The prosthetic that can feel pain
Remarkable device wrapped in electronic skin could help amputees sense touch to avoid injury
A prosthetic wrapped in electronic skin that can feel both pain and touch could help amputees avoid injury. The skin, known as e-dermis, is a thin layer of rubber and fabric fits over the fingertips of a prosthetic hand and generates pulses of electricity. These small shocks fire into nerves in the stump to simulate a real feeling of touch when the electronic skin makes contact with objects.
The team has already tested e-dermis on an anonymous amputee, who described the experience ' as if a hollow shell got filled with life again'.
Feeling pain is vital to a fully-functioning limb as the sensation helps us to protect our bodies by removing them from danger.
'Pain is, of course, unpleasant, but it's also an essential, protective sense of touch that is lacking in the prostheses that are currently available to amputees,' project researcher and John Hopkins University graduate student Luke Osborn said. 'Advances in prosthesis designs and control mechanisms can aid an amputee's ability to regain lost function, but they often lack meaningful, tactile feedback or perception.'
The team at John Hopkins School of Medicine in Baltimore, used the complex network of touch receptors in human skin as inspiration for their device.
Sensors in e-dermis connect to nerves in the wearer's stump through electrodes placed on the skin, firing signals in a similar way to real nerves. Depending on the pattern of pulses sent by the device, it can convey a range of sensations from light touch through to pain.
'With the sensory feedback we can provide natural sensations to the hand of an amputee,' Mr Osborn said. ' This is important because it's taking us one step closer to a life-like upper limb prosthesis.'
The researchers tested a prototype e- dermis on an anonymous amputee who tried the device out while grasping different objects. The test subject and prosthesis were able to experience a natural reaction to both pain while grasping a pointed object and touch when feeling a round object.
The team also introduced auto- matic pain reflexes, in which the hand dropped objects that were too sharp without waiting for instructions from the brain, as would happen with a real hand.
The participant said of his experience with the prosthetic: 'After many years, I felt my hand, as if a hollow shell got filled with life again.'
The work, published in the journal Science Robotics, shows it is possible to restore a range of natural, touch-based feelings to amputees who use prosthetic limbs.