The patented Single Particle Extinction and Scattering (SPES) technologies by EOS Instruments redefines particle analysis by leveraging the optical signatures of individual particles to enable advanced classification of complex particles, particle mixtures and particles in heterogeneous fluids.
SPES (Gen 1): the established standard in single‑particle analysis. Experience it!
SPES² (Gen 2): now released as an upgrade module. Contact us to learn more!
SPESe / SPESr (Gen 3/4): next‑gens expected in the coming years. Stay tuned!
By capturing calibration-free and particle-model-free information on light scattering and absorption of individual particles, SPES technology by EOS Instruments enables deeper insight into particle systems where traditional particle analysis techniques fall short. Advanced data analysis algorithms transform SPES data into reliable, actionable information, supporting R&D and QC workflows across lab-scale development, industrial production and monitoring in biological, industrial and environmental fluids.
- Calibration-free optical particle classification, absolute particle size distribution measurement and numerical particle concentration for each individual particle population, regardless of polydispersity and complex particle mixtures.
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Advanced quality control of particle properties including porosity, wetting, aspect ratio, payload, impurities and shelf-life, without intermediate steps such as purification or filtration.
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Direct measurement of particle behaviour and formulation stability in heterogeneous, non-filtered fluids, including biological, industrial and environmental samples.
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High-resolution continuous flow particle analysis, ready for integration with analytical devices and systems such as cFFF separators, small-scale chemical reactors and pilot lines.
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Advanced statistical analysis methods such as oversize detection and Principal Component Analysis (PCA) for batch-to-batch comparison and out-of-spec detection in product formulation, production and quality control.
How Does SPES Work?
Among particle analysis methods currently available, optical techniques offer unique advantages, placing light scattering at the forefront of analytical tools in both scientific research and industrial particle analysis applications.
The scattering behaviour of a particle is influenced by multiple parameters. As a result, simple measurement of scattering intensity or light extinction from a single particle provides only a rough estimate of particle size. The complexity increases when analysing collections of particles, where interpreting experimental data requires solving complex mathematical inversion problems.
SPES technology by EOS Instruments relies on the interference of light scattered by particles when illuminated by a focused laser beam, either within a fluid flow in a cuvette or in an aerosol particle stream. The scattered light is measured both in the forward direction, superimposed on the incident laser beam, and at 90 degrees, enabling accurate single particle analysis.
In the forward scattered light, the transmitted laser beam interferes with the scattered wavefront, generating an interference pattern of intensity modulations. This interference pattern is the core of SPES measurement, as it contains multiparametric information about key optical properties of each individual particle.
At the same time, the scattered intensity at 90 degrees is analysed during the particle’s transit through the measurement region, providing additional independent data for particle characterization.
For each particle, three independent optical scattering properties are measured:
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the total attenuation caused by the particle, defined as the extinction cross section (Cext), which quantifies the fraction of incoming laser power removed and supports accurate particle measurement.
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the particle’s polarizability (α), proportional to particle volume, derived from the amplitude of constructive and destructive fringes in the interference pattern.
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the total scattered intensity at 90 degrees (F90), integrated over a wide solid angle (SPES²), enabling additional particle characterization
The extinction cross section (Cext), particle polarizability (α) and F90 values are obtained for each detected, validated and counted particle using a robust Pulse Shape Analysis scheme. This approach avoids common limitations of ill-posed problems such as inversion or deconvolution, improving reliability in particle analysis. Within minutes, SPES technology by EOS Instruments generates EOS CLOUDS, a unique 2D or 3D particle distribution histogram where data can be visually explored and analytically processed. In heterogeneous samples, each particle population forms a distinct and identifiable cloud, enabling independent selection, analysis and comparison of particle populations.
Particle size distribution, numerical particle concentration, oversize analysis and advanced statistical insights can be derived from selected particle populations, either from the entire sample or from each time frame acquired in Continuous Flow Analysis (CFA). Advanced statistical methods such as Principal Component Analysis (PCA) enable extraction of additional information often inaccessible with conventional particle analysis techniques.
