Encapsulated soft particles are commonly encountered in nature (seeds, cells, phospholipid vesicles) and in different industrial applications (biotechnology, pharmacology, cosmetics, food industry). The role of encapsulation is to protect a substance with a solid envelope. It avoids its dispersion in the ambient environment or its degradation in contact with it. The membrane may be a lipid bilayer (vesicles), a reticulated membrane with elastic properties (artificial capsules) or a lipid bilayer connected to a cytoskeleton (cells).

There are many open issues regarding the mechanics of capsules/vesicles/cells:

The characterization of their mechanical properties is difficult owing to their small size and fragility.

The role of the fabrication process on the physical and mechanical properties of artificial capsules or vesicles (shape, size, degree of reticulation, membrane mechanical properties) remains to be better understood. Controlling the membrane properties is essential to optimize the design and production of specific particles for each application.

When suspended in an external flowing fluid, capsules/vesicles/cells deform in a complex fashion and may eventually burst (the breakup is to be induced or prevented depending on the application). Relatively few experimental studies of these phenomena exist, but recent progress in microtechnology has opened new perspectives. Correlatively, the theoretical study of the motion and deformation of these particles is a complex fluid-structure interaction problem. The present numerical models all include simplifying assumptions, the relevance of which has yet to be established.

The occasion of the present Symposium will allow a unique analysis of the similarities and differences of the mechanics, physics and biology of capsules, vesicles and cells. It will provide the opportunity to confront the various approaches used to study these deforming particles and establish some guidelines for future research.