A novel structural analysis technique for particle suspensions with the size ranging from nanometers to micrometers by ultrasound scattering

Abstract

During the past 10 years, we have developed two major techniques called dynamic ultrasound scattering (DSS) and ultrasound spectroscopy (US). The former is an acoustic analog of dynamic light scattering (DLS), which allows us to investigate the particle motion as well as the hydrodynamic radius in liquid. Besides the advantages of in situ evaluation of particle suspension without drying, the sample must be transparent to allow transmission of light source. In order to overcome this problem, high frequency DSS was developed. Thanks to the phase information of the broadband pulse, the technique also allows us to examine the particle structures involving long-ranged hydrodynamic interactions. The second technique has rather long history and has been well studied by many researchers. We incorporated the particle scattering function into conventional ultrasound absorption measurements to allow evaluation of the elasticity of particles in addition to their size distribution. More recently, microcapsules made of water/oil/water emulsion as a template were studied and the elasticity as well as shell thickness were evaluated simultaneously during their polymerization.