What are we looking at?
These fascinating images show tiny tracer particles being investigated as a potential way of improving the traceability of critical raw materials.
Captured using the GT Vision UltraDIGI-4KMZ-M 4K Digital Inspection Microscope, the images form part of research carried out through the MaDiTraCe – Material and Digital Traceability for the Certification of Critical Raw Materials project.
But what exactly are these particles, and how could something so small help address a much bigger challenge?
What are microscopic tracer particles?
Critical raw materials such as lithium, cobalt and natural graphite are essential to many modern technologies, including batteries, electronics and renewable energy systems.
Their supply chains can involve multiple stages of extraction, processing, transportation and manufacturing. As materials move through these stages, establishing where they came from and verifying their identity can become increasingly challenging.
One approach being investigated is artificial fingerprinting.
The concept is to introduce a distinctive tracer particle into a material at a defined point in the supply chain, then detect that tracer at a later stage. If it can be reliably identified, the tracer could provide physical evidence that a particular material or batch has passed through a defined stage of the supply chain.
In simple terms, the tracer acts as a kind of microscopic fingerprint.
It is not intended to replace documentation, supplier records or other traceability measures. Instead, it could provide an additional physical means of checking what is actually present in a material.
The MaDiTraCe project
The Material and Digital Traceability for the Certification of Critical Raw Materials (MaDiTraCe) project was formally launched in Paris in January 2023.
The 42-month European Union project focused on improving the transparency, traceability and sustainability of complex critical raw material supply chains, including those involving cobalt, lithium, natural graphite and rare earth elements.
One area of the project focused on material fingerprinting (MFP) and artificial fingerprinting (AFP).
As part of this work, researchers investigated whether tailor-made 3D-printed tracer particles could be developed for use with different critical raw materials.
The research documented in D2.6 – Final report on MaDiTraCe artificial fingerprinting technologies examined tracer particles in seven host materials from lithium, cobalt and natural graphite supply chains.
Sixteen prototype 3D-printed tracer particles were produced from different materials, including polymers, metal alloys and mineral-polymer composites. Commercially sourced tracer particles were also tested for comparison.
The researchers weren't simply looking at whether the particles could be detected. They wanted to understand how the particles behaved once they were introduced into real raw materials.
What did the researchers investigate?
The study examined a range of factors that could affect whether artificial fingerprinting would work in practice.
These included:
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How effectively tracer particles could be mixed with different raw materials
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How evenly they were distributed
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How easily they could be detected
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How particle size affected their behaviour
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Whether they remained identifiable after ageing and transportation tests
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Whether they reacted with their host materials
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The minimum concentration at which different particles could be detected
The results showed that particle size had a significant effect on both detectability and distribution.
Smaller tracer particles tended to adhere more readily to the surfaces of host material particles and were easier to detect. Larger particles were more likely to occupy spaces between particles and could therefore be less detectable.
Some of the smallest particles tested were detectable at the lowest concentration investigated — 0.1 parts per million (ppm).
The type of tracer material also made a difference. Overall, the polymer-based 3D-printed tracers performed particularly well, while some metal-based tracers were found to react with air and sulphur-containing materials, resulting in degradation.
These findings highlight an important consideration for artificial fingerprinting: tracer particles need to be designed with the material and environment in which they will be used in mind.
What are we seeing under the microscope?
The images from the research provide a visual look at how these tiny particles behave within different raw materials.
The study examined tracer particles within host materials including spodumene concentrate, nickel concentrate, mixed hydroxide precipitate and black mass.
Some images were captured under natural light, while others use excitation light to make fluorescent tracer particles stand out more clearly.
Examples of tracer particles within different host materials from the MaDiTraCe research. Images captured using the GT Vision UltraDIGI-4KMZ-M Digital Inspection Microscope.
Under magnification, researchers can examine much more than simply whether a particle is present. Imaging can help reveal differences in particle size, shape, distribution and interaction with the surrounding material.
This is particularly useful during R&D, where researchers are comparing different tracer designs and trying to understand why some perform better than others.
Why does digital microscopy matter?
For artificial fingerprinting to work effectively, a tracer needs to be detectable, distinguishable and sufficiently well distributed within the material being tested.
Digital microscopy provides a practical way to investigate these characteristics.
High-magnification imaging can help researchers:
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Locate individual tracer particles
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Examine particle size and shape
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Assess how particles are distributed
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Identify aggregation or clustering
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Compare particles against surrounding material
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Examine how different lighting conditions affect detectability
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Capture images for further analysis and documentation
Excitation light can be particularly useful when working with fluorescent tracer particles. By making the particles stand out from the surrounding material, it can make detection much easier.
The MaDiTraCe research therefore provides an interesting example of how digital microscopy can support R&D in materials science, helping researchers investigate features that cannot be seen with the naked eye.
The GT Vision UltraDIGI-4KMZ-M
The images featured in this article were captured using the GT Vision UltraDIGI-4KMZ-M High Resolution Digital Inspection Microscope.
The UltraDIGI is an all-in-one digital inspection system combining a 0.7–5.6× continuous zoom lens, 4K camera and built-in display, without requiring an external computer.
Its high-sensitivity Sony sensor provides real-time 4K imaging, with still image capture and 4K video recording at up to 30fps.
Key features include:
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4K high-resolution imaging and video
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0.7–5.6× continuous zoom
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Built-in display for a compact, computer-free setup
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Wireless magnetic 6500K LED ring light
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Built-in measurement and imaging software
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Optional objectives for biological and metallurgical applications
For inspection and R&D applications, the combination of high-resolution imaging, continuous zoom and measurement capabilities provides a flexible way to examine and document small features in detail.
Explore the UltraDIGI-4KMZ-M Digital Inspection Microscope →
What could this mean for raw material traceability?
The MaDiTraCe research demonstrates the potential of artificial fingerprinting as one part of a wider approach to critical raw material traceability.
A tracer particle cannot provide every piece of information about a material's history or origin. Instead, its potential value comes from combining physical evidence with supply-chain records and other verification methods.
The research also highlights the challenges that still need to be addressed.
Tracer properties need to be tailored to individual materials, production methods need to be scalable and cost-effective, and application and detection systems need to work alongside existing industrial processes.
Further testing and refinement will therefore be required before 3D-printed tracer particles can be used for widespread traceability of critical raw materials.
For microscopy, however, the research demonstrates an interesting real-world application: using high-resolution digital imaging to investigate and document microscopic features as part of cutting-edge R&D.
Read the original research
This article is based on D2.6 – Final report on MaDiTraCe artificial fingerprinting technologies, produced as part of the MaDiTraCe project.
Authors:
Omar Amri (AHK)
William Hartley (AHK)
Laurance Donnelly (AHK)
Robert Dunn (AHK)
Ian Corfe (GTK)
Quentin Dehaine (GTK)
Aidan Wilson (AHK)
Read the full D2.6 report on Zenodo →
The research report contains the full methodology, testing procedures, results and discussion behind the work featured in this article.
Images featured in this article are from the MaDiTraCe D2.6 research report and are credited to the research team. The microscopy images were captured using the GT Vision UltraDIGI-4KMZ-M Digital Inspection Microscope.
Interested in digital microscopy for R&D or inspection?
The UltraDIGI-4KMZ-M combines 4K imaging, continuous zoom and built-in measurement tools in a compact digital inspection system.
Find out more about the UltraDIGI-4KMZ-M →
If you're working on an inspection, imaging or R&D application and aren't sure which microscope would be suitable, please contact the GT Vision team for advice.