Researchers at Johns Hopkins University have spent years developing an amazing prosthetic limb called the Modular Prosthetic Limb, which mimics upper body movement controlled by thought. The project was funded by DARPA in the 2005 to assist veterans who had sustained injuries and amputations to their arms. The process of actually using the device involves rerouting the electrical signals of the body to the prosthetic limb, and requires mental imagery exercises of the clients in order to develop the networks similar to how we build them to control limbs in our own bodies.

To mimic upper body movement is incredibly difficult and a feat in and of itself. The fine movement and precision of an arm is much different than that of a leg. While the lower extremities are primary used for ambulation and mobility, the man purpose of the hand and upper extremity is for dexterity; grabbing and reaching objects, helping us eat, dress, and complete most daily tasks. The Modular Prosthetic Limb features more than 100 sensors and 26 degrees of freedom (variations in movement). It can open and close the hand, differentiate grasp as a human hand does, and has the strength of a human arm. In an incredibly complicated system, the device communicates with the brain as would a regular limb. The details of the development are discussed in their paper An Overview of the Developmental Process of the Modular Prosthetic Limb, a look into the arduous process of developing this product.

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Revolutionizing Prosthetics 2009 Modular Prosthetic Limb–Body Interface: Overview of the Prosthetic Socket Development (Johns Hopkins APL Technical Digest, Volume 30, Issue 3, pp. 240–249, 2011)