- News Home
13 March 2014 11:08 am ,
Vol. 343 ,
In the shadow of the crisis in Crimea, Ukrainian legislators are weighing a pair of science and education bills that...
Researchers dependent on government funding would face a flat future under the White House's $3.9 trillion budget...
Reservoirs of cells that harbor HIV DNA woven into human chromosomes have become the bane of researchers trying to cure...
Geochemists have now incorporated in their models some details of the way naturally acidic rainwater dissolves rock...
Schizophrenia is a devastating mental disorder that afflicts about 1% of the world's population at one time or another...
Surface tension is a force to be reckoned with, especially if you are small. It enables a water strider to skate along...
- 13 March 2014 11:08 am , Vol. 343 , #6176
- About Us
New Backpack Powers Up
8 September 2005 (All day)
Something old is new again: Ancient Chinese once used springy bamboo shoulder poles to transport heavy loads. Now, a researcher has designed a springy backpack that generates electrical energy through walking, eliminating the need to carry heavy batteries. Such a portable, efficient power source could be especially helpful to soldiers, scientists, or relief workers operating in remote areas.
Walking involves a lot of mechanical energy. From one step to the next, each hip, for example, rises and falls about 4 to 7 centimeters. Strap on a heavy pack, and even more energy is involved--a lot of it wasted. With a rigid pack, there's no way to access it, says muscle physiologist Lawrence Rome of the University of Pennsylvania in Philadelphia. So Rome created a suspended-load backpack that taps into this vertical movement.
Rome's pack uses springs to suspend the load from a fixed frame, allowing it to ride up and down freely during walking. As the pack bounces, it periodically runs a toothed rack across a gear attached to small generator on the fixed frame (see picture), thus converting the mechanical energy of walking into electrical energy.
A 38-kilogram pack can generate a maximum of about 7 watts, if the walker hustles, Rome says. At the more moderate pace of 5.5 kilometers per hour, a 29-kilogram load can generate about 4 watts, more than enough to operate a number of small portable devices at once, such as a cell phone, handheld GPS, PDA, and even night vision goggles, Rome and colleagues report 9 September in Science.
"It's a clever way to have power on the fly," says integrative physiologist Rodger Kram of the University of Colorado at Boulder. An added feature of the suspended-load backpack is that it doesn't just generate power--it also appears to more than double the metabolic efficiency of carrying any load, Kram notes. "So it may just be a better backpack."