University of Washington (UW) Professor Joan Sanders, PhD, and her team are creating a new type of transtibial prosthetic leg that automatically adjusts its fit throughout the day. Their latest prototype alters its fit without the need for adjustments to padding or user action. It detects in real time how well the prosthetic socket and amputation site are fitting and responds by automatically changing the size of the socket. Test results with volunteers are so promising that the researchers hope to eliminate the need to add or remove padding throughout the day.
It contains several key features to make auto adjustment possible:
- A gel interface material—shaped like a sock that users typically wear over the amputation site—that contains a small amount of iron.
- Three ultrathin sensors embedded within the wall of the prosthetic limb’s socket detect the distance to the iron in the gel and send that data to the socket’s microcontroller.
- The microcontroller calculates whether adjustments are needed. If so, it transmits instructions to 3 motorized “panels” within the socket wall—2 in the front, 1 in the back. The panels can move in to make the socket smaller, or out to make it bigger.
The adjustments that the panels make, which can also be controlled manually via an app on the user’s smartphone, are usually tiny—less than a millimeter. Through trials with volunteers, the team has found that these automatic adjustments take the place of switching out padded socks that prosthesis users normally wear and change throughout the day. Through user trials with volunteers, Sanders’ team is collecting more detailed data on the device’s performance and is working to make the prototype’s motors smaller and lighter.
