The scientists are working on “biohybrid” limbs that will use regenerated tissue, lengthened bone, titanium prosthetics and implantable sensors that allow an amputee to use nerves and brain signals to move the arm or leg.
For proper knee rotation and propulsion, special fluids will be used: they solidify into a paste when passed through a magnetic field, then reliquify when the energy is removed. Force will be controlled by a tendon-like spring powered by an electric motor. The ankle system will either use a similar spring or an artificial muscle, made of electroactive polymers, which turn electrical energy into mechanical work.
To control these joints, BION (TM), a wireless microchip about the size of a grain of rice, will be injected into existing leg muscle, where they pick up signals from nerves and send movement instructions to the knee and ankle. Additional sensors, attached to the heel and forefoot of an external prosthesis, will relay information about ground reaction forces to a microprocessor to further guide movement of the artificial joints.
Via MIT News.