Samuel Alderson developed the first working model of an electrically powered artificial arm, which appeared in 1949. Designed for factory workers who had suffered amputation, the device was very bulky and was plugged into an external power source.
Reinhold Reiter, a physics student at Munich University, patented the first myoelectric prosthetic arm. Also requiring an external power source, it used muscle-contraction signals from the remaining biceps to control the opening and closing of the hand. It was bulky and used vacuum tubes. The transistor would have made the technology more feasible, but this was not invented until 1948. By then the German currency was revalued, and the project lost its funding.
In 1958 a Russian team led by A. E. Kobrinski had developed a myoelectric hand controlled by signals from surviving wrist muscles. Both Otto Bock Orthopaedic Industry in Germany and Viennatone in Austria marketed versions of the "Russian hand."
The first successful myoelectric arm is the "Boston Elbow." Mathematician Norbert Weiner, orthopedist Melvin Glimcher, Amar Bose, Robert Mann, and others from the Massachusetts Institute of Technology (MIT) created working prototypes in 1968 and a viable prosthetic arm by 1974.
The device worked by having sensors in the socket that sensed the currents generated by muscle contractions; these small signals were amplified and moved the prosthesis with the aid of battery-driven motors. Future advances are expected to include transmission of temperature and tactile sensation.
