Scientists at the University of Pittsburgh Rehab Neural Engineering Labs played a key role in progressing neuroprosthetic brain-computer interface (BCI) technology that enables people to feel the shape and movement of objects over the "skin" of a bionic hand.
New studies in Nature Biomedical Engineering and Science document major progress of a technology designed to recreate realistic tactile feedback to prosthetic hands by direct, carefully timed electrical stimulation of the brain.
Led by the University of Chicago, the group also included scientists and engineers at Northwestern University, Case Western Reserve University and Blackrock Neurotech. Together they are designing, building, implementing and refining BCI devices and robotic prosthetic arms that could restore both movement control and sensation in people who have lost significant limb function.
"We hope to integrate the results of these two studies into our robotics systems, where we have already shown that even simple stimulation strategies can improve people's abilities to control robotic arms with their brains," said co-author Robert Gaunt, Ph.D., associate professor of physical medicine and rehabilitation and lead of the stimulation work at Pitt.
The researchers' approach to prosthetic sensation involves placing tiny electrode arrays in the parts of the brain responsible for moving and feeling the hand. On one side of the brain, the arrays enable a participant to move a robotic arm by simply thinking about movement. In the other side of the brain dedicated to touch, feedback from sensors on the robotic limb can trigger pulses of electrical activity called intracortical microstimulation, producing a tactile sensation.
In the Nature Biomedical Engineering study, published last December, scientists focused on ensuring that electrically evoked touch sensations were stable, accurately localized and strong enough to be useful for everyday tasks. The testing revealed that when two closely spaced electrodes were stimulated together, participants felt a stronger, clearer touch, which improved their ability to locate and gauge pressure on the correct part of the hand. The researchers also conducted exhaustive tests to confirm that the same electrode consistently created a sensation corresponding to a specific location.
The complementary Science paper, published this week, went a step further to make artificial touch even more immersive and intuitive. After identifying pairs or clusters of electrodes whose "touch zones" overlapped, the scientists activated them in carefully orchestrated patterns to generate sensations that progressed across the sensory map, creating sensations that could let users feel the boundaries of an object or the motion of something sliding along their skin.
These advancements help move bionic feedback closer to the precise, complex, adaptive abilities of natural touch, paving the way for prosthetics that enable confident handling of everyday objects and responses to shifting stimuli. The researchers hope that as electrode designs and surgical methods continue to improve, the coverage across the hand will become even finer, enabling more lifelike feedback.
The work at the University of Chicago and at Pitt was supported by the National Institute of Neurological Disorders and Stroke of the National Institutes of Health (grants UH3 NS107714 and R35 NS122333).
"Evoking stable and precise tactile sensations via multi-electrode intracortical microstimulation of the somatosensory cortex" was published in Nature Biomedical Engineering in December 2024. Authors include Charles M. Greenspon, Giacomo Valle, Natalya D. Shelchkova, Thierri Callier, Ev I. Berger-Wolf, Elizaveta V. Okorokova, Efe Dogruoz, Anton R. Sobinov, Patrick M. Jordan, Emily E. Fitzgerald, Dillan Prasad, Ashley Van Driesche, Qinpu He, David Satzer, Peter C. Warnke, John E. Downey, Nicholas G. Hatsopoulos and Sliman J. Bensmaia from the University of Chicago; Taylor G. Hobbs, Ceci Verbaarschot, Jeffrey M. Weiss, Fang Liu, Jorge Gonzalez-Martinez, Michael L. Boninger, Jennifer L. Collinger and Robert A. Gaunt from the University of Pittsburgh; Brianna C. Hutchison, Robert F. Kirsch, Jonathan P. Miller, Abidemi B. Ajiboye, Emily L. Graczyk, from Case Western Reserve University; Lee E. Miller from Northwestern University; and Ray C. Lee from Schwab Rehabilitation Hospital.
"Tactile edges and motion via patterned microstimulation of the human somatosensory cortex" was published in Science in January 2025. Authors include Giacomo Valle, now at Chalmers University in Sweden; Ali H. Alamri, John E. Downey, Patrick M. Jordan, Anton R. Sobinov, Linnea J. Endsley, Dillan Prasad, Peter C. Warnke, Nicholas G. Hatsopoulos, Charles M. Greenspon and Sliman J. Bensmaia from the University of Chicago; Robin Lienkämper, Michael L. Boninger, Jennifer L. Collinger and Robert A. Gaunt from the University of Pittsburgh; and Lee E. Miller from Northwestern University.
