Major advancements in prosthetic limb development keep coming. The Defense Advanced Research Projects Agency (DARPA) is contributing with neural technologies that are designed to allow those who are paralyzed or missing limbs to actually feel sensations with their prosthetic limbs.
“We’ve completed the circuit,” said DARPA program manager Justin Sanchez. “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. 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.”
How it works is electrode arrays are placed onto a person’s sensory cortex, which allows for identifying thinks like pressure, and also on the motor cortex, which directs body movements. Wires are then run from the arrays on the motor cortex to the mechanical hand developed by the Applied Physics Laboratory (APL) at Johns Hopkins University.
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The APL hand has torque sensors that can detect when pressure is being applied to any of its fingers. Those physical sensations are then converted into electrical signals.
According to DARPA:
In the very first set of tests, in which researchers gently touched each of the prosthetic hand’s fingers while the volunteer was blindfolded, he was able to report with nearly 100 percent accuracy which mechanical finger was being touched. The feeling, he reported, was as if his own hand were being touched.
“At one point, instead of pressing one finger, the team decided to press two without telling him,” said Sanchez, who oversees the Revolutionizing Prosthetics program. “He responded in jest asking whether somebody was trying to play a trick on him. That is when we knew that the feelings he was perceiving through the robotic hand were near-natural.”
This is a pretty phenomenal development for those who need prosthetic limbs. DARPA is working on other similar endeavors as well. Its neural technology programs includes the Restoring Active Memory (RAM) and Systems-Based Neurotechnology for Emerging Therapies (SUBNETS) programs. These seek to develop closed-loop direct interfaces to the brain to restore function to individuals living with memory loss from traumatic brain injury or complex neuropsychiatric illness.
Photo: Flickr user Amber Case
