The power of thought
A group of researchers from the Federal Polytechnic School of Lausanne has developed a lightweight and portable arm exoskeleton that can be controlled using electromagnetic waves generated in the brain. The device also helps to restore the grasping function of the damaged hand.
The most convenient and portable exoskeleton of the hand greatly facilitates the performance of everyday manipulations. It is easily attached to the body with textile Velcro fasteners within a few minutes. Metal cables mimic tendons and run along the back of each finger. The palm remains free, this allows you to bring the sensations of working in an exoskeleton as close as possible to the natural ones. The wires go to the bag with the power plant and control system.
The exoskeleton interface allows you to customize it for each individual patient, depending on the degree of his motor disorders. The device can be controlled in various ways: from reading eye movements in complete paralysis to voice control based on smartphones, from residual muscle strength in the affected limb to brain activity using a special headset.
The latter option especially interested the developers. They observed the brain activity of patients while using the exoskeleton. They found that the repetition of the same movements is accompanied by the formation in the brain of areas of activity similar to those when moving hands in healthy people.
The parts of the brain that control movement are called the motor cortex. It is divided into right and left. The right motor cortex is active with the movements of the left limbs, the left – with the movement of the right. This property is called contralateral brain control.
With passive arm movement using an exoskeleton, the researchers observed contralateral brain activity. But when the subjects were asked to control the movement of the device with their brains, activity was observed from the side of the brain, the hand of the same name.
In other words, when the subjects were asked to actively think about moving the exoskeleton, the part of the brain that is responsible for the movements of the opposite arm was involved in the process.
As the developers suggest, this "one-sided" brain activity can be used to control the hand in case of damage to the brain on the opposite side, which in normal condition should have been responsible for movement. It is very important to have feedback, which is provided by the perception of the position of the hand in space (proprioception).
The exoskeleton was tested among patients with motor disorders resulting from a brain stroke or spinal cord injuries. The next step is to improve the device for auxiliary purposes, performing household tasks, as well as using it as a tool for rehabilitation.
Article by Luca Randazzo et al. A Wearable Hand Exoskeleton for Activities of Daily Living and Neurorehabilitation authors is published in the IEEE Robotics and Automation Letters journal.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on EPFL News: Feedback enhances brainwave control of a novel hand-exoskeleton.