alex smith is He was 11 years old when he lost his right arm in 2003. A drunk driver driving a boat on Lake Austin collided with a family’s boat, sending him overboard. He hit the propeller and severed his arm underwater.
A year later, he received a myoelectric arm, a type of prosthetic arm that is powered by electrical signals from the muscles in his residual limb. However, Smith rarely used it because it was “very, very slow” and had a limited range of movement. He could open and close his hands, but couldn’t do much else. He tried other robotic arms over the years, but they had similar problems.
“It’s not super high-performance by any means,” he says. “There’s a significant delay between performing a function and the prosthetic limb actually performing it. Even in daily life, we’re finding other ways to do things faster.”
Lately, he’s been trying out a new system by Austin-based startup Phantom Neuro. This system has the potential to provide more life-like control of prosthetic legs. The company is developing thinner, more flexible muscle implants that allow amputees to have a wider range of more natural movements by simply thinking about the movements they want to perform.
“Not many people are using robotic limbs, and that’s largely because of how bad the control system is,” says Connor Glass, CEO and co-founder of Phantom Neuro.
According to data shared exclusively with WIRED, 10 participants in a study conducted by Phantom used a wearable version of the company’s sensor to control a robotic arm already on the market, and 11 They achieved an average accuracy of 93.8 percent for hand and wrist gestures. Smith was one of the participants, along with nine other healthy volunteers, as is common in early prosthetic limb research. The success of this study paves the way for testing Phantom’s implantable sensors in the future.
Current myoelectric prostheses, like the one Smith attempted, read electrical impulses from surface electrodes placed on the amputated limb. Most robotic prosthetics have two electrodes, or recording channels. When a person bends their hand, the muscles in their arm contract. Contractions of these muscles also occur when upper limb amputees flex. Electrodes pick up electrical signals from these contractions, interpret them, and initiate movement of the prosthesis. However, surface electrodes can slip and move around, so they cannot always capture a stable signal, reducing accuracy in real-world environments.
