RE: The Next Big Thing: Wireless Charging From Across The Room
Clever technology, but I can't help thinking there may be consequences to pumping out this much energy into the RF spectrum.
Our bodies are made up of vibrating molecules and there have been links between cancer and cellphones that are held close to the body for long periods of time.
There has even been studies showing that cellphones may be causing infertility in men: https://www.ncbi.nlm.nih.gov/pubmed/17655195
Cellphones only output around 500-600mW of power. The Energous/WattUp device transmits 15W @5.8gGHz for 5ft distance; Ossia Cota 8W @2.4GHz for 1 device; Wi-Charge 10Watts of Infrared using a Class 1 laser (which sounds the safest).
These devices do sound wonderfully convenient, but nobody knows what long-term effects they may have at power levels many times those of cellphones - which are having unintended effects on some people's bodies.
Sources...
Energous/WattUp:
http://www.tomshardware.com/news/energous-wattup-wireless-charging-haier,27944.html
The standard CB radio transmitter thats in every truck has up to 12-16 watts of power. Ham radios (which you need an operators license for) broadcast in the 2.4ghz band at up to 1500 watts.
What youre forgetting about is the inverse square law. The power of the RF signal thats actually hitting your body is inversely porportional to the square of your distance from the source. WHat makes cell phones potentially dangerous (though theres nothing really conclusive) is that they are typcially kept so close to the body. For example, your cell phone transmits at .5 watts, and you carry it so that the transmitter is around .5 inches from your body (my personal estimate).
A wireless charger in the ceiling transmits 15W power, but its always at least 1 foot from you (unless youre really tall, or have low ceilings).
The 15w power is 24 times as far from you (.5 inches compared to 12 inches), which means the sigmal power has 1/(24*24)=1/576 as much power. So though the signal starts out with 30x more power, but by the time it actually hits you, its only has about .05 times the power as the signal hitting you from your cell phone.
In order to give you comparable exposure to having a cell phone in your pocket, you would to need to have something transmitting at around 250w in the ceiling.
Well, I do not fully understand the technicality of it, but, the companies working on the various ways of achieving wireless charging have stated again and again they are totally safe. Whether that really is the case is, of course, yet to be seen.
Also, as with any technology, improvements will come in the future once the said technologies are introduced, which will make them safer to use.