Abstract

Acoustic levitation allows us to manipulate droplets without any physical contact, opening up new possibilities in fields such as microfluidics, analytical chemistry, biology, medicine, and beyond. At the core of this technology lies a deeper understanding of droplet dynamics—how droplets behave at their interfaces and how heat and mass transfer occur within and around them when they are levitated in an acoustic field. These dynamic behaviors can be highly complex, involving aspects of nonstationarity, nonlinearity, and nonequilibrium, and they require innovative measurement and analysis techniques to fully uncover. In this seminar, I will introduce the concept of a “lab-in-a-drop,” where contactless droplet manipulation using acoustic fields can facilitate various physicochemical processes in levitated droplets. By exploring topics such as the principle of acoustic levitation, levitation stability (atomization), coalescence between levitated droplets, novel visualization methods for mixing, and evaporation-induced phase separation and freezing, this talk will provide a comprehensive overview of the exciting frontiers in droplet research enabled by acoustic levitation.

Biography

Dr. Koji Hasegawa is an Associate Professor at Kogakuin University in Japan, where he specializes in multiphase flow. He received his PhD from the University of Tsukuba in 2013. His research focuses on the fascinating dynamics of droplets, ranging from interfacial dynamics and transport phenomena to phase change processes. Dr. Hasegawa has received multiple awards for his work, including the Japan Society of Mechanical Engineers Young Engineers Award, the Japanese Society for Multiphase Flow Young Researchers Award, and the Japan Society of Microgravity Application Young Scientists Award.