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The word nanometrology has been derived from the Greek word “nanos'' which means one billionth and “metrologia” means a theory of ratios. In other words, nanometrology can be deﬁned as the science of measurement at the nanoscale dimension. Nanometrological measurements are associated with measuring at a nanoscale dimension (shape, aspect ratio, and size distribution) and the assessment of nanoparticle concentrations, chemical composition, and determination of electrical, optical, mass, force, and various other properties of nanomaterials.
The term nanometrology was first used in 1992 in a journal named Metrologia by a group of researchers from Japan’s National Research Laboratory of Metrology. This research group determined fundamental constants and tested physical theory relating to silicon lattice spacing and magnetic flux quantum using precision measurements. Nanometrology is widely used in scientific research and technology where precise measurements are essential. Recently, this technique has been used to measure distances up to 100 nm which is important for analyzing the texture of a surface. In biological research, nanometrology is used to examine the interaction between two biomolecules.
Various techniques such as Scanning Tunnelling Microscopy (STM), near field optical microscopy, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) are used to make nanoscale measurements. Fluorescence Resonance Energy Transfer (FRET) is also used to measure distances between fluorophores between 1 and 10 nm. Fluorophores bind with biological molecules and help to determine distances between actives sites of the interacting molecules. Fluorophores can be tagged with biological components such as proteins. The fluorescing property is exploited to study the interaction between proteins and DNA interactions using simple optical microscopy.
Importance of Nanometrology
The progress of nanotechnology is strongly associated with advancements in nanometrology. Nanotechnology could not have received its due popularity without the existence of nanometrology.
Scientists have revealed that the property of a material is different at the nanoscale than its bulk form. Nanomaterials have a large surface-to-volume ratio, which makes them extremely reactive. For example, they can efficiently react with other molecules such as antigens.
For the development of highly accurate and reliable nanodevices, the characterization of nanomaterials, i.e., evaluation of their size, shape, physical, optical, and other properties are extremely crucial. The foremost important feature of nanomaterials is their nanoscale dimension and unique properties. The understanding of nanostructures, i.e., the arrangement of atoms or particles, is also important for research. For exploring new applications of nanomaterials, a thorough characterization and understanding of the nanomaterials are vital.
Nanometrology has innumerable applications in scientific research, especially, biological, medical, and environmental science. This has been made possible by advancements in instruments such as Scanning Probe Techniques (SPT), Electron Beam Techniques (EBM), and Optical Tweezers. Some of the instruments associated with nanometrology that are used in scientific applications are discussed below.
Transmission Electron Beam Technique
One of the common types of electron microscopy is Transmission Electron Microscopy (TEM) which is used to study micro and nanostructures. Scientists have revealed that the finest details of internal structures, in some cases individual atoms, can be examined using TEM and high-resolution transmission electron microscopy (HRTEM).
This instrument is used to detect components in heart vessels that can cause a heart attack. In this case, the sample is placed on a TEM carbon grid film and studied. The study of cerebellar Golgi cells by using TEM has helped scientists understand the role of Golgi cells in the formation of mossy glomerular islands.
Optical Tweezers Technique
This technique utilizes the radiation pressure of light to analyze objects as small as an atom. In optical tweezers, a high-quality microscope objective is used to focus on a spot (optical traps) that contains the sample. This technique is used to study strands of DNA, bacteria, viruses, living cells, cell organelles, and small metal particles.
In 1987, optical trapping was first exhibited by Arthur Ashkin and Joseph M. Dziedzic, for the study of tobacco mosaic virus and Escherichia coli. The laser-based optical tweezers are also used to investigate the mobility of sperm. In this study, the mobility and the relative swimming forces of a single sperm are analyzed in real-time by combining optical traps with computer tracking algorithms. This combined technique has enabled scientists to determine the evolutionary effect of sperm’s competition in primates.
Scanning Probe Techniques
Scanning Probe Microscopy (SPM) involves the imaging, alteration, and manipulation of nanoparticles. Some of the techniques based on SPM and associated with nanometrology are Magnetic Force Microscopy (MFM), Friction Force Microscopy (FFM), and Scanning Near-field Optical Microscopy (SNOM). However, two of the most common techniques used in nanometrology are Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFMs).
STM helps examine the atomic arrangement of a surface. AFM was first developed in 1986 and is used to analyze weak biomolecular interactions. It is also used to study the interaction between biomolecules, such as antibodies and antigens, complementary strands of DNA, and receptors and ligands under varied physiological conditions. AFM examines uncoated virus particles and RNA of viruses (e.g., TMV).
References and Further Readings
Kim, H. A. et al. (2014). Nanometrology and its perspectives in environmental research. Environmental Health and Toxicology, 29, e2014016. https://doi.org/10.5620/eht.e2014016
Jamakhani, M.A. et al. (2011). Nanometrology in biological and medical sciences. International Journal of Advanced Biotechnology and Research, 2, (1), pp. 213-223
Herrera-Basurto, R. et al. (2013). Nanometrology. Encyclopedia Analytical Chemistry: Applications, Theory and Instrumentation. Available at:
Graham, D. (2007). Nanometrology—is it the next big thing in measurement? Analyst, 132, pp. 95-96. DOI: 10.1039/B609722G