Nanoparticle sizing by dynamic ultrasound scattering

When ultrasonic waves are incident on a suspension of nanoparticles dispersed in a liquid, scattering occurs. The size of nanoparticles can be analyzed from the amplitude of the ultrasonic scattering field. We are developing a dynamic ultrasound scattering method that directly captures the motion of nanoparticles instead of the conventional ultrasonic attenuation method. In this case, only the viscosity and sound velocity of the solvent are required to measure nanoparticles. Applying a focused beam at a high pulse repetition rate for nanoparticle measurement induces unexpected flow of particles. In this presentation, we describe a novel nanoparticle sizing technique using ultrasound that overcomes these problems. In particular, we will discuss the advantages of the target sample compared to similar optical methods and the hydrodynamic advantages of utilizing long wavelength ultrasound. In addition to the analysis of silica particles from 30 nm to tens of micrometer in diameter while using long wavelength ultrasound, we will outline the latest dynamic ultrasound scattering studies for complex samples of highly concentrated and polydisperse particle dispersion systems.