The Sharpest Object Ever Made

ultracool writes "Forget the phrase 'sharp as a tack.' Now, thanks to new University of Alberta research, the popular expression might become, 'sharp as a single atom tip formed by chemically assisted spatially controlled field evaporation.' Maybe it doesn't roll off the tongue as easily, but considering the researchers have created the sharpest object ever made, it would be accurate."

Ancient tools/weapons were close

[SatanClauz]

I remember watching a documentary on Discovery or History about the technique of chipping the edges on weapons and tools created molecule sharp blades.

they didn't need all that research and science, just a couple rocks! ;)

Re:I bet

[surdsforme]

from the not-as-sharp-as-my-wit dept.

Scanning Tunneling Electron Microscope

[florescent_beige]

The STM [nobelprize.org] uses a stylus with a single-atom tip and is about a decade old. IIRC it's a carbon atom.

Re:Get dull?

[RobertNotBob]

from TFA, they are planning on using it for an electron emitter in an electron microscope.

In THAT application, the small size of the point is of great advantace without ever physically touching anything.

Re:Aleut harpooner

[Elvis Parsley]

Um...we (that is, humanity) have been making blades like that for millenia. The knives Raven uses in Snowcrash are simply flaked stone tools, a technology which appeared in the Upper Paleolithic. Their major drawback is that they lose their edge quickly when used, but they're nigh-trivial to make if you've got a lump of obsidian or other cryptocrystaline material. Eye surgeons were starting to use stone blades a few decades ago, though their use has been superceded by lasers.

Re:Aleut harpooner

[milamber3]

Actually, if you bothered to think before replying you would have realized that science has not only caught up but has also surpassed the book since an ATOM is smaller than a MOLECULE.

Re:Get dull?

[Random Destruction]

Hard to break off? Put any weight on it and it would just deform. Its a single atom man. A tomato would destroy it.

Re:Still not as sharp as...

[KDR_11k]

or the fact that the three moderation categories don't add to 100%.

You are aware that that list only shows the three mods with the most percentage?

Not really

[Moraelin]

I'll assume that they'll (eventually) going to make the tip or edge or whatever out of some cristalline metal. In which case, not really.

Let's first define "sharp". No object in the world is a perfect edge ending in a clean zero-width edge. All knives, pins, etc, have a tip that, under a powerful enough microscope looks "blunt". What you'd see would be something like a pretty rounded "tip". What makes it "sharp" is that it's a very small surface.

In other words, imagine two cones, both ending up in a bit of a section of a sphere. Except one is a 0.01 inch radius and the other is a 1 inch radius. What makes the first one sharp and the other one blunt? Pressure. Pressure equals force divided by surface. The surface rises with the square of that radius. So the first one needs 10,000 times less force to produce the same pressure. You can create enough pressure with your thumb to push a tack's small tip through wood, but you'd need an industrial press if you wanted to push a 1 inch steel ball into wood.

In other words what makes something sharp is simply having a small enough tip. You need the same pressure to break through a given material. Having a smaller tip just means you can reach that pressure with less force. At some point you need very little force, and at that point we consider the object to be "very sharp".

How does that help us here? Let's say you had such a pyramid, and let's say you managed to break off the atom at the tip. So now you have a "blunt" tip that's made of a 2x2 atom square. That's still _incredibly_ sharp. It's million times smaller than the tip of a tack or pin, hence it would need accordingly less force to push through the material of your choice.

In other words, forget about breaking off an atom. You'd coukd lose _thousands_ of layers from that tip and still count as sharp.

Re:Scanning Tunneling Electron Microscope

[Jandar0]

Actually the Scanning Tunneling Microscope does not demand a single-atom tip (in the sense considered here). Rather, a reasonably sharp apex will have one atom which is slightly closer to the surface than its neighbors from which most of the electron tunneling takes place. A tip with a radius of curvature less than, say, 100 nanometers is generally sufficient for most STM usage. Problems can arise when the tip has multiple protrusions which are a roughly equal distance from the surface, especially when scanning larger surface features such as carbon nanotubes (as compared to an atomically flat surface).

That said, better tips mean better images, especially with larger surface features, and also lower field emission voltages, which means applications in electron microscopy and even flat-panel display technology.

That said, I've make single-atom tips (of the sort discussed in this article) in the lab on a regular basis over the past several years with an ion sputtering-based process, a technique that is not limited to tungsten (tungsten is hard, but oxidizes, meaning the tip will not withstand removal from an ultra-high vacuum environment). This is a very interesting technique, but claiming it to be the sharpest object ever made is certainly overstating the achievement.