Numerical modeling of acoustic radiation force on a bubble through layered mediums.

Non-contact bubble manipulation with acoustical tweezers has shown significant potential in the field of ultrasound-driven controlled drug delivery and subdiffraction imaging. While these works are implemented recently by experiments, the numerical modeling of the acoustic radiation force (ARF) on a bubble in the real biological environment has not yet been well developed. In this work, we establish the theoretical calculation model for the bubble selective manipulation across the layered mediums of real biological environment and compute it by the derived across-medium ARF calculation method based on the angular spectrum method (ASM). With the consideration of the multiple biological mediums, the value of the axial ARF decreases by two to three times. In this context, this work establishes quantitative models for the ARF acting on a bubble and presents a single-beam three-dimensional (3D) trapping strategy based on focused vortex beams. These results offer practical guidance for designing acoustic fields that enable non-contact bubble manipulation both in vitro and in vivo applications.