Chafing, blisters, and sores are common problems for people fitted with an artificial limb.
The artificial limb's fixed, rigid shape can't adapt to changes in a person's body, ultimately causing it to rub against a person's residual limb.
"Ultimately, no matter how sophisticated the limb itself is, if it cannot connect closely and comfortably with the human body, it becomes unwearable," researcher Firat Guder, a reader in intelligent interfaces in the Department of Bioengineering at Imperial College London, said in a news release.
But a new advance aims to solve this 200-year-old problem by revolutionizing the fit of prosthetic limbs, according to a recent report in the journal Nature Communications.
A patented new material called "Roliner" allows amputees to change the shape, volume, and stiffness of the liner used to attach an artificial limb's socket to their body, researchers report.
In fact, amputees can make these tweaks on the fly using their smartphone, creating a more comfortable fit in real time, researchers said.
"Badly fitting prosthetic limbs are a constant struggle for amputees," said lead researcher Uğur Tanriverdi, co-founder of Unhindr, the wearable robotics company that produces Roliner.
"They increase the risk of blisters and sores that can become infected, and the situation can become so painful that there is no choice but to go back to using a wheelchair," Tanriverdi said in a news release. "Alongside causing extreme physical pain, problems with prosthetics not fitting can also impact on a person's mental health as they are unable to live as independently and freely as they deserve."
Roliner is made from elastic silicone containing channels that can be pressurized to change its volume and shape, researchers said.
"Just like a basketball, it becomes bigger and more rigid when it is inflated, and smaller and softer when it is deflated," Tanriverdi said.
Six amputees who used Roliner with their everyday artificial legs found it "to improve fitting and their experience to be less frustrating compared to their everyday liner," researchers reported in the journal article.
Roliner also can incorporate AI so that each liner can "learn" the personal preferences of the person using it, researchers said.
Driven by AI, the limb could automatically adjust its properties according to how the human body changes throughout the day, or due to hormonal fluctuations, researchers said.
People also could change the fit to match the activity they're pursuing. For example, they might prefer a looser fit while sitting and a tighter fit while walking.
The research team also thinks that the technology can be used in applications beyond prosthetics.
For example, it could be used to increase the flexibility of exoskeletons used in rehab, modulate the pressure points of hospital beds, or improve the fit of protective gear like ski boots.