Abstract

The sound-based 3D printing method, introduced as Direct Sound Printing (DSP) by our research group, represents a novel advancement in additive manufacturing. DSP, driven by sonochemical polymerization, has traditionally been limited to a single acoustic focal region, resulting in a voxel-by-voxel printing approach. To address this limitation, this dissertation leverages advanced acoustics, including acoustic holography, to enhance robustness and reduce printing time.
First, design considerations for Phased Array Transducers (PAT) in DSP were investigated, focusing on element size, spacing, and configuration to optimize real-time acoustic field reconfiguration. Building on this, the primary focus of this PhD work is the development of Holographic Direct Sound Printing (HDSP). HDSP uses acoustic holography to store cross-sectional images, patterning acoustic waves to induce regional cavitation bubbles and enable on-demand polymerization. Compared to DSP, HDSP improves printing speed by an order of magnitude and produces layerless printed structures. In HDSP, the holographic field remains stationary while the printing platform moves in three dimensions using a robotic arm.
Extensive experiments, including sono-chemiluminescence and high-speed imaging, validated HDSP's capabilities, demonstrating applications such as remote ex-vivo in-body printing and free-form printing with robotic arm control. Multi-object and multi-material printing were also demonstrated, with comprehensive characterization of the process, including hologram design, polymerization tracking, porosity tuning, and robotic trajectory computation.
Additionally, acoustic holography was optimized using the Adaptive Iterative Angular Spectrum Approach (IASA) and a novel deep learning method called Deep Holographic Reconstruction Network (DHR-Net). The optimization improved the uniformity and quality of acoustic fields, enhancing the printing process. The impact of 3D printing parameters on hologram performance was examined, focusing on energy transfer and material loss reduction.
This dissertation establishes HDSP as a new paradigm in sound-based 3D printing, integrating advanced acoustic holography to overcome traditional DSP limitations and expand applications in additive manufacturing.