When Assistant Professor Hossein Rouhani started his undergraduate degree in mechanical engineering, he thought he wanted to learn how to build cars. “I think we all start in mechanical engineering to learn how to build Ferraris,” he says. But by the time he’d finished his Master’s degree at the University of Tehran, he says, “It was not motivating enough to build fast and luxury cars. I wanted to be of some service to society.”
While pursuing his PhD in Switzerland, Dr. Rouhani met the chief medical officer of the orthopedic hospital of the University Hospital of Lausanne, a foot surgeon. This surgeon was looking for a means to objectively assess the clinical outcome of his surgeries in order to improve outcomes. “He said that his patients had much better foot function after their surgeries, but still not normal foot function. And he wanted find ways to help them have even better foot function after surgeries. This would require quantitative assessment of the foot biomechanics before and after surgery and to compare them with normal foot biomechanics. And this was a biomechanical engineering problem” Rouhani explains. “I realized that I had finally found a way to apply my engineering knowledge and be of service to society.”
To study human motion, engineers typically place people in lab setting and put cameras all around them. The subjects have reflective markers on their bodies and as they walk the engineers can reconstruct their 3D body motion. There are, however some limitations to this method. “It’s fun for the engineers,” says Rouhani. “But the patients say they feel like ‘a Robocop in a cage’.” What’s more, the subjects’ discomfort affects the way they walk and move and so the method decreases the quality of the data collected and the information extracted.
Rouhani therefore set about building sensors that people could wear in their daily life that would not affect or interfere with their actions or movements. “I used little inertial and pressure sensors and built up small boxes that can be placed in the shoes or on the foot, the shank, the thigh – any segment that we were studying,” he says.
Rouhani then developed effective methods to analyze “the noisy raw data” and turn it into clinically relevant information. “I developed a ‘magic combination’ of signal processing, instrumentation, statistics and engineering mechanics, all of which I learned in my undergraduate and graduate mechanical engineering degree,” he laughs. Rouhani’s next step then was to take his developed wearable system out to doctors and patients in hospitals, and to prove that it was suitable for clinical research and practice. “Seeing that doctors and the patients find my technology useful in clinical routines was very rewarding,” he says. “And those hospitals are still using my sensors.”
After his PhD in Switzerland, Rouhani took up a postdoctoral fellowship in neuro-rehabilitation at the University of Toronto’s Lyndhurst Centre, the largest spinal cord injury rehabilitation hospital in Canada. One day in Toronto, Rouhani saw a young woman walking down the street, pushing an athletic-looking fellow in a wheelchair. The wheelchair hit a bump and the man fell out of the chair. When Rouhani went over to help, the man told him that such falls were a regular occurrence and that he had even established a protocol for getting up. Rouhani was inspired then to use his wearable technology to help people at risk of falling to improve their balance and prevent falls and consequent injuries.
“Our body has a closed loop system that controls and executes motion. If I want to stand, my body’s sensory systems send message to my central nervous system to process the information. Then my central nervous system sends message to my muscles to maintain my standing balance,” he explains. “The closed loop circuit can be impaired due to an injury. An engineering solution is to place an external sensor on the body to send the necessary information to a portable computer instead of the central nervous system. This computer can then control actuators to maintain standing or sitting balance.” This entire system replaces the injured neural control system; it’s called ‘neural-prosthesis.’
Ultimately then, even though he’s not building Ferraris, Rouhani’s research helps to re-build the most important vehicle we have - our bodies.