National Physical Laboratory


Nanoparticles30 nm gold nanoparticles imaged by (a) TEM, (b) SEM and (c) AFM Nanoparticles are a current area of intense scientific research as they are a bridge between atomic and bulk structures. This means they have unique properties that can be exploited commercially, for example as highly concentrated suspensions in the ink industry, as drug delivery agents for the pharmaceutical industry or in novel composite materials for the transport industries. Well-documented toxicological concerns highlight the need for strict and well define standards to be applied. Currently no recognized traceable calibration of nanoparticles exist and, as their properties are strongly dependent on size, new metrological capabilities are required in order to ensure consistency in quality and innovation.

Our aims are to provide new traceable standards and procedures to determine the size, shape and distribution of nanoparticles with an accuracy of better than 1 nm. This will be correlated with preparation method and the end-product environment (on a surface or in suspension). No technique can currently provide metrology of highly concentrated dispersions of nanoparticles, which is critical because the nature of nanoparticles change with concentration. Improved metrology will be developed to address this issue. Additionally we intend to lay the groundwork for future analysis requirements of nanoparticles. First mapping the surface properties (charge, coating coverage and doping level) and finally in-situ technology capable of reproducing the ex-situ analysis. Dissemination will take the form of development of new standards, scientific papers, good practice guides and reference materials.

This project will focus on a comparison of methods that offer a relatively direct route to traceability with some more accessible methods used in industry. Electron microscopy (SEM and TEM), Dynamic Light Scattering (DLS) and Atomic Force Microscopy (AFM) are the methods of choice to investigate particle and agglomerate size, shape and structure. All these techniques are carried out at NPL on dry powders and nanoparticle dispersions. Although these methods are powerful, they require an extensive sample preparation, expensive equipment and skilled people to interpret the results, and thus will not be widely accessible to industry.


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Last Updated: 9 Sep 2010
Created: 9 Sep 2010


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