I was really skeptical about her company but the pictures in the article and the article itself seem legit.
I wonder how they'll combat the inverse square law and make their technology actually feasible.
I wonder how they'll combat the inverse square law and make their technology actually feasible.
Usually the inverse square law is very much in effect when it comes to audio, this is because the medium (waves in air) behaves as water does with waves do in a pond rather than say the light coming out of a laser or any other focused source of electromagnetic radiation.
Distance from the transmitter will very much be a factor.
I think uBeam is another Theranos, but granted at a much smaller scale. Still can't believe it has raised so much money and so much press without basic questions really being answered.
The research was aimed at basically heating carcinomas above the 44 oC needed to kill the cells.
So you can focus an ultrasound beam, but it seems like a heck of a way to charge a phone.
That's the whole point of the exercise here: if the efficiency isn't there the whole thing is dead because you can't be pumping kilowatts into space in order to get a few watts (or milliwatts) back out. The difference between the two will get converted into heat!
So the only way this will work is if the efficiency is really high, much higher than seems to be feasible right now.
Abstract: An alternative approach to the wireless transfer of energy is proposed, employing acoustic waves in air. Unlike conventional methods, acoustic energy transfer is able to achieve energy transfer at high efficiencies over distances that are large in comparison to the dimensions of the transmitter and the receiver. This paper gives an overview of the principle and explains the different loss mechanisms that come into play. A theoretically limit on the achievable efficiency is calculated. It exceeds that of a comparable inductively coupled system by an order of magnitude. First preliminary measurements indicate that AET is feasible, although the measured efficiency is lower than the predicted theoretical limit.
Is there anything in that paper that could explain the difference?
I don't know any more because that was how I found that and skimmed the paper about three years ago, for a prior discussion of uBeam here on HN.
The maximum output they measured was 37 uW, so 1000 of these would output ~37 mW, with an input power 1000's of times higher.
If anything this paper is a nice example of how theory and practice differ. It also highlights another big loss factor for ultrasound power transmission, the angle of incidence, the power falls of as the co-sine of the angle between the transmitter and the receiver (maximum at 0 degrees, minimum at 90 degrees).
Or some valuable wallets.