Robotician Mohamed Bouri with TWIICE exoskeleton - 2024 EPFL / Alain Herzog - CC-BY-SA 4.0
When we're healthy, activities like walking, sitting down, speaking and remembering things can be done with ease. But if an accident or illness impairs our physical or cognitive capabilities, such everyday tasks can become difficult or even impossible. Researchers are working to develop systems that can help patients regain lost physical abilities.
Some assistive devices now go virtually unnoticed - eyeglasses for seeing nuances and details, for example, and hearing aids for perceiving the sounds around us. But others are more visible. That's the case for many of the assistive devices intended to restore mobility to patients who have lost it.
These are the devices that Mohamed Bouri, a robotics engineer and head of EPFL's REHAssist research group, is working on. "When I see a patient who can no longer walk, one of my main goals is to help them regain that capability," he says. He's developing exoskeletons for individuals who are paraplegic, suffer from a neuromuscular disease or have other kinds of mobility impairment. The exoskeletons are attached to the waist and legs, much like a pair of trousers. They're not intended to heal these patients, but rather to let them walk again and stand upright for hours - with all the social and health-related benefits that a vertical position brings.
Helping the paralyzed walk again
The scientists and engineers at REHAssist are exploring various kinds of systems. One is TWIICE, an exoskeleton for people who are partially or completely paralyzed from the waist down but who have the use of their arms. It has two battery-powered motors on each leg that bend and extend the hip and knee joints. The exoskeleton's full weight - 17 kilos - is supported by the structure itself with the help of the motors. "It's the lightest one in the world," says Bouri. "Patients can use it to walk, climb stairs and go up and down ramps." Wearers control the device using crutches with integrated buttons that also help maintain balance. They can choose between several walking modes based on the desired speed and the surface they're on; each mode corresponds to a given magnitude of hip and knee movement. In short, the exoskeleton does all the work involved in displacing the wearer's legs.
"Exoskeletons aren't very complex in terms of design and robotics," says Bouri. "The technology is out there. The hard part is adapting the devices to the human gait and the needs of human patients while managing the system's weight, providing enough torque density for assisted walking and enabling effective control strategies. There are two "drivers" to consider - the wearer and the exoskeleton itself - and they've got to operate in synergy."
A device for each pathology
Bouri's research group has also teamed up with local neuromuscular research associations to develop exoskeletons specifically for patients with muscular disease. For instance, REHAssist is working with the Swiss muscular disease foundation and the French-speaking Switzerland association for neuromuscular disease to create exoskeletons that enable motorized abduction and adduction movements of the legs - allowing lateral leg movement - and assisted movements of the arms, in order to provide partial support while walking and improve balance. "What's important for these associations is to delay the need for a wheelchair for as long as possible," says Bouri. Doctors have found that people with muscular disease quickly lose the use of their arms, meaning they can't manipulate an exoskeleton such as TWIICE ONE that involves crutches.
REHAssist is also designing systems to enable sports activities. Engineers have adapted TWIICE so that it can be used for ski mountaineering - in this case, wearers place a section of their lower leg into a standard ski mountaineering boot. In 2020, a parasport enthusiast was able to practice the sport using this system. Going further, the research group is developing a device for people with no particular pathology but who prefer not to walk for various reasons.
Of all the systems in the pipeline at REHAssist, TWIICE is the furthest along. An eponymous startup is in the process of setting up production facilities.
Exoskeletons aren't very complex in terms of design and robotics. The hard part is adapting the devices to the human gait and the needs of human patients while managing the system's weight, providing enough torque density for assisted walking and enabling effective control strategies.
Assistance on the job, too
Exoskeletons can also provide valuable assistance in the workplace. But here the goal is not to turn people into
super-workers capable of carrying heavier loads for longer hours or to boost our productivity. "Occupational exoskeletons are intended solely for prevention purposes," says Julie Beuret, an ergonomics consultant at the Swiss company ergoexpert. "They can help reduce the incidence of musculoskeletal disorders (MSDs) and protect employees." Beuret and her colleagues at ergoexpert advise companies that are interested in using exoskeletons for their operators.
Such devices address a real public health problem. According to Switzerland's State Secretariat for Economic Affairs, MSDs are one of the biggest occupational health and safety challenges for Swiss companies, resulting in lost-time injuries and the associated costs. MSDs include a number of painful, debilitating and common afflictions such as carpal tunnel syndrome, chronic lower back pain and shoulder tendonitis.
MSDs are generally caused by lifting heavy objects, performing repetitive tasks or conducting certain kinds of movements - precisely the activities that exoskeletons can assist with. Different models have been developed for different parts of the body. The most widely used ones support the back and shoulders through either an "active" battery-powered device that stretches the lower back, or a "passive" device that transfers the load from the lumbar area to the thighs, providing relief to the lower back. They can assist operators who often have to carry large items or make repetitive movements. Shoulder exoskeletons also exist, and are designed for professionals, such as painters, who work with their arms raised.
Occupational exoskeleton experts are contacted regularly, and demand for these devices is growing. However, Beuret notes that few Swiss companies use exoskeletons in the workplace and awareness remains low.
Occupational exoskeletons are intended solely for prevention purposes. They can help reduce the incidence of musculoskeletal disorders (MSDs) and protect employees.
What about cognitive capabilities?
Accidents and diseases can also affect our cognitive and emotional capabilities. Strokes, head trauma and brain tumors, for instance, may result in loss of language and memory, an inability to concentrate, inappropriate social behavior, apathy and other neurological problems.
For these patients, neurorehabilitation protocols typically have two objectives: "The first is to restore the lost capabilities by having patients carry out repetitive exercises that form new connections within the brain," says Arseny Sokolov, a neurologist, University of Lausanne professor, and chief physician at the university neurorehabilitation service (SUN) run jointly by Lausanne University Hospital (CHUV) and the Lavigny Institution. "The second is to teach patients compensatory strategies so they can learn to live with lost capabilities that are hard to restore, like memory."
The ultimate aim of neurorehabilitation is to enable patients to once again live at home, drive and work. "Ideally patients would have four or five sessions a week with a therapist to properly restore cognitive function," says Sokolov. "But unfortunately, that's not feasible given existing resources, whether at SUN or elsewhere."
Intense training with the help of virtual reality
That's where technology comes in. Scientists at SUN are testing various types of new technology under SwissNeuroRehab, a project led by Innosuisse, coordinated by CHUV and involving a number of organizations including EPFL's NeuroRestore center. The developments include exoskeletons, robotics (for impaired motor function), haptic robots (for impaired sensory function) and virtual reality. One big advantage of virtual reality is that it allows patients to train intensely regardless of the availability of therapists and other resources. "Virtual reality isn't for everyone, but nine out of ten patients who try it decide to follow through - and we've seen excellent outcomes," says Sokolov.
In addition, virtual reality can encourage patients to stay motivated by having them play games, immersing them in situations outside the hospital - a kitchen or a tennis court, for example - or presenting them with challenges that would be nearly impossible with conventional methods.
SwissNeuroRehab will eventually spell out a new approach to neurorehabilitation that leverages innovative technology and includes a set of standard guidelines, as practices today are still fragmented.
Applying design principles to treat tinnitus
Intense training could also become an important factor in the treatment of tinnitus, or ringing in the ears. Tens of thousands of people in Switzerland suffer from this condition, which is usually caused by aberrant neural activity in the auditory cortex. EPFL+ECAL Lab is taking part in a multidisciplinary project called Advancing Neurofeedback in Tinnitus to develop novel treatment options. The initiative brings together neuroscientists from Zurich along with experts in cognitive psychology and user experience from the Bern University of Applied Sciences and the University of Fribourg.
The neurofeedback approach they're studying involves using electrodes to measure a patient's targeted brain activity and displaying it to the patient in real time. In this way, the patient can adapt their behavior based on what they see on the screen. It's a noninvasive training method that teaches patients how to regulate their condition independently.
"Our research project has two goals," says Delphine Ribes, an engineer and project manager at EPFL+ECAL Lab. "The first is to measure signals in the part of the brain that generates the tinnitus, in order to obtain data that are as accurate as possible and treat the disorder. The second is to establish standards for how signals are displayed so that the resulting images let patients do the training effectively, stay motivated and understand the information quickly, with minimal artefacts."
Design plays a crucial role in this approach, since neurofeedback is based on showing patients effective, easy-to-understand and motivating stimuli that also convey key information to practitioners. Designers at EPFL+ECAL Lab therefore conducted systematic visual-design research that encompasses both the content and how it's displayed. Their work will be used to develop guidelines for the design and assessment of neurofeedback stimuli and to provide the scientific community with a collection of proven, fit-for-purpose stimuli.
