Patients who have lost a limb, even if they regain function through a prosthesis, would never experience feeling of that limb again. And it's not just that these patients can't feel grass beneath their feet or water running over their hand, a sense of touch is extremely important for having a sense for things like how hard to grip items.
“It’s definitely a milestone in brain-computer interfaces,” says neuroscientist Sliman Bensmaia of the University of Chicago, who is developing touch-feedback systems for human prosthetics. Too many of the robotic arms now being developed, even very advanced ones, he says, ignore the importance of touch. “Sensory feedback is critical to doing anything,” he says. Even mundane tasks like picking up a cup require a great deal of concentration so the wearer does not drop or crush it.
The new work is still an early step, however, he says. A biological arm receives countless inputs not only from texture but also from temperature and its position in space.
According to Wired, researchers have used monkeys to test the technology. Neuroscientist Miguel Nicolelis placed electrodes on the monkeys brains that allowed them to control a virtual arm that they saw through a computer screen with their brain and when they hit a target with the virtual hand, electrical pulses passed through another electrode on the brain, simulating a sense of touch. Wired reports that by giving monkeys a reward when they hit the right target and felt the right texture from the pulse, the animals were able to distinguish textures from each other in as little as four weeks.
Nicolelis describes this as creating a "sixth sense". Watch him explain the technology here:
BBC reports that Nicolelis and his colleagues are working on wearable technology that would allow paralyzed patients to move their limp body parts with their brain and also feel touch. Nicolelis envisions a vest that would "not only carry their body, it will provide sensory feedback so that they know if they are stepping or walking or grabbing objects."