Researchers from the University of California, Irvine, along with Caltech and Keck School of Medicine of USC, announced on April 16 the development of a bidirectional brain-computer interface (BDBCI) that enables a person to control a robotic walking exoskeleton using brain signals while receiving artificial leg sensation through direct electrical stimulation.
This advancement is significant for people living with spinal cord injuries and paralysis. The new system addresses two major challenges: restoring both movement and the sensation of walking, which are crucial for rehabilitation and reducing secondary health risks.
“Millions of people worldwide suffer from paralysis from spinal cord injury, with loss of lower-extremity motor and sensory function leading to wheelchair dependence and increased risk of serious secondary conditions including heart disease, osteoporosis and pressure ulcers,” said Dr. An Do, UC Irvine associate professor of neurology. “Recovering the ability to walk ranks among the highest rehabilitation priorities for paralyzed individuals.”
The study involved a participant who was able to operate the BDBCI-controlled exoskeleton in multiple exercises. She identified steps with nearly 93 percent accuracy during blind step-counting tasks and distinguished between right leg, left leg, or no stimulation feelings at high accuracy rates. No adverse events were reported during testing.
Dr. Charles Liu, professor at Keck School of Medicine at USC, said: “Although interhemispheric ECoG implantation is more complex than other conventional approaches, our team demonstrated that it can be performed safely and yields superior results.” He explained that this approach provides more reliable neural signals related to leg movements.
The entire BDBCI system uses three microcontrollers in a compact design without needing an external computer connection. Jeffrey Lim, UC Irvine postdoctoral scholar in biomedical engineering, said: “This type of portability is necessary to be practical for patients’ everyday use. We hope that our system can serve as a prototypical example for such technologies henceforth.”
Payam Heydari from UC Irvine discussed future plans: “We are looking ahead to a fully implantable version… Such a system would eliminate transdermal components that pose infection risks and enable chronic implantation in paraplegic spinal cord injury patients.” Zoran Nenadic added their goal is further technical improvements so future systems can provide continuous artificial sensation.
Richard Andersen from Caltech noted: “This study by UC Irvine’s Jeffrey Lim and colleagues represents an important proof of concept for a bidirectional interface for walking…” He described how current exoskeletons lack natural somatosensory feedback but this research opens new possibilities.
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