Use of orifice-in-throat device to make alginate scaffolds with embedded voids of sub-millimeter tunable dimensions

During the co-flow of a gas and a surrounding liquid film, the inner thread of gas breaks due to Rayleigh instability, and produces a series of bubbles in the embedding liquid. This article describes a co-flow arrangement that generates bubbles in the alginate solution to form a hydrogel scaffold. The flow arrangement utilized an "orifice in throat" configuration for a second squeeze on the bubble that resulted in further split into the bubbles of smaller size. The images under a microscope demonstrate the self-alignment of bubbles, without coalescence, or shrinkage. Application of the CaCl2 solution as cross-linker on the scaffold resulted in the formation of a robust free-resting gel film with the embedded voids. The gelation took place within minutes. The gel film did not stick to the glass plate. The scaffold was dried under vacuum, and was imaged using a scanning electron microscope. The voids retained its alignments after the shrinkage.