Acoustofluidic Active Flow Sculpting Enables Dynamic, Reconfigurable Cross-Sectional Patterning

Soft materials created with flow lithography exhibit distinct functionality depending on the shape and material composition of the precursor fluids, enabling applications ranging from tissue engineering to anti-counterfeiting. However, current manufacturing techniques largely rely on static nozzle geometries or passive hydrodynamic focusing, which commit to a fixed structure during fabrication and limit the ability to actively reconfigure material architecture in continuous flow. Here, we introduce ActiSculpt, an acoustofluidic platform that replaces physical constructions with dynamic, programmable, non-invasive elements to configure the continuous flow. By exploiting the interplay between laminar stability and acoustic streaming, we decouple deterministic fluid deformation from chaotic mixing, enabling the precise sculpting of cross-sectional flow structures. We demonstrate the high-throughput generation of a diverse library of hydrogel particles with continuously tunable moments of inertia. We further demonstrate continuous fiber fabrication in which acoustic parameters are varied in real time, using temporal control to encode structural variation along the fiber's length. Finally, we translate this platform into a motion-controlled 3D printer, establishing printability of fully-curable and half-curable fiber configurations and confirming that acoustically programmed cross-sections, along with their capacity for multi-fiber structural assembly, are preserved in the printed output. The result is a platform that overcomes the one-device, one-geometry constraint of existing techniques, enabling not only on-demand reconfiguration between fabrication runs but real-time control of material architecture within a single continuous flow, extending from bench-scale characterization to an operating additive manufacturing process. This spatiotemporal control establishes a new design axis for engineering soft materials with programmable mechanical and functional properties.