MIT Media Lab's Trackable Magnets Could Revolutionize Prosthetic, Exoskeleton Control

Researchers at the Massachusetts Institute of Technology (MIT) Media Lab have developed a system for tracking tissue strain in real-time using magnetic beads, claiming it could lead to a minimally-invasive system for the control of prosthetic limbs.

Building on work carried out in 2019 on an algorithm for tracking multiple magnets at the same time, a team led by Cameron Taylor is hoping that magnetomicrometry (MM) will prove a breakthrough for prosthetic limb control — offering the ability to accurately track muscle movements and communicate them to a control system within milliseconds.

"Our hope is that MM will replace electromyography as the dominant way to link the peripheral nervous system to bionic limbs," says Hugh Herr, professor of media arts and sciences and head of the Biomechatronics group in the Media Lab, of the team's work. "And we have that hope because of the high signal quality that we get from MM, and the fact that it’s minimally invasive and has a low regulatory hurdle and cost."

The MM system, which in its current incarnation uses magnetic beads inserted into the muscles themselves, offers the ability to track the length and speed - an improvement on electromyography (EMG), which only tracks electrical activity. In trials, the system proved able to track the magnets' positions to precision of 37 microns — around the width of a human hair — within three milliseconds.

The team is working to make the system less invasive, however, and is hoping that future MM implementations will drop the directly-implanted magnetic beads for ones attached to the user's skin, clothing, or the prosthetics themselves. The researchers are also investigating the use of MM for improving functional electrical stimulation, and for driving exoskeletons.

The team's work is available to download under open-access terms on the project website, following the publication of its latest paper in the journal Science Robotics this week.