Described in a study released yesterday, October 26, 2016 in Science Translational Medicine, a new prosthetic hand was tested on two amputees who had each lost a hand in a traumatic accident.
The prosthetic hand is equipped with touch sensors that pick up information about how hard the user is gripping an object, which is then converted into neural code for the correct amount of pressure. The neural code is delivered directly to the nerves with tiny amounts of electricity via surgically implanted electrodes.
The artificial sensors essentially operate like natural sensors in the skin, relaying sense data to the brain, which, in turn, generates the sense of touch.
The study subjects claim the new prosthetic feels much more like a real hand than a tool used to assist the remaining one. With the ability to actually feel what they were doing, the subjects said they felt two-handed again. Explaining the exact sensations, however, is a bit more complicated.
“Stimulation through individual electrode contacts produces sensation on the tip of the index finger or the tip of the thumb, for example. The sensations feel like touch or vibration or any number of sensations that they might experience with a real hand. What is important to note is that users are able to feel as though their entire hand is interacting with objects and that they can perform complex and delicate tasks,” said two of the study’s authors Dustin Tyler and Emily Grazcyk.
What is currently more limiting is not the subtleties of restored sensation, but the actual mechanics of the prosthesis.
Tyler and Grazcyk are currently developing a fully implantable sensory and motor restoration system that they hope will be ready for clinical trials in about three years, and the market – in roughly ten.