Suddenly, Wireless Power Transmission Is Everywhere

Wireless power transfer exists right now, but it’s not as cool as Tesla’s Wardenclyffe tower and it’s not as stupid as an OSHA-unapproved ultrasonic power transfer system. Wireless power transfer today is a Qi charger for your phone. It’s low power – just a few amps — and very short range. This makes sense; after all, we’re dealing with the inverse square law here, and wireless power transfer isn’t very efficient.

Now, suddenly, we can transfer nearly two kilowatts wirelessly to electronic baubles scattered all over a room. It’s a project from Disney Research, it’s coming out of Columbia University, it’s just been published in PLOS one, and inexplicably it’s also an Indiegogo campaign. Somehow or another, the stars have aligned and 2017 is the year of wirelessly powering your laptop.

disney-research-quasistatic-cavity-roomThe first instance of wireless power transfer that’s more than just charging a phone comes from Disney Research. This paper describes quasistatic cavity resonance (QSCR) to transfer up to 1900 Watts to a coil across a room. In an experimental demonstration, this QSCR can power small receivers scattered around a 50 square meter room with efficiencies ranging from 40% to 95%. In short, the abstract for this paper promises a safe, efficient wireless power transfer that completely removes the need for wall outlets.

In practice, the QSCR from Disney Research takes the form of a copper pole situated in the center of a room with the walls, ceiling, and floor clad in aluminum. This copper pole isn’t continuous from floor to ceiling – it’s made of two segments, connected by capacitors. When enough RF energy is dumped into this pole, power can be extracted from a coil of wire. The video below does a good job of walking you through the setup.

As with all wireless power transmission schemes, there is the question of safety. Using finite element analysis, the Disney team found this room was safe, even for people with pacemakers and other implanted electronics. The team successfully installed lamps, fans, and a remote-controlled car in this room, all powered wirelessly with three coils oriented orthogonally to each other. The discussion goes on to mention this setup can be used to charge mobile phones, although we’re not sure if charging a phone in a Faraday cage makes sense.

motherbox-charging-phone-squareIf the project from Disney research isn’t enough, here’s the MotherBox, a completely unrelated Indiegogo campaign that was launched this week. This isn’t just any crowdfunding campaign; this work comes straight out of Columbia University and has been certified by Arrow Electronics. This is, by all accounts, a legitimate thing.

The MotherBox crowdfunding campaign promises true wireless charging. They’re not going for a lot of power here – the campaign only promises enough to charge your phone – but it does it at a distance of up to twenty inches.

At the heart of the MotherBox is a set of three coils oriented perpendicular to each other. The argument, or sales pitch, says current wireless chargers only work because the magnetic fields are oriented to each other. The coil in the phone case is parallel to the coil in the charging mat, for instance. With three coils arranged perpendicular to each other, the MotherBox allows for ‘three-dimensional charging’.

Does the MotherBox work? Well, if you dump enough energy into a coil, something is going to happen. The data for the expected charging ranges versus power delivered is reasonably linear, although that doesn’t quite make sense in a three-dimensional universe.

Is it finally time to get rid of all those clumsy wall outlets? No, not quite yet. The system from Disney Research works, but you have to charge your phone in a Faraday cage. It would be a great environment to test autonomous quadcopters, though. For MotherBox, Ivy League engineers started a crowdfunding campaign instead of writing a paper or selling the idea to an established company. It may not be time to buy a phone case so you can charge your phone wirelessly at Starbucks, but at least people are working on the problem. This time around, some of the tech actually works.

89 thoughts on “Suddenly, Wireless Power Transmission Is Everywhere

    1. 95% would be. And it depends how much power. For charging a phone, an extra 5 watts isn’t going to be missed. TVs are quite low power nowadays. I can see the advantage in something shorter-range and lower powered, like a desk that means you don’t have to bother bringing your laptop charger and finding somewhere to plug it in.

      Low-power electronics are where this would be good. Running microwave ovens probably not so much. Actually a couple of tweaks and you might not need the oven. Any food you bring into the room might start to heat up by itself!

      I was expecting something directional here, that aims energy at particular spots, a 2-way connection where your laptop etc tells the room where abouts it is, then the transmitter beams at it using a phased antenna array, or something. Is it safe to flood a room with a few kilowatts of RF?

      1. Unfortunately I found no indication of the used frequency here. And for a TV I don’t see much use. You need an antenna connection anyway – especially in this Faraday cage room :-) If you really don’t want two cables you could supply it with DC over the antenna line.

        1. The film clip mentions 1.3 MHz – bang in the middle of the AM broadcast band. Those metallic walls would need to fit well at the edges. But (3*10^8)/(1.2*4) = 62.5 MHz is what the copper dipole resonates at, I figure, so I can’t see it radiating well at 1.3 MHz.

          I’ll settle for wireless power from that very remote fusion reactor to my off-grid holiday home. That saves me over $60,000 in wiring costs.

          1. Unfortunately the power transfer is often interrupted, on regular and irregular intervals. So storage batteries are a must. If you really had to pay 60k for the connection, you can buy some big batteries.

            In my case the grid connection would be near the garden, but up to now I did not want to invest the connection and running cost and so I have only a very small system (50Wp and 2 old car batteries) for a car radio and some LED strips.

      2. While it might be _safe_, wouldn’t occupying people get a “warm fuzzy feeling” like the Air Force radar guy who invented the microwave oven? If so, you have an opportunity to have a room where an anemic supervisor and a polar bear of a white boy can BOTH be comfortable! The “polar bear” would wear coveralls of screen material while the always-cold supervisor doesn’t and the temperature turned down so the supervisor is getting microwaved like that radar guy got the one day.

        If that is the case, the Disney guys will have solved that one HVAC Engineer’s Nightmare of a problem. And save big bucks on heat by only heating the people who want it instead of the whole building and getting polar bear types pissed off and still not satisfying supervisors who’ll bitch until it’s 83F/24C.

  1. What a stupid crap. There is already enough RF-noise in the air. We have quite good batteries today, why on earth do we need this? (or better: Do we actually need this?). It’s not so difficult to plug your whatever-device to a charger (or a USB port) before going to sleep/lunch/…

      1. The potential for causing a major rise in the RF noise floor IS an issue. Leaded gasoline was an innovation, CFCs were an innovation, and lack of foresight caused a great deal of problems down the road. We have reached the point where asking what the broader impacts of introducing a new technology is a very valid line of inquiry.

      2. I am a little nervous about all of this because I’m curious what effect it is going to have on people’s bodies. Will there be a sharp uptick in cancer for the people that use this technology? Plus since this is Disney researching this, I’d assume they’d like to use it in attractions in their parks. If so, that could be a lot of people exposed to it without possibly realizing what is going on. We are talking about almost 2kw of energy in a confined space. It’s not good to be right next to an antenna putting out 2kw of RF. Is that what is happening here?
        I mean, I want to live in the future where nothing ever has to be plugged in too. Just walk into your house and instantly your cellphone/laptop/tablet starts charging. No power cables to trip over. Just imagine no power cable to trip over while running the sweeper. But, I don’t want to live in a world where everyone has to have cancer to do all of that.

          1. Take with a pinch of salt, I wasn’t around when the military microwave antennas were being rolled out… So the following is mostly hear-say(seems reliable as the source is an electrical/electronic+software engineer’s first-hand experience.)……

            Heard enough ex-military personell stories (Old folk from the army) about people being literately cooked to death infront of a microwave antenna. Apparently they couldn’t work out the deaths until they spotted a common theme: The microwave antennas. They put out massive warnings a few days after the incidents occurred.

            Aparently the personell would go to the wfront of the horn for a smoke because they were warmer in that spot. LOL. Some people learn’t a bit too late.

            Mobile signals are less than rubbing your hands in the cold worth of heat at best (For comparasion sake).

          2. Ah bullshit, you are electronic too, from how your nerves work to how ATP drives your metabolism. Just because you are organic does not mean you do not interact with electromagnetic phenomena.

          3. @Dan: I would call it (electro)chemical. The used frequency (although not really specified I assume them in the two figure MHz range) will not affect you as a signal, but sure can do it somehow as heat. And of course too much heat is not good. I wonder about people being anxious about 1 or 2W from a phone’s transmitter but I am not sure if 2kW of power is a good idea.

            @Unferium: With this military radars there was also another issue: x-rays. From the HV tubes used to generate the microwave power.

          4. …”The ones presented here and most of our electronics do not affect us.” and YOU know this how? You speak with a such conviction which can only suggest that you brain was sanitized of the good sense by using your iphone next to it.

          5. DV82XL- “That’s just it. There are legitimate health issues at high field strengths, mostly via thermal effects, but nevertheless RF is not benign. The silliness comes from those claiming that cellphones are causing brain cancer in the total absence of any verifiable evidence.”

            Lmao, more of your ignorant crap :D
            MicroNucleation is well documented and known for a while….what do you think will happen when cell rupture and spill their guts over and over??

        1. >>Will there be a sharp uptick in cancer for the people that use this technology?

          No, there will not be a sharp uptick in cancer. RF is not ionizing radiation. You can do the calculation yourself, it does not have enough energy to break chemical bonds. Worst case scenario the little gold bits on your favorite Christmas sweater start sparking possibly causing injury.

            The FCC’s website does say that results are inconclusive on whether RF exposure can cause cancer, but then they mention cellphones. Cellphones are low wattage and intermittent. This is 2000 watts and presumably constant. Big difference. Check out the sections about what levels are safe for exposure to RF energy.

            This is not an unfounded concern.

          2. That’s just it. There are legitimate health issues at high field strengths, mostly via thermal effects, but nevertheless RF is not benign. The silliness comes from those claiming that cellphones are causing brain cancer in the total absence of any verifiable evidence.

          3. Did you know that with the release of smart phones there was a really sharp uptick in sexually transmitted diseases :P
            But on a more serious note its not just a case of breaking the chemical bonds or causing cellar damage, there are a pile of other factors. Some people are sensitive to low power EMF and some are not, Back in the day of CRT monitors I was able to sense if a monitor had been turned on in another room as it would cause irritability and headaches. One of my kids had huge issues sleeping at night because his bed was on the other side of the wall where out RV was in the lounge. Moved the TV and these issues went away,
            The issue is not just one of cancer there are a lot of other problems including mental health issues that could be triggered. And lets face it with the increase of electronic devices in the home and work place there has also been a huge increase in suicide and mental health issues. The two may not be related but until we get an independent research team who can examine all these factors we will never really know for sure.

            In most cases there is such a thing as “Acceptable Risk” where something is released and in most cases it should not cause issues but no one will know for sure until years down the track. History is rife with examples of this.

          4. @ Doc Oct

            RF causing cancer IS and unfounded concern. A handful of poorly described, unreplicated, small sample studies is not proof. Especially if it’s done on lab rats, the most common of which are so inbred and engineered that debilitating tumors and cancer are a certainty. RF energy giving you a nasty burn or a headache is not. Yes, 2kW is a lot of energy but it’s gonna follow some sort of di-pole radiation pattern. With up to 60% losses. Sure I don’t want to stand inside a 800W dorm microwave either, but this is optimized for energy transfer not boiling people. The biggest threat is finding a high gradient region of the pattern and somehow grounding yourself.

            EMF has a long history of known side effects, dizziness, nausea, headache, blurry vision, feelings of distress. These are no secret, but to boldly tie them to suicide & mental health is spurious at best.
            Since the 1960’s the US suicide rate has been pretty steady between 10-13% I don’t think there’s any meat to the claim that suicide is rising in a troubling way, it’s just cycles based on the economy, wars, & the housing market.

          5. @Boris: Of course young people could “sense” CRTs. They hear the whine from the flyback and deflection coils. With age the high frequency hearing decreases below 16kHz in most people.

        2. Tin Hat prices are going to rise dramatically again! The young will adopt without question. Historic products like tobacco, baby powder, and asbestos come to mind. Anyone that has pause to stop and consider rather than blindly accepting is wise. For this one I would look up the subject of “rife” as a starting point and pay close consideration to the frequency used, and remember that the Inverse Square Law is your friend. Be mindful.

          We do make good use of magnetic fields to deliberately screw with your atoms and then ping them with rf and listen for the decaying rf ring they send back. MRI is real stuff. Seems to cause no harm. Point is that we already have proof that magnetic and rf fields do affect our every cell. Was a day they said x-rays good too and even used them to help you fit shoes RIGHT at the store, then physicians and dentists came up with cancers. Someone saying it’s not harmful is not necessarily correct even if they ARE an expert.

          We always find out LATER, not up front. It’s years and years between the two.

          1. I agree with the contents of your post, including the inverse square law, just one extra comment:

            Given that most humans and radiating devices by humans are located on a 2dimensional surface (earth surface), then consider the ring of area from a human subject defined by the radius r to r+dr and assuming an average radiating device density: the 1/r^2 radiation from these devices is proportional to r/r^2 = 1/r … well, except earth is not an infinite plane…

        3. With highest probability there will be no uptick in cancer. But cataracts are a more serious risk in my opinion, being constantly in an RF diathermy environment, and they are also no fun at all.
          Although Disney does the research I am sure they will (can) not use it in the amusement attractions, without much further investigation and proof of public safety.

      3. Because innovation for innovation’s sake is so sweet!

        Sorry, had to be said.
        To offer a more constructive answer: I’m all for cooler, more powerful chips, to an advancement of MIPS/Watt. I’m all for more efficient motors, for shifting cars to electric (if in the process they could specialize/differentiate more into city/short range and long range the better). I’m all for more efficient lighting, for smart homes (if my data/control isn’t pulled through Google or any similar giant I don’t trust).

        But innovation can be downright stupid (like putting radium in toothpaste [1]), and I think *this* is one of them. Unless we are talking microwatt devices. That might make sense, actually.


        1. Basically right, but I am against this kind of “specialization” in cars. True, most of my drives are below 50km but I also want to drive for holidays, camping, etc. I do not want to have to own two cars. With my today’s gasoline powered car I can do what I need, I do not want a reduction in versatility or power. For me a new electric vehicle has to compete successfully with the existing technology.

          1. Just think out of the box. Why should you *own* a car you use just once a year (vacations)? Why shouldn’t it be possible to transport a small car optimized for the 50Km range in a train?

            Isn’t our job as engineers to think out of the box?

            I think the car as we know it is outdated. It’ll take some time to change, sure, but it has to.

          2. @tomás zerolo:
            No, the car as we know it is not outdated, it is the most comfortable and flexible solution. It does not need a train for the long distance. So I prefer it.

    1. I see a room with metal walls forming a resonant cavity in there, so there should not be too much leaking out. Except doors and windows, but still.
      On the bonus side, if you are cold you can just crank up the power and shift the frequency to 2.4GHz.

        1. I have just started going through the meat of the paper but unless I am very much mistaken the cage is required as it forms the cavity. The cage geometry can vary as well as the center pole location/shape according to the authors, but ultimately it seems to require an enclosed metal volume with a vaguely central conductive pole to function.

          1. In which case this is of very limited utility. Disney may find some applications in some future attractions, but it isn’t anything the rest of us will likely run into outside of that sort of venue.

          2. The paper says it works by being a high-Q cavity. Good luck with that when more than one or two people are inside. If this was a crowd funded idea I would pass on it; Disney may well have some sort of niche use for the idea so they may find it useful but as a general solution for avoiding charging cables it’s a failure.
            The field strengths reported get a bit high also. The paper seems only to consider the whole body absorption figures when considering safety – at the relatively low frequency they report 1.32 MHz they should consider also the RF current that that could flow through vulnerable parts of the body (the wrists and ankles). They should consult the specific safety regulations for the frequencies they are using.

        1. Why do you think that? It does not look terribly asymmetric. :-) And if it produces thrust, the just build it out of some real building materials like bricks and concrete instead of paperboard :-)

    2. That’s what I say ….. Even at 90% efficiency it means you are likely emitting 10% more CO2 than necessary

      I think these things should be banned, we are trying to RAISE efficiency to LOWER CO2 emissions and this is going backwards …. All because people are too damned LAZY to plug in a cord or put their phone in a charging dock

      Really? We ban incandescent light bulbs and then turn around and do something knuckleheaded like this

      Big Picture people, Big Picture

    1. So basically Arrow is just getting their name out there by doing something literally any PCBA house will do, and calling it a certification. Seems kinda stupid, but their prices beat Mouser for a lot of parts so I’ll keep buying things there.

      1. I also don’t understand why they do that. What is the target audience? Electronics illiterate crowdfunders? They would typically not start buying straight from Arrow so why get your name out? If its people who may actually buy things from them, their calling it a certification looks just weird and misleading…

        1. Yes.
          People see certification and stop reading. The often advertised “mil-spec dust and water cert” isn’t actually for the equipment being tested and says nothing about passing the test, it’s for the test methods.

    1. That’s why I got rid of my electric (heated) blanket and move my alarm clock away from my bed. No way I’d want that kind of power radiating around my house. In an age where we are looking for more efficiency why would we want something that wastes energy. No energy star logo for you.

      1. I normally don’t use an electric blanket because I don’t need it. I have central heating and normally my cats come to me at night also. :-) But why should I put the alarm clock away? I want to be able to see, read, hear and use it.
        That does not mean, that I am sure about the safety of this RF power transmission. Efficiency is good and important, but of course I would use energy for convenience.

    1. This turns a whole room into a resonator, so 1/r^2 doesn’t apply. There’s still resistive losses in the resonant cavity and whatever’s inside it. And a cell phone or radio isn’t going to work well inside this room.

      1. In theory the resonator walls could be made reflective for only a narrow bandwidth frequencies (at which the power transmission system works) but are otherwise unused / reserved as channel that should not be relied on in critical systems…

      2. Sounds like opportunity to finally experience being inside an active klystron tube!

        Whole body diathermy!!!

        Please remove keys and coins from pockets. Metal rim glasses not allowed. Metal zippers may induce burns. Please see an attendant if you have metal amalgam dental fillings, metal stents, surgical pins or artificial metal joints.

  2. Question: How well does you mobile phone work in this environment?
    Let’s assume the worst:

    In order to charge your phone in this manor, you must be inside a cage (looking at the photo’s it is a pretty nice cage… which will also act as a Faraday cage). This cage that makes it possible to charge your phone but could very well be blocking your phone (problems finding a network?)

    If Disney gets it’s way we’d live in a metal room without windows with a hideous pole in the middle. A pole that should be avoided in a radius of halve a meter (from a technical point I understand, but how do I explain this to my wife?!?!). All this nonsense just to loose the charging cable? One thing will be certain… when living inside your windowless metal box, prevented from contact with the outside world, you’ll soon discover that “it’s a small world after all”.

    1. Look, I’m no bigger fan of this fad of super-lossy, marginally-convenient power delivery systems than the next guy. But you’re failing to apply even a little creative thinking here. The house will be a resonant chamber with a pole in the middle, but that pole need not be in the middle of any room; it can be in a carefully-positioned 1m-square utility closet. (No, it won’t be easy or simple to retrofit in existing homes.)

      Your home WiFi router will be in the Faraday cage with you, so no “prevented from contact”, and if you really need the phone network, you can have a repeater for that, too.

      The waste heat from the 40% efficiency case will be a problem (unless you live in a cold climate, I suppose), but your complaints needn’t be.

      1. Dear Ben, I fully agree because you are completely right. But where’s the fun in that. My main intention was to make fun of the situation that was created in this slightly silly setup. I therefore started my comment with “lets assume the worst:”. Because seriously, just look at the setup… it’s just too crude to be practical. They need to do so much in order to make this more practical. My main worries are the efficiency of the overall system, the 95% is hard to believe and what about standby power. But then again these problems exist for all cordless power solutions.
        Anyway if this is the future, I doubt it will reduce our emission footprint.
        Regarding about emission… how will they ever get this certified?

    2. Well, some families implement no-cellphone policies in the home. So for those people turning the house into a wireless power zone means your phone is always charged, but always in your purse/pocket so you bring it out of the home with you. And nightlights/computers/whatever can be carried through the house on a whim.

      1. “some families implement no-cellphone policies in the home” – what crazy shit should that be? It’s probably not good that small children have cell phones or use them too much. But a complete ban is just ridiculous. And even if restrictions for kids can be justified, I would not see this for adults. I myself don’t even have a landline phone.

  3. Well, that was interesting to read about. However I can’t imagine myself doing anything beyond experimenting with the idea unless they reworked it to use beamforming like in phased array antenna’s to massively cut down on the interference and energy waste. Although if you were going to use a sort of phased array antenna then ya might as well mount it in the ceiling for better room coverage, perhaps even behind a ceiling light.


    However I do like the casing they used for the MotherBox.

    1. The wavelengths are long enough that they wouldn’t couple well into a human sized or smaller conductor, unless it was a coil tuned with a capacitor near the operating frequency.

      1. “The wavelengths are long enough that they wouldn’t couple well into a human sized or smaller conductor”. The paper mentions e field strengths up to hundreds of volts per meter at 1.3MHz. You will get hurt playing around in such an environment. Permanently damaged, probably not.

  4. Motherbox is bullshit, “Arrow approved” or not. No way that you can stick a receive coil on a mostly metal phone and get any significant range due to eddy-current losses in the metal. Add it to the uBeam pile of impractical failures.

    1. BTW Qi chargers don’t have this issue as they use ferrite sheets to close the magnetic circuit outside of the bulk of the phone. This doesn’t work at distance, and even if it did you’d need to keep the phone pointing at the transmitter.

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