How sensors, rewiring nerves could help prosthetics feel and function like real limbs

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• Judy Woodruff:

  New technology is changing the way we think about the human brain.

  Miles O'Brien gives us a personal look at how rewiring the mind with the aid of machines is transforming the lives of those with amputated limbs.

  It is the second part of this story in our Breakthroughs series on innovation and invention.

• Dan Werner:

  , Study Participant: Hey, hi, guys.

• Man:

  Welcome. Please have a seat.

• Miles O’Brien:

  Fifty-two years after a land mine took his leg on patrol in Vietnam, Dan Werner is on point once again. His mission? Help make his fellow leg amputees more sure-footed.

• Dan Werner:

  Oh, man, this is pretty wild.

• Miles O’Brien:

  He is testing a limb that can feel what his prosthetic foot is touching.

  You can feel your foot, essentially?

• Dan Werner:

  Yes. Yes, it is great. I knew the first time I could actually feel my foot on the ground, it was like a mind-blowing experience.

• Miles O’Brien:

  He is a participant in a study at the Cleveland VA Medical Center aimed at directly connecting prosthetics to the nerves that once transmitted commands to muscles and received sensations of touch, in other words, wired into the brain like the real thing.

• Dustin Tyler, Cleveland Functional Electrical Stimulation Center:

  I don't want people to think about all of that gear. They should forget it. And I think we're getting very close to that point.

• Miles O’Brien:

  Principal investigator Dustin Tyler is a professor of biomedical engineering at Case Western Reserve University. He and his team have been working with amputees for 15 years.

  Dan Werner can feel thanks to a pressure sensor attached to the bottom of his prosthetic foot and some rewiring of the nerves in his stump. Surgeons identified the ones that controlled the muscles and provided sensory perception from his missing leg and then attached wires on them with tiny cuff electrodes. The wires transmit current to the nerves when the sensor is depressed.

  How similar is it to the real thing?

• Dan Werner:

  It is pretty darn close. Yes, it's pretty darn close. It is not — I mean, it is not like 100 percent. Like, I can do a lot of things with this foot with ankle movement and stuff.

  But, as far as feeling, when you're standing on it or when you're walking, that's the big thing.

• Miles O’Brien:

  I feel you, Dan, but four arm amputees like me, this is even an bigger deal. After all, a sense of touch is one of the primary missions of our hands and fingers. And my body-powered prosthetic is little more than a pair of pliers at the end of a stick. There is really no way for me to feel how much I'm grasping.

• Man:

  Basically, we're trying to get the deep nerve, instead of the surface nerves.

• Miles O’Brien:

  Our sense of touch is crucial because it is faster than our vision by several hundred milliseconds. And every millisecond counts. Dustin Tyler and his team gave me a demonstration of that.

  I got a big head. A lot of people have known that for years.

  (LAUGHTER)

• Miles O’Brien:

  With a virtual reality headset on, I played a game of popping bubbles with just the right amount of force. Simple, right? And yet, with the sensory turned off, I consistently overdid it.

  But once they energized the sensors attached to my hand, I could precisely feel the outer edge of the bubbles.

  Oh, yes, I'm feeling something. Oh, wow. Wow. Oh, wow. That is so amazing.

  Dustin Tyler says this technology might enable another big leap.

  Thanks, guys.

  A future where humans are no longer limited by their skin.

  Brandon Prestwood lost his arm in a workplace accident in 2012, and is also a participant in Tyler's study. He too had surgery connecting his nerves to sensors in the fingertips of a sophisticated prosthetic limb.

• Brandon Prestwood, Study Participant:

  Basically, they have mapped where, if they put this electrical signal to this contact on the nerve cuff, then that makes me feel a pinprick in my index finger.

• Miles O’Brien:

  But he doesn't even have to wear it to get that feeling.

• Dustin Tyler:

  The fact it's attached to his arm is actually kind of arbitrary. We can put the prosthesis anywhere in the world, and he would still feel like his hand.

• Miles O’Brien:

  Prestwood is trying out the idea with his prosthetic arm mounted across Tyler's lab.

• Dustin Tyler:

  And so now we can extend his capability. We can essentially amplify the person by taking that sense of connection, the sense of touch, and putting it on any machine in any part of the world and bring it back to your nervous system.

  And then I can connect it to devices that can do far more than my weak biologic system.

• Miles O’Brien:

  Talk like that is generating commercial interest.

• Dexter Ang, Pison:

  What we're recognizing, is that the human body is incredibly important to tap into as a data source to be used to make people's lives easier.

  So, we have our sensor here.

• Miles O’Brien:

  Dexter Ang is co-founder of a small start-up called Pison. The company is developing a wrist-worn sensor that detects the faint electrical signals controlling simple hand gestures.

• Dexter Ang:

  Point upwards. We are actually going to take a selfie together.

• Miles O’Brien:

  Simply lifting a finger creates a distinct signal.

• Dexter Ang:

  I can zoom in, and I can navigate around.

• Miles O’Brien:

  The device is connected to a smartphone, allowing control of it or other devices, conveyor belts in factories, drones, even pinball machines, to name a few.

  Ang's inspiration came from his late mother, who contracted ALS in 2015. An MIT-trained engineer, he wanted to make her life easier.

• Dexter Ang:

  And when we started doing testing on people affected by ALS and others, we saw this larger idea that was completely uncovered in the market, which is, how do we apply neural interfaces at the wrist in the simplest manner possible?

  And that's where we saw the best pathway to have accessibility to reach hundreds of millions of users long-term for the company. And that's our ambition.

• Miles O’Brien:

  This will likely be good news for people with disabilities, who stand to benefit from all the added investment in trying to read our minds en masse.

  Dustin Tyler welcomes the newfound interest in work he's pioneered for the disabled.

• Dustin Tyler:

  And, in fact, I think that limb loss, I think that spinal cord injury will actually move farther ahead if we can find a larger market to develop this that we can use that technology back. That's exactly the point.

• Miles O’Brien:

  If he's right, maybe it won't be too long before I can give this old-fashioned out-of-touch arm the hook.

  For the "PBS NewsHour," I'm Miles O'Brien.

• Judy Woodruff:

  So exciting, Miles O'Brien. And we certainly hope that's the case.