3D Hydrodynamic Flow Lithography

ABSTRACT Continuous‐ and stop‐flow lithography are widely used to fabricate multi‐dimensional microstructures whose cross‐sectional morphology is dictated by the flow profile of multiple co‐flowing streams. Here, we introduce three‐dimensional hydrodynamic flow lithography (3D HFL), a platform for programmable generation of multi‐layered flow profiles and their conversion into solid anisotropic microparticles and fibers. By strategically combining variable inlet, intra‐channel pillar, and outlet configurations, we achieve precise and versatile sculpting of flow profiles under non‐inertial conditions, as validated by computational fluid dynamics simulations and experimental production of microparticles. The flow‐sculpting devices are fabricated using low‐cost 3D‐printed molds to cast PDMS channels with precisely aligned inlets and complex geometries that are difficult or impossible to achieve with conventional soft lithography. We demonstrate anisotropic multi‐material microparticles and fibers tailored for specific applications: amphiphilic particles for uniform microdroplet capture, biocompatible patterned hydrogels for controlled cell adhesion, and dual‐layer fibers for temperature sensing. To support this, we develope a rapid, predictive software tool for flow‐profile design and 3D particle engineering. Ultimately, 3D HFL integrates straightforward device fabrication, accessible computational design, and high‐throughput production into a scalable platform for creating microstructures with tailored geometries, compositions, and functionalities.