Researchers Turn to Implantable Magnets to Provide High-Detail Muscle Movement Info for Robotics

Researchers at the Massachusetts Institute of Technology (MIT) have come up with a novel way to accurately track the movements of muscles using tiny implantable magnets — in the hopes the technology could one day help people control prosthetic limbs more naturally.

"We're able to provide the muscle-length tracking functionality of the room-sized X-ray equipment using a much smaller, portable package," claims co-lead author Cameron Taylor of the work on what the researchers are calling "magnetomicrometry," comparing it to traditional X-ray fluoromicrometry, "and we're able to collect the data continuously instead of being limited to the 10-second bursts that fluoromicrometry is limited to."

The team's work is split across a pair of studies, one of which proved that the approach — that sees tiny spherical magnets implanted into muscle tissue — could be used in living creatures without discomfort, inflammation or other issues. The other study, meanwhile, showed that once implanted into turkey's calf muscles the magnets could be used to provide high-quality data on the creature's muscle movements — even as it ran and jumped.

In addition to providing continuous readings and without the bulk — or radiation — of X-ray fluoromicrometry, the magnetomicrometry approach is claiemd to be considerably more accurate than surface electromyography (EMG). This, senior author Hugh Herr claims, has the potential to "improve the control and efficacy of bionic limbs for persons with limb-loss."

"The place where this technology fills a need is in communicating those muscle lengths and velocities to a wearable robot, so that the robot can perform in a way that works in tandem with the human," adds Taylor. "We hope that magnetomicrometry will enable a person to control a wearable robot with the same comfort level and the same ease as someone would control their own limb.

"Magnets don’t require an external power source, and after implanting them into the muscle, they can maintain the full strength of their magnetic field throughout the lifetime of the patient."

The team's work has been published in two papers, both available under open-access terms in the journal Frontiers in Bioengineering and Biotechnology: One on the viability of the implants for clinical use, and the other on using the implants to track muscle movement wirelessly.