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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.
Just hand these out to teenage girls and we'll have enough power to supply the entire world for all its needs.
-- Will program for bandwidth
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...
Current cell phone technology is perhaps four orders of magnitude away from piezo power. At ten times the piezo power level, say 10mW, you may as well use small cheap batteries. One non-rechargable AAA cell would run for approx 700-800 hours at those levels.
Engineering is the art of compromise.
Hey, my phone's running low on power, let me find some heavy traffic and big trucks so it'll be loud enough for me to hear you!"
Next thing you know you'll have to shake your phone to get features to work (oh, wait...)
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
...I'm just charging my batteries.
"battery's almost dying, I need to talk some more, let me call AOL and try to cancel."
It does not matter if they improve the microphone efficiency to exactly 100% The amount of power in any reasonable voice is miniscule at best. And most of the power is in the lower part of the register, where the sound wavelengths are several meters long. And to get even a fraction of the power out of a wave, you need a microphone at least a quarter wavelength across.
So even if cell phone microphones were a foot in diameter, they'd only capture a few milliwatts on voice peaks. And cell phones need a couple watts of power full-time to output a watt or so to the antenna. No way, Jose, and by at least three zeros after the "1".
As if millions of cellphone users cried out "bullshit!" and were suddenly silenced.
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.