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Power Science Technology

Tiny ARM-Based Sensor System Makes Battery Replacement Obsolete 96

An anonymous reader writes "University of Michigan researchers have crammed an ARM Cortex microcontroller, a thin-film battery, and a solar cell into a package that is only 9 cubic millimeters in volume. The system is able to run perpetually by periodically recharging the on-board battery with a solar cell (neglecting physical wear-out of the system)."
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Tiny ARM-Based Sensor System Makes Battery Replacement Obsolete

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  • by Shadow of Eternity ( 795165 ) on Friday February 12, 2010 @06:49PM (#31121896)

    I think this is the first time I've ever actually seen a legitimate claim of a device drawing less power than it can charge from ambient sources.

    • by Anonymous Coward on Friday February 12, 2010 @06:55PM (#31121984)

      Never had one of those nifty solar calculators?

    • by nicknamenotavailable ( 1730990 ) on Friday February 12, 2010 @07:07PM (#31122132)

      Batteries have a limiting lifespan.

      If they used a capacitor instead, this device would run virtually forever.

      Place this in a solid glass marble, and it might last forever too.

      • I was wondering the same thing. Can't they make a Supercap small enough to put in this? That would eliminate its single biggest weakness.
      • Solar cells also have a limited lifespan. I'm skeptical that the battery is necessarily the limiting factor.

      • Re: (Score:3, Insightful)

        by vertinox ( 846076 )

        Batteries have a limiting lifespan.

        If they used a capacitor instead, this device would run virtually forever.

        Place this in a solid glass marble, and it might last forever too.

        Note:

        When something is sold as "infinite" or "forever" it doesn't actually have to meet its claims.

        It just has to last longer than the person who paid for it.

        The person who inherits its will think its quaint and let their kids break it.

        • Re: (Score:2, Insightful)

          by Anonymous Coward

          > It just has to last longer than the person who paid for it.

          Wrong! It just has to last longer than the person who sold it ;-)

    • looks like this could take Smart Dust closer to viability http://en.wikipedia.org/wiki/Smart_dust [wikipedia.org]
    • Why on earth would they want to attach an ARM to a sensor? 8 bit micro is more than enough to service a sensor. And will take a fraction of a power that the ARM requires.

      • Re: (Score:3, Insightful)

        by kju ( 327 ) *

        Why on earth would they want to attach an ARM to a sensor

        Because it can be done.

        What do you gain by lower power requirements? You probably didn't RTFA, but at least take a look a the picture in full resolution (http://ns.umich.edu/Releases/2010/Feb10/MINISENSOR.JPG). The solar panels are already included in that tiny device, and it powers the ARM already. Decent processing power is good, think encrypting the - probably sensitive - data in the sensor.

      • Because this "ARM" is barely an ARM at all, and is simpler than even the original ARM1 and ARM2, and can't run ARM code, and is aimed at the 8 and 16-bit microcontroller market?

      • by sznupi ( 719324 )

        The real question is - when will Intel announce that their Atom will be soon similarly capable of running at low power levels.

    • I was expecting something more like these [ieee.org], which use radioisotopes and ambient vibrations to generate power respectively.
      • by toastar ( 573882 )

        I was expecting something more like these [ieee.org], which use radioisotopes and ambient vibrations to generate power respectively.

        Finally! A device that will actually get better performance when you Kick It!

  • by nurb432 ( 527695 ) on Friday February 12, 2010 @06:49PM (#31121900) Homepage Journal

    And lack of sunlight....

  • by Anonymous Coward on Friday February 12, 2010 @06:50PM (#31121910)

    If we ignore wear-out, battery replacement is obsolete.

    Uh hum.

    • by arielCo ( 995647 ) on Friday February 12, 2010 @07:12PM (#31122204)

      “Our system can run nearly perpetually if periodically exposed to reasonable lighting conditions, even indoors [...] Its only limiting factor is battery wear-out, but the battery would last many years.”

      By the time the battery wears out, you have gotten a few years of data; then you toss away the tiny thing.

      • by Gerzel ( 240421 ) *

        Yeah but many uses require functioning w/o maintenance for more than just a few years where battery life does become important.

      • Oh God (Score:5, Funny)

        by TopSpin ( 753 ) * on Friday February 12, 2010 @07:52PM (#31122728) Journal

        then you toss away the tiny thing

        Right. So it goes from some interior space where light is good, but not daylight, to some landfill where it is exposed to the Sun. What was 'worn out' now has an abundance of photons and reactivates. It's not happy about ending up in Fresh Kills with the other 500,000 discarded and reanimated sensors. Eventually they unify into a vast, angry landfill monster and wade across the water to crush New York.

        Please do not contribute to garbage self-awareness.

      • I wonder why they couldn't integrate a supercapacitor rather than a battery -- while their capacity is less, they charge nearly instantaneously and have no memory. Then the lifetime would be even longer, perhaps over a decade if no extreme temperature variations were present. The things are designed for short bursts between sleeps, so a supercap could be suitable.

        • by Kizeh ( 71312 )

          Check out the titanium manganese batteries Citizen uses in their eco-drive. They're supposed to last for decades while being charged and discharged.

    • Apple seems to have embraced this strategy with all their recent devices.

  • Bogus logic (Score:3, Insightful)

    by DavidR1991 ( 1047748 ) on Friday February 12, 2010 @06:51PM (#31121928) Homepage

    "Neglecting physical wear" when it comes to batteries is like saying "This car runs forever (neglecting its need for fuel)"

    I didn't think the ability to charge batteries was ever the problem - it's the fact that the innards of the batteries themselves slowly degrade and eventually become unusable

    • It's not really that slow, either. The claim that the batteries will run perpetually is RIDICULOUS. Slashdot occasionally makes me feel ill.
      • It's not really that slow, either. The claim that the batteries will run perpetually is RIDICULOUS. Slashdot occasionally makes me feel ill.

        Occasionally? You have a stronger stomach than I, it makes me want to vomit most of the time.

        • Re: (Score:3, Funny)

          by Rei ( 128717 )

          > It's not really that slow, either. The claim that the batteries will run perpetually is RIDICULOUS. Slashdot occasionally makes me feel ill.

          Occasionally? You have a stronger stomach than I, it makes me want to vomit most of the time.

          Vomit? It makes me want to cut out my spleen with a dinner fork and stomp on it with high heels!

          By the way -- did you know that people who use lots of hyperbole are worse than Hitler?

          • By the way -- did you know that people who use lots of hyperbole are worse than Hitler?

            Hitler? They're worse than if Hitler and Stalin had a baby, and it was blessed by the Anti-Christ (hmm, anti-Christened?), and it grew up to enslave humanity and make us work menial jobs 50 hours a week and then when we got home the only thing on TV was Fox News!
          • people who use lots of hyperbole are worse than Hitler.

            Overuse of hyperbole is a leading cause of slow painful death.

    • Re:Bogus logic (Score:5, Informative)

      by rockNme2349 ( 1414329 ) on Friday February 12, 2010 @07:39PM (#31122564)

      "Neglecting physical wear" when it comes to batteries is like saying "This car runs forever (neglecting its need for fuel)"

      No, neglecting physical wear is like saying this car will constantly fuel itself, so it can run forever, until the engine or other components physically break down hundreds of thousands of miles later.

    • by astar ( 203020 )

      maybe, but what came to mind is a belief that a solar cell has a lifespan of say 20 years. Googling a bit, it seems UV constantly degrades solar cells. Here is someone working on this. http://www.treehugger.com/files/2008/02/solar-cell-coating.php [treehugger.com]

      I can image some greeny reading the headline and thinking he is going to power his house forever on these.

    • by Firehed ( 942385 )

      That's more akin to the gas tank no longer functioning, not its emptiness. By the sounds of it, this car analogy is smart enough to drive itself to the nearest gas station and fill up for you (on someone else's dime, no less) when it's running low on gas.

  • Dust computing (Score:1, Interesting)

    by robi5 ( 1261542 )
    We get nearer ambient computing where maybe we buy granular stuff by the pound and spread it on things.
  • Cool! (Score:1, Insightful)

    by chickenrob ( 696532 )
    Just like my 1987 calculator? Am I missing something here?
  • by Kenja ( 541830 ) on Friday February 12, 2010 @07:07PM (#31122136)
    The Day Star burns us, we dont care that it can recharge our toys. We're still not going outside.
  • This device is a charging device for low power devices. Someone doesn't seem to have read the article. There are plenty of ordinary devices that can be powered by solar panels. I got a neat little one for Christmas. It charges my phone and iPod. The novelty in this device is that it is so good at running small devices that can be left alone for a long time - not that it will make your phone or flashlight into sealed devices.

  • I saw some vibration-powered wearable devices that made similar claims, as long as you moved as often as your average sedentary person across an average week. Doesn't seem particularly new...
    • While we're on the subject of timepieces powered by their environment, may I present the Atmos Clock [wikipedia.org], which is powered solely by the small changes in temperature and atmospheric pressure that occur naturally every day. It was designed by Jean-Léon Reutter in 1928, and over half a million have been sold to date.

    • My dad has watch built on that premise. It doesn't work well for him, because it's always running a bit fast. Why? He's a barber, so it gets 20x the motion that "your average sedentary person" would give it.

      I guess I shouldn't be surprised that they didn't build some sort of charging/current regulator into it. It is a normal-sized watch after all. Still, the fact that they either didn't care it ran fast, or didn't test it at full charge 8+ hours at a time is a bit dodgy to me.
  • by macemoneta ( 154740 ) on Friday February 12, 2010 @07:38PM (#31122544) Homepage

    For something that small, a capacitor would be better than a battery. Better utilization of short peak light to stored energy. Short term high current draw (e.g. for a transmitter). Much (much) longer life than a rechargeable battery. It could run for hundreds of years.

    • There is a commercial product already with this sort of technology. The Citizen Eco-Drive watch uses a supercapacitor that supposedly will run the watch for 6 months without exposure to light, and retains 80% of that storage capacity after 20 years of use.

  • Nowhere in TFA does it mention exactly what this "sensor" actually SENSES. It apparently wakes from sleep mode occasionally to "make measurements", but no specifics are given.

    Consisting of only a CPU, battery, and solar cell, the only things it COULD actually measure would be ambient light levels or the battery charge state.

    Without the ability to actually measure something external to itself, and just as importantly, output the results of those measurements somehow, this device seems like it's only function

    • Re: (Score:3, Funny)

      by karnal ( 22275 )

      It probably just sits there and senses how much juice is left in the battery, and then lets the solar cell charge it.

      • It probably just sits there and senses how much juice is left in the battery, and then lets the solar cell charge it.

        And I assume that it is just as optimistic as every other battery sensor on this planet: A report of "50% charge remaining" really means "Shutdown in less than one minute."

  • Very cool device, but battery life won't be "infinite" or anything close. The article doesn't specify battery chemistry, but it does say that the battery will last "a few years"... and I don't imagine they're replaceable. This is not to knock - this is a great achievement! Mainstream micro-controller that can power itself in a hassle-free manner? Awesome =]
  • The system is able to run perpetually by periodically recharging the on-board battery with a solar cell (neglecting physical wear-out of the system)."

          Yeah that's cute. Able to run perpetually neglecting physical wear out of the system. And I have invented a perpetual motion machine, neglecting friction, air resistance and gravity.

  • ... how does this thing interact (communicate/measure/control) with the outside world, and what are the power demands of that?

    Just having a plain uC alone doesn't do much. You'll also want some external circuitry to acutally make measurements (even if it's just some filter for a built-in ADC), communicate with the outside world (hm, could this thing use something similar to RFID when communicating?) and/or change things about the outside world (with a DAC or some output pins).

  • I think we may be missing the really amazing part of this; that penny is huge!

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