Nanoparticle Size Measurement and Characterization Techniques

Accurate determination of nanoparticle dimensions underpins advances in fields ranging from drug delivery to environmental monitoring. A suite of complementary methods is routinely employed: imaging techniques such as scanning electron microscopy (SEM) and atomic force microscopy (AFM) yield direct visualisation of morphology and individual dimensions, while ensemble approaches—including dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS)—provide rapid size distributions in suspensions. Metrological rigour demands traceable calibration protocols, uncertainty evaluation and harmonised sample preparation to ensure reproducibility across laboratories. Recent developments emphasise hybrid metrology, combining height profiling by AFM with lateral measurements by SEM, and novel algorithms that convert two-dimensional micrographs into three-dimensional size or surface‐roughness metrics. These advances enable regulatory compliance, foster inter-laboratory comparability and support the translation of nanoparticle technologies into practical applications.

Research from Nature Portfolio

Innovations in quality-control algorithms have extended SEM beyond two-dimensional imaging. A newly developed procedure tilts the sample stage to capture multiple SEM contours of core–shell microparticles, enabling quasi-three-dimensional reconstruction of surface roughness. Validation against AFM confirms that this approach yields reproducible root-mean-squared profile roughness values, suitable for routine batch verification.

Addressing the challenges of irregular, agglomerated nanopowders, a systematic study has introduced embedding in hot-mounting resin followed by cross-sectioning. Correlative analysis by SEM, DLS, Brunauer–Emmett–Teller adsorption and differential mobility analysis, supported by simulations of size-deviation effects, clarifies how cross-section geometry influences measured dimensions. The work establishes best practices for representative sampling of industrial nanopowders.

Research from all publishers

A multi-laboratory intercomparison has benchmarked TEM, SEM, AFM and SAXS for complexly shaped and bimodal nanoparticles, demonstrating that consistent sample preparation, instrument calibration and measurand definition yield SI-traceable size results with low dispersion. A semi-quantitative error source matrix guides uncertainty estimation for each technique and recommends hybrid measurements for the most irregular shapes.

A comprehensive strategy for SEM-based size metrology outlines calibration workflows, uncertainty budgets and the impact of electron-beam parameters on edge detection. By mapping the interplay between primary-electron energy, substrate signal convolution and measurement bias, the study provides a clear roadmap for establishing traceability and minimising operator-dependent variability.

Extending traceable SEM sizing to larger particles, a simulation-driven method adapts inelastic-scattering models and non-linear image-analysis protocols. Implemented in transmission-mode SEM (TSEM), the revised workflow achieves agreement with international reference values for particles up to 500 nm, broadening the applicability of electron microscopy for aerosol and colloidal research.

Nanoparticle Size Measurement and Characterization Techniques publication trend

The graph below shows the total number of articles in nanoparticle size measurement and characterization techniques across all publications each year (not limited to Nature Index journals).

Technical terms

Scanning Electron Microscopy (SEM): An imaging technique that scans a focused electron beam across a sample to produce high-resolution projections of lateral nanoparticle dimensions.

Atomic Force Microscopy (AFM): A probe-based method that maps surface topography and measures particle height by detecting forces between a sharp tip and the sample.

Dynamic Light Scattering (DLS): An ensemble technique that determines the hydrodynamic diameter of particles in suspension by analysing fluctuations in scattered light intensity.

Small-Angle X-Ray Scattering (SAXS): An ensemble method that infers size distributions from the angular distribution of X-rays scattered by particles in solution.

SI-traceability: The property of a measurement result whereby its relation to the International System of Units metre is established through an unbroken chain of calibrations.

Feret Diameter: The distance between two parallel tangents on opposite sides of a nanoparticle projection, often reported as minimum, maximum or equivalent values.

References

1. Development of a new hybrid approach combining AFM and SEM for the nanoparticle dimensional metrology. Beilstein Journal of Nanotechnology (2019).
2. Towards 3D determination of the surface roughness of core–shell microparticles as a routine quality control procedure by scanning electron microscopy. Scientific Reports (2024).
3. Embedding and cross-sectioning as a sample preparation procedure for accurate and representative size and shape measurement of nanopowders. Scientific Reports (2024).
4. Metrological Protocols for Reaching Reliable and SI-Traceable Size Results for Multi-Modal and Complexly Shaped Reference Nanoparticles. Nanomaterials (2023).
5. Strategy for Ensuring the Metrological Traceability of Nanoparticle Size Measurements by SEM. Nanomaterials (2024).
6. Traceable determination of the size of nanoparticles up to 500 nm by scanning electron microscopy in transmission mode based on simulation. Measurement Science and Technology (2023).