It covers a broad size range from the lower nanometer range up to several micrometers. DLS provides information on the mean particle size as well as on particle size distribution. Dynamic light scattering analysis is used in medical. This class of particle size analyzer interprets particles’ sizes from the fluctuations in scattered laser light created by the particles’ Brownian motion.
The dynamic information of the particles is derived from an autocorrelation of the intensity trace recorded during the experiment. Dynamic light scattering is a well-established, standardized technique for particle size analysis in the nanometer range and has been used for about 40 years. Dynamic light scattering particle size analyzers are used to measure the size of very small particles (0.6 nm to 6 um) in solution. Sample preparation either by filtration or centrifugation is critical to remove dust and artifacts from the solution.
This scattered light then undergoes either constructive or destructive interference by the surrounding particles, and within this intensity fluctuation, information is contained about the time scale of movement of the scatterers. This fluctuation is due to the fact that the small molecules in solutions are undergoing Brownian motion, and so the distance between the scatterers in the solution is constantly changing with time. 1 2 DDM is suitable for typical soft materials such as for instance liquids or gels made of colloids, polymers and liquid crystals but also for biological materials like bacteria and cells. If the light source is a laser, and thus is monochromatic and coherent, the scattering intensity fluctuates over time. Differential dynamic microscopy (DDM) is an optical technique that allows performing light scattering experiments by means of a simple optical microscope. When light hits small particles, the light scatters in all directions ( Rayleigh scattering) as long as the particles are small compared to the wavelength (below 250 nm). In vertical/horizontal (VH) geometry the second polarizer allows light not in same direction as the incident light. One is a vertical/vertical (VV) geometry, where the second polarizer allows light through that is in the same direction as the primary polarizer. Dynamic light scattering (DLS) is a technique for determining particle size by measuring the Brownian motion (the random movement) of particles in a suspension. The polarizers can be set up in two geometrical configurations. This process is repeated at short time intervals and the resulting set of speckle patterns are analyzed by an autocorrelator that compares the intensity of light at each spot over time.
The diffracted light from all of the molecules can either interfere constructively (light regions) or destructively (dark regions). All of the molecules in the solution are being hit with the light and all of the molecules diffract the light in all directions.