Knee brace harvests power from walking

Bionic Power makes wearable technology for charging batteries. Today, we are focused on developing our PowerWalk® Kinetic Energy Harvester for military use and began multi-unit field trials with the US Army, US Marine Corps and Canadian Forces this year.

Alexis Madrigal, Wired February 7, 2009

Scientists have created a three-and-a-half pound knee brace that converts the power of your leg muscles into the energy for your electronics. By using the same principle that charges hybrid cars, the team of physiologists and robotics specialists say that their device can generate five watts of power without requiring additional human effort.

“People-power is a desirable thing to tap into it because we are these incredible batteries. We store enough energy in fat to charge a 1000 kilogram battery,” said Max Donelan, a researcher at Simon Fraser University Locomotion Laboratory in Burnaby, British Columbia. “With our device, you could walk for one minute and get ten minutes of talk time on your cell phone.

But that energy comes with a price. Donelan said that the knee brace alone, without all the energy scavenging technology, would cost at least $1000, so don’t expect to pick one up at Wal-Mart for charging your cell phone anytime soon.

The Innovators: Bionic knee brace transforms energy. In the final installment of our Innovators series, Robin Gill sits down with the researchers behind a knee brace that converts inefficient body movements into a battery powered energy saver. Global News October 28, 2018

Described in the journal Science online, the knee brace is the latest so-called energy harvester, a class of devices — including shoes, backpacks, flooring, and batteries themselves — that use human muscle power to generate electrical power. As designer Dawn Danby pointed out a few years ago, harvesters are the linchpin of the designer dream to “magically embed energy generation capacity into really mundane actions.” If they worked well, they could eliminate the use of batteries and completely power small devices. Unfortunately, most of them either produce too little energy (like the shoes) or are too unwieldy (like the backpack).

One product, Potenco’s energy generating yo-yo creates about as much power as the knee-brace, but there are two key differences between the two products. One, Donelan’s knee brace gathers energy in the background, sipping energy out of your daily activities. The yo-yo requires focused, albeit simple, effort. Two, Potenco’s solution is much, much cheaper. While they haven’t set a price, the Potenco power generator was developed to accompany the sub-$200 One Laptop Per Child computer.

Donelan’s team’s work has spawned a startup called Bionic Power, which has received seed investment but no rounds of venture capital. Donelan told that their initial markets were “people whose lives depend on portable power.” These off-grid power users include backwoods hikers and the military, which is always looking for ways to reduce energy usage. Donelan called soldier battery use “astonishing,” noting that soldiers can pack 30 pounds of batteries for a 24-hour mission. All those batteries add up to an equally astonishing $57,000 per soldier per year in battery costs.

If you really want to take a deep dive into the technology, check out the company’s Canadian patent filing and take a look at this video explaining the core technologies, gait sensors combined with generative braking.

Source Wired

Knee device makes phone charging a walk in the park. A new knee device developed by researchers at Simon Fraser University can generate enough electricity to power ten cell phones at once. New Scientist, Youtube Feb 7, 2008

Biomechanical energy harvesting: generating electricity during walking with minimal user effort, Donelan JM, Li Q, Naing V, Hoffer JA, Weber DJ, Kuo AD. Science. 2008 Feb 8;319(5864):807-10. doi: 10.1126/science.1149860.

Development of a biomechanical energy harvester, Li Q, Naing V, Donelan JM. J Neuroeng Rehabil. 2009 Jun 23;6:22. doi: 10.1186/1743-0003-6-22.

Also see
Device Gives New Meaning to “Power Walking” in Science
Ultrathin device harvests electricity from human motion in Vanderbilt University

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