Prostheses have been around for millennia, restoring structure, range of motion, and even dexterity to those who have lost limbs. But one crucial function has always eluded researchers looking to mimic the subtle architecture of the body: a sense of touch to rival that of a human hand.
Now, that might be on the cusp of changing. According to a study published Wednesday in the journal Science Robotics, a team of researchers at the University of Utah has engineered a prosthetic system that’s given a man whose hand was amputated the ability to feel the sensation of touch. Though the prosthetic hand remains imperfect, the findings suggest the new device is the most sensitive of its kind to date.
As a result, the patient, Keven Walgamott, can now text on his cell phone, pluck a grape from its stem, and even put on his wedding ring—everyday acts he hasn’t been able to perform with both hands since 2002.
In an attempt to capture the capabilities of a human hand, the prosthesis itself came equipped with a series of advanced sensors capable of detecting pressure, movement, and several other types of perception. But the crux of the breakthrough was an innovation called the Utah Slanted Electrode Array (USEA)—a series of electrodes implanted into Walgamott’s arm that provided an electrical link between his limb’s remaining nerves and the prosthesis. Traversing this wireway, signals passed from the prosthesis to a nearby computer, which converted the message into something interpretable by the brain.
This, in effect, translated the device’s output into “the body’s natural language,” study author Jacob George told Anna Ploszajski at The Guardian, giving human and machine an easy way to communicate.
With the device, Walgamott was able to distinguish between hard and soft objects, pick up and handle eggs, and even stuff a pillow into its case. The prosthesis didn’t feel quite like a natural hand, producing sensations that instead felt like “electrical impulses or little electric shocks,” he told Art Raymond at Deseret News.
All the same, Walgamott was overcome when he was able to use the prosthesis to take his wife’s hand—something he hadn’t done with his left hand in over a decade, Raymond reports.
Because the team’s prosthesis can’t sense things like pain and temperature, it’s still a long ways off from completely simulating human touch. It also isn’t yet commercially available, and each unit—consisting of the hand itself and the accompanying electrode array—costs somewhere in the neighborhood of $100,000 to 200,000, Scientific American’s Jeff DelViscio reports.
What’s more, the setup isn’t portable, as it still needs to be tethered to a computer to relay signals from prosthesis to brain. And there’s not yet data to show how users would react, physically and emotionally, to wearing the device long term, Sarah Wilkes, a researcher at the University of College London who was not involved in the study, told Ploszajski.
But the researchers think the future still looks bright. Already, the team has conducted successful trials in several other patients. “We can’t yet fully replicate nature’s rich repertoire of sensation and perception,” study author Gregory Clark told Gizmodo’s Ed Cara. “But we can do far, far better than occurs when there’s no sensation at all.”