Brain-Controlled Bionic Hand Offers Most Advanced Artificial Touch Yet

Scientists are getting closer to something that wouldn’t look out of place in a science fiction film: bionic limbs that can sense and convey touch to their users.

In a new study published this week, researchers debuted a bionic hand system that can reportedly reproduce the most complex tactile sensations seen to date. Scientists at the Cortical Bionics Research Group developed the novel brain-computer interface (BCI) device, which was tested out by volunteers with spinal cord injuries.

Across a series of experiments, the researchers were able to translate and relay sensations tied to motion, curvature, and orientation that allowed the volunteers to perform complicated tasks with their bionic limb. The researchers say their device has now accomplished a new level of artificial touch.

There have been some important advances in prosthetic and bionic limb technology in recent years, but these limbs are currently still a long way away from fully approximating the complex nature of human touch. Some scientists have begun to use intracortical microstimulation (ICMS) of the brain’s somatosensory cortex to bridge this gap, since experiments have shown that such stimulation can produce vivid tactile sensations on people’s skin. According to study researcher Giacomo Valle, however, early attempts with ICMS have largely focused on reproducing sensation location and intensity. But there’s much more that goes into feeling something than just those two aspects.

“While contact location and force are critical feedback components, the sense of touch is far richer than this, also conveying information about the texture, material properties, local contours, and about the motion of objects across the skin. Without these rich sensations, artificial touch will remain highly impoverished,” Valle told Gizmodo. In their new study, published Thursday in Science, Valle and his team believe that they’ve gone a crucial step further with ICMS.

The researchers recruited two people with spinal cord injuries for their experiments. The volunteers were first given brain implants in the sensory and motor regions of the brain that govern the hands and arms. Via these implants, the researchers recorded and then deciphered the different patterns of electric activity produced by the volunteers’ brains as they thought about using their paralyzed limbs. The volunteers were then connected to a BCI device that acted as a bionic limb. With their thoughts alone, the volunteers could control the limb, which was outfitted with sensors that communicated with the brain implants. The researchers were then able to translate and send more complex sensations related to touch through the bionic limb into the volunteers’ brain implants.

“In this work, for the first time, the research went beyond anything that has been done before in the field of brain-computer interfaces—we conveyed tactile sensations related to orientation, curvature, motion and 3D shapes for a participant using a brain-controlled bionic limb,” said Valle, a bionics researcher at Chalmers University of Technology. “We found a way to type these ‘tactile messages’ via microstimulation using the tiny electrodes in the brain, and we found a unique way to encode complex sensations. This allowed for more vivid sensory feedback and experience while using a bionic hand.”

The volunteers could not only feel more layered sensations like touching the edge of an object—these sensations felt as if they were coming from their own hands. The added input also appeared to make it easier for the volunteers to perform complex tasks with the bionic limb more accurately, such as moving an object from one place to another. And it’s this richness, Valle said, that “is crucial for achieving the level of dexterity, manipulation, and a highly dimensional tactile experience typical of the human hand.”

These are still early days, the researchers note. More complex sensors and robotic technology, such as prosthetic skin, will be needed to truly capture the sensations that researchers can now encode and convey to a user, Valle says, and more advanced brain implants will also be needed to increase the array of sensations that can be stimulated. But Valle and his team are hopeful that such advances can be made, and that a truly human-feeling bionic limb is well within the realm of possibility.

“Although many challenges remain, this latest study offers evidence that the path to restoring touch is becoming clearer. With each new set of findings, we come closer to a future in which a prosthetic body part is not just a functional tool, but a way to experience the world,” he said.

The immediate next phase of Valle and his team’s research will be to test their BCI systems in more naturalistic settings, such as at patients’ homes. And their ultimate goal is to improve the independence and quality of life of people with disability.