Ryerson bio-engineering duo’s brain-controlled bionic arm may not give amputees super-human strength but could restore nearly all natural function one day soon.
Winning multiple awards is not nearly enough for Ryerson University biomedical engineering undergrads Thiago Caires and Michal Prywata. They’re also president and CEO respectively of Bionik Laboratories Inc., a company that’s on the cusp of changing the lives of amputees worldwide.
Controlled by brain signals and compressed air, their “Artificial Muscle-Operated” arm will cost four times less than traditional prosthetics and provide much greater functionality. Usually, when people lose their whole arms, they’re offered a very basic prosthetic which often has only a hook at the end.
“The only other option is for amputees to have muscle re-innervation surgery which is extremely expensive, not available in Canada and only performed by a handful of surgeons worldwide,” Prywata explains. “After the surgery, there’s also a long healing process after which you start learning to use the prosthetic. It became pretty obvious to us that there’s a need for a fully-functional non-invasive prosthetic arm.”
Their creation involves a headset worn by the patient that senses brain signals. A thought corresponding to, for example “down,” is sent wirelessly to a small computer in the prosthetic. “EEG brain signal capture has been around for a long time,” says Prywata. “The signals in your brain are essentially electrical bio-potentials which are measured, amplified and sent to the on-board CPU for processing.”
The software compares the signal to those in the database and sends a new signal to the arm’s pneumatic system (comprised of simulated muscles) to provide the required motion. Compressed air to run the “muscles” is stored in a small, refillable tank carried with the user.
There are eight “muscles” in the arm; one in the shoulder and elbow, one for rotating the wrist, one for the thumb, and four for the fingers. “That gives an amputee much more motion than any other arm on the market,” says Prywata. “We’re also very excited because we’ve also invented capacitive material-sensing technology, so when the hand is brought close to a given object, sensors detect the material and a maximum pressure is set.”
This means a user will be able to exert enough force to grasp something heavy, but won’t crush an object like an egg. Bionik Labs technology may also be used eventually by the military to facilitate remote robotic operations.
Since they began working on the arm, Caires and Prywata have experimented with a number of different headsets, added new circuit boards, an extra micro-controller, a faster CPU, more efficient muscles and improved the mechanics to consume less air. The biggest challenge was definitely achieving proportional air pressure control, says Prywata.
“We weren’t able to find any sufficient proportional valves on the market so we ended up designing our own with a custom feedback system,” he says. “It’s more power-efficient, consumes less air and gives accurate repeatability.”
Getting the tank in the arm is one of the next steps, but Prywata says the big concern will be getting each finger to move individually. “We’re approaching that problem by creating modes for the user so they can select which fingers to use when grasping an object,” he explains. The team also has plans to make the entire system adaptive so it can learn from a user and carry out movements more smoothly.
The arm has already won first prize at the 2011 Ryerson Engineering Competition; achieved first-place awards for innovative design and social awareness at the recent Ontario Engineering Competition in February 2011 and second place in innovative design at the Canadian Engineering Competition.