Soft Robotic Exosuit Lets Stroke Survivors Walk Faster, Farther — and Weighs Just 11 Pounds

Built from smart textiles and Bowden cables, the soft robotic exosuit has proven effective in assisting stroke survivors with mobility.

A soft robotic exosuit, worn on one or both legs, could assist stroke survivors. (📷: Rolex Awards/Fred Merz)

A multidisciplinary team from Harvard and Boston Universities have designed a soft robotic exosuit which, they claim, allows stroke survivors to walk faster and farther than ever before.

"The vast majority of people who have had a stroke walk slowly and cannot walk very far. Faster and farther walking after physical therapy are among the most important outcomes desired by both, patients and clinicians," explains Wyss Institute Associate Faculty member and first author Dr. Lou Award "If neither speed nor distance are changed by a therapy, it would be difficult to consider that therapy to be effective.

"The levels of improvement in speed and distance that we found in our exploratory study exceeded our expectations for an immediate effect without any training and highlight the promise of the exosuit technology."

The exosuit designed and studied by the team weighs under five kilogrammes (around 11lbs) including the battery which powers it. An actuator unit is worn at the hips, with mechanical power transferred to the ankles via cables connected to lightweight functional textiles - and thanks to a modular design and the use of soft materials, it's possible to wear it at only one side in order to reduce gait asymmetry issues where assistance on both legs it not required.

The system works by assisting with plantar flexion, where the ankle pushes the foot down into the ground during walking, and with dorsiflexiion, where the foot is lifted up with the toes reaching towards the shin — both movements which are often hampered post-stroke.

Testing the system on a short walkway, the team found that the exosuit had no impact on its wearers while unpowered by when activated "we saw important and immediate improvements in walking speed and distance which are meaningful outcomes that make a real difference in everyday lives of individuals who have sustained a stroke," according to co-author Dr. Terry Ellis. "It's these kind of clinically meaningful outcomes that stimulate excitement among physical therapists and others in the rehabilitation community."

The team's work has been published under open-access terms in the journal IEEE Open Journal of Engineering in Medicine and Biology.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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