Forget about setting up that windmill on top of your backpack to juice up all those gadgets; now you can just use the weight of the backpack itself to generate power with these energy-harvesting backpack straps. Sure, someone thought of an energy-generating backpack before, but these straps are the tricky part here, using a special piezoelectric material called polyvinylidene fluoride (PVDF), generating electrical charges when stress is applied. Sounds like some serious magic.

Instead of cutting into your shoulders, these nylon-like straps convert that mechanical strain into electrical energy, and researchers have figured out that if you carry a 100-pound pack and walk at 2-3 mph you can generate 45.6 mW of power. That's enough to the power an iPod, or maybe a head-mounted flashlight. But a 100-pound pack? They're saying that's a typical weight for soldiers to carry. That'll make you think twice about signing up to go to Iraq. [Physorg, via Medlaunches]