A platform of exogenous acoustic vortices for fabricating dimension-controllable cellular blocks

This article presents a method for fabricating an individual dimension-controllable cellular block, such as a spheroid and organoid, using exogenous and focused acoustic vortices. The interaction of phased-delayed ultrasonic signals generates acoustic waves characterized by helical wavefronts, thereby having the potential to transfer orbital angular momentum (OAM) into a suspension. A follow-up generated null region at the beam center provides trapping force to trap the free cells literally. This research contains comprehensive investigations of pulsing conditions and media compositions expected to affect the dimension quality of a single block. Comparative and systemic analyses of the pulsing parameters, such as pressure, duty cycles, and driving frequency, are first performed to identify the optimized conditions for fabricating a block. A collagen-supplemented media provides more stable tethering conditions for fabricated blocks by vortices in comparison to a normal medium. As fully demonstrated in the Results section, the quality of the dimension-controllable block is affected by total sonication time, as well as trapping force inherently restricted by the size of the null region. By understanding the comprehensive effects of both pulsing and cellular conditions on the fabrication procedure, this study aims to propose that OAM-based exogenous vortices are promising for various biological modeling research, with high tunability in their dimensions.