A team of engineers at the Johns Hopkins University have created an electronic skin that, when layered on top of prosthetic hands, aims to help restore a sense of touch through the fingertips.
Made of fabric and rubber laced with sensors to mimic nerve endings, the e-dermis is designed to re-create a sense of touch as well as pain by sensing stimuli and relaying the impulses back to the peripheral nerves.
“We’ve made a sensor that goes over the fingertips of a prosthetic hand and acts like your own skin would,” says Luke Osborn, a graduate student in biomedical engineering, in a media release from Johns Hopkins University. “It’s inspired by what is happening in human biology, with receptors for both touch and pain.
“This is interesting and new,” Osborn adds, “because now we can have a prosthetic hand that is already on the market and fit it with an e-dermis that can tell the wearer whether he or she is picking up something that is round or whether it has sharp points.”
Human skin contains a complex network of receptors that relay a variety of sensations to the brain. This network provided a biological template for the research team, which includes members from the Johns Hopkins departments of Biomedical Engineering, Electrical and Computer Engineering, and Neurology, and from the Singapore Institute of Neurotechnology.
The e-dermis is engineered to convey information to the amputee by stimulating peripheral nerves in the arm, making the so-called phantom limb come to life. It does this by electrically stimulating the amputee’s nerves in a non-invasive way, through the skin, according to Nitish Thakor, senior author of a study about the e-dermis, published recently in the journal Science Robotics.
“For the first time, a prosthesis can provide a range of perceptions, from fine touch to noxious to an amputee, making it more like a human hand,” adds Thakor, a professor of biomedical engineering and director of the Biomedical Instrumentation and Neuroengineering Laboratory at Johns Hopkins.
Thakor is also co-founder of Infinite Biomedical Technologies, the Baltimore-based company that provided the prosthetic hardware used in the study, per the release.
In their study, 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, or EEG, 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 noninvasive method known as transcutaneous electrical nerve stimulation, or TENS. 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 researchers plan to further develop the technology and better understand how to provide meaningful sensory information to amputees in the hopes of making the system ready for widespread patient use, the release explains.
[Source(s): Johns Hopkins University, Science Daily]