Playing in a Nanoscale Playground: Atomic Force Microscopy (AFM)

July 7, 2017

Among all the research I have done up to now, I had the most fun while pushing the limits of atomic force microscopy (AFM aka SFM – scanning force microscopy). I have been ever since fascinated by being able to generate images of smallest surfaces imaginable, sense forces between the smallest dust particles, the ability to manipulate things with the precision of several tens of molecules and reflecting the power of software to the physical world in nearly atomic scale. I wanted to pay my tribute to this magic tool by writing shortly about it.

For you who has no experience with an AFM device, it is not really a “microscope” in its classical meaning. It does not use light and lenses to “see” things. It rather “feels” things, very small things indeed, things that are more than 1000 times smaller than the thickness of a single hair. What do I mean by “feeling”? Imagine you have a small thorn in your skin that you cannot spot with your naked eye. You then either use a magnifying glass (classical microscope principle, magnification) or “feel” it with your finger (AFM principle, feeling). Roughly speaking, if your finger’s tip were so small that it is only several nanometers in radius, you could feel things that are only nanometers in size. The “tip” used in AFM is therefore very small and it is attached to a highly force sensitive cantilever (spring).

Exactly as your brain can make a picture of your keyboard just by scanning it through with your finger even if your eyes are closed, the AFM tip scans through a much smaller surface and the collected signal is used to generate an image by help of a computer. There are hundreds of dedicated websites and books about AFM, so I will not go deeper into the principles. Park Systems, for example, has a very good Youtube channel dedicated to AFM. Or the animation below made by CNRS Universite Paris-Sud shows the basics of AFM pretty well:

AFM is used routinely in material, polymer and life sciences as well as in solid-state and semiconductor research. Its most common use is generating surface images in nanometer resolution but it offers many other major functions to researchers: measuring forces between small particles, nanomechanics, electrical measurements, nanoprintingnanolithography and many more. There is no way we can include all applications in one paragraph but AFM is currently one of the most common and affordable toys if you want to play in a nanoscale playground. I will write more about its applications and the current status of the technology in future blogs.

Dr. Cagri Üzüm

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