At MIT, a team of engineers has developed a system that claims to improve user control of a bionic limb. The technology consists of implantable magnetic beads and a series of sensors that can control their movement. When implanted within a muscle in a residual limb, pairs of beads can provide information about muscle movement that sensors can transmit to a prosthesis, potentially controlling their movements more accurately than existing electromyography systems. Researchers hope this approach can improve the experiences of users with assistive technology, including bionic limbs or other assistive devices to improve movement in cases of muscle weakness.
Neuroprostheses must revolutionize the way amputees and other patients with mobility or dexterity problems interact with the world. However, they are still in their infancy, often proving too expensive, heavy, or complex for widespread adoption. Researchers are working hard to perfect them, with the ultimate goal that they work smoothly and be accessible to everyone who needs them.
It is not an easy task to infer the intended movement of an amputee from electrical activity in the muscles of its residual limb, but this electromyography is the current standard when it comes to communicating between a user and a limb. bionic. “When you use electromyography-based control, you are seeing an intermediate signal. You’re seeing what the brain is telling the muscle to do, but not what the muscle is really doing, ”said Cameron Taylor, a researcher involved in the study, in an MIT ad.
In an effort to streamline communication between muscles and an external device, these researchers resorted to implantable magnets and a technique called magnetomicrometry. “Our hope is that magnetomicrometry will replace electromography as the dominant way to link the peripheral nervous system with bionic limbs,” said Hugh Herr, another developer of the new technology. “And we have that hope because of the high signal quality we get from magnetomicrometry and because it’s minimally invasive and has a low hurdle and regulatory cost.”
The approach involves implanting pairs of small magnetic beads into the muscles of a residual limb or other areas of the body that require bionic assistance, such as a limb with muscle weakness. As the muscles contract and lengthen, the magnetic beads move with each other and researchers can read and interpret these movements using external sensors, which can be applied to the skin or form part of the bionic device. So far, the technique has proven to be promising in animals and researchers hope to move on to human studies.
“With magnetomicrometry, we directly measure muscle length and speed,” Herr said. “By mathematical modeling of the entire limb, we can calculate the target positions and velocities of the prosthetic joints to be controlled, and then a simple robotic controller can control those joints.”
Watch an MIT video on the new technique:
Study a Robotic Science: Magnetomicrometry