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Power Technology

Motor Made From Liquid Film 241

Posted by CmdrTaco
from the makes-my-water-spin dept.
KentuckyFC writes "Last year, a group of Iranian physicists made a puzzling discovery. They placed a thin film of water in a small cell and bathed it in two perpendicular electric fields. To their surprise this caused the water to rotate. They called their device a liquid film motor and posted on the web a cool set of movies showing the phenomenon. The puzzle is this: the electric fields are static, so what's driving the motor? Now another group of physicists has the answer: a complex interaction between the electric field, the cell container and the liquid causes water to move along the cell wall. Crucially, it moves in opposite directions on opposite sides of the cell and so sets up a circular flow. The phenomenon works only when friction and surface tension are significant forces so the effect is entirely scale dependent. That's probably why we haven't seen it before and also why it could have important implications for microfluidic devices such as lab-on-a-chip."
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Motor Made From Liquid Film

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  • at least something (Score:3, Interesting)

    by roman_mir (125474) on Thursday February 26, 2009 @11:03AM (#26998105) Homepage Journal

    Nice to see at least something coming out of that region of the world nowadays that has no relation to terrorists or nukes.

    As for the actual story: this can be used to build the world's smallest washing machine.

    • by N1AK (864906) on Thursday February 26, 2009 @11:39AM (#26998637) Homepage

      Nice to see at least something coming out of that region of the world nowadays that has no relation to terrorists or nukes.

      It is nice to see something that isn't negative about Iran getting into western news. Iran has a population around that of the United Kingdom so I have no doubt that numerous beneficial scientific discoveries are made there.

      • by Jurily (900488)

        Iran has a population around that of the United Kingdom so I have no doubt that numerous beneficial scientific discoveries are made there.

        How is scientific discovery and population related?

        http://www.nationmaster.com/encyclopedia/List-of-famous-Hungarians#Math_and_Sciences [nationmaster.com]

        • The link does not really fit into the relation of scientific discovery and population as the people on the list are only required to have had a Grandparent from Hungary. Not having to have been born in, or lived in, hungary, kind of removed the relation to population.
          • by Jurily (900488)

            Not having to have been born in, or lived in, hungary, kind of removed the relation to population.

            True, but consider the fact that living there wasn't exactly a smooth ride in the last 100 years. Read up on Trianon [wikipedia.org], Rákosi [wikipedia.org], and 1956 [wikipedia.org], and you'll get the idea.

            Basically, bright people always had some really good reasons to leave the country.

    • Re: (Score:3, Funny)

      by ptelligence (685287)
      Are you kidding me? This definitely looks like it has WMD potential.
    • by msormune (808119)
      Wow, you're right! The story does not mention USA at all
    • Re: (Score:2, Funny)

      by Hal_Porter (817932)

      Nice to see at least something coming out of that region of the world nowadays that has no relation to terrorists or nukes.

      Nonsense. This is clearly a prototype terrorist water tentacle.

  • Not Often... (Score:2, Insightful)

    Here's an interesting effect discovered by a group of Iranian physicists at Sharif University of Technology in Tehran, Iran (it's not often we hear from these guys).

    Aside from the actual scientific content of the article, I found this lead quote to be interesting with many subtle and not so subtle implications. Discuss.

    • by dkleinsc (563838) on Thursday February 26, 2009 @12:07PM (#26998977) Homepage

      Well, without the scientific content of the article, I thought it was really a dastardly plot to DDOS Iran with the Slashdot Effect, especially with the inclusion of video.

    • Re: (Score:2, Offtopic)

      by TubeSteak (669689)

      I found this lead quote to be interesting with many subtle and not so subtle implications

      Westerners assume that the Middle East is a 14th Century backwater and cannot contribute to the world in meaningful ways.
      Ditto for religious fundamentalists and non-capitalists.
      Where would they ever get such ideas?
      /News at 11

      • I don't care what religious fundamentalists have to offer. I don't want it.

        Their ability to make contribute to modern society doesn't undo the harm they cause.

        • Their ability to make contribute to modern society doesn't undo the harm they cause.

          Regardless of who is actually "right", they feel the same way about us.

          • by DM9290 (797337)

            Regardless of who is actually "right", they feel the same way about us.

            Scripture makes it very clear how you are supposed to feel about infidels and heretics. But just because you base your beliefs on scripture that doesn't mean everyone who disagree with you is being equally irrational and nonobjective.

            • Scripture makes it very clear how you are supposed to feel about infidels and heretics

              Depends on which scripture. I've always 'enjoyed' a good philosophical debate when the person opposing my religion has no clue what my religion even is.

        • I don't care what religious fundamentalists have to offer. I don't want it. Their ability to make contribute to modern society doesn't undo the harm they cause.

          I'd offer to lend you a hand so we could build a wall between the two, but you wouldn't take it, and I wouldn't accept it. In the end, I think we can be unhappy in shouting at each other from across the yard.

          That'll show em.

      • by gtall (79522)

        Iran is in S. Asia, not the Middle East. And if they didn't want to get labeled as a bunch of religious loonies, they could repeal their stoning laws, stop fomenting anti-semitic hatred, start respecting the rights of women, etc.

        "What goes around, come around" is true for the Western Nations as well as the Eastern. Iran will rue the day they decided they needed to attempt a take over of the direction of Islam. The Sunnis will never forgive them for it.

        Gerry

        • by e2d2 (115622)

          It depends on the definition one uses and it certainly isn't clearly defined. The Middle East is generally thought to extend well into South Asia and also into Africa. That comes from the origin of the phrase (British labels: near east, middle east, far east). BUT The US State Dept defines Iran as South Asia and modern western usage usually excludes Iran.

          Iran baffles me. Their population doesn't seem to be "in step" with their leadership. Everything I see coming from inside Iran contrasts the typical world-

        • by qbzzt (11136)

          And if they didn't want to get labeled as a bunch of religious loonies, they could repeal their stoning laws, stop fomenting anti-semitic hatred, start respecting the rights of women, etc.

          Good idea, but all the people who suggested this in Iran got stoned (and I don't mean the hashish kind). Now the sane Iranians just sit quietly and wait for things to get better.

          They could use a few George Washington types, but the popular support isn't really there.

      • by StikyPad (445176)

        To be fair, we assume the same thing about West Virginia.

      • People in the Middle East often assume that Hollywood gives a good representation of US culture, and that the US is a completely irreligious country.

        The fact is that parts the Middle East are socially 14th century, with a thin overlay of technology purchased from other places. But as with most 3rd world countries, there are westernized islands that can be every bit as high tech as anything we have.

  • There is friction, so this requires energy - where does it come from ? My guess is that the electric field is actually lowered, so they are converting E field energy to rotational energy, but that the losses are small enough to make this quasi-static.

    Now off to RTFA.

    • Re: (Score:3, Funny)

      by UbuntuLinux (1242150)
      The energy comes directly from the physicist's beards. We all know that Iranians have beards, this is what is powering this device. Unfortunately in nations where beards are less prevalent, this effect will be less pronounced, or maybe not evident at all.
    • by mbone (558574) on Thursday February 26, 2009 @11:24AM (#26998377)

      OK, having read the "real" article [arxiv.org], the best response is that this may explain the observed effects. The major differences

      - the depth of the film is an important parameter, but that isn't known for the original experiments, so they can't compare results to theory in a detailed fashion.

      - the theoretical work leads to at most one steady vortex in a container, but the experimental results show both one and two. The two vortex results may, of course, be transient.

      - the theoretical results have flow speeds largest at the outer boundary. The experimental results have it increasing towards the center. This may be explainable by other effects, such as surface tension, but it is a discrepancy.

      And the article says nothing directly about where the energy is coming from, but, reading it, it must be the electric field.

      • by Jesrad (716567)

        That device sounds like a parietal accelerator [mhdprospects.com] wound into a loop. French scientist Jean-Pierre Petit suggested it would make an ideal submarine propulsion method.

        My guess is that the depth of the film has to be small for the flow to remain stable and entrain all the water.

    • by Anonymous Coward on Thursday February 26, 2009 @11:41AM (#26998659)

      From the will of Allah, you insensitive infidel.

    • Right in the summary: bathed it in two perpendicular electric fields
      • A field, by itself, does not provide energy. Only when something moves perpendicular to the field is energy transferred. What with The Fancy Article being all slashdotted, I'm going to guess that the motion is caused by normal brownian motion within the water, and that the electric fields act on the polar nature of the water in a manner similar to a ratchet. In other words, it's easier for the water molecules to move in a certain direction than in another.
        • ... which violates the second law of thermodynamics, last time I heard.

          By the way: What the HELL is "two perpendicular electric fields"? Electric fields applied by two sets of electrodes combine to form their vector sum.

          I'd like to see a MUCH better description of the design. Including especially any VARIATION in the fields.

        • by jc42 (318812)

          A field, by itself, does not provide energy.

          Hmmm ... I've seen a number of comments like that, and I was curious. I'm sitting in a rather strong (gravitational) field that seems to be totally static. Yet I can feel its push, by the pressure my bottom surfaces feel from the chair I'm sitting in, even when I'm not moving. If I hold an object out to the side and release it, it falls to the floor every time. The energy required to produce that motion has to come from somewhere, and the gravitational field s

          • by corsec67 (627446)

            F=ma.

            Force = (mass) * (acceleration).

            If the mass isn't accelerating, there is no force.
            If you are sitting in your chair feeling a "push" from gravity, that isn't a force unless you are falling.

            A force acting on an object gives it energy (or takes it away, if you are slowing the object down).

            In your case of lifting the book, you are giving the book potential energy when you move it away from the earth. Gravity turns that potential energy to kinetic energy when you drop it. The same for your magnets, but rela

  • good for iran (Score:5, Interesting)

    by circletimessquare (444983) <circletimessquare AT gmail DOT com> on Thursday February 26, 2009 @11:28AM (#26998457) Homepage Journal

    the ayatollah has made science a high priority:

    Ali Khamenei has been supportive of scientific progress in Iran. He was among the first Islamic clerics to allow stem cell research and therapeutic cloning.[27] In 2004, Khamenei said that the country's progress is dependent on investment in the field of science and technology. He also said that attaching a high status to scholars and scientists in society would help talents to flourish and science and technology to become domesticated, thus ensuring the country's progress and development.[28]

    http://en.wikipedia.org/wiki/Ali_Khamenei [wikipedia.org]

    he recongizes the truth: iran will be a second rate power unless it leads in the field of science, through which it retains its independence and preeminence. this is why attacking iran's nuclear pursuits is hopeless, since iran attaches so much pride in iranian science and technology exploits. they just launched a satellite too. but all of these advances came from science and technology stolen or borrowed from other countries

    but the history of persian science is a rich one, and there is no reason its future shouldn't be bright as well, if only the ayatollah would also realize that the preeminence of the west in science came only after the enlightenment

    what else happened in the west during the enlightenment? religion was questioned. this is not a mistake or a coincidence: the questioning of religion is inseperable from being a strong scientific thinker. the probing mind of a scientist must be able to question everything, no taboos, in order to do the best science one can. you train young minds to question everything, and in this way, you make great scientists

    so dear ayatollah: i celebrate your desire to reassert persia at the forefront of science and technology. so why don't you further this great goal along by relaxing the stifling theocratic censorship of your society, ensuring bright young minds are trained to their utmost? in order to ensure that persian civilization flowers again, let little discoveries like this thin film motor not by isolated gems, but instead be the beginning of a rich tapestry of persian thought

    do that, by relaxing your fundamentalist stranglehold on the mind of the young iranian

    • I almost regret my dashed-off sarcastic comment below when you took the time to write something so much more appropriate and balanced. 5's too low a score for this.
    • Re: (Score:2, Offtopic)

      by Ash Vince (602485)

      He also said that attaching a high status to scholars and scientists in society would help talents to flourish and science and technology to become domesticated, thus ensuring the country's progress and development.[28]

      Now if only we in the west would catch up and do the same.

      I now earn more than my friend doing vital scientific research into the human brain and the effects of ageing. He has a PhD and has just published his first paper. I flunked out of uni while studying a Physics BSc. Go figure.

      The fact is that in our society the main status symbol is how much you earn, yet we pay people like teachers or university lecturers a pittance compared to the people who cause global financial disasters with an excess of greed.

    • Re:good for iran (Score:4, Interesting)

      by jambox (1015589) on Thursday February 26, 2009 @12:06PM (#26998963)
      Its true that the enlightenment was crucial in putting western science where it is today. OTOH the situation the middle east faces today is very different from Europe in the dark ages, mainly because there is already a more advanced (no offense but the amount of research done and stuff actually invented in the west dwarfs the middle east and asia) culture outside their borders. Iranians would love to recapture the scientific power they held in times gone by but presumably are terrified their culture will be destroyed by western influence, with orthodox religion being their only defence. So It's not just as simple as calling up the Ayatollah and shouting "Hey! Do the enlightenment already!".
      • well said (Score:5, Insightful)

        by circletimessquare (444983) <circletimessquare AT gmail DOT com> on Thursday February 26, 2009 @01:10PM (#26999895) Homepage Journal

        pride has an upside and a downside, and one downside of pride is you would rather retain your identity even though it also means being in a weaker position

        the muslim world sees elements of the west that alternately repel and attract. unfortunately, some of those elements of the west aren't things unique to the west, but are actually more accurately described as elements of simple humanity. such that a lot of the fighting of westernization that goes on in the name of pride in the middle east are actually wars against humanization

        for example: women's rights. when you fight that, because it's "western", you are actually retarding the development of your own societies on a human level. if the west never existed, one can imagine the fight for women's rights continuing in the middle east, because such a fight does not depend upon the west as some sort of example, but is a fight valid within itself in islamic societies. that is, the fight for women's rights is not some sort of decadent western influence betraying traditional identity, but is instead a humanist, organic struggle native to the middle east. but humanist struggles always entail a bit of the strange and unknown, to breakway from traditional ways, and so it is easy to confuse two sources of conflict: westernization and humanization. and so, in the name of fighting the west, muslim societies subjugate their own women, and wind up hobbling the development of half their societies. for doing that, the middle east can never hope to be as powerful and as influential as the west, with half their population treated like cattle

        there's plenty of things the islamic world says it hates about the west that are shared by the west and, for example, the far east. such that to describe these concepts they say threatens the middle east as some sort of western thing is false: they are human concepts. the islamic world, in the name of retaining an identity distinct from the west, are embracing agendas that are not really anti-western, but are actually anti-human

        • by jambox (1015589)
          Actually a lot of people are starting to think that, while women's rights should of course be equal to men's, having both parents out to work leads to nothing like twice the productivity as the traditional worker/homemaker model still enjoyed in most of the rest of the world. Obama talks about this at some length in his second book and I tend to agree that it's possibly a side-effect of rising prices and greater investment pressure on real-estate. So in effect a growing upper-middle class sh1ts on everyone
          • i see your point a: the value of the tradional female homemaker

            and i see your point b,c,d: inflation, real estate, the upper middle class sucks

            how those are all related completely escapes me, and i think it completely escapes you too

            make a coherent argument, or say nothing at all

    • by tnk1 (899206)

      Actually, there are many things that happened during the Enlightenment period, but honestly, Western science was much farther along well before that.

      Questioning religion is just that, questioning religion. You don't need to rid yourself of religion to make progress in science. In this day and age, there are billions of people who follow some sort of religion and science has done quite well. The reason for that is simple. Religions themselves do not inhibit science or thought, rather the habits of author

      • yes religion the more nebulous concept doesn't stand against science. but religion, ie organized religion, which i should have said explicitly, but was referring to in shorthand, does stand in the way of science

        simply because organized religion is, by definition, dogmatic. and whereever organized religion dominates society, its dogmatic approach bleeds into legal and social attitudes and automatically squelches and reduces the free thinking that is required for science to flourish

        and yes, any dogmatic syste

    • by Venik (915777)
      Enlightenment may be too broad of a concept. Generally, progress in science occurs when people stop taking their religion too seriously. God is bad for science. Science is a quest for knowledge and knowledge cannot be heretical, unethical, immoral, or illegal. Organized religion in general is the biggest enemy of scientific progress. Best scientific and technological progress is made when we lift restrictions imposed by religion, law and morality.
  • [confused]I thought they were only a cover for nuclear weapons development[/confused]
  • by frankie (91710) on Thursday February 26, 2009 @11:34AM (#26998543) Journal
    It's been about 20 years since I took E&M Physics, but... How exactly would "two perpendicular electric fields" be different from one diagonal electric field equal to the vector sum? Mathematically, you can only describe two things as "perpendicular" if they are reasonably linear and uniform.
    • by gardyloo (512791)

      Exactly. Additionally, I just skimmed their paper, and if the external fields are truly static, then I don't see any way to break the symmetry about the z-axis (their rotational axis). Since all of their little film-cells rotate in the same direction, this says to me that there is an unaccounted-for field which is breaking the symmetry and starting the effect. Alternatively, they could have shown a subtle coupling in which one cell starts its rotation one way, and through interactions with the other cells,

      • by jc42 (318812)

        Since all of their little film-cells rotate in the same direction, this says to me that there is an unaccounted-for field which is breaking the symmetry and starting the effect.

        Huh? In that video that's linked to, the film begins with a visible counter-clockwise rotation, and after a few seconds, it visibly halts. Then it begin again with a clockwise rotation. This seems to be initiated by some motion along the top edge of the cell.

        So what are you seeing that's different from what's running on my screen?

    • Re: (Score:3, Interesting)

      by snoop.daub (1093313)
      The two perpendicular fields are not identical. One of the fields is external, the other was applied as an electrode potential. So one of them is applied in air and gets screened at the interface, the other is applied directly to the cell and is not screened in the same way. I'm not sure what the consequences of this are, but I'm sure the difference is important.
  • by alta (1263) on Thursday February 26, 2009 @11:34AM (#26998549) Homepage Journal

    By posting links to MOVIES hosted in IRAN you have used the /. effect to saturate that entire country's available bandwidth. This is terrorism sponsored by the capitalist west! You have fired the first shot, but I ran WILL retaliate. You knew we had nukes, now we will prove it to the doubters. Kiss your precious Israel goodbye!

    It'll take us a while to get the nukes into launch position though. The servos are these really cool little motors made out of water and electricity. They have to be really small, so we have a whole lot of them working together.

  • Micropropeller? (Score:2, Interesting)

    by tjstork (137384)

    I wonder if you could use this effect to make a sort of a propulsion system for a small submarine. If you don't have a propeller at all, and were just spinning water around, it could be very quiet.

  • Call me when they have a motor made from liquid video...

  • Doesn't Microsoft hold a patent on this?
  • But will it spin other way round in other hemisphere (sorry had to say it).

    In Soviet Russia, water spins electric field !

  • by Markrian (931172) on Thursday February 26, 2009 @12:17PM (#26999135)
    I don't understand. They seem to be setting up two static, plane electric fields at some angle to one another. Surely the resultant field is just another field at a different angle? Say the two fields are E and J , with
    E = ( E , 0 , 0 )
    J = ( 0 , J , 0 )
    Then you've just got the resultant field, E' = E + J , where
    E' = ( E , J , 0 )
    which is just another static, plane electric field. So, given that two fields are really equivalent to one, if you set up just the resultant field in the first place, would this motor effect still occur?
    What am I missing?
  • Glycerin and water? (Score:3, Interesting)

    by gardyloo (512791) on Thursday February 26, 2009 @12:24PM (#26999263)

    I'd love to know how they got stable films, showing thin-film optical interference, of thicknesses on the order of several millimeters (stated a couple of times in the paper). They specifically call it a "suspended liquid film" and say that the z-boundaries are considered "free", so I don't think these films are sitting in a little box with just the top open.

  • This sounds awfully close to electroosmotic flow [wikipedia.org] a phenomenon that has been known about for 200 years. Maybe someone better informed in this field could clarify the difference.
    • by Cassini2 (956052)

      I think you are on the right track. They have built something not all that different from an induction motor. Essentially, there are two different types of electrodes. The first pair is in the solution, and a current is going to be established. Given this is water, the current will be established by lining up positively charged hydrogen sides of the atoms with the negative electrode (the electron source). The negatively charged oxygen side of the water molecule will line up with the positive electrode

  • by n3tcat (664243)
    phenomnomnomnom [omnomnomnom.com]
  • Video mirror here (Score:3, Informative)

    by azav (469988) on Thursday February 26, 2009 @07:53PM (#27006031) Homepage Journal

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