The Bionic Energy Harvester – Increasing the Power of One

9 March 2010

Imagine for a moment that you could generate enough energy by walking to power your cell phone – and that you could store that energy in a small device. Now imagine that you have a prosthetic leg that requires power, and that by wearing this device you could reduce your reliance on external power sources such as batteries. If you think this sounds like science fiction you'd be wrong – it's science fact.

The Bionic Energy Harvester was developed by Dr. Max Donelan, professor of Biomedical Physiology & Kinesiology at Simon Fraser University, and his team. It came about as part of a larger research program on human locomotion and gait recovery after stroke funded by MSFHR.

"My central interest is to develop rehabilitation devices and therapies to improve people's ability to walk if they cannot walk well," Dr. Donelan explains. Part of his research has focused on answering the question 'what is it about the way we walk that determines how much energy we use, and how does injury change that equation?"

"Take stroke as an example, where you have partial paralysis of one side of your body," says Dr. Donelan. "It changes your gait biomechanics such that it increases the metabolic cost of getting around—we would like to fix that."

During his research on the intricacies of human locomotion, Dr. Donelan found that a person’s gait is largely defined by the energy expended transitioning between steps. He focused on the premise that some of that energy could be saved, which would make walking less metabolically “expensive.” That's how the Bionic Energy Harvester came about.

"The Harvester functions on the same principle as regenerative breaking in a hybrid car," Dr. Donelan explains. "It engages a generator to assist muscles in slowing down the body, producing electricity with no increase in effort from the user. The electrical power can be stored to power portable electrical devices such as two-way radios, cell phones, portable GPS devices and, in the future, prosthetic limbs."

The Harvester resembles an orthopaedic knee brace, weighs about two pounds, and extracts about six watts of electricity from each leg after only one minute of walking – roughly enough energy to produce 15 minutes of talk time on a typical cell phone.

"Eventually we hope to put the device on a healthy limb so it can power the prosthetic limb," Dr. Donelan says

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