Friday, February 3, 2017

uBeam - Still All Sizzle?

An eventful day yesterday on the uBeam front, with Meredith Perry finally giving a demo of uBeam technology and showing it charging a phone at the Upfront Summit - well more precisely showing a big box and then a light on a phone coming on if it was put in front of it. Essentially a slightly more glitzy version of the "All Things D" demo done in 2011, showing what 6 years and $25 million gets you.

From what we see here, in my opinion, is proof that you can take a non-technical audience and baffle them with bullshit - if you want to know that the phone is charging, you need to do more than turn a screen on. Perhaps there is more not seen here, I'm just going on the info that's public, but you need to show voltage, current (at both transmitter and receiver to get efficiency), and the phone sitting in front of that panel for several minutes and see the actual charge level increase over time. But that isn't what they showed - and if it isn't, please enlighten me and tell me what is the difference between what's shown in that video, and what was shown at All Things D 6 years ago.

It seems at least some are not convinced and there are journalists taking a sceptical view, such as Axios (albeit promoted with a tweet that is more sensational than what was shown and the content of the article, and sadly is all that is quoted by most)

This is a science project that is clearly progressing, but not nearly finished yet.

Pretty faint praise after $25 million. There was also this interesting statement:

we're told Perry picked that particular Android for the demo because of its highly-visible charging icon

Why would that be mentioned so specifically by the company, and why does it make me raise an eyebrow?

Now, let's be clear, no-one ever said that transmitting power via ultrasound is impossible, of course it's possible - but is there a way to do so in a safe, efficient, and cost effective manner? That's the challenge, and in any practical sense it had never been shown publicly. In my opinion, it still hasn't. All that has been shown is a screen lighting up.

I'm sure uBeam now have potential funders lining up outside willing to throw money at them, based on this, even though nothing was really shown. And if I'm wrong about that, tell me what was shown that proves it works. What's the charge rate? How long to charge a phone? What is the efficiency? How does this line up with "4 meters, any angle, multiple devices, faster than a wire" touted before? Is it a safe and legal level? (OSHA now seems to have gone back to a 115 dB limit, not the 145 dB from a few years ago, I certainly hope there's no-one in the way of that beam, or there are any grating lobes giving the audience a facefull.)

Now the fact the phone charge indicator comes on proves they are charging at a minimum of 500mW (around 5 volts at 100 mA) needed on the USB port, which is awesome as that's enough to at least trickle charge a phone over about 10 hours. Or does it? Potentially you could access the Qi chipset on the phone to show the charging light when at <500 mW, or other similar bypassing of standard input methods, but in the end there's no way to know without looking at actual charge rate - which isn't shown in any form. If it works so well, I'm surprised those numbers aren't released - "more than 500mW" is a very straightforward statement to make. Or leave the phone in front of the transmitter and see it gaining battery level during the talk. But that would be too easy.

And at what efficiency? At 30% end-to-end it's incredible, at 1% it's very difficult to justify, at <1% it's ridiculous. We don't know those numbers.

How many devices can this charge at a time? What does the system cost? Can it track the phone? What happens at an angle? Was the beam always on, or did it switch on when it saw the phone? What were the safety measures to stop an always on-beam being pointed at someone accidentally? If this is the best case demo today, why were some people saying they had seen a similar working demo years ago? Weren't they moving to production 18 months ago? All questions still unanswered.

I'm really sad, of course, for the senior staff who just left the company over the last couple of months, and what I guess is the closure of the San Jose office (or that's how it appears if you check the LinkedIn profiles). Amazing they would leave just on the verge of a breakthrough like this, but more fool them I guess, what do they know? Passing by on the billions... 

Overall, with a skeptical eye, there's nothing new here. IMO, no significant new information, nothing to show commercial success or capability, and no path to a realistic product. But it won't stop investors from piling in without doing significant due diligence (investors, feel free to call me and prove me wrong), and it won't convince anyone with one iota of technical capability that there's more there than they thought a week ago. More of the same, move along.

For those of you with a technical bent, I'm including a more detailed analysis from what I saw in that demo below. Anyone non-technical, you may want to stop now.

Taking a technical look at what's there and bearing in mind this is with a lot of assumptions - the video shows an array that seems to be made up of a (approx) 30 by 30 collection of circular transmitters, and given what I see on stage it's about a 30 by 30 cm panel, so each is a 1 cm diameter cylinder. Very much like the Murata MA40S4S used in car parking sensors and available off the shelf at around $3 each in bulk. Of course they couldn't use them because that would be a $2700 transmitter BOM component right there, but let's use them as a starting point.

Assume 40 kHz, and let's say we can drive much harder because why not, something like 6 times more (120 volts p-p, or approx 16 dB in sound pressure) to be generous so that's 120 + 16 = 136 dB sound pressure level. They are circular, so we lose 2 dB from area, that's 134 dB out, across a 0.09 m2, and at that level that means a peak pressure of 180 Pa and about 37 W/m2 or actual 3.35 W transmitted. Incidentally the capacitance of those devices at 2550 pF means (at P=nCV2f) gives 1.3 kW (900 * 2550e-12 * 120 * 120 * 40e3) so right there is around 0.25% efficient on transmit at best, along with a one bar electric fire. A few million people doing this every day means GW more generation capacity, so I hope I'm wrong or we better start building some power stations. (updated efficiency numbers below - a bit better than here, but still pretty awful).

As a side note, those values of amplitude, if I'm in the right ballpark, may avoid the worst effects of acoustic nonlinearity in the distances shown, but in my opinion (and that of physics), would result in nonlinearity if you tried to increase from there, decreasing efficiency considerably.

Now at 1 to 2 m distance you're probably looking at around 3dB loss in the air (pretty low, yay, but still 50% efficiency), so saying you get all of that power at the phone (about 5 by 10 cm) you'd have an focus gain of around 18 times (25 dB), so now we're at 156 dB (wow, that's loud). Now we convert back to electricity, let's say 30% efficient there (massively higher than the Murata MA40S4S), and around 90% on some awesome conversion electronics, it's about 27% conversion efficiency, and you now get to 450 mW to the battery which is almost enough to charge it. Let's go with that - yay we're charging a phone in about 11 hours. If I'm assuming low numbers, then divide that by about 5 to get a 5% overall rate and 90mW, maybe enough to turn on the charging light (and about 2 days to charge your phone, if you don't move it)

At what efficiency? 0.25% at transmitter (I'm ignoring some losses here, but they're minor in comparison to that capacitive loss), a further 50% in the air, and 27% at the receiver, and you've got 0.034% efficiency. (As noted earlier, not including non-linearity). At 12 c/kWh, that's $2 to charge your phone. Ouch. OK, I'm being mean, let's say it's 10x more efficient, it's 20 cents to charge your phone, only $70 per year done every day, still an ouch. And you can heat your room at the same time with a kW scale transmitter, that costs $7500 because of the high BOM and doesn't make you feel so bad about having spent $1500 on a toaster oven.

As an added note from the original post, I noticed on a Twitter feed that some there indicate that the transmitter seemed to be covered by some form of fabric, which looking again at the video you can see is there. This does not mean that ultrasound can pass through clothing, as was previously claimed, but a thin membrane that is significantly smaller than a wavelength and is of a low enough impedance material will not be 'seen' by the ultrasound, for example a mylar film on the order of 10s microns compared to around 8mm wavelength in air at 40 kHz will likely have a minimal effect. Just as with the membranes or meshes used on car parking sensors like the Murata mentioned above... 

I'll add to this as I have time to do so, and check my calcs for any mistakes. Comments welcome on why I'm wrong, and just a disgruntled former employee :)

Edit: Just an update to some of my numbers here. Looking at the Murata data sheet is seems that SPL was measured at 30cm, not at the source, so some modification needed to the calcs. Using Murata's published factors, a further ~10dB needs applied for the diffraction and absorption (BTW that's quite a good document on how those transducers work), so they could be producing as much as 130 dB at source, so I can reduce the applied voltage by a factor of around 3 to around 40 volts, and does reduce the capacitive loss to around 130 W for 3.35 W acoustic transmitted, meaning 2.5% efficiency in that portion of the calculation, so it's overall 0.34% efficient at best, not 0.034%. Yes, that means the sound field could be of greater intensity and higher power, however that would start to push it into the nonlinear regime, and also you'd then be beaming very high sound levels at that cameraman and of course they totally considered safety in this demo...

Interestingly, this means those Murata's can put out over the 115dB level mandated by OSHA, however I'd note that a) the Murata operate at a duty cycle of about 0.4% or less (20 cycle bursts until return signal at up to around 2 m, another good link on car parking sensors), and b) there is a single transmitter, that is as loud as it will get, and decay rapidly after that - unlike a phased array for power which operates at a 100% duty cycle and uses antenna gain to amplify the sound by a factor of several hundred.


  1. Theranos shows that a smart sounding blonde girl in black can suck money out of a VC's pocket with no proof of concept. This is a physical law, apparently.

  2. Wouldn't you use resonant drive?

  3. I'm a skeptic person myself but your story doesn't seem to add up. You claim to be their old lead engineer for years whilst you also claim their technology is bullshit....wouldn't that mean that everything you engineered is bullshit....?

    1. Did I say the technology was bullshit? I think I said it's possible, but is it practical or cost effective? I said the demo has clearly baffled people with bullshit - from what was seen in that video (is there more?) there is no proof of charging, just that a phone was put in front of a box and a light came on. The press puts a eye grabbing headline, even if they temper it later saying 'science experiment', and people run with that. If it's actually charging at 500mW plus, why not actually say so, it's a pretty simple statement to make, leaving out even the efficiency and system cost. But I'm surprised, since this is what's shown when they were moving to production 18 months ago?

      Anyway, as always, attack the messenger not the message, keep it up.

    2. Pretty sure JChan is one of the investor. Say byebye to your $$. Don't invest in things you don't understand.

  4. JChan726- myself, I have worked for years on highly speculative technology that didn't turn into a successful product. It "worked" in some sense but it just wasn't commercially viable, somewhat analogous to uBeam. I wouldn't say that everything I did is "bullshit" and I'd bet that Paul feels the same way.

    1. Indeed.

      And mostly I'm not going after uBeam here, you can't blame them for trying - but you can blame the press for continuing to be failures in how they report on this type of thing. I'd hoped post Theranos they would be a little more sceptical but nooooo.

    2. Yes, you can blame UBeam. High school physic stuff here. Yes, I can create wireless charging(500ma to 2amp) at not near field distant, but it will cause great harm to unlucky person who cross the beam path.

    3. On that front, safety, I completely agree. No excuses.

      OSHA exists for a reason and the limit is 115 dB. Which is about 0.3W/m2, or 27mW from an array of that area, which is 1/20th the amount needed to trigger charging from USB (assuming 100% efficiency elsewhere). Either the phone was not actually charging, or OSHA was exceeded. Also looked to be permanently on while pointed at that cameraman, and with spacing of those transducers, grating lobes were insonifying the audience. (All based on info from a 20 second video, could be more, or less, to it than that)

      Who is the acoustics safety expert there now?

    4. ..Or it was faked; one assumes there was _some_ amount of ultrasound being emitted, but not at all impossible they either (a) used it to gate the power from a battery hidden in their (quite bulky) receiver, or (b) they modified the phone to indicate charging when less than a useful amount of power was supplied.
      I'd love to have a poke around inside that receiver and play "spot the shenanigans"...

      I have no specific evidence that they did cheat, but if you _were_ going to cheat, (y'know, to reassure investors after failing to ship anything and the majority of your senior engineering team have fled) those two options are pretty much what you'd do.

      BTW "insonifying" - nice word!

  5. Slimjim, interesting data point but I hear this may be a trend with Paul in his career. A friend of mine is a former colleague of Paul's at Weidlinger, and I'm told he left Weidlinger in a very similar way to uBeam: resigned angry and vindictive because management didn't care to pay him more or give him authority - one can only wonder why. Don't get me wrong, I love a good scandal, but I'd bet some money that this guy is a sham himself looking for his 15 minutes of fame.

    1. You do realise that most people leave jobs because they aren't paid more or get more authority, and leave for a better opportunity? As for vindictive - care to show me examples of that? I could point to me helping them in the weeks following my departure to get a near $1 million contract, and in the years since have been directly responsible for pushing several hundred thousand dollars of business their way. It's a great team and a great product, and even right now I'm working on projects with them.

      Anyway, more on you, given you literally just created your account to post on here. Feel like attacking my message rather then me as the messenger?

    2. I worked w/ Paul so have *first* hand experience. I never viewed those traits and from my perspective, had nothing to do with his (our) departure; ours was more a realization of the inevitable.

      Paul and others were world class talent. When they were repeatedly dismissed and ignored over things that didn't even pass a giggle test to a much less talented audience (myself), you start realizing where the issues lay.

  6. This comment has been removed by the author.

  7. I don't normally comment on threads, but as part of the team mentioned I feel the remarks about Paul's conduct after leaving Weidlinger are unwarranted. Whatever Paul's personal feelings when leaving Weidlinger he maintained a very professional relationship with his former colleagues in all business dealings, and continues to do so to this day.

  8. I just found this blog after seeing the tweets about ubeam, and after reading thru his post I've been wondering the same. I was hoping for some actual information but the maths in his post are based off of assumptions entirely from a 20 second video clip...anyone can start with assumptions and then do math against those assumptions to try to prove a point. This post proved nothing just as the video proved nothing. He also just confirmed that he left the company cause the co didn't give him more money or authority. Skimmed through other blogposts he's written and this dude's entire blog seems to be devoted to bitching and moaning about his old boss and whether or not the technology of the startup he was part of two years ago is practical for consumer markets. It's really pathetic and sad. Get a life man.

    1. Your comment is absurd. "anyone can start with assumptions and then do math against those assumptions to try to prove a point" ... well.. quite, what's wrong with that? He's walking us through how you'd get some ballpark estimates (by using public information, i.e. what we see in the video) of whether this system is even remotely practical. Sure, some assumptions may be wrong, and Paul frequently throws them a bone e.g. "OK, I'm being mean, let's say it's 10x more efficient" and shows that even with the most generous possible assumptions, the math shows us it's an absurd, impractical proposition. I'm sure he could regale us with many actual examples of UBeam's internal engineering prototypes but that'd be both violating his NDA _and_ we wouldn't be able to verify. If you want to challenge his assumptions above and come up with the math showing a different conclusion, have at it.
      The name of this blog is "lies, damn lies and startup PR" and that's what he's been discussing since day one. Move along, uninformed troll.

    2. It would be helpful if UBeam would:
      a) ship something,
      b) allow a 3rd party test,
      c) do a proper demo providing hard numbers and state the parameters under which those numbers were measured (including both favorable and unfavorable results, i.e. what the power falloff is like when the device is moved around relative to the transmitter, as it would be in everyday use),
      d) address the dozens of specific technical questions/challenges that have been compiled in the EEVBlog thread.

      Lots of startups fail, but few have a declared mission that was debunked pretty much from day one. Here's the original skeptical post from pretty much the same day UBeam went public back in 2014:
      the choicest quote is (verbatim) "IT’S AN IMPOSSIBLE IDEA".

      When Mark Suster invested $10M in UBeam ( - sadly he subsequently switched blog hosting and all the comments on that got lost, because there were several very prescient ones) he said a lot of things, including a bunch of puff about how much due diligence he'd done ("Did the physics actually work? Check").. but where are we now?

      Ms Perry's demo (5 years later) doesn't prove a thing.

      Marc Berthe (mentioned in Suster's piece) lasted barely a year as CTO before bailing out to go do contract gigs for Raytheon.

      The author of this blog was there for just over two years before quitting.

      Suster later wrote a strongly supportive post when UBeam was having a PR crisis because of the revelations in this very blog ( ) which was thin on detail and thick on cheerleading but did give praise to their 'very talented VP of Engineering, Sean Taffler' (who bailed in October last year, to do consulting gigs), and VP of acoustics Paul Chandler (who also bailed last October to go back to consulting) - only two of the four people Suster mentioned are still there - and one of them's Meredith!

      So all these undoubtedly talented and experienced staff have left the company, presumably of their own volition, and we can see it's not because they were lured away to lucrative jobs at mega-successful companies; the logical conclusion is the scientists on board decided to quit their comfortably paid - but futile - jobs and go do something meaningful with their lives instead, even if it was just picking up consulting gigs.

      Here's the EEVBlog FAQ - probably the single most comprehensive and thorough demolition job on the UBeam concept.

      $29.3 million dollars have been spent on this so far. I hope it keeps going for a little while longer because it's a very entertaining story, although it seems we've known for years how it will end.

    3. $10 mil to someone with a billion to invest is like $1000 to most of us. Many men throw $1000 easily at hookers and never gave it second thought the next day, unless the ROI included STD.

  9. BTW; completely off topic but marvelous:

  10. Someone please bring their cat to the next demo.

    1. No, please don't. I like cats and dogs.

    2. Don't bring yours. Bring the neighbors dog, the one that barks all the times at 2 in the morning.

  11. Paul,

    Thanks again for your analysis, don't worry about the distractors, killing the messenger is standard operating procedure of charlatans. I've read all of your posts and find it refreshing that you've taken the time to express your views. I've worked in the Information Technology space for almost three decades and as a consultant bound by confidentiality agreements = (Paid to keep your mouth shut because you know where the bodies are buried). I've gotten a front row seat to lots of clown shows. There are many companies that from the outside appear to be well put together but inside are rotten to the core because they are overrun by sociopaths.

    1. Sounds like we've worked at some of the same companies! :)

      And I'm not worried about them trying to defame me - I take it as a compliment.