It seems like I’ve writing endlessly about bionic prosthetics lately, thanks to the many breakthroughs that have been happening almost back to back. But I would be remiss if I didn’t share these latest two. In addition to showcasing some of the latest technological innovations, these stories are inspiring and show the immense potential bionic prosthetics have to change lives and help people recover from terrible tragedies.
For instance, on the TED stage this week in Vancouver, which included presentations from astronaut Chris Hadfield, NSA whistle blower Edward Snowden, and anti-corruption activist Charmiah Gooch, there was one presentation that really stole the stage. It Adrianne Haslet-Davis, a former dance instructor and a survivor of the Boston Marathon bombing, dancing again for the first time. And it was all thanks to a bionic limb developed by noted bionics researcher Hugh Herr.
As the director of the Biomechatronics Group at the MIT Media Lab, Herr is known for his work on high-tech bionic limbs and for demonstrating new prosthetic technologies on himself. At 17, he lost both his legs in a climbing accident. After discussing the science of bionic limbs, Herr brought out Adrianne, who for the first time since her leg amputation, performed a short ballroom dancing routine.
This was made possible thanks to the help of a special kind of bionic limb that designed by Herr and his colleagues at MIT specifically for dancing. The design process took over 200 days, where the researchers studied dance, brought in dancers with biological limbs, studied how they moved, and examined the forces they applied on the dance floor. What resulted was a “dance limb” with 12 sensors, a synthetic motor system that can move the joint, and microprocessors that run the limb’s controllers.
The system is programmed so that the motor moves the limb in a way that’s appropriate for dance. As Herr explained in a briefing after his talk:
It was so new. We had never looked at something like dance. I understand her dream and emotionally related to her dream to return to dance. It’s similar to what I went through.” Herr says he’s now able to climb at a more advanced level than when he had biological legs.
Haslet-Davis’s new limb is only intended for dancing; she switches to a different bionic limb for regular walking. And while this might seem like a limitation, it in fact represents a major step in the direction of bionics that can emulate a much wider range of human motion. Eventually, Herr envisions a day when bionic limbs can switch modes for different activities, allowing a person to perform a range of different tasks – walking, running, dancing, athletic activity – without having to change prosthetics.
In the past, Herr’s work has been criticized by advocates who argue that bionic limbs are a waste of time when many people don’t even have access to basic wheelchairs. He argues, however, that bionic limbs–which can cost as much as a nice car–ultimately reduce health care costs. For starters, they allow people to return to their jobs quickly, Herr said, thus avoiding workers’ compensation costs.
They can also prevent injuries resulting from prosthetics that don’t emulate normal function as effectively as high-tech limbs. And given the fact that the technology is becoming more widespread and additive manufacturing is leading to lower production costs, there may yet come a day when a bionic prosthetic is not beyond the means of the average person. Needless to say, both Adrianne and the crowd were moved to tears by the moving and inspiring display!
Next, there’s the inspiring story of Igor Spectic, a man who lost his right arm three years ago in a workplace accident. Like most people forced to live with the loss of a limb, he quickly came to understand the limitations of prosthetics. While they do restore some degree of ability, the fact that they cannot convey sensation means that the wearers are often unaware when they have dropped or crushed something.
Now, Spectic is one of several people taking part in early trials at Cleveland Veterans Affairs Medical Center, where researchers from Case Western Reserve University are working on prosthetics that offer sensation as well as ability. In a basement lab, the trials consist of connecting his limb to a prosthetic hand, one that is rigged with force sensors that are plugged into 20 wires protruding from his upper right arm.
These wires lead to three surgically implanted interfaces, seven millimeters long, with as many as eight electrodes apiece encased in a polymer, that surround three major nerves in Spetic’s forearm. Meanwhile, a nondescript white box of custom electronics does the job of translating information from the sensors on Spetic’s prosthesis into a series of electrical pulses that the interfaces can translate into sensations.
According to the trial’s leader, Dustin Tyler – a professor of biomedical engineering at Case Western Reserve University and an expert in neural interfaces – this technology is “20 years in the making”. As of this past February, the implants had been in place and performing well in tests for more than a year and a half. Tyler’s group, drawing on years of neuroscience research on the signaling mechanisms that underlie sensation, has developed a library of patterns of electrical pulses to send to the arm nerves, varied in strength and timing.
Spetic says that these different stimulus patterns produce distinct and realistic feelings in 20 spots on his prosthetic hand and fingers. The sensations include pressing on a ball bearing, pressing on the tip of a pen, brushing against a cotton ball, and touching sandpaper. During the first day of tests, Spetic noticed a surprising side effect: his phantom fist felt open, and after several months the phantom pain was “95 percent gone”.
To test the hand’s ability to provide sensory feedback, and hence aid the user in performing complex tasks, Spetic and other trial candidates were tasked with picking up small blocks that were attached to a table with magnets, as well as handling and removing the stems from a bowl of cherries. With sensation restored, he was able to pick up cherries and remove stems 93 percent of the time without crushing them, even blindfolded.
While impressive, Tyler estimates that completing the pilot study, refining stimulation methods, and launching full clinical trials is likely to take 10 years. He is also finishing development of an implantable electronic device to deliver stimuli so that the technology can make it beyond the lab and into a household setting. Last, he is working with manufacturers of prostheses to integrate force sensors and force processing technology directly into future versions of the devices.
As for Spetic, he has drawn quite a bit of inspiration from the trials and claims that they have left him thinking wistfully about what the future might bring. As he put it, he feels:
…blessed to know these people and be a part of this. It would be nice to know I can pick up an object without having to look at it, or I can hold my wife’s hand and walk down the street, knowing I have a hold of her. Maybe all of this will help the next person.
This represents merely one of several successful attempts to merge the technology of nerve stimulation in with nerve control, leading to bionic limbs that not only obey user’s commands, but provide sensory feedback at the same time. Given a few more decades of testing and development, we will most certainly be looking at an age where bionic limbs that are virtually indistiguishable from the real thing exist and are readily available.
And in the meantime, enjoy this news story of Adrianne Haslet-Davis performing her ballroom dance routine at TED. I’m sure you’ll find it inspiring!
Sources: fastcoexist.com, technologyreview.com, blog.ted.com