A prosthetic device called SPARKy (Spring Ankle with Regenerative Kinetics) has been developed by researchers at Arizona State University. The device is a robotic ankle system which helps amputees get around with a literal spring in their step.
The researchers have developed and refined SPARKy into a smart, active and energy storing below-the-knee (transbitial) prosthesis.
SPARKy is the first prosthetic device to apply regenerative kinetics to its design, which resulted in a lightweight (four pound) device that allows the wearer to walk on grass, cement and rocks, as well as ascend and descend stairs and inclines.
Thomas Sugar, an ASU associate professor of engineering at the Polytechnic campus who led the research, said that SPARKY operates by employing a spring to store energy as the wearer walks during normal gait.
Sugar and his colleagues have been developing and refining SPARKy for three years as part of a U.S. Army grant.
SPARKy uses a robotic tendon to actively stretch springs when the ankle rolls over the foot, thus allowing the springs to thrust or propel the artificial foot forward for the next step.
Because energy is stored, a lightweight motor is used to adjust the position of a finely tuned spring that provides most of the power required for gait.
"SPARKY basically removes the old passive devices and makes it an active device the wearer uses to attain normal gait, which for an amputee is a significant return to normal function," Sugar said.
SPARKy is not only an active prosthetic device, but it also allows a wider range of movement than previous devices, it weighs less and it causes less fatigue for the wearer