A number of researchers around the world are working on a variety of sensory systems for artificial limbs. Currently, even the best artificial limbs are not capable of creating the kinds of sensations that human skin can impart. Robotic prostheses can approach the dexterity of the human hand, for example, but they don’t impart a sense of touch. They can send vibrations to imply that they are touching something, but it’s not the same, and as a result people with such prostheses must rely on vision to use their hand.
A number of systems are in the early stages of development or brainstorming that would be able to return the sense of touch to people who have lost limbs, especially hands or arms. Direct neural stimulation would allow users to identify aspects of a touched item, such as stiffness, shape, or size, and would allow for navigation without vision. Targeted muscle re-innervation would send signals to existing muscles and overlaying skin.
The various systems in the works all have the same goal: allowing amputees to have greater control over their surroundings, and assume a more natural experience, akin to what they were used to before they lost a limb. With this returned sense of touch would likely come a new sense of wholeness. The loss of upper limbs is generally harder on people; especially because those loses tend to come for younger patients. For an otherwise healthy individual, the sudden loss of a hand can be devastating.
Our hands are our primary tools for interacting with the world, and part of what essentially makes us human. Giving people who have lost a hand or an arm a prosthesis capable of returning some sense of normalcy is a huge step. Finding a way to make that prosthesis feel, allowing it to transfer sensory data to replicate or replace the lost sense of touch, would be a huge accomplishment.