Mind-Controlled Movement: Advancements in the Field of Prosthetics

In brief:

The first prosthetic was an iron toe developed over 3000 years ago for an Egyptian woman so she could don her sandals.

The history of prosthetics has been long and fruitful from the first tiny iron toe to the first prosthetic arm, to a Civil War-era leg prosthesis with knee and ankle hinges. The sleek, mind-controlled prosthetics of today are a vast improvement, and the work is not over yet.

In 2007, a Johns Hopkins University (JHU) team including Albert Chi, MD (now also at Oregon Health & Science University and a leader in the field of 3-D printable hands and arms), Courtney Moran, MS, and Robert Armiger, MS, began developing a mind-controlled prosthetic arm. The artificial limb translates messages from the user’s brain into movements that it executes as a regular human limb would.

Dr. Chi explains that an approach called Targeted Muscle Reinnervation (TMR) is at the heart of the technology. It is a surgical procedure that reassigns nerves in people with missing limbs to control advanced prosthetics.

In 2012, a man who had lost his arm to cancer and tested previous generations of prosthetic devices was chosen to test the JHU Modular Prosthetic Limb (MPL) in a research setting. His name is Johnny Matheny. “Everybody tells me that I’m the only one that has had my stump into every advanced prosthetic in the United States,” he said.

After Johnny had tested the prosthetic extensively in the JHU lab, the team delivered the device to him in Florida for a year’s trial, making him the first person to use an advanced mind-controlled prosthetic arm under real-life conditions. His only limitations? Don’t use it to drive, and don’t get it wet.


Though Johnny Matheny’s prosthesis can “feel” soft versus hard objects, scientists are going beyond this level of prosthesis “feeling.” A JHU research team recently created an E-dermis: an electronic skin made of fabric and rubber that can convey feeling to the fingers of a prosthetic arm. The e-dermis is embedded with sensors that can detect a stimulus and send a signal to the peripheral nervous system to respond to the stimulus, allowing the prosthesis to respond by reflex to certain stimuli.
Johnny Matheny’s prosthesis can “feel” soft versus hard objects. JHU researchers have created an E-dermis, an electronic skin made of fabric and rubber that can convey feeling to the fingers of a prosthetic arm.


The MPL was developed over a decade, at a cost exceeding $120 million. Funding came from the US Defense Advanced Research Projects Agency (DARPA), which is responsible for developing technologies for military use.

Mind-controlled prosthetics enable a wide range of motion and allow movement of the separate joints within a limb. Johnny’s device contains 26 joints, 17 of which can be moved individually. His MPL can also “feel” differences between hard and soft objects. “I . . . have an arm as close to my natural arm as humanly possible,” Johnny said during the “real-life” test period – a period in which he reached a personal goal of playing the piano.

But research hasn’t stopped. Konrad Kording, PhD of the University of Pennsylvania and Eva Dyer, PhD of Georgia Tech and Emory University and a former Kording protégé, are working to streamline how a prosthetic such as Johnny’s is calibrated, or “trained” on nearly all possible limb movements and each one’s corresponding neural component.

Drs. Kording and Dyer have developed an approach that may prove to be more practical, dubbed Distribution Alignment Decoding (DAD), to decipher the neural impulses governing movement. DAD could mean a prosthetic may need only enough “training” data to be able to find a consistent pattern, or formula, that maps each neural recording to the corresponding motion. Once DAD finds the formula, it can receive a neural signal that wasn’t included in the prosthetic’s original “training,” apply the formula, and execute the intended movement. The objective is to enable a DAD-trained prosthetic to be just as accurate as a prosthetic like Johnny’s but with less data and therefore less individualized “training.”

Despite technical progress, researchers are concerned about the commercial availability of advanced prosthetics. “To be clear, we are still years away from having this become commercially available for clinical use,” stresses He (Helen) Huang, PhD, a mind-controlled prosthetics researcher. “It is difficult to predict potential cost, since our work is focused on the software, and the bulk of the cost for amputees would be in the hardware [physical prosthetic] that actually runs the program.”

Johnny returned the prosthetic to the JHU lab after the yearlong trial. However, he continues to work with the device to help researchers understand its limitations and its promise. The journey spanning thousands of years and miles that began with a single iron toe continues. Wouldn’t the Egyptian lady who wanted to wear her beautiful sandals all those years ago be impressed?


Robert Armiger, MS, is a member of the principal professional staff at the Johns Hopkins University Applied Physics Laboratory. He leads the Health and Biological Sciences Branch, which performs leading research and development in the areas of biological sciences, human performance and biomechanics, health data analytics, and next-generation care delivery. He received his MS in biomedical engineering from Johns Hopkins University, and in 2015 was named the Maryland Academy of Sciences Outstanding Young Engineer.

Albert Chi, MD, MSE., serves as medical director of the Oregon Health and Science University (OHSU) Targeted Muscle Reinnervation program and is an associate professor of trauma, critical care and acute care surgery in the OHSU School of Medicine. Before coming to OHSU in 2016, he was the medical director of the Targeted Muscle Reinnervation Program and medical director of the Physician Assistant Surgical Residency Program at Johns Hopkins University where he continues to hold an appointment with the Johns Hopkins Applied Physics Lab.

Eva Dyer is an assistant professor in the Wallace H. Coulter Department of Biomedical Engineering at the Georgia Institute of Technology and Emory University. She runs the Neural Data Science (NerDS) Lab, where she and her team develop new machine learning and data science approaches for making sense of large-scale neural datasets. Before joining Georgia Tech, she was a research scientist at Northwestern University, where she worked with Konrad Kording, PhD (now at UPenn). Dr. Dyer received degrees in Electrical and Computer Engineering, including a PhD and MS from Rice University.

Konrad Kording received a PhD (Physics) from the Federal Institute of Technology, Zurich. He is currently a professor of neuroscience at the University of Pennsylvania Perelman School of Medicine. Early research in Dr. Kording’s lab focused on computational neuroscience and, in particular, movement. Recently his lab has been working how new data sources and emerging data analysis may affect deep learning and its neural implementation.

Johnny Matheny was diagnosed with cancer in his left arm in 2005. After Johnny underwent six surgeries and 39 radiation treatments, his arm was amputated. He says he lives by two rules: “there’s a reason for the season” and “positive mental attitude.” Johnny found out about Johns Hopkins University’s project to construct an arm that could revolutionize prosthetics. Hopkins needed humans to start testing the arm. Johnny was introduced to Dr. Albert Chi and became the first person to test a mind-controlled prosthetic arm. See https://www.medgadget.com/2016/09/jonny-matheny-worlds-advanced-prosthetic.html for his story.

Courtney Moran, MS is a member of the senior professional staff at the Johns Hopkins University Applied Physics Laboratory. She received her MS in biomedical engineering/prosthetics from Rutgers/UMDNJ. She is certified by the American Board for Certification in Orthotics, Prosthetics & Pedorthics, Inc.

Works Cited

  1. Demkovich, Laurel. “With New Mind-Controlled Robotic Arm, Port Richey Man Is Living in the Future.” Tampa Bay Times, 5 June 2018, www.tampabay.com/news/health/research/With-new-mind-controlled-robotic-arm-Port-Richey-man-is-living-in-the-future_168741687.
  2. Gohd, Chelsea. “Florida Man Becomes First Person to Live with Advanced Mind-Controlled Robotic Arm.” Futurism, Futurism, 3 Feb. 2018, futurism.com/mind-controlled-robotic-arm-johnny-matheny.
  3. North Carolina State University. “New tech may make prosthetic hands easier for patients to use.” ScienceDaily. ScienceDaily, 22 May 2018. <www.sciencedaily.com/releases/2018/05/180522132703.htm>.
  4. Templin, Jacob. “The US Spent $120 Million on a Robotic Arm, Then Gave It to Someone for a Year.” Quartz, Quartz, 2 Feb. 2018, qz.com/1194939/the-us-government-just-gave-someone-a-120-million-robotic-arm-to-use-for-a-year/.
  5. “The History of Prosthetics.” UNYQ The History of Prosthetics Comments, unyq.com/the-history-of-prosthetics/.

Image Credits:

By Team Graphic Designer: Selena Liu

Chief Editor: Akila Saravanan
Creative Team Manager: Lucia Tian
Team Editor: Mary Chen
Team Graphic Designer: Selena Liu

This article was written by Jessica Yatvitskiy. As always, before leaving a response to this article please view our Rules of Conduct. Thanks! -cSw Editorial Staff