HomeRoboticsMagnetic sensors monitor muscle size

Magnetic sensors monitor muscle size

A small, bead-like magnet utilized in a brand new method to measuring muscle place. Picture: Courtesy of the researchers

By Anne Trafton | MIT Information Workplace

Utilizing a easy set of magnets, MIT researchers have provide you with a complicated strategy to monitor muscle actions, which they hope will make it simpler for individuals with amputations to manage their prosthetic limbs.

In a brand new pair of papers, the researchers demonstrated the accuracy and security of their magnet-based system, which might monitor the size of muscle groups throughout motion. The research, carried out in animals, provide hope that this technique might be used to assist individuals with prosthetic gadgets management them in a means that extra intently mimics pure limb motion.

“These current outcomes display that this software can be utilized outdoors the lab to trace muscle motion throughout pure exercise, and so they additionally recommend that the magnetic implants are secure and biocompatible and that they don’t trigger discomfort,” says Cameron Taylor, an MIT analysis scientist and co-lead writer of each papers.

In one of many research, the researchers confirmed that they may precisely measure the lengths of turkeys’ calf muscle groups because the birds ran, jumped, and carried out different pure actions. Within the different research, they confirmed that the small magnetic beads used for the measurements don’t trigger irritation or different opposed results when implanted in muscle.

“I’m very excited for the scientific potential of this new know-how to enhance the management and efficacy of bionic limbs for individuals with limb-loss,” says Hugh Herr, a professor of media arts and sciences, co-director of the Ok. Lisa Yang Middle for Bionics at MIT, and an affiliate member of MIT’s McGovern Institute for Mind Analysis.

Herr is a senior writer of each papers, which seem within the journal Frontiers in Bioengineering and Biotechnology. Thomas Roberts, a professor of ecology, evolution, and organismal biology at Brown College, is a senior writer of the measurement research.

Monitoring motion

Presently, powered prosthetic limbs are normally managed utilizing an method often called floor electromyography (EMG). Electrodes connected to the floor of the pores and skin or surgically implanted within the residual muscle of the amputated limb measure electrical alerts from an individual’s muscle groups, that are fed into the prosthesis to assist it transfer the best way the particular person sporting the limb intends.

Nevertheless, that method doesn’t take note of any details about the muscle size or velocity, which might assist to make the prosthetic actions extra correct.

A number of years in the past, the MIT crew started engaged on a novel strategy to carry out these sorts of muscle measurements, utilizing an method that they name magnetomicrometry. This technique takes benefit of the everlasting magnetic fields surrounding small beads implanted in a muscle. Utilizing a credit-card-sized, compass-like sensor connected to the skin of the physique, their system can monitor the distances between the 2 magnets. When a muscle contracts, the magnets transfer nearer collectively, and when it flexes, they transfer additional aside.

The brand new muscle measuring method takes benefit of the magnetic attraction between two small beads implanted in a muscle. Utilizing a small sensor connected to the skin of the physique, the system can monitor the distances between the 2 magnets because the muscle contracts and flexes. Picture: Courtesy of the researchers

In a research revealed final yr, the researchers confirmed that this technique might be used to precisely measure small ankle actions when the beads had been implanted within the calf muscle groups of turkeys. In one of many new research, the researchers got down to see if the system might make correct measurements throughout extra pure actions in a nonlaboratory setting.

To do this, they created an impediment course of ramps for the turkeys to climb and packing containers for them to leap on and off of. The researchers used their magnetic sensor to trace muscle actions throughout these actions, and located that the system might calculate muscle lengths in lower than a millisecond.

Additionally they in contrast their information to measurements taken utilizing a extra conventional method often called fluoromicrometry, a kind of X-ray know-how that requires a lot bigger tools than magnetomicrometry. The magnetomicrometry measurements assorted from these generated by fluoromicrometry by lower than a millimeter, on common.

“We’re capable of present the muscle-length monitoring performance of the room-sized X-ray tools utilizing a a lot smaller, transportable package deal, and we’re capable of accumulate the info constantly as a substitute of being restricted to the 10-second bursts that fluoromicrometry is restricted to,” Taylor says.

Seong Ho Yeon, an MIT graduate scholar, can also be a co-lead writer of the measurement research. Different authors embrace MIT Analysis Help Affiliate Ellen Clarrissimeaux and former Brown College postdoc Mary Kate O’Donnell.


Within the second paper, the researchers centered on the biocompatibility of the implants. They discovered that the magnets didn’t generate tissue scarring, irritation, or different dangerous results. Additionally they confirmed that the implanted magnets didn’t alter the turkeys’ gaits, suggesting they didn’t produce discomfort. William Clark, a postdoc at Brown, is the co-lead writer of the biocompatibility research.

The researchers additionally confirmed that the implants remained secure for eight months, the size of the research, and didn’t migrate towards one another, so long as they had been implanted at the least 3 centimeters aside. The researchers envision that the beads, which include a magnetic core coated with gold and a polymer referred to as Parylene, might stay in tissue indefinitely as soon as implanted.

“Magnets don’t require an exterior energy supply, and after implanting them into the muscle, they will keep the complete power of their magnetic area all through the lifetime of the affected person,” Taylor says.

The researchers at the moment are planning to hunt FDA approval to check the system in individuals with prosthetic limbs. They hope to make use of the sensor to manage prostheses much like the best way floor EMG is used now: Measurements relating to the size of muscle groups will likely be fed into the management system of a prosthesis to assist information it to the place that the wearer intends.

“The place the place this know-how fills a necessity is in speaking these muscle lengths and velocities to a wearable robotic, in order that the robotic can carry out in a means that works in tandem with the human,” Taylor says. “We hope that magnetomicrometry will allow an individual to manage a wearable robotic with the identical consolation stage and the identical ease as somebody would management their very own limb.”

Along with prosthetic limbs, these wearable robots might embrace robotic exoskeletons, that are worn outdoors the physique to assist individuals transfer their legs or arms extra simply.

The analysis was funded by the Salah Basis, the Ok. Lisa Yang Middle for Bionics at MIT, the MIT Media Lab Consortia, the Nationwide Institutes of Well being, and the Nationwide Science Basis.


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