From soap-film packed droplets to multilayer antibubbles: Formation and stability

An antibubble is an object in which a liquid core is separated from a surrounding liquid by a thin spherical gas shell. Such structures can be generated when a droplet crosses a soap film with sufficient kinetic energy to become wrapped by the film, which then merges upon contact with a liquid bath. When droplets fall through multiple soap films, multilayer antibubbles can be generated. In this paper, the conditions required to successfully generate monolayer and multilayer packed droplets are studied in order to optimize the formation of monolayer and multilayer antibubbles. In particular, the geometrical factors and the composition of the liquid that makes up both the droplets and the soap films are discussed. The stability of antibubbles generated using this method is also investigated as a first case study. The robust formation of monolayer and multilayer antibubbles is a key to open opportunities in drug delivery without the use of either oil or solid compounds. Moreover, this method allows for the production of monodisperse, millimetric, and multilayered antibubbles.