Sandia Labs develops sensor system to make prosthesis fit better
Sandia National Laboratories have developed a sensor system to make a Prosthesis fit better. Along with Robotics and Cybernetics group, Sandia’s Intelligent Systems is working on a liner with sensors that will tell what’s going on in a limb and a system that can automatically accommodate changes. As a limb doesn’t stay the same shape during the day because of natural fluid fluctuations and as people gain and lose weight, thus, a custom-made socket between a prosthesis and a limb doesn’t always fit. Therefore, an amputee walking on a prosthetic leg is deprived of the comfort, which should be there in the first place.
The robotic researchers have developed a small sensor that can detect pressure in three directions. About the size of a quarter, the prosthesis sensor has been developed to be hooked up inside the socket to monitor fit and detect any changes. Unlike other pressure sensors that measure normal pressure, Sandia’s three-axis pressure sensor can measure pressure in three directions at several sites. Incorporated into the liner that slips into the socket of a prosthesis, the sensors can detect shear forces that can cause problems such as problems as rubbing, blisters and abrasions.
To improve a socket’s fit and comfort, the socket shape is automatically adjusted by Sandia’s system for moving fluid into bladders inside the liners that amputees normally wear. As modifying a custom socket would be expensive and burdensome and could require several fittings, a liner made of elastomeric material similar in thickness to a gel liner have been used by the researchers to adapt. Adjusting to limb changes by placing bladders inside the liners, The Sandia system fills the bladders using valves and pressurized liquid on the outside of the liner.
Working with University of Washington, Sandia has done limited testing with a prototype sensor liner. Though, sensor and bladder systems have not yet been tested together as a closed loop system, Sandia are still working on the system.