Effects of the viscosity of the liquid in the microcapsule on deformation process of a bubble for developing DDS using shock waves

This paper describes the fundamental investigations for developing new DDS using shock waves and bubbles, especially effects of the viscosity of the liquid in the capsules on the deformation process of the bubbles. The viscosity of the liquid in the microcapsules requires controlling the bubble position and motion, deformation process to optimize the disintegration of the capsules. Using plane shock wave in the water by shock tube apparatus, a bubble near the curved gelatin wall was observed by high-speed framing camera. The deformation process for a bubble was analyzed by image processing. From these experiments, it is found that the viscosity of the liquid around the bubble suppress the amplitude of the bubble oscillations and collapsing the bubble. This means that the viscosity of the liquid in the capsule should be as small as possible for developing DDS using shock waves. In spite of this result, the effects of curvature and elasticity of the wall on the deformation process is almost the same as low viscosity. [Work supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture, Japan.]