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Talk-Powered Cell Phones Won't Need Batteries
alphadogg writes "It's possible that in the future conversations on your cell phone could generate enough electrical power to run the phone, without batteries.
That's one possible outcome of recent work by a team of Texas researchers, who appear to have discovered that by building a certain type of piezoelectric material to a specific thickness (about 21 nanometers, compared to a typical human hair of 100,000 nanometers), you can boost its energy production by 100 percent. And the technology could power not just phones, but a whole range of low-power mobile devices and sensors. The breakthrough is an example of 'energy harvesting' that can convert one kind of energy, such as vibrations or solar rays, into electricity."
That's why people are always shouting at them?
Just set it in a Pyramid and use pyramid power to keep it topped off. That is what they ancient Egyptians did.
Don't forget to call your Mummy.
Sorry about the writing. Robot fingers, you know? Cliff Steele in DOOM PATROL #23
Most modern phones are probably much too power hungry to be get enough energy from audio vibrations, even you manage to ramp up the efficiency close to 100%, which is unlikely to ever be practical.
Where this could be useful is in specialized low-power devices that get bundled into emergency survival
kits.
OTOH, future cellular devices might incorporate enough improvements into power efficiency (e.g., e-ink displays), such that you could significantly extend battery life and perhaps even power a very basic subset of the phone when the battery runs out.
Also, harnessing vibrations efficiently might be very useful in surgically implanted medical devices where replacing the battery can be rather inconvenient.
TurnKey Linux: if it can be easy, it should be easy
Wonderful. I can just imagine being in a restaurant or an elevator with a group of people with phones all saying "Low Power - please speak louder."
Have you tried turning it off and on again?
Lets assume that a minimum channel capacity (bits/s) is required to support a conversation, even if we use the absolute best vocoder that eliminates all redundant information. Shannon's Law then says that for a given noise power (set by the environment) there is a minimum signal power which must be transmitted to get error free transmission. Again we are assuming we have an optimal codec, which achieves Shannon's bound. This sets the absolute minimum power consumption of an ideal radio telephone. A real life phone will use more than this. My guess is that this theoretical minimum power is greater than the power which can be harvested from the human voice.
I don't know if this would work for me, because I usually just end up listening on my phone.
Yes, honey. Ok, honey. Will do, honey.
Why would you want one? We have watches working off the constant motion of our body/arm/wrist/whatever. Mine takes a few days before it winds down. I think that anyone that stays immobile for that long will not be doing so great in respect of body heat, either.
No good deed goes unpunished...
If you assume normal human speech is about 60dB. We know dB = 10 log(I/I0) where I0 is 10^-12 W/m^2. So 60dB works out to about 10^-6 W/m^2 -- that's a microwatt per square meter. With 100% efficiency and a mike of 1 cm^2 collecting area, that's around 10^-10 W -- 0.1 nano-watts. (Thanks phliar for the calculations.)
Then utilize this energy using recent advances in String Theory, and you have a workable solution.
Here's a picture of a prototype.