Max Donelan

Breakthrough technology harvests people power

February 7, 2008

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SFU researchers have developed a new wearable technology that generates electricity from the natural motion of walking and promises to revolutionize the way we charge portable battery-powered devices.                 

The Biomechanical Energy Harvester is the culmination of years of biomedical engineering research in SFU’s locomotion lab by Max Donelan, assistant professor of kinesiology (above), in collaboration with researchers Qingguo Li, Veronica Naing, Andy Hoffer and Mei Young. Their device, which resembles an orthopedic knee brace, harvests energy from the end of a walker’s step, when the muscles are working to slow the movement of the leg, in much the same way that hybrid-electric cars recycle power from braking.

Wearing a device on each leg, an individual can generate up to five watts of electricity with little additional physical effort. Walking more quickly generates as much as 13 watts of electricity: at that rate, one minute of walking provides enough electricity to sustain 30 minutes of talk-time on a mobile phone.

A physiologist who specializes in the biomechanics of walking, Donelan explains that the device uses sensors and a real-time control system to assist the hamstring muscles in slowing the knee motion. The system only turns on power generation at the end of the walker’s swing phase, just before the foot hits the ground.

“Power from our bodies is efficient and portable,” says Donelan, who points out that eating a 35-gram granola bar, which has as much energy as a 3.5 kg lithium-ion battery, can be efficiently transformed into electricity using the Energy Harvester. What’s more, he says, “the idea of reducing the number of disposable batteries and charging rechargeable batteries with our own motion is compelling.”

Donelan has established an SFU spin-off company, Bionic Power, to commercialize the device. He expects the Energy Harvester to have applications for the military, medical and consumer markets. Soldiers, for example, can carry as much as 13 kg of non-rechargeable batteries to power up to 30 electronic devices. Donelan sees his energy-harvester, coupled with a one-kilogram rechargeable lithium ion battery, as a welcome alternative. A civilian application might help amputees with power-assisted prostheses or extend the operating time of GPS transceivers, digital cameras or headlamps. “It also means a better quality of life for the developing world, where a half-billion children live without easy access to electricity,” he says.

The Biomechanical Energy Harvester is featured in the Feb. 8, 2008 issue of the prestigious U.S. journal, Science.

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