AmanNanavaty Report Atomic Force Microscopy.pdf

A brief introduction on Atomic Force Microscopy, an emerging microscopy method for material science analysis. Learn about the basic principles, modes of operation, advantages, applications and future aspects of AFM. Perfect for academic and personal learning purposes.

1. ATOMIC FORCE MICROSCOPY
AMAN NANAVATY

2. WHAT IS AFM?
•Atomic Force Microscopy (AFM) is a type of Scanning Probe
Microscopy
•It has very high resolution, more than 1000 times of an
optical diffraction, despite not using beam irradiation and
lenses
•AFM was developed by IBM scientists in the 1980s as an
improvement on Scanning Tunnelling Microscopy (STM)
•AFM is now the foremost tool for measurements,
observations and detection on the nanoscale
•It has been used in many different fields such as nano-
biomechanics, cell biology, semiconductor science,
molecular biology, pharmaceutical industry and polymer
chemistry
•Microtubule imaging and detection of cancer cells have
been facilitated by advanced AFM techniques

3. PRINCIPLE
•Basic Principle- Silicon Cantilever has sharp Probe that scans sample surface. Detector then
measures the probe-surface interactions to produce 3D Surface Profile
•When Probe near sample surface, Cantilever experiences deflections due to interactive forces
•When Probe interacts with sample surface, Cantilever bends. This bending is detected by Laser
Diode and Split Photodetector
•Solvation Forces, Van Der Waals Forces, Electrostatic Forces and Capillary Forces are measured
•By measuring the experienced forces, a 3D image of the sample (Topography) can be
generated. This image has a very high resolution
•Depending on the requirements, AFM can be operated in 3 modes:
(a)Contact Mode: Probe dragged across Surface, contours measured via Cantilever
deflections
(b)Tapping Mode: Cantilever driven to oscillate up and down at meniscus layer (for liquid
samples)
(c)Non-Contact Mode: Cantilever oscillates at Resonant Frequency without touching
Surface

4. (a)CONTACT MODE
(b)TAPPING MODE
(c)NON-CONTACT MODE
TYPICAL
AFM SETUP

5. AFM COMPONENTS
A typical Atomic Force Microscope consists of the following
components:
1. Probe: Sharp tip attached to Spring-like Cantilever made up of
Silicon or Silicon Nitride. Tip dimensions in order of 1-10 nm. For
soft sample, Silicon Nitride. For hard/durable sample, Silicon
2.Photodiode Source: Source of Suitable Laser beam
3.Piezoelectric Elements: Facilitate tiny and accurate movements (z-
motion) for efficient Scanning
4.Photodetector: Detects deflections in Laser beam
5.Sample Stage
6.Control Computer

6. AFM COMPONENTS
SILICON PROBE

7. STEPS INVOLVED
(1)Put Sample in AFM
(2)Insert Probe in AFM
(3)Alight Laser
(4)Photodetector Alignment
(5)Probe Approach Mode
(6)Sample Scanning
(7)Retract Probe from Sample

8. FACTORS AFFECTING RESULTS
Van Der Waals Forces- The weak intermolecular electric forces that attract
sample surface and cantilever tip towards each other
Tip/Probe Material- High Resistance Materials often distort AFM images.
Soft samples are also damaged by Silicon
Mode of Operation
Electrostatic Forces- prevents Cantilever Tip to come too close to Sample
Surface
Meniscus Force- Thin Layer of Water between Tip and Sample pulls the Tip
towards Surface
Tip Quality- Degraded/Contaminated Tip gives incorrect results
Stiffness of Sample- Mechanical Strength of Sample Surface

9. APPLICATIONS
Protein Imaging
Cancer Cell Detection
Polymer Characterisation
3D Imaging of Cellular Organelles
Interaction between Nanoparticles
Studying Pathogen-Drug Interactions
Observing real-time cellular
processes such as Respiration and
Metabolism
Nano-biomechanics
Photovoltaic Research
Studying Receptor-Ligand Interaction
AFM IMAGING OF SSB PROTEINS

10. AFM REVEALING THE NANOSCALE
ORGANISATION OF CELL WALL COMPONENTS

11. ADVANTAGES
The advantages of AFM are:
1.Extremely high lateral resolution, in the order of Angstrom
2.Living Samples can be analysed without killing it, hence we
can observe live phenomena
3.3D Surface Profile produced (Topography)
4.Can be combined with other Microscopy Techniques (Optical,
Fluorescent, Raman and IR) as well as FTIR Spectroscopy
5.Unlike SEM, doesn’t require vacuum conditions. AFM works
well even in liquid environments
6.Minimal Sample Preparation
7.Wide range of Compounds can be analysed
8.Greater Level of Detail than SEM
POLYMER SURFACE
TOPOGRAPHY, IMAGED
BY AFM

12. LIMITATIONS
AFM suffers from the following limitations:
1.Significant Background Noise
2.Tip Contamination possible
3.Tip Degradation possible
4. Limited Vertical Range
5.Affected by sample thickness
6.Results are dependent on Tip Quality
7.Slow Scanning Speed
8.Shear Forces arising in Contact Mode can
damage soft samples BACKGROUND NOISE IN AFM

13. FUTURE OF AFM
High Speed Atomic Force Microscopy (HS-AFM) is the only analytical
technique that allows us to study both the structural properties as well as
dynamics of single protein molecules.
AFM is being used to study enzymes, antibodies and motor proteins
Rapid Cancer Detection is now facilitated by AFM
AFM is now used to observe Human Chromosomes
Protein Dynamics of newly discovered Proteins are studied using AFM
The Global Market Size of AFM is projected to reach $806 Million by 2031,
growing at a CAGR of 5.4% from 2022 to 2031
Diameter of Cornea, Rhodopsin Structure and Mucin Topography are
being elucidated from enhanced AFM

14. REFERENCES
Voigtländer, Bert (2019). Atomic Force Microscopy. NanoScience and Technology. Springer.
doi:10.1007/978-3-030-13654-3. ISBN 978-3-030-13653-6. S2CID 199490753.
García, Ricardo; Pérez, Rubén (2002). "Dynamic atomic force microscopy methods". Surface Science
Reports. 47 (6–8): 197–301. Bibcode:2002SurSR..47..197G. doi:10.1016/S0167-5729(02)00077-8.
Garcia, Ricardo; Knoll, Armin; Riedo, Elisa (2014). "Advanced Scanning Probe Lithography". Nature
Nanotechnology. 9 (8): 577–87. arXiv:1505.01260. Bibcode:2014NatNa...9..577G. doi:10.1038/
NNANO.2014.157. PMID 25091447. S2CID 205450948.
Suprakas Sinha Ray (2013). “Techniques for characterizing the structure and properties of polymer
nanocomposites”. Woodhead Publishing. (4): 74-88. ISBN 97808557097774.
Fu W, Zhang W. Hybrid AFM for Nanoscale Physicochemical Characterization: Recent Development and
Emerging Applications. Small. 2017 Mar;13(11). doi: 10.1002/smll.201603525. Epub 2017 Jan 25. PMID:
28121376.
Patel AN, Kranz C. (Multi)functional Atomic Force Microscopy Imaging. Annu Rev Anal Chem (Palo Alto
Calif). 2018 Jun 12;11(1):329-350. doi: 10.1146/annurev-anchem-061417-125716. Epub 2018 Feb 28. PMID:
29490193.
Ando T. High-Speed atomic force microscopy and its future prospects. Biophys Rev. 2018
Apr:10(2):285-292. doi: 10.1007/s12551-017-0356-5. Epub 2017 Dec 18. PMID: 29256119; PMCID:
PMC5899716