The bionic arm of the future is here
“We all grew up watching Star Wars… we saw Luke Skywalker get his arm replaced after a lightsaber duel,” Clark says. “I was always interested and kind of fascinated by brain-machine interfaces and I just fell in love with it.”
That’s Gregory Clark, associate professor of biomedical engineering and director of the Center for Neural Interfaces at the University of Utah, he’s spearheading a project dedicated to integrating bionic limbs with the human body.
At the center of this project is a bionic arm known as the “Luke Skywalker Arm” which allows individuals who have lost their natural arms the opportunity to not only to use their arm but also to experience the sense of touch again―even if it was presumed to be lost forever.
This project is not only revealing the fact that bionic limbs are now beginning to be incorporated into the nervous system, but also that our bodies are composed of a deeply encoded language that we are only just beginning to understand.
Clark explains that he became interested in the nervous system when he was in college. “[A] new understanding [of the nervous system] started to come along, and after I got interested in the nervous system, I got interested in ways to help fix problems with it… We all have stories of people we know with one nervous system disorder or another. My mother had a stroke and she lost a lot of her motor capabilities and my stepmom had Parkinson’s disease. These people are always in the back of my mind as I do my own work.”
Clark extended his research into spinal cord injuries and prosthetics between 2004 and 2005 when he was approached by individuals hoping to use experimental medical techniques to help veterans injured in the Middle East. “Pretty much on the spot I said yes. We would just take our same device and our same approach and we’d flip it around in a certain way so what we used to record we would now stimulate and what we used to stimulate we’d now record. Instead of reanimating limbs that were paralyzed, we would instead be able to control limbs that aren’t there by recording motor signal instead of stimulating motor signal.”
The bionic arm you can control with your thoughts
University of Utah researchers are currently working with two local Utah companies, Ripple Neuro and Blackrock Microsystems, on the Luke Skywalker Arm―which was created by DEKA Research and Development in New Hampshire. Both companies focus on the creation of devices that are implanted into the human body and are then connected to the bionic arm in an integrated system.
“What we do at the University of Utah is take all of these functional devices and integrate [them] with the human and make the cyborg person that’s able to feel and move the arm,” says Jacob George, a doctoral candidate at the University of Utah in the department of biomedical engineering and a National Science Foundation research fellow.
“Our goal is to get all these devices working so that we can develop a bionic arm that is controlled entirely by thought that provides dextrous and intuitive control over the hand. And not only that, but that prosthetic hand or bionic arm can send signals back to the user through [his or her] own natural pathways through [the] nervous system. These allow [him or her] to have an intuitive and high-resolution sense of touch coming from the bionic arm.”
George went on to explain how an individual would be able to control the bionic arm: “When a normal person thinks about moving our hand, we have signals that start in our brain and go down from our brain through our spinal cord, and then go from our spinal cord to our nerves. From our nerves, they go to our muscles, and then our muscles actually cause a contraction which actually causes your fingers to move.
“What’s interesting is that the muscles that control your hand are located in your forearm. So, if you put your hand out and grab your forearm and then…make a fist and move around, you should actually feel the movement of your forearm. That’s because your muscles are contracting and controlling your hand. So, those muscles that control your hand still exist if you lose your hand―all of the natural control process is there. You’re still sending information from your brain through your spinal cord through your nerves to your muscles. Your muscles are still contracting, it’s just that they don’t have anything to pull on. They don’t have the fingers to actually cause [something] to move.
“What we do is take that same pathway, and we record the electrical signals that are coming from the muscles, and instead of having the muscles directly control the prosthetic, we record those signals, and estimate what the user was trying to do. For example, if you’re trying to make a grasp [with your hand], you might have one certain type of muscle activity; if you’re trying to open your hand, you might have a different type of activity. We use a computer to classify or predict each one of those movements, and then those predictions get sent to a prosthetic hand or a bionic arm that then recreates those movements.”
The bionic arm you can actually feel
What makes the University of Utah’s development especially extraordinary is how researchers have been able to restore the sensation of touch through the use of the prosthetic―something George has contributed to tremendously. “Current devices on the market have pretty much no sense of touch. If you get the prosthetic, you might feel…a residual bump from it moving and being attached to your residual limb, but you can’t tell how hard you’re squeezing; if you reach out and try to shake someone’s hand, you don’t know how hard to squeeze without hurting them.
“The way our body would naturally work is we have little sensors on our fingertip, and if you reach out and touch your fingertip, what happens is that touch is being transduced from a force on your fingertip into an electrical signal, and then that electrical signal travels up through your spinal cord and back up to your brain where your brain then interprets it as, ‘oh that’s touch on my index finger!’ So those pathways exist naturally.”
George calls this pathway a “biological wire,” and says that these wires remain in our forearms even after we’ve lost our hands. BlackRock’s device, a series of microscopic needles, actually go inside the nerves. The idea is that, through hundreds of tiny electrodes, the scientist can go through and stimulate each one. “The participant will say, ‘Oh, woah! It feels like you just touched my index finger!’”
The scientists map each reaction, noting which electrode elicited which response. “Then we can do all sorts of combinations so when that hand touches things, we stimulate the appropriate pathways that already exist in the body to then recreate that sensation of having a hand,” George says. “We found that if we mimic the body’s natural language, then the sensations the person feels become more intuitive and more useful. The participant we worked with was able to describe whether an object was hard or soft and whether it was small or large while he was blindfolded and earmuffed.”
In one case study George mentions, an individual was able to think about moving his hand, and then actually see the bionic hand move. But the real difference came when George was able to tie the thought, the movement, and the sensation together. When that happened, the individual reached out to touch a door and suddenly jumped back with shock, “I just felt that door!” he exclaimed. “Wow, I can feel it.”
But the benefits of the device go even beyond touch. As George explains, many amputees develop “phantom pain,” and often take a number of medications to tolerate it. So when one of the test subjects’ brains was able to truly believe the prosthetic hand was his own hand, his pain went down. “The [participant’s] brain truly did incorporate the prosthetic into its body image… and he started referring to the prosthetic as if [it were] his own hand.”
It’s moments like these that Clark is most driven by: the opportunity to do what he calls “restoring a person’s sense of self.” “Hands are a big part of who we are and how we explore the environment,” he says. “To lose your hands is, to some extent, to lose the way we interact with the world―and even a sense of your very body and your personhood.”
Creating “superhumans” is not too far away
What is, perhaps, even more fascinating about the research taking place is what these discoveries could mean for the future of health as a whole. “One of my colleagues and former collaborators is taking the same ideas we have, but instead of restoring simple sensory and motor function, they are restoring memory,” Clark says. “People who get older start having memory problems and experience things like Alzheimer’s disease.”
Though Clark assured me that this type of research is still highly experimental, it is also something that is extremely attractive to venture capitalists. As Clark explains, the ability to convert thoughts into typed text is highly attractive. As is the possibility of capturing memories, so they can live on even after a person has died. “There are all sorts of really speculative things,” Clark says, “but the reason it’s so exciting, and why people are dreaming so big, is because the nervous system is more than an arm or leg or artificial heart or artificial hip. It’s really the essence of who we are.”
Though these ideas may sound speculative, Clark thinks they may be a reality. “There’s a part of the nervous system that’s missing, I take the input, I know what the input should be, I skip the missing part, and I stimulate the next stage to replicate the digital pulse code,” he says.
In this way, if the part of the brain that is responsible for memory becomes damaged, scientists could effectively bridge the gap between what is supposed to be sending a signal, and what is supposed to be receiving it. And if that can be done, then we can open up new possibilities for people affected by depression, Alzheimer’s disease, sensory loss, stroke, or other cognitive or movement disorders. “The landscape that lies before us is really quite wide because the nervous system interacts with basically every body part that we have. The commercial potential is really quite large.”
The future of this field is bright, fascinating, and unknown. Beginning to restore touch is just the beginning. With the studies these individuals are engaging in, it may just be possible to one day restore the very nature of who we are, and make us even better than we’ve ever been before.
Clark has a kind of Utopian optimism when he thinks about the future of his research, even hinting at “superhuman” possibilities. “If you can make bad things good,” Clark ponders, “can you make good things even better?”