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Alita's got nothing on this mind-controlled robotic arm that links to your nerves

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Mar 5, 2020

Alita may be able to take on robots twice her size because she's a cybernetic powerhouse, but while sentient robots aren't a thing (yet), cyborg limbs you can control with your brain now are.

Ingenious scientists at the University of Michigan have developed a prosthetic arm that can be controlled with just your brain. The non-invasive process requires almost negligible muscle grafts and machine-learning algorithms from a brain-computer interface (BCI). This isn’t the first attempt at merging robotics with mind control, since DARPA (which also funded this study) is developing weapons with this kind of technology, but it is the first prosthetic limb that successfully does this. There was one amputee who described it as feeling like he had his arm back.

“This is the biggest advance in motor control for people with amputations in many years,” said Paul Cederna, University of Michigan professor of plastic surgery and biomedical engineering, who recently published a study in Science Translational Medicine. “We have developed a technique to provide individual finger control of prosthetic devices using the nerves in a patient’s residual limb. With it, we have been able to provide some of the most advanced prosthetic control that the world has seen.”

Mobius (if that name is giving you déjà vu, think Mobius Final Fantasy) Bionics' LUKE arm takes advantage of an often-neglected group of nerves to give amputees the use of a limb that is supposed to feel eerily real. Peripheral nerves extend outside the brain and spinal cord. They have been ignored in the past because they tend to transmit weak signals, which needed invasive probes to pick them up. These nerves are already fragile, and implanting probes created scar tissue that muffled the signals even more.

Enter the regenerative peripheral nerve interface. Cederna’s team tapped the potential of peripheral nerves by figuring out how to untangle bundles of them into smaller fibers they could actually work with. These nerve fibers could then be manipulated to give the patient more precise control than any prosthetic ever has.

This was achieved by a muscle graft wrapped around nerve endings in patients’ arms, and the procedure amplified nerve signals. Electrodes implanted in the arms of two patients were then able to record these otherwise faint signals and transmit them to the prosthetic hand.

“The regenerative peripheral nerve interface (RPNI) serves as a biologically stable bioamplifier of efferent motor action potentials with long-term stability in upper limb amputees," Cederna said in the study.

Such tech differs form Neuralink in that Musk’s company is looking to create AI that specifically targets neurological diseases and could eventually give the brain a proverbial hand with artificial intelligence. Both Neuralink and the LUKE arm rely on brain-computer interfaces that connect the brain to a computer so communication can happen. The difference is that Neuralink would work to reverse illnesses like Alzheimer’s and Parkinson’s by targeting neurons in the parts of the brain that are degenerating rather than putting the focus on peripheral nerves that can control a limb.

The Michigan team found that voltage recorded from nerves ended up being not just higher than previous results, but the highest recorded so far. They were able to pick up the first millivolt signals ever. Signals coming from individual finger movements could be accessed, and another plus was that no learning was required from the patient, since the BCI algorithms were already there in the prosthetic arm. Patients have been able to play a modified version of “rock, paper, scissors” and pick up objects just by thinking of the action. The tech also lasts without degrading and creating scar tissue.

Cederna and his team are determined to keep upgrading the LUKE arm and doing more investigation into neuroprosthetics. If this sounds sci-fi now, just wait.

(via University of Michigan/Science Translational Magazine)


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