First magnet-controlled prosthetic hand lets amputees perform everyday tasks

Researchers have created the first prosthetic hand controlled by magnets, enabling amputees to move it by thought.

The project, from a research team at the BioRobotics Institute of the Scuola Superiore Sant’Anna in Pisa, allows precise control of grip strength and is useful for handling fragile objects.

The prosthetic hand operates without wires or electrical connections, relying solely on magnets and muscles to control finger movements. This allows users to perform everyday tasks like opening jars, using screwdrivers, and picking up coins.

“We have finally developed a functional prosthesis that meets the needs of a person who has lost a hand,” said Christian Cipriani, professor at the BioRobotics Institute of the Scuola Superiore Sant’Anna, in a statement .

Magnet-based prosthetics

A team at Scuola Superiore Sant’Anna is exploring myokinetic control to advance prosthetics by implanting small magnets in muscles to interpret motor intentions.

Funded by the European Commission, this innovative interface allows the movement of residual muscles in the amputated arm to control a robotic hand. When the muscles contract, the magnets move, triggering an algorithm to instruct the prosthesis to move its fingers.

“There are 20 muscles in the forearm and many of them control the hand movements. Many people who have lost a hand keep on feeling it as if it is still in place and the residual muscles move in response to the commands from the brain,” said Cipriani.

The study team mapped the movements to direct the robotic hand’s fingers and converted them into signals. The magnets have an inherent magnetic field that is easily localized in space. A unique algorithm converts the movement of the magnet—which occurs when a muscle contracts—into a particular command for the robotic hand.

The first patient, 34-year-old Daniel from Italy, who utilized the prosthesis for six weeks, underwent successful testing of the implant, which was integrated with the Mia-Hand robotic hand created by the spin-off Prensilia.

Magnets enable dexterity

Daniel, who lost his left hand in 2022, became the first patient to test a new prosthesis using implanted magnets .

In April 2023, surgeons at Azienda Ospedaliero-Universitaria Pisana successfully implanted the magnets, enabling his residual muscles to control the prosthesis. The surgery involved precise preoperative imaging to identify viable muscles, with intraoperative adjustments made due to scarring.

Daniel had six magnets inserted in his arm. The group of medical professionals and surgeons found and separated the muscle in each case, then placed the magnet and made sure the magnetic field was pointed in the same direction.

“To make the connection between the residual arm where the magnets were implanted and the robotic hand easier, we made a carbon fibre prosthetic socket containing the electronic system capable of localising the movement of the magnets” said Cipriani.

According to researchers, the experiment’s outcomes considerably exceeded even the most optimistic predictions.

Daniel demonstrated the ability to manipulate his fingers, pick up and move objects of various forms, and execute commonplace tasks like opening jars, using screwdrivers, cutting with knives, and zipping shut. He also demonstrated the ability to regulate his force when handling delicate objects.

“This system allowed me to recover lost sensations and emotions: it feels like I’m moving my own hand,” said Daniel.

The team is now ready to apply these results to a broader range of amputations. “In fact, our work on this new implant is going ahead thanks to European and national funding,” said Cipriani.