back to article Battery-free IoT sensor feeds off radio waves

Dutch researchers have invented an internet-of-things sensor that powers itself from router radio waves. The first sample chip measures just 2mm square, weighs 1.6 milligrams and measures temperature. It draws power from a Wi-Fi router via a tiny antenna, takes a reading, and then broadcasts it back, using a slightly different …

  1. PleebSmasher
    Mushroom

    It was cool until the 2.5cm to theoretical 5m range was mentioned.

    Shrink the process node, and maybe the power requirements will go down and the range can be extended again.

    1. Chris Evans

      Shrinking wouldn't help significantly

      I would expect most (90%+?) of the power used to be in the transmission.

    2. fuzzie

      So 2.5cm is ouch, but at 1m you might be able to do something more clever with meshes, e.g. sensor A harvests some energy from sensor B phoning home and piggybacking sensor C's response when A phones home.

  2. Lusty

    Just. Use. Wires.

    1. Mike Shepherd

      Just. Use. Wires.

      Or a battery. A remote thermometer I threw together runs for over three years on two AAA cells. I'm sure that, with more serious effort, the same or better should be possible from a CR2032, with far more than 5m range.

      1. Anonymous Coward
        Anonymous Coward

        Re: Just. Use. Wires.

        But isnt the point of this NOT to use batteries or other power sources.

        So thats no lithium or cadmium mined, no battery to go to landfill, no reprocessing or reclamation etc.

        As much as i rage againt IoT, i do think this technology has promise.

    2. Jimmy2Cows Silver badge

      Re: Just. Use. Wires.

      Quite.

      Lack of range makes the suggested use of "Building-wide temperature maps" a complete non-starter.

      Even at the theorised 5m range, if you need a router every 5m to supply enough power to the sensor, obviously you need to get power to all those routers.

      The chips might cost 20c each, but sufficient routers, their power cabling, ducting etc certainly costs more.

      Cheaper and easier to just use wired sensors. Less wifi noise too. Imagine the channel interference with a router every 5m...

      Neat that it can power itself. Pretty much useless in situations where you want blanket coverage.

  3. Barbarian At the Gates

    Age of the IoT Zombie Hackpocolypse Sensor

    Imagine a future in which a device along these lines has a remotely exploitable bug, and you can't shut the darn thing off as a last ditch mitigation because you've slapped a few thousand of these doohickeys into a building's fabric, and there's no easy way to power only the "good" IoT bugs with RF without also powering the "bad" ones.

    Dave: "HAL, turn on the heat in here, it's freezing!"

    HAL: "I'm sorry, Dave. I'm afraid I can't do that. The temperature sensors indicates that the internal temperature of your room is 127°C."

    1. Anonymous Coward
      Anonymous Coward

      Re: Age of the IoT Zombie Hackpocolypse Sensor

      Sounds like a business opportunity - a pest controller for the 21st century, prowling your building at considerable expense armed with a buggy-IoT-thingy detector and an EMP pulse gun. Like Ghostbusters, but without the slime.

      1. Anonymous Coward
        Anonymous Coward

        Re: Age of the IoT Zombie Hackpocolypse Sensor

        I bet it would be cheaper to throw a big mesh over the whole building and pulse the inside real good. Would require removing all desirable electronics tho, and you don't get to keep the 'good' IoT nodes, if such ever exist.

  4. Hatless Pemberty
    Headmaster

    The icThing

    I wonder if their next invention will be some kind of electronic musical instrument that can be used to make spooky music for SciFi films[*].

    Leon Theremin's "The Thing" is this-a-way:

    https://en.wikipedia.org/wiki/Thing_%28listening_device%29 [**]

    * Interestingly, Dimitri Tiomkin's soundtrack for Howard Hawks' "The Thing from Another World", uses a theremin.

    ** I have no idea how to embed links. So there.

  5. Joe 35

    20cents? I don't think so.

    Maybe the chip is 20 cents, but then there's repeaters every few metres which will bump the effective cost up to, errm, whatever a repeater costs, maybe $20, so the chip cost is an irrelevance !

    Plus add the cost of installing the power cabling to run the repeaters, and the hassle of that.

    So you might as well, as a comment above says, just run wires and embedded sensors.

    Back to the drawing board I think.

  6. Crazy Operations Guy

    It still needs power

    I've never liked the whole 'harvest power from radio waves' idea since you still need to produce the power anyway and converting it to/from radio waves is ridiculously inefficient (Not to mention the interference caused by bumping the power up). Wouldn't it just be easier to use a layer of conductive paint and harvest energy by way of micro pulses? I figure that you'd place these along the top/bottom edge of the wall or in corners, so a thin strip of paint is all that would be needed. You could even base it off the 1-wire bus standard so that the conductive strip also transfers the information.

    1. Lusty

      Re: It still needs power

      I actually really like the idea. It sucks out the background waves, so actually if you have enough of these in the walls then wifi will improve immeasurably because your neighbour will be shielded from you. This kind of thing also has the potential to create a faraday cage that powers your house - quiet and cheap :)

      1. AndyS

        Re: It still needs power

        >This kind of thing also has the potential to create a faraday cage that powers your house - quiet and cheap :)

        I assume you're being sarcastic, but this only works in the same sense that wind turbines will stop hurricanes, or solar panels will plunge the world into darkness.

        In other words, it doesn't.

        What it will do, though, is give the EM-sensitivity crowd a headache (another, anyway), trying to work out if it's good or bad.

        1. Jimmy2Cows Silver badge
          Mushroom

          Headaches...

          What it will do, though, is give the EM-sensitivity crowd a headache (another, anyway), trying to work out if it's good or bad.

          You say that like it's a bad thing. I'm hoping their heads will explode so we can finally be rid of that particular shower of idiots.

          1. Anonymous Coward
            Anonymous Coward

            Re: Headaches...

            Nope, it'll just give them enough of a headache to sue but not enough to prove it causes cancer so you end up trying to find the contradiction to prove the negative.

        2. Lusty

          Re: It still needs power

          Um, it is dark under solar panels, and the wind is slower on the other side of a turbine. That's how both of those actually work and this tech takes EM and turns some of it to power, removing that power from the ether. I'm not being sarcastic, I just seem to have a better grasp of physics than you do

  7. a_yank_lurker

    Not that new

    Nikola Tesla did something like this about 1900. He used radio waves to power light bulbs. Using radio waves to transfer energy has been done. Now whether it is all that practical remains.

    1. Anonymous Coward
      Anonymous Coward

      Re: Not that new

      Tesla's problem was that radio energy dissipates quadratically with distance: as in to provide the same amount of power twice as far away you'd need four times the power. In other words, for any practical distance, the amount of power you can draw has to be pretty tiny, which is what this is trying to achieve.

  8. frank ly

    How do you tell them apart?

    If you have more than one of these things, or other similarly operated sensors, how do you know which one of several mass produced chips you are listening to?

    1. Jason Bloomberg Silver badge

      Re: How do you tell them apart?

      Presumably, like iButton and similar devices they'll all come with a unique serial number laser cut into the chip during production or set by OTP fuses which can be blown during software install and testing. The technology to do that exists today and has been around for years.

      1. DropBear
        Trollface

        Re: How do you tell them apart?

        " they'll all come with a unique serial number"

        You mean like Ethernet shields for Arduinos that still come with a MAC address on a sticker that you're supposed to kindly hardcode into your software yourself...?

        1. Lusty

          Re: How do you tell them apart?

          That makes sense. On an Arduino you may want to use a private range or a range assigned to you rather than their MAC range. MAC addresses are no different to IP addresses, just usually devices come with fixed MAC because they are finished when you buy them.

  9. Mage Silver badge
    Paris Hilton

    Hype

    The 5m is optimistic, with RF quiet environment and large direction receiver, unless this is a perpetual motion machine breaking the laws of physics.

    A 2.5cm to 20cm range is more realistic. It doesn't matter how little power the chip uses. Even if it has a BIG capacitor and only transmits in 1:100 duty cycle low data rate bursts.

    You can't fit any kind of sensible WiFi aerial on a 2mm x 2mm chip either.

    This is no different to an RFID chip, simply sending temperature rather than an ID Tiny range unless less specialist kit to power and talk to it and listen to it. "Smart Building" uses are fantasy.

  10. M7S

    Wasn't there a court case once about this kind of tech?

    I seem to recall that a farmer rigged up some fluorescent tubes in a barn that leeched power from, I think, the broadcast of a nearby TV tower (it might have been the leakage from power lines, any confirmation either way would be appreciated). I think that complaints of lack of signal from people in the "shadow" eventually helped the relevant powers that be locate the source.

    The charge might have been abstraction of electricity but again I am not sure of what they did him for, or if he was just given words of advice. I believe I read about this incident on this might organ but cannot find it to use as a reference.

    If I'm not too far wide of the mark, then might this tech, in the UK at least, fall foul of the same law? I think the issues regarding "domestic" wifi are few but what if it affects a public wifi signal or even mobiles?

    1. Nifty Silver badge

      Re: Wasn't there a court case once about this kind of tech?

      That would make crystal radio sets illegal then.

      As a kid I had one - shaped like a toy rocket - picked up Radio Luxembourg perfectly, no batteries required.

      1. RubberJohnny

        Re: Wasn't there a court case once about this kind of tech?

        In early radio much receiving gear was home made and a favourite kids project was to wrap wire round a pickle jar to build a long wave receiver that didn't need power. It could only drive audio through an earpiece though, and loudspeaker would need a powered amplifier circuit.

        I think just about all the stories about people harvesting useful power from RF belong in the urban myth category.

        http://www.telegraph.co.uk/technology/3336114/Over-to-you-Mythical-electricity.html

    2. Anonymous Coward
      Anonymous Coward

      Re: Wasn't there a court case once about this kind of tech?

      Sounds like variants on an (sub)urban myth. Anyway, it's been covered by the MythBusters. Any amount of power you could draw from being ambient radio towers or power lines will be limited by the distance and the impractical amounts of wire you'd need to leech enough energy to power a watch As Adam Savage put it, "You might as well just go get a battery."

      That said, there can be situations where batteries would be impractical, such as very remote or embedded (in the literal sense) applications.

  11. This post has been deleted by its author

  12. leeCh
    Black Helicopters

    Speaking of Tesla

    I vaguely remember something from the '80s about Texas Instruments fabbing the circuit of a Tesla coil onto a chip.

    The thing ended working like a broadband RF receiver and could pull a little power from radio waves.

    No idea what happened to it ... (looking over my shoulder at the Union Carbide man)

    1. Nifty Silver badge

      Re: Speaking of Tesla

      Now for the equivalent to perpetual motion phone charger

      http://techcrunch.com/2015/05/04/nikola-labs-launches-iphone-6-case-which-harvests-electricity-from-the-air/

  13. Anonymous Coward
    Anonymous Coward

    I wonder if it would also be possible to use a tiny PV cell. Assuming it's embedded in paint then a small amount of light will penetrate into the paint possibly enough to power the device - it can't require very much power after all. In the future I could imagine devices that are powered by decomposing random organic molecules that land on them although that might not work so well if they are embedded in paint!

    1. Richard 12 Silver badge

      Don't touch the walls

      They'll eat you.

  14. Alan J. Wylie

    Smartdust / Localizers

    Vernor Vinge - A Deepness in the Sky (1999)

    https://en.wikipedia.org/wiki/A_Deepness_in_the_Sky#Localizers

  15. cortland

    HT wires in back of the house? Light up

    http://www.richardbox.com/field.htm

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