Engineers Create Bionic Arm That Restores Natural Behaviors in Patients

Researchers at the Cleveland Clinic have engineered a new bionic arm that restores natural behaviors in patients with upper-limb amputations. The technology is the first-of-its-kind, and the research was published in Science Robotics.

The international research team combined three important functions in the bionic system: intuitive motor control, touch and grip kinesthesia. The last of the three is the sensation of opening and closing the hand. 

The team, which was led by the Cleveland Clinic, also included researchers from the University of Alberta and the University of New Brunswick. 

Paul Marasco, Ph.D, is lead investigator and associate professor in Cleveland Clinic Lerner Research Institute's Department of Biomedical Engineering. 

“We modified a standard-of-care prosthetic with this complex bionic system which enables wearers to move their prosthetic arm more intuitively and feel sensations of touch and movement at the same time,” said Dr. Marasco. “These findings are an important step towards providing people with amputation with complete restoration of natural arm function.”

The Bionic System

The newly developed system is the first to test all three sensory and motor functions at one time in a neural-machine interface in a prosthetic arm. The neural-machine interface is able to connect with the wearer's limb nerves, and it enables patients to send nerve impulses from the brain to the prosthetic. They can also receive physical information from the environment, which is able to be sent back to their brain through their nerves.

The artificial arm has bi-directional feedback and control, and this is what enables wearers to perform certain tasks on par with non-disabled individuals. 

Dr. Marasco leads the Laboratory for Bionic Integration.

“Perhaps what we were most excited to learn was that they made judgments, decisions and calculated and corrected for their mistakes like a person without an amputation,” said Dr. Marasco. “With the new bionic limb, people behaved like they had a natural hand. Normally, these brain behaviors are very different between people with and without upper limb prosthetics.”

Testing the Bionic Arm

The bionic arm was tested on two study participants with upper limb amputations. The individuals had previously undergone targeted sensory and motor reinnervation, which redirect amputated nerves to remaining skin and muscles to establish a neural-machine interface. 

The researchers now must expand on the work since the study size was so small.

Participants wore the advanced prosthetic while performing tasks that reflected basic behaviors, or those that require hand and arm functionality. The researchers then assessed the performance through advanced evaluation tools and found that the participants’ brain and behavioral strategies changed. They were then on par with those of an individual without an amputation. 

The participants were able to carry out behaviors without having to watch the prosthesis, and they could more effectively correct for mistakes.

“Over the last decade or two, advancements in prosthetics have helped wearers to achieve better functionality and manage daily living on their own,” said Dr. Marasco. “For the first time, people with upper limb amputations are now able to again ‘think' like an able-bodied person, which stands to offer prosthesis wearers new levels of seamless reintegration back into daily life.”