Current robotic prostheses approach the fine dexterity provided by the human hand, but these advances have outpaced developments in providing sensory feedback from the artificial limb. The lack of sensation is the key limitation to re-establishing the full functionality of the natural limb. With researchers exploring new approaches to designing prosthetic hands capable of providing sensory feedback, 'touchy-feely' bionic hands could soon be a reality.
University of Michigan's Paul S. Cederna and colleagues wrote, "Emerging sensory feedback techniques will provide some sensation and enable more natural, intuitive use of hand prostheses. These breakthroughs pave the way to the development of a prosthetic limb with the ability to feel." The researchers revealed that the upper limb loss is a particularly devastating form of amputation, since a person's hands are their tools for everyday function, expressive communication and other uniquely human attributes. The functional, psychological, economic, and social impact is even greater since most upper limb amputations occur in young and otherwise healthy individuals.
Providing some sense of touch to the artificial limb would lessen the cognitive burden of relying solely on vision to initiate and monitor movements, while also providing tremendous psychological benefits for patients. This review focuses on recent and emerging technologies to create sensory interfaces with the peripheral nerves to provide feeling to prostheses. Already a technique called sensory substitution in being used.
A promising newer technique is targeted muscle reinnervation (TMR), in which the nerves are transferred to provide sensation to intact muscles and overlying skin. Another 'next generation' approach is the use of optogenetic technology for controlling nerve signaling using specific light wavelengths.
Researchers wrote, "The ultimate goal is to develop a prosthesis that closely mimics the natural limb, both in its ability to perform complex motor commands and to elicit conscious sensation."
The study appears in Plastic and Reconstructive Surgery.