“Nanoparticle sizing in the presence of large particle by oblique incident dynamic ultrasound scattering method”, by Kana Kitao, Manami Yamane, Tomohisa Norisuye, Jpn. J. Appl. Phys., 64(2), 02SP19, 2025

We are the pioneering laboratory that developed a technique for tracking the Brownian motion of nanoparticles using ultrasound in real time (Dynamic ultraSound Scattering, DSS method). The results have been published in several peer-reviewed journals.

The problem with using very strong ultrasound to improve the sensitivity of nanoparticle measurements is that the energy of ultrasound can induce an unfavorable flow of particles. Therefore, while the DSS method can be used to easily measure large submicron particles alone and also provide information on the motion of nanoparticles, for some surprising reason, it was difficult to analyze mixtures of particles that differ in size by an order of magnitude. Sub-micron to micron sized particle analysis was originally very difficult even with light scattering due to the transmission of light, but ultrasound also had problems from a different perspective.

This time, we found a way to overcome this problem. The solution, simply speaking, is to sandwich the sample between two films and measure the very thin sample at an oblique incidence angle. This is very useful in the sense that we can perform experiments on precious samples such as metal nanoparticles and biological proteins in very small quantities.

We are also pleased to announce that the Japanese Journal of Applied Physics (JJAP) has chosen to feature our work as a “Spotlights” in their journal. It is a great honor and pleasure to have our paper featured. Thank you very much.