I do a lot of Atomic Force Microscopy (AFM) for my graduate research. AFM uses a very, very small stick to determine the topography of a sample. Think of a topographic map of the mountains, but the scale bar is on the order of a hundred nanometers, rather than a few miles.

Because AFM can detect picometer-scale changes in topography, it’s important to have a flat, clean surface to put your sample material on. I’m talking… as close to atomically flat as we can get.

Luckily, nature makes a really cool substance that does this: mica! You can think of mica as like a stack of slightly-sticky paper. When you peel off the top sheet of paper, you’re left with a pristine surface. Now let’s shrink that down so that the sheet of paper is only a couple nanometers tall and made of aluminum and silicon oxide. Peeling mica nicely by hand presents a challenge – how do you get a grip on something that small?


Here I am holding a piece of mica that’s glued to a round magnet. I’ve just pressed a piece of regular tape to the mica surface.

Pressing a piece of scotch tape against the mica surface and then ripping it off can get you that perfect surface, as a couple layers of mica come off with the tape. This is similar to how graphene was first made – much like mica, graphite has a sheet-like structure that can be peeled apart. In fact, for some AFM samples, graphite is a really great substrate.

When I rip the tape off, I’m left with that shiny circle stuck to the tape – that’s a few layers of mica!

That’s the explanation for my blog header: Scotch tape is an indispensable research tool for me! Plus, I really enjoy putting in fancy purchase orders with thousands of dollars of highly specialized AFM equipment… and ten dollars of scotch tape tagged on at the end.

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