Blue Arbor Technologies is developing implantable sensors to give patients better control of cutting-edge prosthetic arms and hands — with potential exoskeleton applications in the future.
In April 2024, the FDA gave breakthrough device designation to Blue Arbor’s RESTORE Neuromuscular Interface System and enrolled it in the agency’s Total Product Life Cycle Advisory Program (TAP) pilot to get the technology to patients faster. (RESTORE is an acronym of “Reimagining Engineering Solutions To Optimize Restoration of Extremities.”)

A patient controls a prosthetic hand using Blue Arbor’s RESTORE Neuromuscular Interface System as co-founder Alex Vaskov looks on. [Photo courtesy of Blue Arbor Technologies]
“I have been performing research in this space primarily to try to enhance function for people with limb loss,” Cederna said in an interview. “That was driven by the patients I take care of on a daily basis who have horrible, traumatic injuries, cancer operations where they lose their limbs, or other medical conditions that lead to limb loss. So for me, it was entirely driven by a world where people with limb loss just were not getting what they needed to rehabilitate their lives back to where they were before.”
Under an FDA investigational device exemption (IDE) for research, Cederna and his co-founder, Chief Technology Officer Alex Vaskov, have implanted their technology into four patients since 2017.

Blue Arbor Technologies co-founder and President Dr. Paul Cederna [Photo courtesy of Blue Arbor Technologies]
‘A biologic solution to a biologic problem’
Ann Arbor, Michigan-based Blue Arbor doesn’t make prosthetics, but rather a system with implanted electrodes to give patients more control over state-of-the-art prosthetics than they have with electrodes placed on their skin. Implanting the electrodes offers a better way to sense a limb-loss patient’s nerve activity to control a robotic hand or arm.
“The biggest issue is there has not been a way to give really fine, delicate control of a prosthetic device using surface electrodes or interfacing with muscles that are in a residual limb after an amputation,” Cederna said. “People have worked for decades to try to interface with the peripheral nerves that, even after an amputation, are still carrying the signals from the brain to the hand. If you could just record those signals from the peripheral nerve, you can control the hand. The problem is the signals are so small, they’re not much bigger than electrical noise in the body. So it was virtually impossible to record those nerve signals long term.”

The Blue Arbor Technologies RESTORE Neuromuscular Interface System amplifies nerve signals using electrodes implanted in muscle grafts. [Image courtesy of Blue Arbor Technologies]
“That little piece of muscle — the regenerative peripheral nerve interface — becomes the nerve signal amplifier,” Cederna said. “Now we know exactly what the nerve is saying. … We created a biologic solution to a biologic problem of tiny, little nerve signals. That eliminated the need for a lot of advanced materials.”
That approach lets Blue Arbor use tried-and-true medical-grade materials and components for their system, which plugs into the grafted muscle with bipolar electrodes.
“They’re stainless steel, intramuscular electromyography (EMG) electrodes that can be put into either remaining muscles or the muscles that are attached to the ends of nerves,” Vaskov said. “That’s big for when we’re thinking about our regulatory path to market and what we need to prove for biocompatibility.”

Components of the the Blue Arbor Technologies RESTORE Neuromuscular Interface System [Image courtesy of Blue Arbor Technologies]
The sensing transmitter does minimal processing and filtering on the nerve signals and transmits packets to a receiver board that sits in the socket of the prosthetic device. That receiver board runs a machine-learning algorithm to decode the nerve signals into movement intention.
“That kind of interplay is how we manage power well, because we don’t want people to have to stop and recharge their device every four hours,” Vaskov said. “A lot of our prototyping was to figure out the jobs of the devices and how they communicate to make sure we have a system that will last at least a full day or even a couple of days before someone would need to recharge it.”
The patient calibrates the algorithm in about five minutes using an app that asks them to mimic finger, wrist and elbow movements with their phantom limb, training the algorithm how those movements relate to the nerve signals.
“In research [with our four patients], we’ve always started with a personalized algorithm, so they’ll calibrate and train from scratch,” Vaskov said. “As we collect more data and can evaluate more data, there’s probably the opportunity to have a general model so someone can go out immediately with a starting point and then tweak it to make it better.”
What’s next for Blue Arbor

Blue Arbor Technologies co-founder and Chief Technology Officer Alex Vaskov [Photo courtesy of Blue Arbor Technologies]
“Blue Arbor Technologies has our RESTORE Neuromuscular Interface System with the external sensing unit as version 1.0,” Cederna said. “At the same time, we are designing the internal unit, which is the fully implantable system. We don’t need anything new and special for either of those.”
Version 3 will include sensory feedback, something that Blue Arbor is already working on with patients, Cederna said.
“As soon as prosthetic limbs start getting fit with better sensorized fingertips, we will have more opportunities to give naturalistic feeling,” he said. “There are lots of really exciting new ways to provide different types of tactile feedback — artificial skins with sensors and things like that — and I’m really excited about all of those being developed, because all of those could get fit onto these advanced prosthetic limbs and then we can use those signals to feed back into the body to give them sensation back.”
Blue Arbor has also researched a slightly different strategy to tap into the nerves of fully intact limbs to control an exsoskeleton. In that case, the implanted muscle would surround the nerve for sensing without disrupting it, and the only difference in the RESTORE system would be new code to control the exoskeleton, Cederna said.
Blue Arbor already has a strategic investment from a lower limb prosthetic manufacturer, though Cederna asked that they not be identified by name because the investment has not yet been announced.
“We’ve had lots of conversations with prosthetic manufacturers,” he said. “Interestingly, the major prosthetic manufacturers already have advanced limbs. They sell very few of them because they don’t have a great control system for them. They are all very interested in our RESTORE Neuromuscular Interface System because that’s going to give them an opportunity to get their really advanced limbs out to people to use.”
Read more from our interview with Blue Arbor co-founders Dr. Paul Cederna and Alex Vaskov in the weeks ahead at Medical Design & Outsourcing.