http://www.physorg.com/news108897656.html

Maybe not a backpack specifically, but this concept of using piezoelectric to harvest energy from the motions of humans has seemed more than obvious to me for quite some time now, I"m curious as to why it"s not used is so many more applications.

I am curious about what someone who is curious about something where potential profits could be made aren't being. If you have had this idea for a while why not design something that could use this technology then contact me to help you with the business side of things.

CKS

piezoelectric used most in barbaque switch for spark among others.

molecule vibration to electric voltage is the principle and is part of ferroelectric perovskites.

http://en.wikipedia.org/wiki/Piezoelectric

Stick them inside the soles of the boots, too!

No such thing as a free lunch. It will require marginally more energy to walk with this generator back pack than with a normal one. Same goes for shoes. If you want to generate electricity with the human body by far the most easy and energy efficient way is to hand (or leg) crank a simple rotating generator e.g the famous wind-up radio

I disagree that it would take more energy to walk, at least from a motion/conversion perspective. Rather, I think, the pack would move around less, the energy converted into electricity instead of wasted backpack motion (swinging, etc).

But, all things considered, it will probably be less weight to carry a few extra batteries than the apparatus that does the conversion and charges the existing batteries. Not to mention, the price.

But, enegry harvesting is a hot topic in so many ways. For example, using radio transmissions from broadcast and other sources to power inaccessible sensors that in turn intermittently transmit valuable informaion.

Lots of money to be made here, but it may be quite some time. Probably a better source of funding than a source of revenue.

The point is that it is done in the background, while other things are being accomplished - even so, how do you figure this will take more energy? It is using the motion that is already happening as a source of energy. Nothing here about a significant weight difference. Granted, if I was relying on electrical devices, I'd have a hand generator too - but this could keep devices charged while in motion so less time is spent turning a hand-crank, and more time is spent finding shelter, maintaining a vigilant lookout, enjoying the scenery, etc...

This is pathetic. 40mW is nothing. What a waste.

-Axemaster