Contactless continuous guidance of matter in its main states using curved elongated Bessel-like acoustic fields

Acoustic manipulation uses sound waves to exert force on matter, enabling contactless movement, trapping, and the structuring of particles in bulk media. It offers a contamination-free approach for handling matter in applications spanning across chemistry, biology, and advanced manufacturing. However, state-of-the-art techniques, including acoustic holograms or phased arrays of transducers (PATs) are limited to transporting individual particles or small clusters one by one, and are not suitable for dispersed matter such as gases or aerosols. Here, we introduce a method for guiding a continuous flow of matter along reconfigurable three-dimensional trajectories using elongated Bessel-like acoustic fields (EBAFs). These fields generate converging radial acoustic forces along a programmable path, forming stable mid-air conduits that continuously transport matter. Compared to existing methods such as near-field acoustic levitation, acoustofluidic separation, particle manipulation with vortex and Airy beams, the proposed method offers enhanced versatility, scalability, and real-time control of transport trajectories in mid-air without requiring physical guiding structures. We developed methods to generate EBAFs with PATs tailored to different particle sizes and material properties, and experimentally demonstrated guidance of solids, liquids, aerosols, and gases along programmable trajectories. This technique enables containerless laboratory operations, precise and contamination-free reagent or energy delivery, and integration into advanced additive manufacturing processes that require controlled distribution of matter in different states to target zones.