In prosthetics, the most common technology for controlling limbs is called electromyography. This technique records electrical activity from the muscles, but only provides only limited control of the prosthesis, preventing users to move the artificial body part the same way they would move a natural limb.

In a bid to overcome this challenge, scientists at MIT Media Lab have developed a new approach that allows more precise control for people with amputation who have prosthetic limbs.

The novel method, called magnetomicrometry (MM) involves the insertion of small magnetic beads into the muscle tissue where the amputation is. This allows the accurate measurement of the length of contracting muscles in a non-invasive way while providing feedback within a few milliseconds.

By inserting a pair of magnets into the muscle, the movement of the magnets can be measured, showing how much the muscle is contracting and how long the contraction lasts. The obtained data is then fed into a computer model that predicts where the patient’s phantom limb would be, based on the contractions of the remaining muscles. This process then instructs the prosthesis to move the way the patient wants it to.

The team plans to conduct a demonstration experiment test with real patients within the next few years.

“Our hope is that MM will replace electromyography as the dominant way to link the peripheral nervous system to bionic limbs. 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,” said Hugh Herr, senior author of the paper.

Study source: Science Robotics — Magnetomicrometry

Image source: MIT Media Lab