In the United States, the leading cause of serious long-term disability in the U.S. is stroke. Approximately 17 million individuals have a stroke each year, and eight out of ten stroke survivors are left with hemiparesis, a type of paralysis that typically impacts the limbs and facial muscles on one side of the body. This type of paralysis usually causes serious difficulties with walking with the loss of balance and an increased risk of falls.
Hemiparesis also leads to muscle fatigue that quickly sets in during exertion and often leaves those who suffer from the condition unable to perform basic everyday tasks. Researchers at Harvard University believe they have a new system that can help stroke patients recover. The soft exosuit was developed by Harvard mechanical and electrical engineers, along with apparel designers and neurorehabilitation experts.
The soft robotic exosuit is tethered to an external battery and motor and was shown in testing to be able to significantly improve biomechanical gait functions in stroke patients when worn while walking on a treadmill. The team has made a critical step forward in turning their device into a rehabilitation strategy. They have been using an untethered version of the exosuit that carries its battery and motor.
So far, the new system has been tested in six post-stroke survivors with hemiparesis found that the soft exosuit was able to significantly increase their walking speed by an average of 0.14 m/s. One individual was able to walk as much as 0.28 m/s faster. The same individuals, when asked to walk as far as they can in six minutes, were able to go 32 m further on average than those not using the system.
The exosuit used in the study weighs less than 5 kg and targets the limbs of stroke survivors during distinct phases of the gait cycle. The suit is fully mobile, powered by a battery, and initiated by an actuator unit worn at the hips. It’s able to deliver mechanical power to the ankles via a cable-based mechanism with cables in other parts of the exosuit anchored to the body by lightweight, functional textiles. The users only wear the exosuit on their impaired side. The team says in testing when the exosuit was powered on, they saw “important and immediate improvements” in walking speed and distance.