A prosthesis that restores the sense of where your hand is

Researchers have developed a new-generation bionic hand that allows amputees to regain their proprioception. The results of the study, published in Robotic science, are the culmination of ten years of research in robotics.

The new generation bionic hand, developed by researchers from EPFL, the School of Advanced Studies Sant Anna in Pisa and the polyclinic of the University A Gemelli in Rome, allows amputees to find a touch very subtle and natural. Scientists have succeeded in reproducing the feeling of proprioception, that is, the ability of our brain to instantly and accurately detect the position of our limbs during and after movement, even in the dark or in the dark. eyes closed.

The new device allows patients to search for an object on a table and check the consistency, shape, position and size of an article without having to look at it. The prosthesis has been successfully tested on several patients and acts by stimulating the nerves of the amputee's stump. Nerves can then provide patients with real-time sensory feedback, almost as they do with a natural hand.

The results are the fruit of ten years of scientific research coordinated by Silvestro Micera, professor of bioengineering at the EPFL's School of Engineering and the School of Advanced Studies Sant & # 39; Anna, and by Paolo Maria Rossini, director of neuroscience at A. Gemelli University. Polyclinic in Rome.

Sensory feedback

Current myoelectric prostheses allow amputees to regain voluntary motor control of their artificial limb by exploiting the residual muscular function of the forearm. However, the absence of sensory feedback forces patients to rely heavily on visual cues. This can prevent them from feeling that their artificial limb is part of their body and make it less natural to use.

Recently, a number of research groups have been successful in providing tactile feedback to amputees, which has improved the function and delivery of the prosthesis. But this latest study has made things happen.

"Our study shows that sensory substitution based on intraneural stimulation can provide both feedback on position and tactile feedback," says Micera. "The brain has no problem combining this information and patients can treat both types in real time with excellent results."

Intraneural stimulation restores the flow of external information by means of electrical pulses sent by electrodes inserted directly into the amputee stump. Patients must then undergo training to gradually learn to translate these impulses into proprioceptive and tactile sensations.

This technique allowed two amputees to recover high proprioceptive acuity, with results comparable to those obtained in healthy subjects. The simultaneous supply of positional and tactile feedback enabled the two amputees to determine the size and shape of four objects with a high level of accuracy (75.5%).

"These results show that amputees can effectively treat the tactile and positional information received simultaneously through intraneural stimulation," says Edoardo D Anna, EPFL researcher and lead author of the study.

Provided by
Federal Institute of Technology in Lausanne