Researchers develop a non-invasive hybrid EEG/EOG-based brain/neural hand exoskeleton that allows quadriplegics to open and close their hand to eat and drink.
Traumatic spinal cord injury (SCI) can result in quadriplegia, or the loss of motor function in both arms and legs. SCI patients with quadriplegia experience the loss of mobility and sensation, and unfortunately, most of their independence. In order to restore autonomy, this population’s greatest need is the return of intuitive hand and arm movements so they can perform daily living activities like eating with cutlery or drinking with a cup.
At present, SCI is incurable. Researchers have not only been working to develop treatments that target damaged neurons and tissue at the injury site, but also technologies that maximize residual motor function using brain-machine interfaces (BMIs). BMIs translate brain activity (electric, magnetic or metabolic) that is associated with the intention of movement (such as reaching or grasping), into motions performed by a robotic device. For example, the visualization of a closing hand can result in a hand-closing action performed by an exoskeleton.
Implanted BMIs have been shown to restore movement in patients with quadriplegia, but entails great risk to patients as craniotomies are highly invasive. Therefore, there is a demand for a non-invasive BMI system. In a recent article in Science Robotics, a group of researchers report that they have developed a non-invasive hybrid EEG/EOG brain/neural hand exoskeleton for quadriplegics and successfully restored independent daily living activities in an everyday life scenario.
Six quadriplegic patients with cervical SCI were outfitted with a hybrid EEG/EOG brain/neural hand exoskeleton (EBNE) connected to a standard wheelchair. The EEG, or electroencephalography, component of the device translates electric brain activity associated with the intention to grasp into exoskeleton-driven hand-closing motions. The EOG, or electrooculography, signals are linked to the patient’s voluntary horizontal eye movements that drive exoskeleton-driven hand-opening motions. The exoskeleton itself is a battery-powered orthosis that actively assists the thumb and index fingers. To control the exoskeleton, EEG and EOG signals are transmitted to a wireless tablet computer that processes the signals in real-time and translates them into control signals. These signals are then sent to a control box and actuators that move the hand exoskeleton.
Each participant was asked to perform right-hand reaching and grasping tasks with and without the EBNE. The study was composed of 3 main parts. The first part of the study examined grasping and manipulation of test objects that included a mug, book, soda can, credit card, and pencil. The second part examined the strength and stability of grasping items in the participant’s palm using wooden blocks, a wooden bar, and a credit card attached to a dynamometer. All movements were assessed using the Toronto Rehabilitation Institute-Hand Function Test (TRI-HRT). The last part of the study involved the participant leaving the laboratory and going to a restaurant, lobby, office, or outdoor environment to perform a number of everyday tasks. All activities were recorded by a video camera mounted on the wheelchair.
All participants were extremely dependent on others and suffered from severe motor dysfunction. TRI-HRT scores before using the EBNE device showed that participants experienced substantial difficulty in grasping and manipulating test objects. When wearing the EBNE, all participants were able to control hand-opening, closing, and interruption of unintended exoskeleton movements within 8 to 10 minutes. Using the EBNE, test objects were successfully grasped, held on to, and manipulated – all of which were reflected in the TRI-HRT scores that significantly increased to 85% of the maximum score. These results demonstrated that there was full restoration of independent daily living activities that require these motor functions.
The EBNE system was tested outside of the lab in part 3 of the study. Results showed that participants were able to perform everyday tasks that were previously incapable of eating potato chips with their bare hands, drinking from a water bottle, grasping a fork to eat, handing over a credit card, and signing a document with a pen. In a real-world environment, the exoskeleton system was reliable to use and practical while performing these daily living activities. No participants experienced any side effects or discomfort when using the EBNE.
This study is significant because it is the first to demonstrate the use of a BMI outside the lab to perform daily living activities. The hybrid non-invasive EEG/EOG brain/neural hand exoskeleton successfully restored the motion of opening and closing a paralyzed hand so participants could eat and drink in an everyday life scenario. These results suggest that integrated and brain/neural-controlled robotic systems can restore the independence and autonomy of quadriplegics in everyday life.
Written By: Fiona Wong, PhD