The technology has already been licensed and a suit could be commercially available for use in clinics within the next few years. That would be life changing for thousands. Every year, 795,000 Americans have a stroke, which stops blood flowing to parts of the brain and can leave survivors with chronic weakness or paralysis, turning walking into a frustrating\u2014even dangerous\u2014chore. For 15 to 35 percent of survivors, learning to walk independently can take more than six months. Many of those who do learn to walk again will not regain their former speed or stability; according to\u00a0Stroke Connection<\/a><\/em>\u00a0magazine, about 40 percent of all survivors have a serious fall within a year of their stroke.<\/p>\n For a robot, the exosuit is understated, more high-tech sports brace than sci-fi cyborg; it weighs only about 10 pounds. A matchbox-sized sensor attaches to the outside collar of the shoe close to the ankle, while two black wraps cover most of the lower leg and the waist. Cables, similar to those used to control bicycle brakes, run from inside the wearer\u2019s shoe to their calf and from the shoe\u2019s tongue to their shin. Motors\u2014worn around the waist and regulated by a computer unit loaded with algorithms\u2014apply forces through the cables to help the wearer walk<\/p>\n \u201cPeople who have had a stroke have trouble with dorsiflexion, or foot clearance,\u201d says Ellis; they have a reduced ability to bend their ankle and lift their foot. When they try to plant their heel on the ground to walk, they instead \u201cdrag their toes and their foot gets caught.\u201d The exosuit counteracts that issue by retracting the cable attached to the shoe\u2019s tongue, applying a small amount of force to bring the toes up. When the wearer needs to take a step forward, the rear cable contracts to ensure their foot pushes off the ground, a movement called plantar flexion.<\/p>\n The exosuit traces its roots to a soft robot designed for the military by a team at the\u00a0Harvard Biodesign Lab<\/a>\u00a0at the\u00a0Wyss Institute for Biologically Inspired Engineering<\/a>\u00a0at Harvard University. That suit, developed in collaboration with Sargent\u2019s\u00a0Kenneth Holt<\/a>, an associate professor emeritus of physical therapy and athletic training, is intended to help soldiers and emergency personnel carry heavy loads with minimum effort. With a similar cable, wrap, and motor combination, it works in harmony with the body to help reduce the strain associated with lugging hefty packs. By applying assistive forces to the ankle and hip, the suit\u2014which is still in development\u2014reduces the amount of energy needed to carry a load equivalent to 30 percent of a wearer\u2019s body weight by around 7 percent, according to a\u00a0study published in the May 2016\u00a0Journal of NeuroEngineering and Rehabilitation<\/em><\/a>.<\/p>\n To adapt the suit to a medical purpose, Wyss invited Ellis and Awad to join its team of engineers, computer scientists, and business developers. They needed \u201cresearchers who are embedded in the clinical world and work with patients,\u201d says Ellis, director of the\u00a0BU Center for Neurorehabilitation<\/a>. The first major challenge was a practical one. The military suit was designed for \u201cfit individuals who can handle the high amount of force\u201d the exosuit applies to the body, says Awad.<\/p>\n For the suit to work, the wearer needs to be able to bear the typical forces our muscles, tendons, and bones absorb every day, as well as those the exosuit adds. That\u2019s less of an issue for an athletic solider than it is for a senior who has suffered a stroke.<\/p>\n When developing the medical version, the team began by exploring less rigid textiles than those used for the military suit. \u201cThe first prototypes used seatbelt webbing,\u201d says Awad, director of the\u00a0BU Neuromotor Recovery Laboratory<\/a>; in contrast, the medical suit is made of \u201ccomposite materials that create a secure, breathable, and form-fitting interface with the wearer\u2019s leg.\u201d They made other changes, too. Although the original is worn on both legs versus the medical suit\u2019s one leg, it only assists with the pushing off\u2014the military doesn\u2019t have to worry about soldiers dragging their toes. \u201cThe goal with the military suit is to beat nature, break that barrier that nature provided,\u201d says Awad. \u201cWith the medical exosuit, the goal is to bring people back to where they were.\u201d<\/p>\n Both versions of the suit have sensors that tell the computer control unit\u2014Awad calls it the brain\u2014where a person is in their stride, so it can deliver the right amount of force for each individual. The brain is adaptive, says Awad, \u201cso if a person suddenly starts walking faster or changes their cadence, it recognizes that and responds accordingly.\u201d It should eventually allow wearers to navigate uneven terrain, although testing has so far been limited to the lab.<\/p>\n Awad says the suit\u2019s on-the-fly thinking is one of the features that sets it apart from others in development\u2014and one of the Sargent team\u2019s major contributions. Like the less rigid fabrics, the algorithms plugged into the medical exosuit\u2019s control unit also help ensure it doesn\u2019t put too much pressure on the wearer\u2019s body.<\/p>\n \u201cIt\u2019s a product of a deep understanding of how people move and how movement goes awry after something like a stroke,\u201d he says. \u201cThat came from our discussions with the biomechanics team, the engineers, teaching them how people with a stroke move; they didn\u2019t have that experience.\u201d<\/p>\n The medical exosuit is light years ahead of the current alternative for rehabilitation after a stroke: the ankle foot orthosis, an ungainly contraption of molded plastic that\u2019s been in use since the early 1980s. The stiff boot runs down the calf and under the heel, holding the leg and foot at a 90-degree angle. By keeping the ankle locked, the orthosis prevents the wearer from stubbing their toes and tripping, \u201cbut because you have a rigid 90-degree angle, you can\u2019t push off, so you sort of lift the leg and lose some of the key features of a normal gait,\u201d says Ellis. The boot allows people to gain a degree of independence, but it doesn\u2019t get them back to the activities they love. And, Awad adds, it may bring its own complications. \u201cIf you had a stroke at a young age,\u201d he says, \u201cthe muscles that may not have been directly impacted by the stroke are going to suffer.\u201d<\/p>\n In testing, some participants wearing the medical exosuit have been able to nearly regain their pre-stroke walking speeds. In one exosuit testing session, the user began outpacing the physical therapist monitoring his progress. In another, Awad watched as a participant began shouting, \u201cOMG! OMG! OMG!\u201d in happiness. \u201cShe told me, \u2018I was thinking about my grocery list; I\u2019m never able to think about anything except walking, the next step in front of me, otherwise I\u2019m going to fall.\u2019\u201d<\/p>\n In a series of presentations and journal articles, the researchers have quantified the suit\u2019s impact. They found participants pushed off from the ground more effectively and used less energy, and that they walked faster over longer distances. The research, which began with military funding through the\u00a0DARPA Warrior Web Project<\/a>\u00a0and has also been supported by the National Science Foundation, Wyss Institute,\u00a0Harvard Paulson School<\/a>, and the\u00a0American Heart Association<\/a>, was published in the\u00a0July 26, 2017, edition of\u00a0Science Translational Medicine<\/em><\/a>. The principal investigator is\u00a0Conor Walsh<\/a>, an associate professor of engineering and applied sciences at Harvard and a core faculty member at the Wyss Institute.<\/p>\n Ellis doesn\u2019t intend for the suit to replace physical therapists in stroke rehabilitation. Instead, it could be used to help people relearn walking in the immediate aftermath of a stroke and allow them to practice walking at home after being discharged.<\/p>\n \u201cIn this country, once you\u2019ve had a stroke, after about three months, you\u2019re done with all the rehab,\u201d she says. \u201cIt\u2019s a real drawback because there are a lot of studies that show that rehab in the chronic phases is very effective and can enhance function. A therapist could prescribe the exosuit with parameters helpful for each individual.\u201d<\/p>\n To continue reading, a complete\u00a0article originally appeared on\u00a0BU Research<\/a>.<\/em><\/p>\nEqualing Nature<\/h3>\n
![\"terry-ellis-lou-awad_800x534_17-1557-AWADELLIS-001\"](\"\/federal\/files\/2017\/08\/terry-ellis-lou-awad_800x534_17-1557-AWADELLIS-001.jpg\")
Sargent physical therapy professors Terry Ellis (left) and Lou Awad are developing the medical exosuit to help people relearn to walk after a stroke. Photo by Dana Smith.<\/em><\/p>\n\u201cOMG! OMG! OMG!\u201d<\/h3>\n
![\"exosuit_800x534_ALT_RAE16Walsh_16fm_224R\"](\"\/federal\/files\/2017\/08\/exosuit_800x534_ALT_RAE16Walsh_16fm_224R.jpg\")
One of the future goals for the exosuit\u2019s developers is to improve the bionic walking aid\u2019s sensors to help it better adapt to different activities. Photo by Rolex\/Fred Merz<\/em>.<\/p>\n