Engineers at Johns Hopkins University have created an electronic skin that when layered on top of prosthetic hands, brings back a real sense of touch through the fingertips.
"After many years, I felt my hand, as if a hollow shell got filled with life again," says the anonymous amputee who served as the team's principal volunteer.
Made of fabric and rubber laced with sensors to mimic nerve endings, this e-dermis recreates a sense of touch as well as pain by sensing stimuli and relaying the impulses back to the peripheral nerves.
The sensor is designed to fit over the fingertips of a prosthetic hand and electrically stimulate the amputee's nerves in a non-invasive way through the skin.
The team created a ‘neuromorphic model’, mimicking the touch and pain receptors of the human nervous system, allowing the e-dermis to electronically encode sensations just as the receptors in the skin would. Tracking brain activity via electroencephalography, the team determined that the test subject was able to perceive these sensations in his phantom hand.
The researchers then connected the e-dermis output to the volunteer by using a non-invasive method known as transcutaneous electrical nerve stimulation. In a pain-detection task, the team determined that the test subject and the prosthesis were able to experience a natural, reflexive reaction to both pain while touching a pointed object and non-pain when touching a round object.
The e-dermis is not sensitive to temperature—for this study, the team focused on detecting object curvature (for touch and shape perception) and sharpness (for pain perception).
The researchers believe this e-dermis technology could be used to make robotic systems more human, and to expand or extend to astronaut gloves and space suits.