Mass-centric particle characterization
Fast size and structure determination via simultaneous measurement of mass and size.
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Next-generation powder characterization
Increase insight and boost the structural understanding of engineered particles:
Carbon Black
Silica
Titanium dioxide
Calcium carbonate
Carbon nanotubes
Fibrous materials
Recovered Carbon Black
And many more ...
Universal particle sizing by mass
More fundamental measurement of particle extend than an equivalent diameter
➜ See application note
Unbiased multicomponent analysis
Independent of material properties (e.g., refractive index, effective density)
➜ See application note
Stability measurements
Assess dispersibility (agglomerate stability) and particle coating strength
➜ See application note
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Nanoparticles are femtoparticles
femtoG provides a world's first and fast method to measure the structural properties of nanoparticles. Adopting aerosol-based measurement concepts, we measure simultaneously the mass and a diameter of individual particles. A femtoG scan throughout the entire particle mass and size distribution opens unique insight into a material's structure. The mass serves not only as a more fundamental sizing standard, but also to directly determine observables such as the aerodynamic diameter to assess health hazards. Further products, such as, the number of particles per gram or the size of a mono-particle layer help to translate changes on the nano-scale to the real world application.
Mass as universal size standard
The term nanoparticle is derived from a length-scale 10-9 m, but a 1-dimensional metric can rarely describe complex structured particles to their full extent.
Different equivalent diameters, or min/max dimensions are used rendering the comparison of particle size distribution challenging - especially for structured particles.
However, there is only one mass to describe a particle. The mass is an intrinsic, fundamental and unambiguous property, which makes it an ideal metric for particle size distribution.
femtoG uses the electrical mobility analysis to measure the geometric dimensions of a particle. Unlike other diameter estimates the mobility diameter it is not affect by particle properties such as material density or refractive index.
Combining the particle mass and diameter distributions gives unique and unbiased insight into the structure of the material.
Our approach employs particle dispersion systems in combination with the newly developed Mass & Mobility Aerosol Spectrometer (M2AS, Cambustion Ltd., UK), enabling the rapid measurement of size distributions for both absolute particle mass and a diameter (electrical mobility) within five to 15 minutes.
Powder analysis is initiated by an aerosolization of the powder material. Three common dispersion techniques are:
- Dry dispersion: Dry powder is aerosolized by turbulence. Afterwards the particles are passed through Venturi-type nozzles for deaglommeration. This approach is practical for fluffy powders such as Carbon Blacks, recovered Carbon Blacks, silica.
- Wet dispersion: Powder is suspended in a suitbale solvent (e.g., water, alcohol, alkane). The suspension is then spray dispersed. Variable deagglomeration can be achieved by prior ultrasonic treatment of the suspension. Before analysis the particles pass through dryers or catalytic strippers to remove rememnants of the solvent. This approach is practical for stronger bound powders such as titanium dioxides, carbon nanotubes, color pigments.
- Direct sampling: A sample stream can also be drawn directly from a particle generator or reactor. Venturi-type nozzles can be used for ensuring deaglommeration.
The aerosol particles produced this way are guided into the M2AS. In this instrument, first particles are electrically charged before, secondly, being exposed to a combination of centrifugal and electrostatic forces allowing the separation of particles by their mass to charge ration. In a third step the particle electrical mobility (“diffusivity”) in air is determine by combining electrostatic and drag force. In the fourth and last step, the particles are counted, and the electric current is recorded. By scanning through the entire population, the (number-weighted) distribution of absolute particle mass and mobility diameter is obtained.
For more information on the setup and measurement procedure please refer to our application notes and presentations in the Downloads section or contact us directly.
Introducing femtoG fingerprint
Structural relation of mass and diameter
The structure of a particle population is encoded in the relation between mass and diameter of the individual particles. This relation can be visualized by the effective density (particle mass divided by the particle enclosed volume) which includes the void volume in the particle. In the case of solid particles the effective density stays constant with increasing particle size. The effective densities of aggregated particles decreases for larger sizes due to a propotionally stronger increase in (pore) volume than mass. The stronger the decrease, the higher the aggregation level of the particles.
When using a diameter that is soley sensitive to the geometry of the particles (e.g. electric mobility diameter) the enclosed volume of the particle can be determined and the effective density can be calculated reliably.
Resolving process impacts on particle structure
To quickly compare different samples or batchesd we make use of the femtoG fingerprint. The fingerprint represents the average interval of mass and effective density of the particle population allowing an intuitive overview of size and structure.
Changes in the fingerprint allow for resolving the impact of a production process on the particle structure. Impacts of e.g., milling, or variation in aggregation time are captured by shifts in the (average) particle mass. Impacts of e.g., particle compaction, or chemical treatments leading to increased porosity are represented in a varying effective density. In addition, for aggregated particles the impact of primary particle size on structure is observed.
By including structure in the size assessment femtoG opens completely new possibilities for production monitoring and quality control.
To quickly compare different particle types (powders) in size and structure, we retrieve a representative interval of the density curve – the femtoG fingerprint. It is defined as the particle effective density curve against particle mass between the first and third quartile of the number-weighted particle distribution. The bars indicate the quartiles spanning the interquartile range of the particle mass and diameter distribution, while the square indicates the median. Therefore, it represents the inner 50% of particles (particles falling into the interquartile range) and their associated structure in the form of the density decay.
Material specific solutions
Distinction of materials based on mass and structure
Using the particle mass, particles size can be assessed with less uncertainties. With the additional knowledge of the effective density different material classes can be further structure due to its dependence on the material density.
Exemplary particle masses and effective densities of common materials:
| Pyrogenic silica: | 1-10 fg, | 0.9 g/cm3 |
| Tire-grade Carbon Blacks | 1-6 fg, | 1.3 g/cm3 |
| Recovered Carbon Blacks | 6-12 fg, | 0.8 g/cm3 |
| Titanium dioxide pigments: | 100 fg, | 3.0 g/cm3 |
In addition to a classification, this also allows a closer identification of material and associated structure in multicomponent analyses.
➜ See application noteServices
Lab analysis
Offline analysis of an individual sample (ideally > 25g needed, as powder or beaded) in our labs in Zurich🇨🇭. Individual sample report featuring mass, density, and size distribution details (optionally: data interpretation upon delivery).➜ See sample requirements
➜ See example report
Process monitoring
Continuous online monitoring of the production process at a time resolution of < 10 minutes. This methodology is currently under development, femtoG welcomes industry partners for the planning of on site pilots.➜ Become a pilot partner
Research projects
Personalized projects tailored to answer your specific research problem. Make use of femtoG's experience in aerosol characterization to boost your business.Consulting
Make use of the experience of femtoG in aerosol sciences, data interpretation, as well as in the planning and execution of custom research projects.Clients
"By taking the mass perspective, femtoG has greatly helped us to understand the physical impacts of our refinement process on the sizes and densities of the aggregates of the rCB produced by the G3C method. The discussions with the experienced team were invaluable and are definitely recommended." - March 7 2023
Dr. Vitaly Khusidman Founder and CEO of G3C Technologies Corporation
"The femtoG measurement technique is currently tested for characterization of titanium dioxide products. First results show that the simultaneous measurement of particle size and effective agglomerate density opens a promising new viewpoint for product characterization." - April 3 2023
Thomas Koch KRONOS INTERNATIONAL, Inc.
Our Team
We are a young startup based in Zurich, Switzerland. Using our extensive background in aerosol research, we are thriving to change the status quo of powder analysis with innovative aerosol technology solutions.
Franz Friebel
Co-founder, Dr. sc. ETH Zürich
Omar Girlanda
Intern, Bsc. ETH Zürich
Jörg Wieder
Co-founder, Dr. sc. ETH Zürich
Our Partners
Contact us
Downloads
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Papers and press
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