Advancements in materials and robotics technology have transformed prosthetic arms and legs in recent years, but the carbon fiber socket between an artificial part and the wearer remains a challenge to a comfortable fit. If it doesn't fit correctly, painful sores and infections develop.
A new re-adjustable socket project, however, has the potential to save amputees from numerous visits to the prosthetist.
"When there's a disaster, people will donate used limbs," said Elizabeth Tsai, a masters student at the Massachusetts Institute of Technology's Media Lab and a cofounder of the Beneficial Technologies for Health, or BETH, Project. "But then what happens is people can't really use these limbs because they don't have a custom socket."
The BETH Project began in February at an MIT conference called H@cking Medicine when Tsai met Asa Hammond, a University of California, Los Angeles undergrad concentrating on physiological science, and industrial designer Jason Hill. Under guidance from MIT alum and businessman Ramin Abrishamian, the group ran with Hammond's suggestion to make improved low-cost sockets.
A prosthetic with the pylon, socket, and liner could cost upwards of $1,000, Tsai said. Amputees must have sockets custom-built, requiring multiple visits with a prosthetist and three to four weeks for construction. After that, even slight changes in weight or physiology can prompt more visits and adjustments.
When the team interviewed amputees about their needs, some revealed that they stuffed art supply sponges into their sockets. "They're hacking it on their own a little bit to make it more comfortable because no one's body stays the same over a number of the years," Tsai said. "We provide a way to get that comfort."
So the project team came up with a re-adjustable socket design made from infinitely remoldable material. Their cup consists of an elastomeric liner that forms a bladder filled with granular material. This material can fit over prosthetic limbs and then operated with a vacuum for adjustments.
The system works much like a package of coffee grounds that's either solid as a brick or soft and pliable depending on how much air it contains.
Three physical prototypes have been built so far and plans to start trials next to find out whether amputees will be able to do self-adjustments, according to Tsai. Although the cost hasn't been finalized, it's expected to be under $150 and could be significantly less depending on the production method. The BETH Project recently became a runner-up for the 2012 James Dyson Award.