The prosthetic is the first bionic lower-leg system to restore lost function of the foot and ankle. It simulates muscle function for people who have had amputations below the knee.
Only five of these bionic feet exist right now.
They are being tested by U.S. servicemen who lost a foot and lower leg while fighting in Afghanistan.
Doctors won't say who created the foot or how much it costs. However, the government did provide an initial grant of several million dollars to start the project.