Consolidating related technologies, engineers at Cleveland Clinic have created a bionic arm that gives people with upper-limb amputations full control of the prosthetic. The greatest test of any prosthetic is the degree to which it replaces the functions and sensations of the natural body part. The researchers describe their success in restoring human-like function in a report in Science Robotics.

The Cleveland researchers worked with two patients with upper-limb amputations. Both people had two prior neural-machine procedures. Each patient had targeted sensory reinnervation and targeted motor reinnervation. Targeted sensory reinnervation enables patients to experience a sense of touch. With targeted motor reinnervation, patients can signal the muscles associated with moving their limbs by thinking about the movement. The bionic arm also has robots that vibrate kinesthetic sensory receptors to signal patients when their arm and hand move.

The upshot of this combination of bi-directional signaling is that patients using the bionic arm can learn to control the prosthesis without looking. The neural interfaces allow them to sense movement, grip, and touch. Patients with traditional prosthesis need to watch the movement carefully for accurate control, but the neural-machine interface in this bionic arm informs and trains the patient’s brain to use the prosthetic without looking.

According to Dr. Paul Marasco, Associate Profession in Cleveland Clinic Lerner Research institute’s Deportment of Biomedical Engineering, the lead researcher, the patients in the study “made judgements, decisions, and calculated and corrected for their mistakes like a person without an amputation.”

The Cleveland Clinic study was limited to just two subjects, but it points the way for advances and prosthetics and highlights the possibilities in consolidating matured technologies for brain/machine interfaces.