Abstract

Observation of the Behavior of a Micro-Capsule by Using a High-Speed Video Camera

D.Koyama, N.Barbier, Y.Watanabe (Faculty of Engineering, Doshisha University, Kyoto, Japan)

e-mail: dta0134@mail4.doshisha.ac.jp

The acoustic fundamental properties of microcapsule are discussed. Microcapsules are currently used as contrast agents in echographic field because of their enhanced echo and their nonlinear properties. Microcapsules are surrounded by thin shell that has elasticity and stiffness and behave the vibration mode different from a free bubble. The analysis of the mechanism of microcapsule.fs vibration and collapse develops echographic field. The behavior of some typed microcapsules in acoustic field is recorded by using a high-speed video camera (FASTCAM, Photoron, Japan). The microcapsule shows non-spherical vibration mode at the low sound pressure. In the case of higher pressure, the microcapsule shows spherical vibration mode like a free bubble. From image processing, the radius versus time curve of microcapsule is obtained and compared with the one for a free bubble calculated by Rayleigh-Plesset equation. The effect of the stiffness and elasticity of the microcapsule's shell are estimated.

Section : 5