An Overview Of Atomic Force Microscope

By Author: Vishal Khosla
Total Articles: 19
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An atomic force microscope can be used for diverse applications such as life science, materials science, electrochemistry, polymer science, biophysics, biotechnology and nanotechnology. It is used for manipulations of nano objects and size measurements in various environments such as air, liquid and vacuum.

Atomic force microscope is used for metrological and high resolution measurements at the nano scale in AFM and STM modes for the advanced materials research. For accurate measurement, you need to source equipment with the latest technology. Procure an atomic force microscope that includes modes such as Kelvin Probe Microscopy, Piezoresponse Force Microscopy, Nanomanipulation and Nanolithography.

An atomic force microscope helps view details at the atomic and molecular level, increasing our ability to use the systems to our benefits. It could be used for applications as diverse as life science, materials science, polymer science, biophysics, electrochemistry, biotechnology and nanotechnology.

The instrument is applied to various environments such as air, liquid and vacuum as well as materials such as ...
... soft biological samples, metal semiconductors, conductive and non-conductive materials. The technique can be used for size measurements and manipulations of nano objects.

Essential property in the instrument is the interaction force between the tip and the sample. When the distance is larger, the force is attractive while at close contact, the force is repulsive. It results in different operation modes allowing the technician to choose one according to the characteristics of the sample.

Tip interacts with the sample surface through a physical phenomenon. The data collected is transferred to a computer with appropriate software which creates an image of the surface.

Atomic force microscope measures the forces acting between a fine tip and a sample. The tip in the instrument, attached to the free end of a cantilever, is brought close to a surface. Positive or negative bending of the cantilever is caused by attractive or repulsive forces arising from interactions between the tip and the surface. A laser beam reflecting from the back side of the cantilever is detects the bending.

Piezocrystals make possible movements in x, y and z direction. These are ceramic materials that contract or expand in the presence of voltage gradient. The probe represents a cantilever with a sharp tip brought into interaction with the sample surface. Probes come in different specifications and shape. Cantilevers providing high resistance to lateral torsion and low mechanical resistance to vertical deflection are more in demand. Integrated cantilevers are made using silicon or silicon nitride. These are characterized by force constant and resonant frequency. Electronics for data acquisition and the management of scanning procedures is essential as well.

A laser is reflected off the cantilever and aggregated in a photodiode to detect the displacement of the cantilever. Force sensor can perform only if the probe interacts with the force field associated with a surface. In contact regime, the cantilever is held less than a few angstroms from the sample and the interatomic force is repulsive. It is held at tens to hundreds of angstroms from the surface in the non-contact regime and the sample is attractive. Nanoscopic layer of contamination present in ambient air causes attractive forces. As the probe begins to contact the surface on atomic force microscope, repulsive forces increase.

The instrument can be used to examine samples in ultrahigh vacuum, ambient conditions and even in liquids.

Author of this article is associated with Rtec Instruments that offers instruments such as atomic force microscope, CMP polisher, multi-functional tribometer, stress tester and many more.