Harnessing Human Energy for Medical Good

By Serena Gordon
HealthDay Reporter
Thursday, February 7, 2008; 3:00 PM

Copyright © 2008 ScoutNews, LLC. All rights reserved.

THURSDAY, Feb. 7 (HealthDay News) -- Anyone who has ever watched a frenetic toddler bouncing around a room has wondered if there might be some way to harvest all of that energy.

While no one has quite figured out how to bottle youthful exuberance, a team of Canadian and U.S. researchers has found a way to capture human energy so it could help people with medical devices such as prosthetic limbs, artificial pacemakers or insulin pumps power their devices using their own energy.

The concept is as simple as it is elegant: The energy is produced and harnessed through walking.

"The main idea is to harvest energy from walking in a manner that you can get electricity without increasing effort," explained study author Max Donelan, a professor in the school of kinesiology at the Simon Fraser University in Burnaby, British Columbia, and chief science officer of Bionic Power Inc., a company formed to develop the energy-harvesting device.

"To design useful ways of producing power for people, you have to understand physiology and take advantage of some of the uneconomical ways we use our bodies," explained Donelan. "Stop and go driving is inefficient, but sometimes you have to do it. You can't always drive on the highway."

Similarly, he said, people have to stop and go all the time. "It's inefficient and unfortunate, but we can take advantage of it for energy harvesting," he noted.

Much like a hybrid car that captures energy that is normally dissipated, the biomechanical energy harvester captures energy from the deceleration phase of walking. To do this, the harvester actually assists with the slowing down phase of a step.

"The generator helps slow the motion of the knee at the right time, and you can get substantial electricity with minimal effort," said Donelan.

An adult walking at a relatively fast pace wearing the harvester -- which looks like a knee brace and weighs just over three pounds -- can generate 13 watts of electricity in one minute. That means you could get about six minutes of laptop computer time for one minute of fast walking. A low-effort walk would produce about five watts of power, which would give you roughly two and half minutes of laptop time, according to Donelan.