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The LUMiCheck works on the back-scattering principle. Light scatters when a dispersed phase (consisting of particles and droplets) has a different index of refraction than the continuous media. The intensity of the scattering light depends mainly on the index of refraction, concentration, and particle size.

By following minute fluctuations and changes in the light scattering intensity, you can measure any changes in your sample. The LUMiCheck measures the light that is back-scattered at the bottom cross-section of specially designed cuvettes as a function of time. The use of special high-powered light-emitting diodes ensures that the scattering signal is of highest quality.

You can then measure the light-scattering signal over any time period you want, using optical sensors that can detect even the smallest changes occurring in your suspension or emulsion in real time.

 

 

 

Depending on the selected method the determined and displayed results allow the quantitative comparison between samples and qualitatively characterize the demixing behaviour, sediment formation, stability etc, respectively permit the quality control of samples. Back-scattering is used to trace the concentration changes due to sedimentation / flotation of particles with high sensitivity.

In case of sedimentation, particles are entering the small region of interest at the sample cell bottom, leading to an increase in backscattering signal. The opposite behaviour occurs for creaming samples. The particles are leaving the region of interest at the bottom of the sample cell. The upwards movement of particles results in a decrease of the backscattering signal over time.

As the region of interest is restricted to a very small volume just above the bottom even small concentration changes are traced very rapidly, therefore the measuring time is normally short.

The curves are fitted with multi parametric equations continuously during the experiment in the device itself. The fitting parameters make it possible to compare different samples quantitatively regarding demixing behaviour, sediment packing, stability etc.