A small, bead-like magnet used in a new approach to measuring muscle position. (Credit: MIT)

Using a simple set of magnets, researchers have devised a sophisticated way to monitor muscle movements, which they hope will make it easier for people with amputations to control their prosthetic limbs. The researchers have demonstrated the accuracy and safety of their magnet-based system, which can track the length of muscles during movement. The studies, performed in animals, offer hope that this strategy could be used to help people with prosthetic devices control them in a way that more closely mimics natural limb movement.

Their strategy takes advantage of the permanent magnetic fields surrounding small beads implanted in a muscle. Using a credit-card-sized, compass-like sensor attached to the outside of the body, their system can track the distances between the two magnets. When a muscle contracts, the magnets move closer together, and when it flexes, they move further apart.

In one study, the researchers showed that this system could be used to accurately measure small ankle movements when the beads were implanted in the calf muscles of turkeys. In one of the new studies, the researchers set out to see whether the system could make accurate measurements during more natural movements in a non-laboratory setting.

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