Amputees often experience the sensation of a “phantom limb”—a feeling that a missing body part is still there. That sensory illusion is closer to becoming a reality thanks to a team of engineers at the Johns Hopkins University that has created an electronic skin. When layered on top of prosthetic hands, this e-dermis brings back a real sense of touch through the fingertips.
Made of fabric and rubber laced with sensors to mimic nerve endings, e-dermis recreates a sense of touch as well as pain by sensing stimuli and relaying the impulses back to the peripheral nerves.
Prosthesis system :
Tactile information from object grasping is transformed into a neuromorphic signal through the prosthesis controller. The neuromorphic signal is used to transcutaneously stimulate peripheral nerves of an amputee to elicit sensory perceptions of touch and pain.
Multilayered e-dermis design and characterization:
The multilayered e-dermis is made up of conductive and piezoresistive textiles encased in rubber.The e-dermis was fabricated to fit over the fingertips of a prosthetic hand. The natural layering of mechanoreceptors in healthy glabrous skin makes use of both RA and SA receptors to encode the complex properties of touch.
The prosthesis with e-dermis fingertip sensors grasps an object.The epidermal layer of the multilayered e-dermis design is more sensitive and has a larger change in resistance compared with the dermal layer.Differences in sensing layer outputs are captured during object grasping and can be used for adding dimensionality to the tactile signal.
E-dermis and neuromorphic tactile response from different objects:
Three different objects, with equal width but varying curvature, were used to elicit tactile responses from the multilayered e-dermis. Note the highly localized pressure during the grasping of object 3 and the resulting nociceptor neuromorphic stimulation pattern, which is realized through changes in stimulation pulse width and the neuromorphic model parameters.
In the case of a painful object (object 3), the prosthesis detected the sharp pressure and released its grip through its pain reflex .
News Source: https://www.youtube.com/watch?v=sPN5niTQBz4
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