The science of prosthetics has come a long way from the crude wood-and-metal devices of earlier generations. Bioengineers have even developed artificial limbs that can be operated by the user’s mind.
Now, a team at the University of Washington’s Center for Neurotechnology is working to take that one step further: engineering a device — say, a prosthetic arm — that can actually deliver the sensation of touch.
“How do you get information from that robotic arm back into your brain that tells you when it’s touched a person’s hand, or is picking up an egg?” says David Caldwell, a doctoral student in the UW lab.
The trick is to find the precise part of the brain that corresponds with a person’s hand, and then tickle it with a little electricity. That should feel to the person like something has touched the hand.
But putting electrodes in someone’s brain to map those connections is easier said than done. Most scientific institutions won’t permit even volunteers to participate in such research. So Caldwell and his team instead have to look to people whose heads are already opened up.
In this case, they recruited people who were having brain surgery for epilepsy. As part of that process, doctors place a small electrode array, about the size of a cocktail napkin, on the surface of the brain. Researchers can then activate different electrodes to home in on just the right spot.
“Oftentimes they’re very surprised when they have what feels like a brushing or a buzzing on some part of their hand,” Caldwell says.
The technology still has some problems to overcome: that feeling of touch is still more nebulous than the researchers would like, and there’s a bit of lag time between stimulating the brain and the person feeling it.
But eventually, Caldwell and his colleagues hope to create a whole new generation of prosthetics and other devices.
“The end goal would be to have a device they didn't even have to think really about using, but just felt like a natural extension of their body, that both allowed them to shake a loved one’s hand, and also to feel that touch,” he says.