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Look small to see big: The use of Atomic Force Microscopy

Humans constantly ask questions and try to find answers in order to better understand the world we’re living in. For some of these questions, we need to looking at really small objects. Throughout centuries of research, scientists developed techniques to observe smaller and smaller objects, always in the intent to visualize their impact on lager scaled processes that sometimes have been observed centuries ago, but not yet understood. Improvements in microscopy techniques allow scientists to see and understand bacteria, cells and even atoms. Observing bacteria and cells helped understanding the way our body and diseases work. Visualising atoms and molecules allowed us to understand the composition, structure, growth and dissolution processes of materials.

Today I will present you an imaging technique called Atomic Force Microscopy (AFM). It has been developed at the end of the 20th century and allows scientists to observe sample’s surfaces structure at the nano-scale.

What is Atomic Force Microscopy and how does it work?

Atomic Force Microscopy (AFM) is a non-destructive surface scanning technique that has sub-nanometer scale resolution. An AFM scans a surface using a sharp  silicon or silicon nitride tip, controlled by a piezoelectric element. The position of the tip is measured by a laser. When a change in the surface’s topography occurs, the tip bends and the movement is registered by the laser.  A piezoelectric element will then move the tip or the sample until the laser hits the centre of the detector again. This movement will give us topography information. Based on this principle, different modifications of the fundamental setup also allow us to map the adhesion, modulus, friction forces, conductivity, surface potential, electric field and magnetic domains of a sample’s surface.(more details on https://www.nanosurf.com/en/support/afm-modes-overview)

Principle of an AFM (Ref: https://microbenotes.com/atomic-force-microscope-afm/)

What is it useful for?

AFM is a polyvalent technique that is used in various research fields: semiconductor  technology, thin film coatings, surface chemistry, polymer science, cell and molecular biology, energy storage and generation for example (https://afm.oxinst.com/outreach/atomic-force-microscopy). The precision of AFM allows scientists to image cells, molecules or even atoms on flat surfaces without having to use a high vacuum as some other microscopy techniques. This makes it easier to observe living cells and makes AFM a useful tool in medicine and biology. It also does not require long sample preparation process and is non-destructive. So, the same sample can be observed by AFM and used for other analysis without problems. Moreover, if one uses a flow-through AFM cell, it is also possible to observe the interaction of a sample’s surface with a fluid in-situ and analyse the dissolution or growth processes, for example on minerals.

Conclusion Atomic Force Microscopy is a versatile technique, allowing scientists to observe topography and physical properties of surfaces and objects at the nano-scale easily. Recent improvements, such as higher spatial resolution, faster imaging rates, and enhanced environmental options, make AFM more valuable than ever before to various fields of research. This technique allows us to better explain larger-scale processes by understanding small scale mechanisms and to improve today’s technologies and overcome present-day’s challenges.

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