Ultrasonic Power Transfer: uBeam’s Curious Engineering

The future is wireless power, or so say a thousand press releases in my spam folder, and with very few exceptions every single system of wireless power delivery has fallen flat on its face. Except for a few niche cases – RFID tags, Wacom tablets and the S Pen, and the Qi inductive power mats for cell phones – the future of wireless power hardly looks bright, and in some cases seems downright dangerous. No one seems to grasp that wireless power transfer is much more inefficient than using a wire, and the inverse square law only makes everything worse.

Now there’s a new wireless power technology that’s a strange mix of running in stealth mode and sending press releases to every tech outlet on the planet. It’s called uBeam. This company says it will deliver wireless power to the world, but it’s not doing it with giant Tesla-inspired towers of power, radios beamed directly at devices, induction, magnetic resonance, or even light. uBeam transmits power via sound, specifically high intensity ultrasound. uBeam has never demonstrated a prototype, has never released any technical specs, and even some high-profile investors that include [Mark Cuban] have not seen the uBeam working. Despite running in a ‘stealth mode’, it has garnered a lot of press, and has been featured on TechCrunch dozens of times. This may just be a consequence of CrunchFunds’s investment in uBeam, but there’s still more Google News results for a technology that hasn’t even been demonstrated than a reasonable person would expect.

In what is perhaps the greatest breakdown ever posted on the EEVForums, [georgesmith] goes over what uBeam is, how the technology doesn’t make sense, and how far you can take a business before engineers start to say, ‘put up or shut up.’ [georgesmith]’s research goes over just some of what makes uBeam impractical, but digging even further reveals how insane uBeam actually is.

The Basic Tech Breakdown

The core technology, and the core criticism of uBeam is that it uses sound to transmit power. All speakers turn power into sound, and microphones operate on the reverse principle. Speakers and microphones can both be called transducers, and this is exactly what uBeam is using to transmit power wirelessly. Of course a gigantic speaker blaring a very, very loud sine wave would be far more annoying than a simple cable to charge your phone, so uBeam is using ultrasound – sound too high for humans, cats, dogs, mice, and even bats to hear.

In the TechCrunch technical teardown of uBeam, we get a small glimpse of what it takes to transmit power via ultrasound. The uBeam team, headed up by [Meredith Perry] created a, “novel high-powered ultrasonic transducer” that is the, “thinnest, most powerful, most complex, and most intelligent … in the world.”

This ultrasonic transmitter is mounted on a room’s wall, converts data and energy into ultrasound, and broadcasts it directly to devices requesting power. This includes cell phones, tablets, laptops, appliances. Of course, all of these devices will be equipped with ultrasonic power receivers, all based on uBeam IP. The promise of beamed wireless power is deafening, and if you’re an investor putting this technology in millions of devices sounds like a great idea.

The Problems With The Tech

Of course uBeam and its investors contend the technology is safe and even innocuous, but is it? I’m completely unable to find any media that will report on the frequency or intensity of the ultrasound used in uBeam. Patents, on the other hand, actually give us information. uBeam will transmit at about 120 kHz, with an intensity of about 155dB. To put the frequency in perspective, humans can hear up to about 20kHz, dogs up to about 60kHz, cats up to about 80kHz, and bats up to about 115kHz. The frequency of uBeam is higher than nearly all land-based animals. The intensity, however, is impressive. The intensity of a jet engine at 100 feet is cited at 140dB. A 12 gauge shotgun blast can be as loud as 165dB, albeit for an instance. OSHA guidelines for sound protection cite 145dB as the loudest recommended exposure with hearing protection, although this is frequency dependant.

The difference between the intensity of uBeam and OSHA guidelines is not small; it’s only 10dB. uBeam operates at 155dB and OSHA guidelines have a limit at 145dB. Decibels are logarithmic, though, and an increase of just 3dB is a doubling of intensity. uBeam is actually 10 times louder than OSHA guidelines, and a 2005 review of ultrasound exposure limits recommended, “sound pressure levels should be less than 110 dB above 25 kHz, regardless of the exposure duration, to prevent the undesirable subjective effects of ultrasound.”

This is the fundamental problem of uBeam. Simply by virtue of a lack of research into very high intensity ultrasound, all arguments about uBeam eventually devolve into appeals to ignorance countering appeals to authority. Personally, I quite enjoy the arguments presented by both uBeam, its investors, and its detractors. It’s an amazing rhetorical rigamarole.

The Insanity Of The Tech

Ultrasound exposure limits and questions of how safe the uBeam system are interesting, but to realize the pure insanity of this wireless power system, you only need to look into the patents and a little bit of physics.

Sound absorption graphed against frequency. Source

Anyone who has ever lived in an apartment will tell you sound absorption is related to frequency. If you’ve ever had the displeasure of having a neighbor with a large subwoofer, you know higher frequency sound is absorbed at a higher rate than lower frequency sound. This trend continues into ultrasound territory, where sound at a frequency of 100kHz will be attenuated 3-4dB (effectively halved in power) for every meter of air it passes through.

You are not reading the last paragraph incorrectly. Because decibels are a logarithmic scale, a decrease of 3dB is half the power. With the uBeam system, being just one meter away from the transmitter will bring the power down by half. Being two meters away will bring the power down to a quarter of what it was at the source. Being three meters away will reduce the power received by any device to an eighth of the transmitters original output, and bring it down to nearly OSHA-approved levels.

The incredible attenuation of ultrasonics is the nearly insurmountable problem of uBeam, but luckily the patents tell us how the uBeam team plans to combat it. They’re using dozens of power transmitters per location; a transmitter every two feet, blaring ultrasonics. It’s not dangerous, though: these transducers will be focused directly on a compatible uBeam device with a “mechanical steering component“. Yes, each transmitter will be mounted to an electromechanical linkage so the transmitter is pointed directly at the device it is powering. If you’re wondering, yes, this means a transmitter is required for each device being powered.

The real solution to wireless power. Source
The real solution to wireless power. Source

Consider a Starbucks. In a small Starbucks, you might find 10 people, sitting on their MacBooks, working on the next Great American Novel, or their screenplay, or just on tumblr. Each of these 10 people will require their own ultrasonic power transmitter, and it will need to be within a few feet of each machine. In the ceiling, or perhaps mounted on the wall, will be an ultrasonic power transmitter that contains motors to ensure each MacBook can charge wirelessly. This is a vision of the near future; Starbucks may be lining up a deal to put this in their stores. It’s also absolutely insane. For something that claims to be as easy as WiFi to install, look at the differences: WiFi merely requires a single router to be installed anywhere in the store. uBeam would require a dozen transmitters, each of with include mechanical steering for their transducers. uBeam would require everyone to buy an ultrasonic power receiver for each device.

Unlike [georgesmith]’s teardown of uBeam, we’re going to stop short of calling it a fraud. It has not been demonstrated to the public, and although it is impractical that does not make it impossible. Consider this, though: you can buy a 10-pack of outlets that include a USB charging port for $200. Including installation, it would cost Starbucks a minimum of $22 Million dollars to outfit each of its stores with USB charging ports, assuming an installation cost of $800. This would be more convenient – and cheaper – than any wireless power scheme, be it RF, inductive, or ultrasonic. Curiously, investors are glomming on to a system that is less convenient, more expensive, and uses fundamentally unproven technology. It’s a curious case indeed.

95 thoughts on “Ultrasonic Power Transfer: uBeam’s Curious Engineering

    1. No, they’re the marks. The problem is that a) most VCs are not particularly technical and b) those who are typically have a poor sense of the limits of their expertise. That means they’re perfect targets for connected people who know how to flatter them.

      1. Undoubtedly some investors get scammed into investing but what I was think is much more sinister. If a VC colludes with the inventor and invests 1 million dollars, this can bait others to invest on the strength of a VC investing so much. The original 1 million dollar is quickly funneled back to VC while other investors are eventually left high and dry. I’ve seen too many stories of VCs investing millions of dollars on an idea which run counter to undergraduate level of engineering analysis.

        1. Eh… Seems unlikely compared to some scam artist types targeting VCs.. Pierce’s comments ring true to me, having worked with VCs and startups.

          The “tech” described above sounds like a outright scam though.

        2. You’ve just described a pyramid scheme. It may be common, but it’s also illegal and nearly impossible to cover up- it’s just a stupid scam that ends with lots of jail time for those responsible.

          1. Not a pyramid scheme, but preferred stock can facilitate the desired effect. (1) The VC’s get Series A Preferred with a liquidation preference for their investment money, which entices (2) a B-team to invest in the next round of Series B Preferred with a junior liquidation preference. Then (3) the VC’s controlling the board call for a liquidation, and (4) the Series B Preferred money flows to the VC’s to satisfy the Series A liquidation preference.

            The result is that the VC’s are made whole, while the B-team takes the loss. Unlike a pyramid scheme, the VC’s wouldn’t usually get a profit, but they do come up even when others lose everything. I could imagine a liquidation preference that included interest, but I think that would be uncommon.

    2. Nah.
      1) There is so much money sloshing around and not any earning interest that VC’s will buy *anything at all* from anyone who has the wits to draw a set of PowerPoint slides featuring an exponential curve on it.

      2) Most of the VC’s are not suckers, they know he score and all. It’s just that they have these KPI’s saying that they are meeting performance targets if they manage to invest “X amount of dollars in Y tech-startups per quarter” – and all the good stuff happens to be sold out many times over.

      3) If we didn’t destroy all this capital on shitty investments, and it went into real things instead – we would have inflation rates that would make Zimbabwe look like a well-run economy. Gods work basically. Might as well get in on it and get a slice of the pie.

        1. “how wouldnt it?” Because that would be a transfer of money that already exists in the economy. All the money spent during the World Series, on the world Series, isn’t going to cause inflation.

    3. All you need to do is to make it sound plausible enough. Most people don’t want to/aren’t capable of doing the math. VCs are mainly looking at the business case. They hire tech “experts” (who sometimes aren’t all that expert) to vet the technology. If you can sling a good line past them, you get the cash.

  1. Excellent summary :-)

    “In a small Starbucks, you might find 10 people, sitting on their MacBooks, working on the next Great American Novel, or their screenplay, or just on tumblr. ”
    One can hope that, given the power levels involved, rather than power their laptop it is instead liquefying their internal organs so other people can actually sit down to drink rather than re-type “War and Peace” while occasionally looking at their shiny coffee container.

    1. From the article: “uBeam will transmit at about 120 kHz, with an intensity of about 155dB. To put the frequency in perspective, humans can hear up to about 20kHz, dogs up to about 60kHz”

      1. What the article doesn’t tell is what happens when a fast moving object interacts with the sound beam, or worse two sound beams slightly out of frequency in the same room: doppler in the first case and heterodyne like mixing in the second, both of them resulting in a change of frequency or creation of (sub)harmonics. Beware of ceiling fans or multiple emitters!

        1. Well, if the sound’s at 120 kHz, ceiling fans aren’t supersonic. So I don’t think you would have to worry.

          Multiple emitters that didn’t know about each other could be seriously dangerous, though.

          1. Doesn’t need to be supersonic. A 120kHz frequency and a 5 Hz frequency will interact and introduce harmonics in a variety of different frequencies all over the place. Any other sources of high frequency sound waves can also introduce harmonics in there, or hetrodyne mixing as querty said. It’s quite likely to introduce all kinds of fun buzzing noises in specific locations throughout a room.

          2. Doppler effect would have to be supersonic.

            Mixed frequencies interfering are a much bigger concern, although until you get mixed frequencies near the transmission frequency, it’s not going to matter. 120 kHz and 5 Hz won’t realistically do anything except fuzz the 120 kHz signal ever-so-slightly.

            That’s why I said multiple emitters would be Very Bad. Two of them trying to point to the same device but just slightly out of phase could… do bad things.

          3. Even at 1% of the speed of sound (3m/second) this will create a reflected sound beam with a frequency difference of 1% or 1200Hz, well in the range of human hearing for the beats.

          4. Well, yeah, but in order to actually do that you’d end up blocking the beam (reflected Doppler shifted sound that interferes would have to be caused by something moving directly towards the transmitter) so presumedly, again, any power-transfer information would tell the transmitter to shut off because it’s lost line of sight.

            That could be done significantly faster than the wavelength of the 1200 Hz mixing frequency (~millisecond scale) so you’d never actually generate that sound.

  2. I really wish folks would stop wasting time with the wireless power crap. We know it doesn’t work well. We know it isn’t efficient. We know it is expensive as hell (both short and long term). The ONLY time it works well is short distance power transfer for things that need to be sealed or where wires get in the way. It should not be thought of as a means to power everything under the sun.

      1. Then everything you have heard about Nikola Tesla’s wireless power program is incorrect. It is a very interesting idea, but EXTREMELY power inefficient. For every bit of power transferred to a device, near endless amounts of power are lost to the surrounding environment and in transmission. If it were so simple and so grand, it would be a commonplace technology. It isn’t, so it’s not.

        1. Actually “the true Wireless” as Tesla named it, was extremely efficient, about 95% per Tesla’s calculations. The problem is that people think about radiation through air, which is a Hertzian radiation, and this, as Tesla noted on many occasions, is just a waste of power. The “the true Wireless” is a transferring of electrical vibrations (with high current) through the Ground, and NOT through the air. Please aquatint yourself with Tesla’s work (from his patents) before making incorrect comments.

          As per your line: “If it were so simple and so grand, it would be a commonplace technology”, One has to go back and read A LOT about the industrial developments about the electrical power systems in the end of 19 and the begging of the 20th century in order to understand what went wrong. A hint: one can own/control wires ( and can invest and can get huge profits out of it), but one can not own/control the Ground.
          In addition your assumption is that the most efficient systems prevail in engineering and, as I were wishing this to be the case, the real (capital) control world dictates totally different and in many cases, extremely wasteful dynamic about using the natural resources.

          1. I thought tesla’s transmission towers were supposed to use the ionosphere as one plate and the earth as another to set up a resonant wave. Also, tesla was sometimes wrong. I recall a quote where he explained a system that would use electricity to break water down through electrolysis and would then burn the hydrogen to smelt metal. “thus very nearly the total electrical energy energy used up in the decomposition of the water would be recovered in the form of heat resulting from the recombination of the hydrogen.” it would have been pretty hard to get decent efficiency with the tech back then.

          2. Tesla was a smart man, but not infallible. He made mistakes much like any other physicist and scientist. Today, however, we understand much more about electricity and magnetism than what could have possibly be imagined back in Tesla’s day. Unfortunately, here Tesla was wrong and your comment is incorrect as well. As an electrical engineer and someone who has spent a great deal of time working with electromagnetics, power, and a number of other things, I do understand what is happening here and the basis for Tesla’s wireless power.

            It seems that you are either trolling or a conspiracy theorist without a good understand of the physics. So, I propose to you this – Please explain what these “electrical vibrations (with high current)” are and how they somehow defy the laws of physics to give a 95% transmission rate.

            You will find that you can’t what you speak of doesn’t exist or is not correct. Electricity and magnetism don’t work that way. Lets say these “vibrations” are a periodic voltage waveform and the current is actually electrical current – as the current flows through the ground, it will encounter resistance. As current encounters resistance, it loses power to heat and a voltage drop occurs. The reason that you have to dump high amounts of current is because you lose efficiency very quickly – high current is never a positive thing unless you are dealing with magnetism and coils in which case this technology becomes even more inefficient give that magnetic fields decrease according to the inverse cube law.

            As far as your “Hertzian” radiation – that is just electromagnetic radiation, aka light, radio waves, microwaves, ect. Funnily enough, if you were to try to transfer power wirelessly, this would be your best bet. You could simply use a laser or a directional antenna without much loss in power over the transmission medium assuming you chose the correct transmission frequency.

          3. “Please aquatint yourself with Tesla’s work (from his patents) before making incorrect comments.”
            Please go and build “the true Wireless” system from Tesla’s patent before claiming that it works. If it does, then, you have just put standard physics over a barrel and screwed it. There is a Nobel Price for that kind of work!

      2. It is quite unfortunate that Nikola Tesla’s “wireless” power transmission is incorrectly viewed/understood today as what is commonly known as (and pervasively used) Hertzian radiation ( effectively loss of power ) through a particular dielectric substance (air, as commonly known). If one technically intelligent were to read what actually he wrote (“Colorado Spring’s Notes 1899-1900”, and most of his patents on that topic), he/she would understand that for an efficient the transmission of energy the GROUND was used as a medium (conductor). It is clearly stated in his research and his patents, and one just have to read them, instead of repeating the 99% of the nonsense about the wireless/radiative power transfer that is spread over the net..

        1. If one technically intelligent were to make this technology work instead of sniffing at other people on the internet, one could become both technically intelligent and rich. Given that this hasn’t happened in the 70 years since Tesla’s death, one must be talking out one’s backside.

      3. Nicola Tesla’s power transmission was basically a Tesla coil. ANYTHING in its field would get power. That “anything” includes you, your cat, your bed…anything. If the “anything” happened to be resonant at the power transmission frequency, watch out.

        His scheme needed a LOT of work to be a safe and practical means of transmitting power.

        He was also the neighbor from Hell.

      4. I didn’t get from either the hackaday article or the evvlog forum thread this was about powering everything under the Sun. Efficiency? When it come to convenience efficiency th low on e priority list. Where would the modern automobile be if everyone followed someone’s advice to forget it? The computer we use to read these article For good reason at the time people forgot about blood transfusion when they where first tried. However there’s no way telling how many would have lived or died if the potential for such a procedure wasn’t forgotten for so long. Prudence? Yes, but the advice forget about it is often bad advice.

    1. Sure we got unlimited power at cheap prices. It is not like we have to worry about running out of power due to failing power infrastructure, or have any environment concerns about pollution or global warming. /NOT!

    1. The way i understand the physics involved in soundwave transmission, not actively “hearing” something does not make it at the same time not interact with the body it is aimed at. So, who says that the extreme levels of soundpressure in a spectrum we can not hear do not destroy cells or inhibit some vital functions in living creatures or “dead” materials? Are there any studies in that field? Maybe these ultrasonic transmitters start to find a resonance-point inside the devices electronics and start to slowly destroy inter-material bonds vital to the function of the device?

  3. Well, to be fair to the uBeam guys, 155 dB is just a description of the local pressure intensity: 155 dB just means that the amplitude of the sound is ~1 kilopascal, since 0 dB is the “reference pressure” of 20 micropascals (and power is the square of pressure, so it’s not like, 10^15 higher). 1 kPa is ~1% of atmospheric pressure – so yeah, that would be one hell of an oscillation. But that only matters if that oscillation actually hits you.

    And it doesn’t say how wide of a beam that ~1 kilopascal pressure increase is over (and it suggests basically using a phased array to generate a seriously focused beam) and it wouldn’t be too hard (using traditional wireless communication) to make sure that unless you have an unobstructed line of sight between the device and the transmitter, you don’t transmit anything. So the instant someone walks through the beam, it shuts off. (Note: this is actually suggested in the patent).

    My big concern though is that no matter what, it’s going to be very, very inefficient. Even assuming ~50% power loss in transmission, the receiver and sender are both going to be about ~40% at best, so you’re talking under 10% total efficiency *at best*. Obviously, there are going to be places that don’t care about this (electricity is still pretty darn cheap) but in aggregate, if it became super-common, it could be a big waste of power.

    1. Also, this comment in the article is wrong:

      “Yes, each transmitter will be mounted to an electromechanical linkage so the transmitter is pointed directly at the device it is powering. If you’re wondering, yes, this means a transmitter is required for each device being powered.”

      which you can quickly verify from the linked patent itself. To quote:

      “A transmitter 101 may server several different devices by, for example, steering and tuning the beam for each receiver device 108, e.g., in a round-robin or random fashion. Thus, the beam for a device A may be at 40 kHz and 145 dB, device B may be at 60 kHz and 130 dB and device C at 75 kHz and 150 dB. The transmitter can tune itself to transmit an optimally shaped beam to each of these dynamically, changing beam characteristics as the transmitter shifts from one device to another. Further, dwell time on each receiver device 108 can be modulated to achieve particular power transfer objectives.”

      Basically, the idea would be that the transmitter can quickly switch between each of the devices to deliver sufficient average power. So you wouldn’t need individual transmitters for each one. Note that I’m not claiming that something that can switch this fast is possible, just what’s said in the patent.

    2. They really should use a fixed frequency for the power transmission. They’ll lose efficiency for driving the transducers outside of their resonant frequency.

      There is going to be a lot of unhappy pet owners for the frequency range in that patent.

      1. I don’t think efficiency at the transmitter is really a concern of this setup. I think this is more along the lines of “electricity is cheap, so screw the transmission efficiency, just make it easy.”

        I don’t understand people thinking that pets, humans, whatever will hear anything. It’s a highly shaped beam. As soon as a pet steps into the beam, the power reception drops, the transmitter finds out (via traditional-wireless side channel), and the audio cuts out immediately. Yes, there’s a lag for that to happen, but it could be at the sub-millisecond level if done right. Outside of the beam you don’t hear anything because the sound’s not there.

      2. Highly shaped beams doesn’t meant that it won’t be reflected by hard flat surfaces. e.g. the display of your mobile device. Reflected wave can bounce a few times from ceiling, walls or windows before they are below the hearing threshold of your pets. Animal like dogs or cats have very large dynamic range too.

        1. True: even if you have a reflection coefficient of ~1% that’s still a 135 dB reflection – but that reflection would entirely kill the power transmission, presumedly. So you’d have to be really, really, really good at detecting when you have a line-of-sight transmission, and when something else is in the path.

        2. The receiving device could report back actual received power data via RF.

          Even if you are pointing directly at the receiving device via the mechanical steering, you can’t be sure that the beam won’t hit the device at an angle. Part of that beam will bounce off and around the room.

          There is also the interesting real estate issue of the location of the receiver. Unlike a RF power transmission, if the receiver is under the display, a large portion of it will be reflected off. Do you want to lose screen space to the receiver on the surface?

          1. Well, if you hit the receiving device, then the material it’s made out of could be made to have a reflection coefficient at that frequency to make the reflected beam negligible.

            “Do you want to lose screen space to the receiver on the surface?”

            Yeah, that’s the part I’m most curious about. But it’s not *completely* crazy to imagine a full case, with a transparent front, that transmits a good portion of the received power to the transducer. But that would be really impressive engineering.

    3. 50 % would be an awesome value; the really big problem with ultrasonic transducers is the (acoustic) impedance difference between air and the transducer itself. You can tweak it a little bit but it is the main reason why you wont get above single digit transmission efficiency with transducers. That is why ultrasonic devices mostly use coupling liquids.

      Same story is on the receiving side, even if they use a focus method like in “Extracorporeal shock wave lithotripsy” ( https://en.wikipedia.org/wiki/Extracorporeal_shock_wave_lithotripsy ).

      Conclusio; you won’t need any heating no more…

      1. From the patent, they mention an “electromechanical conversion efficiency” of up to 40%:

        “Sending transducer 106 may have a high electromechanical conversion, for example an efficiency of about 40%, corresponding to about a 3 dB loss.”

        Is that them just quoting electrical power -> mechanical motion (and not to acoustic power)? There’s a fair amount of bits in the patent about talking about finding the best impedance match for the whole path dynamically (using a side-channel communication) – however I agree that fundamentally matching the transducer/air is the hardest part.

        1. There’s always some fudging in situations like this, but the 40% can’t be pulled from thin air – otherwise why not say 80, 90, 95, 99%?

          It just seems like there’s a disconnnect here between people who’ve worked on ultrasound (saying 1% at best) and the patent (claiming up to 40% at best). That’s a big disconnect.

  4. It’s even worse than you might think. I have actually worked with ultrasound, designing transducer amplifiers. If they get even 1% power transmission efficiency at one meter I will be totally shocked. That would be an astonishing achievement.
    When transmitting a pulse you routinely drive the transducer with 100V. The return pulse is usually in the millivolts range, and heroic filtering and amplification is necessary. And this is with highly directional transceivers and using a frequency of 40kHz.

    1. Is the idea of transferring power from A to B (extremely inefficiently) using ultrasound, something that you have heard in your everyday life ? If it is then it is not a hack to you, but for most people a hack can be an idea.

  5. ISTR some years ago some dude invented ultrasonic power & data transmission to work through the hull of a submarine, I’m 75% certain it was from Portsmouth university. Of course, transmitting vibrations through a few inches of solid steel / unobtainium is a very different prospect and their use case was more focused on short-range / high data-rate for sensors to avoid cutting a hole in the side of the sub for a cable. Fairly sure nuclear subs wouldn’t care if the power usage was a bit high as long as it got the job done ;)

    Also you missed a key dB measurement: ~126dB is the pain barrier (if memory serves).

    1. Not sure sending masses of sound of any frequency out the side of a submarine is a good idea, aren’t enemy subs going to hear it? They use sonar after all, so ultrasound must travel fairly well through water.

  6. I guess we’re just forgetting about wave interference like it doesn’t exist. Also, wouldn’t this produce radio waves from the transmitters? If so, how would they plan to combat that to keep it within Part 15?

  7. Of note, the peak energy from this ultrasonic experiment was around 165dB. Many experiments were done at less. Yes, it is done at 40KHz, it just means they’ll target smaller things. I fully suspect that they’ll also kill flies.

  8. What of the receiving side? Wouldn’t I have to fiddle with propping up my cell phone at a certain angle to maximize reception? Wouldn’t the human act of holding or touching or using or sitting close to the phone ruin the power reception? Couldn’t a single waylaid napkin break the whole thing down? Also, wouldn’t the operation of the side-channel RF (presumably wifi) burn almost as much power as the trickle that could be received from ultrasound?

    I’m no acoustic engineer, but I’m just not seeing how this could ever be practical.

  9. I worked on PZT actuators that ran in the 30-45 KHz range at much lower power. In air they would burn up due to self heating in about 90 seconds. To keep them running for hours required forced convention oil cooling and a refrigeration system to cool the oil. Find out how efficient these new sound actuators are and take a look at the heat you will need to reject. That should be an eye opener.

  10. Excellent writeup, uBeam is either a total scam or just a plain horrible idea. If this is ever actually built and sold it will be inefficient, dangerous, and a massive waste of money. I cannot believe they already have millions in funding when the other products mentioned in the writeup ACTUALLY HAVE A WORKING PROTOTYPE and not only that, but are incredibly more efficient and less dangerous than the uBeam device will be if it ever even exists in the first place

    1. Ah, but people are afraid of electromagnetic “radiation” because it’s “radiation” and therefore bad and causes cancer in their minds. Whereas most people are ignorant to the dangers of high power sound.

  11. There is something that everyone keeps missing in these wireless power articles. They always go back to the patents. Any A-hole can get a patent. All it takes is some good story telling using the appropriate techno-babble. You do not need a working prototype or even a valid idea. All you need is a well defined idea(valid or not) and a good description of said idea. The patent office doesn’t examine the idea for soundness in theory, but only for prior art or obvious duplication. Today a patent is just a weapon of war in a court battle. Moral of the story…Having a patent does not equal having a valid product.

  12. After reading the post at eevblog, and googling the names of the initial founders, then considering high profile techcrunch involvement, I would say this whole thing is a sort of.. community project of rich and powerful startup people to make some women, one from a prominent family, wealthy and powerful.

    The founder is being compared to elon musk and mentioned for a future nobel prize! For what comes achingly close to a free-energy scam!

    1. May be it is just me, but I don’t think they hand out Nobel prizes like those free samples at supermarket. Even the HaD 2015 finalists deserve more than her because some of them are trying to solve more serious problems rather than creating more inefficient way of charging devices for lazy people.

      1. Indeed…But then – the modern concept of an entrepeneur leaves a lot of room for flim-flam and huge over statements of a ‘executives’ value.

        Reading the stuff the investors say about the founders – it is like the worst word salad from events like techcrunch – with a self serving over-earnestness. These are very prominent people backing this project, it turns out..

        It seems to be money they dont necisarilly plan on ever seeing again – they probably consider this charity or some other outlandish excuse.

        The funny thing is how low the impact of this product is likely to be, even if it succeeds at all it’s claims. It isnt going to be widely adopted, it does not achieve the buzzwords ascribed to it – the typical breathless repetitions of ‘disruptive’ and ‘world changing’.

        I suppose if it succeeds wildly it could be in some handhelds and some retail settings will install it? At best?

      2. It is a chicken and egg problem. It won’t reach the same level of market penetration as QI (or other?) wireless chargers already on the market licensed to actual products and have chip vendors supporting it. Those chargers are pretty simple and cheap to make and have no moving parts.

        Star Buck now has wireless charging in some limited locations. http://www.digitaltrends.com/cell-phone-accessories-reviews/starbucks-wireless-charging-hands-on/

        1. Contact-limited inductive charging is far different from this concept, unless I miss something?

          It charges from the back, no logarithmic efficiency degradation, plus the no moving parts!

          I think the founders were too appealing for the apparently reality-buffered investor class they successfully woo’d

          Reading about the co-founders paints an obvious picture. Never expected to succeed – some % fail, right, might as well choose the failures? Something like this.

          1. Wouldn’t hurt Starbucks just to have a few USB power ports scattered about the place. Now that most devices charge from a micro or mini USB, means there’s no problem with having the right leads. Just have a few of the right leads hanging around. Wouldn’t be a big endeavour to just supply USB power, and would attract customers coming in to charge their gadgets.

  13. I love how the VC defending the idea protests “But I’ve seen it working!”. I have seen a lady cut in half and put back together. Surgery will be revolutionised!

    Where, oh where is James Randi when you need him? If I’d been the this demonstration, the first thing I’d do is interpose myself between the transmitter and receiver and see if the receiver continued to be getting power.

    1. You mean people choosing to take it up? Qi and the other wireless thing aren’t doing badly. If something’s useful, people will buy it, and eventually manufacturers will build it in. Not in this case of course, because with your eyeballs dripping down your cheeks and your skull in fragments, you won’t be able to find your phone.

  14. I heard UAV’s use ground lasers to recharge without landing before flying off to patrol or whatever..over long distance this can be a good thing like satellite relaying of power back to earth or the moon or wherever. Watched a few videos by a guy called Gerard Morin recently. He is claiming that teslas tower was a receiver and not a transmitter for receiving RF and using copper in the antenna. Something about mass being the contributing factor. Any way if anyone knows the details of this, could they shed any light on this particular area? I am not knowledgable enough to determine whether or not the math works. Or if the theory is right.

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