# How do engineers work with extremely small objects?

Please excuse me if my question is not well-worded. My background is pure mathematics and I am not familiar with engineering, but sometimes I feel fascinated by the things engineers have achieved.

Anyway, when I read about neuroscience or nano-engineering, I read things like engineers have been able to arrange atoms on an extremely small metal (like the IBM movie) or neuroscientists can measure voltage changes of an ion-channel inside the membrane which is extremely small.

When I was a child, I learned that levers enable us to move extremely heavy objects but we were never told how engineers work with extremely small objects. For example, how is it possible for neuroscientists to insert an electrode under the membrane of a single neuron to measure voltage changes? Or how is it possible for scientists at IBM to arrange atoms in an IBM shape? Or if I want to build a robotic arm that it can move with a precision under 1mm, how can that be done?

I know how microscopes and scanners work, I don't understand how moving things in very small regions work. In short, what I am looking for is a short list of methods or tools that engineers use to tackle engineering challenges at extremely small scales.

• I think it was an adaptation of a scanning election microscope. May 27 '20 at 1:08
• The modern push began in 1960 after Feynmans classic lecture there's plenty of room at the bottom. But Feynman himself wasn't all that aware of how small we could go even then. One of his challenges could already be accomplished with off the shelf equipment, and a second only took a few weeks to pull off. May 27 '20 at 23:25

You wrote that you know how microscopes work. Atomic Force Microscopes (AFM) can manipulate things. Tunneling microscopes can "see" atom level.

Imagine a sharp needle with only one atom at its pointy part (if you cut a tungsten filament with scissors, you probably got one, so it's not impossible to make one). If you move a needle like that over a surface (like a blind man would move his fingers over Braille writing), and follow its shape, you can explore it. Putting voltage over a piezo chrystal slightly changes its shape. This can be used to position that needle very precisely in tiny distances. You can fix the needle to a springy lever, and using a laser light and detectors you can detect very small changes in that lever's position. This way by drawing your needle over the surface gently you can explore its shape, and pressing it a bit in you can alter it.

AFMs and Tunneling microscopes are similar, but the later uses the tunneling effect in quantum theory, and it's possible to find out the electron cloud around individual atoms.

• Thank you. I still can't understand how you can build a sharp needle with only one atom at its pointy end? You explained that I can do that by cutting a tungsten filament. But shouldn't that filament already be an ultra fine material? So, it seems that something is missing and we have a chicken or the egg dilemma here. May 29 '20 at 11:02