Spatially selective ultrasound field formation using acoustic holography for cultured-cell applications.

Abstract

Spatially selective ultrasound exposure is essential for investigating mechanotransduction and for developing targeted ultrasound-based therapies. However, conventional low-intensity pulsed ultrasound (LIPUS) systems provide limited control over the spatial distribution of acoustic pressure and acoustic intensity. In this study, we propose an acoustic holography-based framework for spatially selective ultrasound field formation and apply it to cultured-cell-compatible environment. A holographic control algorithm combining Iterative Angular Spectrum Approach (IASA) and gradient-based optimization using Adaptive Moment Estimation (Adam) was used to compute phase and amplitude distributions for a 4 × 4 phased array transducer system. A specialized culture vessel configuration was designed to provide a clinically inspired ultrasound propagation distance while maintaining stable cell adhesion. Transducer-specific frequency tuning, output compensation, and phase correction were implemented to address hardware variability. Acoustic intensity distributions at cell adhesion plane were evaluated using hydrophone-based measurements and standing-wave reconstruction. The proposed system achieved spatial confinement of the acoustic field, with 100% of the non-target region maintained below the clinically inspired acoustic-intensity criterion. In the target region, 51.7% of the area exceeded the clinically inspired acoustic-intensity criterion, with performance affected by experimentally observed transducer variability. The framework demonstrated suppression of off-target exposure and localized formation of acoustic intensity distributions. This study establishes a platform for spatially selective ultrasound field formation in cell culture systems, providing a foundation for controlled in vitro mechanobiology studies and future spatially controlled ultrasound stimulation systems. Preliminary biological observations are discussed to support the feasibility of cultured-cell applications, although biological validation remains future work.