, self-contained sensor recorded and transmitted brain activity data wirelessly for more than a year in early stage animal tests, according to a study funded by the National Institutes of Health. In addition to allowing for more natural studies of brain activity in moving subjects, this implantable device represents a potential major step toward cord-free control of advanced prosthetics that move with the power of thought. The report is in the April 2013 issue of the Journal of Neural Engineering.

“For people who have sustained paralysis or limb amputation, rehabilitation can be slow and frustrating because they have to learn a new way of doing things that the rest of us do without actively thinking about it,” said Grace Peng, Ph.D., who oversees the Rehabilitation Engineering Program of the National Institute of Biomedical Imaging and Bioengineering (NIBIB), part of NIH. “Brain-computer interfaces harness existing brain circuitry, which may offer a more intuitive rehab experience, and ultimately, a better quality of life for people who have already faced serious challenges.”

Recent advances in brain-computer interfaces (BCI) have shown that it is possible for a person to control a robotic arm through implanted brain sensors linked to powerful external computers. However, such devices have relied on wired connections, which pose infection risks and restrict movement, or were wireless but had very limited computing power.

Building on this line of research, David Borton, Ph.D., and Ming Yin, Ph.D., of Brown University, Providence, R.I., and colleagues surmounted several major barriers in developing their sensor. To be fully implantable within the brain, the device needed to be very small and completely sealed off to protect the delicate machinery inside the device and the even more delicate tissue surrounding it. At the same time, it had to be powerful enough to convert the brain’s subtle electrical activity into digital signals that could be used by a computer, and then boost those signals to a level that could be detected by a wireless receiver located some distance outside the body. Like all cordless machines, the device had to be rechargeable, but in the case of an implanted brain sensor, recharging must also be done wirelessly.

The researchers consulted with brain surgeons on the shape and size of the sensor, which they built out of titanium, commonly used in joint replacements and other medical implants. They also fitted the device with a window made of sapphire, which electromagnetic signals pass through more easily than other materials, to assist with wireless transmission and inductive charging, a method of recharging also used in electronic toothbrushes. Inside, the device was densely packed with the electronics specifically designed to function on low power to reduce the amount of heat generated by the device and to extend the time it could work on battery power.

Testing the device in animal models — two pigs and two rhesus macaques — the researchers were able to receive and record data from the implanted sensors in real time over a broadband wireless connection. The sensors could transmit signals more than three feet and have continued to perform for over a year with little degradation in quality or performance.

The ability to remotely record brain activity data as an animal interacts naturally with its environment may help inform studies on muscle control and the movement-related brain circuits, the researchers say. While testing of the current devices continues, the researchers plan to refine the sensor for better heat management and data transmission, with use in human medical care as the goal.

“Clinical applications may include thought-controlled prostheses for severely neurologically impaired patients, wireless access to motorized wheelchairs or other assistive technologies, and diagnostic monitoring such as in epilepsy, where patients currently are tethered to the bedside during assessment,” said Borton.

Human brain treats prosthetic devices as part of the body

People with spinal cord injuries show strong association of wheelchairs as part of their body, not extension of immobile limbs injuries.

The human brain can learn to treat relevant prosthetics as a substitute for a non-working body part, according to research published March 6 in the open access journal PLOS ONE by Mariella Pazzaglia and colleagues from Sapienza University and IRCCS Fondazione Santa Lucia of Rome in Italy, supported by the International Foundation for Research in Paraplegie.

The researchers found that wheelchair-bound study participants with spinal cord injuries perceived their body’s edges as being plastic and flexible to include the wheelchair, independent of time since their injury or experience with using a wheelchair. Patients with lower spinal cord injuries who retained upper body movement showed a stronger association of the wheelchair with their body than those who had spinal cord impairments in the entire body.

According to the authors, this suggests that rather than being thought of only as an extension of the immobile limbs, the wheelchairs had become tangible, functional substitutes for the affected body part. As Pazzaglia explains, “The corporeal awareness of the tool emerges not merely as an extension of the body but as a substitute for, and part of, the functional self.”

Previous studies have shown that people with prosthetic devices that extend or restore movement may make such tools part of their physical identity, but whether this integration was due to prolonged use or a result of altered sensory input was unclear. Based on the results of this study, the authors suggest that it may be the latter, as the brain appears to continuously update bodily signals to incorporate these tools into a sense of the body. The study concludes that this ability may have applications in rehabilitation of physically impaired people.

(Image: University of Miami)

World premiere of muscle and nerve controlled arm prosthesis

For the first time an operation has been conducted, at Sahlgrenska University Hospital, where electrodes have been permanently implanted in nerves and muscles of an amputee to directly control an arm prosthesis. The result allows natural control of an advanced robotic prosthesis, similarly to the motions of a natural limb.

A surgical team led by Dr Rickard Brånemark, Sahlgrenska University Hospital, has carried out the first operation of its kind, where neuromuscular electrodes have been permanently implanted in an amputee. The operation was possible thanks to new advanced technology developed by Max Ortiz Catalan, supervised by Rickard Brånemark at Sahlgrenska University Hospital and Bo Håkansson at Chalmers University of Technology.

“The new technology is a major breakthrough that has many advantages over current technology, which provides very limited functionality to patients with missing limbs,” says Rickard Brånemark.

Big challenges
There have been two major issues on the advancement of robotic prostheses: 1) how to firmly attach an artificial limb to the human body; 2) how to intuitively and efficiently control the prosthesis in order to be truly useful and regain lost functionality.

“This technology solves both these problems by combining a bone anchored prosthesis with implanted electrodes,” said Rickard Brånemark, who along with his team has developed a pioneering implant system called Opra, Osseointegrated Prostheses for the Rehabilitation of Amputees.

A titanium screw, so-called osseointegrated implant, is used to anchor the prosthesis directly to the stump, which provides many advantages over a traditionally used socket prosthesis.

“It allows complete degree of motion for the patient, fewer skin related problems and a more natural feeling that the prosthesis is part of the body. Overall, it brings better quality of life to people who are amputees,” says Rickard Brånemark.

How it works
Presently, robotic prostheses rely on electrodes over the skin to pick up the muscles electrical activity to drive few actions by the prosthesis. The problem with this approach is that normally only two functions are regained out of the tens of different movements an able-body is capable of. By using implanted electrodes, more signals can be retrieved, and therefore control of more movements is possible. Furthermore, it is also possible to provide the patient with natural perception, or “feeling”, through neural stimulation.

“We believe that implanted electrodes, together with a long-term stable human-machine interface provided by the osseointegrated implant, is a breakthrough that will pave the way for a new era in limb replacement,” says Rickard Brånemark.

The patient
The first patient has recently been treated with this technology, and the first tests gave excellent results. The patient, a previous user of a robotic hand, reported major difficulties in operating that device in cold and hot environments and interference from shoulder muscles. These issues have now disappeared, thanks to the new system, and the patient has now reported that almost no effort is required to generate control signals. Moreover, tests have shown that more movements may be performed in a coordinated way, and that several movements can be performed simultaneously.

“The next step will be to test electrical stimulation of nerves to see if the patient can sense environmental stimuli, that is, get an artificial sensation. The ultimate goal is to make a more natural way to replace a lost limb, to improve the quality of life for people with amputations,” says Rickard Brånemark.

A sensational breakthrough: the first bionic hand that can feel

The first bionic hand that allows an amputee to feel what they are touching will be transplanted later this year in a pioneering operation that could introduce a new generation of artificial limbs with sensory perception.

The patient is an unnamed man in his 20s living in Rome who lost the lower part of his arm following an accident, said Silvestro Micera of the Ecole Polytechnique Federale de Lausanne in Switzerland.

The wiring of his new bionic hand will be connected to the patient’s nervous system with the hope that the man will be able to control the movements of the hand as well as receiving touch signals from the hand’s skin sensors.

Dr Micera said that the hand will be attached directly to the patient’s nervous system via electrodes clipped onto two of the arm’s main nerves, the median and the ulnar nerves.

This should allow the man to control the hand by his thoughts, as well as receiving sensory signals to his brain from the hand’s sensors. It will effectively provide a fast, bidirectional flow of information between the man’s nervous system and the prosthetic hand.

“This is real progress, real hope for amputees. It will be the first prosthetic that will provide real-time sensory feedback for grasping,” Dr Micera said.

“It is clear that the more sensory feeling an amputee has, the more likely you will get full acceptance of that limb,” he told the American Association for the Advancement of Science meeting in Boston.

“We could be on the cusp of providing new and more effective clinical solutions to amputees in the next year,” he said.

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