A 28-year-old man whose hand was paralyzed as the result of a spinal cord injury is reported as the first person to feel the touch of another human hand with nearly 100% accuracy, aided by a sophisticated prosthetic.
Behind the scenes of this accomplishment is the United States military’s Defense Advanced Research Projects Agency (DARPA). The agency developed a new breed of technologies that orchestrate signals from the sensory cortex and motor cortex so that a prosthetic hand can register a sense of touch.
The new prosthetic, developed by the Applied Physics Laboratory at Johns Hopkins University, provided the 28-year-old male test subject with the capacity to control the prosthetic’s movement using his thoughts. The prosthetic hand’s sense of touch was created as the result of torque sensors contained in the hand that detect pressure. Thus, when pressure is applied to any of the fingers on the prosthetic hand, that sensation is converted to electrical signals.
Those signals are then routed to the user’s brain via a set of wires that run from the mechanical hand.
According to a media release from DARPA, during the first set of tests researchers gently touched each of the prosthetic hand’s fingers while the male test subject was blindfolded. The test subject subsequently identified which mechanical finger was being touched with nearly 100% accuracy. The feeling reported by the test subject was as if his own hand were being touched, the DARPA release notes.
DARPA program manager Justin Sanchez characterizes the milestone as “completing the circuit.”
“Prosthetic limbs that can be controlled by thoughts are showing great promise, but without feedback from signals traveling back to the brain it can be difficult to achieve the level of control needed to perform precise movements,” Sanchez states in the DARPA media release. “By wiring a sense of touch from a mechanical hand directly into the brain, this work shows the potential for seamless bio-technological restoration of near-natural function,” he adds.
Additional details about the work are being withheld pending peer review and acceptance for publication in a scientific journal, according to the DARPA media release.