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Science Technology

A Thermometer In A Nanotube 18

Stone Rhino writes: "Yet another marvel has been created in the quest to create minature machines: a thermometer of liquid gallium within a carbon nanotube. The New York Times has an article on this. The thermometer is 10 microns long and measures temperatures from 120-950 degrees farenheit. Of course, the part I find most impractical about it is the fact that you need a scanning electron microscope to read it."
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A Thermometer In A Nanotube

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  • by Anonymous Coward
    But do you want that scanning microscope stuck up in your ass as well?

    Well, okay, but do you want it in there the whole time they take your temperature?
  • you need a scanning electron microscope to read it.

    I can't wait for the day that someone will figure out how to just hook bluetooth up to this thing :)
  • by Hadlock ( 143607 ) on Tuesday February 12, 2002 @02:21AM (#2992719) Homepage Journal
    a better use of this (does this even have a use, other than proof-of-concept yet?) might be to, um, install one of these on nanobots, and have the liquid metal spurt from the end....somehow alerting the operator that the nanobots are about to overheat.

    that's fascinating though, i was under the impression that carbon atoms were pretty small, and a nanotube would only be about 6 atoms across...from what i recall, lithium is pretty far away from carbon on the periodic chart. how does one fit one (or more) lithium atoms inside this tiny tiny tube?
    • by CounterZer0 ( 199086 ) on Tuesday February 12, 2002 @06:24AM (#2993126) Homepage
      A) Lithium isn't very far away, it's element #3 (to Carbon's 6), so it's ultra tiny.
      But that's irrelevant, as this thermometer uses Gallium is #31 (the first element to be predicted before it was discovered), and Gallium is much bigger than carbon. But that's why the carbon is arranged into tubes - multiple atoms across, able to hold gallium atoms.

      What I want to know, is if using the SEM to read the temp changes the temp? All those impinging electrons must raise the kinetic energy of the Gallium atoms at least a little?
      • I was also thinking about the feedback effects of measurement, but from a different angle. Also, my physics & chemistry are admittedly weak:

        Does anybody know if liquid Gallium, or any other suitable replacement, conducts electricity? Then one could measure the current induced by an electric field, or vice versa, to infer the temperature. I think these might provide less 'feedback' than an electron microscope, if the field and current measurement were also nano-localized.

        Or maybe if is there a liquid dielectric of suitable scale, the temperature could somehow be inferred from this (using a wall of several adjacent nanotubes perhaps to create a varying area)?

        Just some speculative questions... Of course, it'd be cool someday to see a nanocomputer.
        • well, IANAC(hemist or Physicist) but I believe liquid mercury can carry current, apparently it was used in thermostats before people realized they didn't want carcinogens in their dwellings
        • Gallium is metallic, and conducts fairly well (resisitvity=14.7 micro-ohm*cm, probably a bit different in the liquid phase).

          The diameter of the tubes, as quoted in the article, is 75nm (that's a lot more than one carbon atom across). The average interatomic spacing of liquid gallium atoms is .26nm, if I did my math right. So the tubes are ~300 gallium atoms across. (BTW, these sound like some exceptionally wide nanotubes.)

          As for changing the temperature of the thermometer by reading it, there is of course some change. But at that scale, thermal conduction is pretty much instantaneous, so you heat up the whole system (gallium, carbon tube, and whatever it's mounted on) at once. The change in temperature of the entire system from the electron beam is presumably negligible.

  • ...asked about carbon nanotube thermometers revealed about their own research: "These go to eleven (microns)."
  • I just wish my mom had one of these, when she wanted to take my rectal temperature.
  • For all the SI oriented people:
    120-950 degrees farenheit
    322-783 Kelvin

    what is wrong with those SI units anyway?
  • When the First transistor [] was made, who would have predicted how we'd be using them now?

    This thermometer probably isn't too useful on its own, but just shows that stuff you can build from 'big' components can also be done in nano scale.

    I wish I was working in nanotech....
    • The inventors of the transistor would have predicted it. The transistor was quite explicitly intended as a replacement for bulky vacuum tubes with inconvenient power requirements, and that's how we are using them.
  • But it's just one more component that could be a very useful thing to have when we start using nanotech and mems on a larger scale.

Nothing succeeds like the appearance of success. -- Christopher Lascl