Max Ortiz Catalan, an industrial doctoral student at Chalmers University of Technology, Gothenburg, Sweden, has developed new technology employing implantable electrodes, with the goal of allowing an osseointegrated prosthetic arm to be controlled by the user’s thoughts. This research project will use the titanium Osseointegrated Prostheses for the Rehabilitation of Amputees (OPRA) Implant System, developed by Rickard Brånemark, MD, PhD, to anchor the prosthesis directly to the skeleton.
Ortiz Catalan demonstrates how the system works with the aid of electrodes, which capture bio-electric signals from the surface of the arm. Photograph by Oscar Mattsson, courtesy of Chalmers University of Technology.
“Our technology helps amputees to control an artificial limb, in much the same way as their own biological hand or arm, via the person’s own nerves and remaining muscles,” Ortiz Catalan said. “We have developed a new bidirectional interface with the human body, together with a natural and intuitive control system,” he added.
In this project, the researchers are planning to implant electrodes directly on the nerves and remaining muscles. Since the electrodes are closer to the source, the bio-electric signals become much more stable compared to placing the electrodes on the skin’s surface. The electrical impulses from the nerves in the residual limb are captured by a neural interface, which sends them to the prosthesis through the titanium implant. The impulses are then decoded by sophisticated algorithms, which allow the patient to control the prosthesis using his or her own thoughts.
With this method, patients receive feedback as the electrodes stimulate the neural pathways to the patient’s brain, in the same way as the human body’s physiological system, rather than using only visual or auditory feedback as with existing prostheses. For example, the motors in each finger can be controlled individually and simultaneously with a turning motion of the wrist. The first operations on patients will take place this winter.
Editor’s note: This story was adapted from materials provided by Chalmers University of Technology.
