20/05/2019

Scanning electron micrographs

Scanning electron micrographs of (a) bipyramidal titania, (b) titania nanoplateles, (c) acicular titania and (d) Au nanocubes. Scale bar equals 100 nm.

Source: BAM, Surface Analysis and Interfacial Chemistry Division

Project period

01/05/2018 - 30/04/2021

Project type

EU project

Project status

Current

Description

This project will develop methods, reference materials and modelling to improve the traceability chain, comparability and compatibility of nanoparticle size measurements.

Location

Bundesanstalt für Materialforschung und -prüfung (BAM) Branch Fabeckstraße
Unter den Eichen 44-46
12203 Berlin

nPSize Logo

Source: BAM

Nanomaterials and nanotechnology are widely used today. The unambiguous correlation of possible health and sustainability risks to nanoparticle size must be enabled by reliable measurement of nanoparticle size, to ensure comparability and compatibility between results measured under different methods. Whilst size can be measured accurately for simple (ideal) nanoparticles, i.e. of spherical shape, mono-disperse, non-agglomerated/aggregated, the analysis of non-spherical nanoparticles with broader size distributions is much more challenging and less accurate.

Stilisierter Programmablaufplan

Source: BAM

In this project the sensitivity of traceable nanoparticle sizing techniques i.e. scanning – and transmission electron microscopy (SEM and TEM), atomic force microscopy (AFM), small angle x-ray scattering (SAXS) to the type of nanoparticle material, shape, polydispersity and number concentration will be investigated

Ein Pfeil in der Mitte einer Zielscheibe

Source: BAM

Contributions to improve the capability of traceable measurement of nanoparticle size and shape, lower uncertainties of nanoparticle size measurement by new reference materials, physical modelling and machine learning, 3D method combination, new ISO and CEN standard on accurate nanoparticle size measurement, guidance and knowledge transfer.

Händeschütteln

Source: BAM

Consortium: 5 Metrological Institutes (LGC, LNE, PTB, SMD and VSL), 1 Designated Institute (BAM) and 4 external funded partners (CEA, DIN, POLLEN and University of Turin) from 6 European countries

Coordination: Dr. Vasile-Dan Hodoroaba, Bundesanstalt für Materialforschung und -prüfung (BAM)

Funding: The project receives funding from the European Metrology Programme for Innovation and Research (EMPIR).

Overview

This project will develop methods, reference materials and modelling to improve the traceability chain, comparability and compatibility of nanoparticle size measurements to support standardisation within the framework of CEN/TC 352 'Nanotechnologies', ISO/TC 229 ‘Nanotechnologies’, ISO/TC 24/SC 4 ‘Particle characterization’ and ISO/TC 201/SC 9 ‘Scanning probe microscopy’.

Needs

Nanomaterials are used in products such as functional clothing, cosmetic products, food and packaging, drug delivery, paints and coatings, etc. Many of the functional properties of nanoparticulate materials depend on their particle size. The unambiguous correlation of possible health and sustainability risks to nanoparticle size must be enabled by reliable and traceable measurement of nanoparticle size, to ensure comparability and compatibility between results measured under different conditions/methods. Whilst the size can be measured accurately for simple (ideal) nanoparticles, i.e. of spherical shape, mono-disperse, non-agglomerated/ aggregated, the measurement and analysis of non-spherical nanoparticles with broader size distributions, such as those in most real-world nanomaterials is much more challenging and less accurate.

Objectives

The overall objective of the project is to improve the traceability chain, comparability and compatibility for nanoparticle size measurements to support the standards development process within CEN/TC 352 and ISO/TC 229 and related groups. The objectives in detail:

  • To assess the performance and establish the traceability of existing nanoparticle sizing methods, such as (transmission) scanning electron microscopy ((T)SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), small angle x-ray scattering (SAXS), in terms of their sensitivity to material, shape and quantity (number, volume or mass) for representative nanoparticulate materials (i.e. metals, oxides)
  • To develop nanoparticle reference materials with non-spherical shapes, non monodisperse size distributions and accurate concentrations
  • To develop improved physical models of the output signals from nanoparticle size measurement systems, that accurately account for nanoparticle material, shape and quantity
  • To use the new physical models to develop validated and traceable methods for the transfer of nanoparticle size from (certified) reference nanoparticles of spherical shape and monodisperse size distribution to other types of nanoparticles
  • To contribute significantly to the standards development work of the technical committees CEN/TC 352 Nanotechnologies and ISO/TC 229 Nanotechnologies

Impact

The project will impact many industries dealing with nanoparticles on a large scale, such as pigment, food, transportation, medicine, textile and construction industries, which all require accurate and reliable characterisation of their nanoparticulate products. Contributions including improved, traceable measurement capabilities will be provided to standardisation documents, together with direct transfer to end users such as operators in analytical laboratories of large or small manufacturing companies and independent (accredited) laboratories, and measurement instrument manufacturers.

UPCOMING EVENT
EMPiR nPSize training course on reference nano-materials development,
December 2019 (tba), LGC Limited, Teddington, UK

Technical work packages

The nPSize project consists of four technical work packages.

Performance and traceability of characterisation methods

WP1: Most previous studies on nanoparticle size measurement focus on suspensions of spherical and monodisperse nanoparticles, and are typically limited to gold, silica or polystyrene particles. Little or no research has been carried out on nanoparticles deviating from this idealised case. In this project the sensitivity of traceable nanoparticle sizing techniques SEM, TEM, TSEM, AFM and SAXS to the type of nanoparticle material, shape, polydispersity and number concentration will be investigated.

LNE Laboratoire National de métrologie et d'Essais, France

Nanoparticle Reference Materials preparation and characterisation

WP 2: Currently, there are no non-spherical nanoparticle reference materials or materials certified for particle concentration. Three classes of nanoparticle-reference materials (RMs) will be developed and validated in the project: well-defined non-spherical shape, relatively high polydispersity index, and accurate particle concentrations.

LGC National Measurement Laboratory, UK

Modelling and development of measurement procedures

WP 3: The performance and traceability of current characterisation methods will be improved with advanced data processing. Different approaches will be considered including physical modelling of nanoparticle shape and simulations to evaluate the signals produced by input models for TSEM, SEM, AFM and SAXS. Modern modelling based on machine learning will use a-priori information from measured data. For the first time, the physical modelling will be implemented and validated into the machine learning algorithm.

POLLEN Institute, France

Standardisation as knowledge transfer to end users

WP 4: Project partners will actively contribute to the development of International and European Standards in collaboration with ISO/TC 229 ‘Nanotechnologies’, CEN/TC 352 ‘Nanotechnologies’, ISO/TC 24/SC 4 ‘Particle characterization’ and ISO/TC 201 ‘Surface analysis’/SC 9 ‘Scanning probe microscopy’ with the new technical knowledge gained within this project. This cooperation with different technical committees will focus on the improvement of the traceability of the nanoparticle size measurements and quantity error evaluation, including method combination. All these aspects are currently addressed only partly or not at all within the respective standardisation projects and are completely absent from European standardisation. In addition, the project will facilitate uptake of the improved procedures, new reference materials candidates and models developed within this project by accredited laboratories, instrument manufacturers and reference material providers.

BAM Bundesanstalt für Materialforschung und -prüfung (BAM)

Results

  • To identify future needs for novel refence nanomaterial a public workshop with stakeholders from academia, industry and standardization committees was held at the beginning of the project.
  • 11 reference material candidates are sourced or synthesized ranging from nanoparticles of titania, silica and gold that possess (i) non-spherical shapes, e.g. cubic, bipyramidal, acicular, rod-like, flaky and/or (ii) defined concentration or (iii) polydisperse or bimodal size distributions. Synthesized candidates are under investigation regarding homogeneity, stability.
  • Simulations of elastic and inelastic scattering in electron microscopy has started using the programs JMONSEL and SETSEM as promising modelling candidates.
  • For AFM, a model for probe shape reconstruction has been established and for SAXS, modelling by using existing or calculated shape factors for the material candidates is under evaluation.
  • Establishment of a framework on the Zenodo platform for a public database containing tagged electron microscopy (SEM, TEM and TSEM) images, AFM and SAXS measurement data
  • First measurement data of the different methods are being processed with the PlatypusTM software to create a machine learning algorithm.
  • The performance of SEM, TSEM, TEM, AFM and SAXS for traceable measurement of nanoparticle size, shape, dispersity, concentration and material is currently under qualitative and quantitative evaluation.
  • Deposition protocols on silicon wafers, TEM grids and mica are in development with the aim of producing large analysable areas of monolayers of non-overlapping particles to facilitate the application of machine learning and automatic data analysis.

Partners

BAM Bundesanstalt für Materialforschung und -prüfung (BAM), Germany
LGC National Measurement Laboratory, UK
LNE Laboratoire National de métrologie et d'Essais, France
PTB Physikalisch Technische Bundesanstalt, Germany
VSL Dutch Metrology Institute, The Netherlands
CEA Le Commissariat à l’énergie atomique et aux énergies alternatives, France
DIN Deutsches Institut für Normung, Germany
POLLEN Institute, France
UNITO L'Università di Torino, Italy
SMD Service Metrologie Metrologische Dienst, Belgium

Coordination: Dr. Vasile-Dan Hodoroaba, Bundesanstalt für Materialforschung und -prüfung (BAM)

Funding

This project receives funding from the European Metrology Programme for Innovation and Research (EMPIR) which is an integrated part of Horizon 2020, the EU Framework Programme for Research and Innovation.

EMPIR EURAMET logo

Source: EMPIR