This is critical for the smallest particles (a few nanometers) which tend to scatter the fewer light.
![malvern zetasizer sample position malvern zetasizer sample position](https://demo.fdocuments.in/img/378x509/reader023/reader/2020100916/5f6844ab48278d46f216c4b8/r-2.jpg)
The light collected at large angle from a transparent solution is really dim, so modern DLS equipments use expensive components such as high intensity lasers and single photon detectors to enhance their signal to noise ratio and enable an accurate measurement within minutes. Since particles in solutions undergo Brownian motion, this collected intensity varies with time and then size can be deconvoluted from the intensity time series. Photons coming from different particles interfere in the detector to yield a specific intensity. The scattered light is collected at a specific angle from the beam (here 90°). More broadly, we hope that this approach will also contribute to future projects involving light scattering or high frequency data logging.ĭynamic Light Scattering works as follows (see figure below): a laser beam is shone onto the sample and is scattered to all directions by the particles (particles dimensions are assumed to be smaller than the laser wavelength). On the contrary, this project aims at exploring DLS principles and boundaries with low-cost components and open-source design. Some recent equipment can even determine the shape of non-spherical particles! Typical commercial DLS equipments are expensive (typically over 40k£) because of the use of high quality lasers and detectors, allowing measurements over a broad range of particle sizes and concentrations. In DLS, particles size is back-calculated from the way light scattered from a laser beam evolves with time as particles undergo Brownian motion in the fluid.
![malvern zetasizer sample position malvern zetasizer sample position](https://data2.manualslib.com/first-image/i25/123/12258/1225799/malvern-zetasizer-nano-series.jpg)
In particular, Dynamic Light Scattering (DLS) is widely used for dilute particles suspensions. For submicron particles however, more advanced and expensive techniques have to be employed such as electron microscopy or light scattering. For particles larger than about a micron, optical microscopy can be used in conjunction with image analysis softwares. Characterising the size of micro and nano-particles is important in many applications such as protein aggregation and complex fluids studies.