Acoustophoretic in situ 3D fabrication of multi-material and porous structures

Abstract Additive manufacturing is critical in modern production, from individualized prototyping to advanced applications across various domains1-5. However, it has several challenges, including the integration of multiple materials with diverse properties into a single print without cross-contamination6, printing on complex surfaces7, and generating customized porous structures8. Here, we present AcoustoFab, an acoustophoretic fabrication system that is capable of in situ multi-material 3D printing with customized porous structures on complex substrates in a contactless manner. Our system utilizes a phased array of ultrasound transducers to precisely control sound fields in 3D space, allowing acoustic levitation of diverse materials (e.g., edible, fluorescent, luminant, and ferromagnetic) and depositing them on complex or non-planar surfaces during the additive manufacturing process. Additionally, we utilize ultrasound focusing to create high-pressure points on the target locations to generate customized porous structures to tune the texture, appearance, and flexibility. AcoustoFab stands out not only as an independent fabrication system but also for its compatibility with existing platforms, such as stereolithography, demonstrated through multi-material printing experiments, which highlights its potential for augmenting current fabrication technologies. AcoustoFab offers opportunities for non-contact, multi-material in situ printing with customized porous structures for various applications, for example, in situ printing, food engineering, soft actuators, optical devices and bioprinting.