Magnets might supply higher management of prosthetic limbs

Magnets might supply higher management of prosthetic limbs

Researchers at MIT’s Media Lab have developed a brand new technique that would supply far more exact management of prosthetic limbs. Credit score: MIT Media Lab

For individuals with amputation who’ve prosthetic limbs, one of many best challenges is controlling the prosthesis in order that it strikes the identical manner a pure limb would. Most prosthetic limbs are managed utilizing electromyography, a manner of recording electrical exercise from the muscle tissue, however this method offers solely restricted management of the prosthesis.

Researchers at MIT’s Media Lab have now developed another method that they consider might supply far more exact management of prosthetic limbs. After inserting small magnetic beads into muscle tissue inside the amputated residuum, they’ll exactly measure the size of a muscle because it contracts, and this suggestions might be relayed to a bionic prosthesis inside milliseconds.

In a brand new examine showing as we speak in Science Robotics, the researchers examined their new technique, referred to as magnetomicrometry (MM), and confirmed that it may present quick and correct muscle measurements in animals. They hope to check the method in individuals with amputation inside the subsequent few years.

“Our hope is that MM will exchange electromyography because the dominant strategy to hyperlink the peripheral nervous system to bionic limbs. And we’ve that hope due to the excessive sign high quality that we get from MM, and the truth that it is minimally invasive and has a low regulatory hurdle and value,” says Hugh Herr, a professor of media arts and sciences, head of the Biomechatronics group within the Media Lab, and the senior creator of the paper.







A analysis workforce at MIT is creating a minimally-invasive expertise utilizing magnetic beads to trace tissue strains in actual time. This new expertise, referred to as magnetomicrometry (MM), might present pure, dependable management of prostheses, exoskeletons and stimulated muscle tissue. MM tracks pairs of magnetic beads embedded inside muscle tissue utilizing a cellular sensing array, which permits the nuanced actions of every muscle to be tracked individually with outstanding velocity and accuracy. This expertise could significantly enhance neural management and has the possibility of basically bettering how people work together with machines. Credit score: MIT Media Lab / Cameron Taylor / Vessel Studios

Cameron Taylor, an MIT postdoc, is the lead creator of the examine. Different authors embrace MIT postdoc Shriya Srinivasan, MIT graduate pupil Seong Ho Yeon, Brown College professor of ecology and evolutionary biology Thomas Roberts, and Brown postdoc Mary Kate O’Donnell.

Exact measurements

With present prosthetic gadgets, electrical measurements of an individual’s muscle tissue are obtained utilizing electrodes that may be both hooked up to the floor of the pores and skin or surgically implanted within the muscle. The latter process is extremely invasive and dear, however offers considerably extra correct measurements. Nevertheless, in both case, electromyography (EMG) presents data solely about muscle tissue’ electrical exercise, not their size or velocity.

“Once you use management primarily based on EMG, you are taking a look at an intermediate sign. You are seeing what the mind is telling the muscle to do, however not what the muscle is definitely doing,” Taylor says.

The brand new MIT technique is predicated on the concept that if sensors might measure what muscle tissue are doing, these measurements would supply extra exact management of a prosthesis. To attain that, the researchers determined to insert pairs of magnets into muscle tissue. By measuring how the magnets transfer relative to 1 one other, the researchers can calculate how a lot the muscle tissue are contracting and the velocity of contraction.

Two years in the past, Herr and Taylor developed an algorithm that significantly decreased the period of time wanted for sensors to find out the positions of small magnets embedded within the physique. This helped them to beat one of many main hurdles to utilizing MM to regulate prostheses, which was the lengthy lag-time for such measurements.

Within the new Science Robotics paper, the researchers examined their algorithm’s skill to trace magnets inserted within the calf muscle tissue of turkeys. The magnetic beads they used have been 3 millimeters in diameter and have been inserted at the least 3 centimeters aside—if they’re nearer than that, the magnets are likely to migrate towards one another.







Credit score: MIT Media Lab / Cameron Taylor / Vessel Studios

Utilizing an array of magnetic sensors positioned on the surface of the legs, the researchers discovered that they have been capable of decide the place of the magnets with a precision of 37 microns (in regards to the width of a human hair), as they moved the turkeys’ ankle joints. These measurements could possibly be obtained inside three milliseconds.

For management of a prosthetic limb, these measurements could possibly be fed into a pc mannequin that predicts the place the affected person’s phantom limb could be in area, primarily based on the contractions of the remaining muscle. This technique would direct the prosthetic gadget to maneuver the best way that the affected person desires it to, matching the psychological image that they’ve of their limb place.

“With magnetomicrometry, we’re instantly measuring the size and velocity of the muscle,” Herr says. “By mathematical modeling of your entire limb, we are able to compute goal positions and speeds of the prosthetic joints to be managed, after which a easy robotic controller can management these joints.”

Muscle management

Inside the subsequent few years, the researchers hope to do a small examine in human sufferers who’ve amputations beneath the knee. They envision that the sensors used to regulate the prosthetic limbs could possibly be positioned on clothes, hooked up to the floor of the pores and skin, or affixed to the surface of a prosthesis.

MM is also used to enhance the muscle management achieved with a method referred to as practical electrical stimulation, which is now used to assist restore mobility in individuals with spinal twine accidents. One other potential use for this sort of magnetic management could be to information robotic exoskeletons, which might be hooked up to an ankle or one other joint to assist individuals who have suffered a stroke or developed different kinds of muscle weak point.

“Primarily the magnets and the exoskeleton act as a synthetic muscle that may amplify the output of the organic muscle tissue within the stroke-impaired limb,” Herr says. “It is like the ability steering that is utilized in vehicles.”

One other benefit of the MM method is that it’s minimally invasive. As soon as inserted within the muscle, the beads might stay in place for a lifetime without having to get replaced, Herr says.


New surgical procedure could allow higher management of prosthetic limbs


Extra data:
Magnetomicrometry, Science Robotics (2021). robotics.sciencemag.org/lookup … /scirobotics.abg0656

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Massachusetts Institute of Expertise


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