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I am reading up on hyperbolic metamaterials and investigating processes like sputtering and electron deposition to create substrates only nanometers thick. For reference, see this paper by Lu et al from 2013: http://www.nature.com/nnano/journal/v9/n1/abs/nnano.2013.276.html. My question may be somewhat naive, but once they have created the material, how do they actually know where it is and how do they maneuver it to complete their experiment? The structures may only have dimensions of up to 100 nanometers, and this seems far too small for a pair of tweezers!

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  • $\begingroup$ Take a look at this, sec. 3 (manipulation) $\endgroup$
    – valerio
    Commented Oct 22, 2016 at 8:24

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Although the exact methods can vary form experiment to experiment the solutions I'm familiar with tend to rely on probabilistic methods.

For example, let's say you figured out how to create nanodots and now you want to examine them under a scanning tunneling microscope for whatever reason. Generally what you would do is create a large amount of nanodots (not just one), get them into a solution, purify them to get rid of most contaminants, then get them on a substrate. If the concentration is large enough it doesn't matter where you start looking on the substarte sooner or later you bump into one of them (the higher the concentration the sooner you will find one).

There are some tricks to increase the probability of finding your nanoscale creations. One of this is to grow them at specific points on a substrate and make sure your creations are sticking to that point. For example this article describes a method to measure the conductivity of single walled carbon nanotubes. They first put a cobalt thin film catalyst onto the substrate where they want the nanotubes to grow. Then, after goring the tubes they deposit electrodes across them. The way this is done practically is to put a large amount of catalyst pads on a surface then right after the growing process depositing wires next to each an every one of the catalyst pads in a predetermined pattern. At this point you don't know and don't really care where the nanotubes are exactly, you just have to know where they probably going to end up. If you have enough catalyst pads ad wires at the right distance form each and every one of them, then some of the wires are bound to connect to one and exactly one of the nanotubes. Now it's just a question of scanning trough the substrate to find one, but since you created the substrate, you know where to look, and you can even deposit markers on it to help you navigate it like a map.

You can also imagine a variation of this, where you grow your nano-structures in a test tube, then put sticky pads on a substrate that your nano-structures like to stick to. Submerge the substrate into a solution of your nanocreations for a while and when you pull it out one or two of them are bound to stick to each of those pads -- no tweezers required. A great candidate for such a glue is DNA since you can code what it sticks to. (You can read more about his here.)

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