Rapid Water-Soluble Sacrificial Scaffolds for Unconstrained 3D Microfabrication via Two-Photon Lithography

Two-photon lithography (TPL) enables high-resolution fabrication of complex microarchitectures but remains fundamentally constrained in realizing truly arbitrary three-dimensional geometries due to the lack of effective microscale support-removal strategies. Here, we report a universal sacrificial-support-assisted TPL approach enabled by a newly developed water-soluble (W-S) photoresist. The W-S photoresist integrates high printing resolution with rapid dissolution, allowing sacrificial scaffolds to be completely removed in mild aqueous media within 10 min. To the best of our knowledge, this represents one of the fastest dissolution performances achieved under such gentle conditions among reported dissolvable photoresists for TPL. This combination of structural stability under dry conditions and rapid aqueous removability decouples fabrication fidelity from post-processing constraints, thereby enabling unconstrained 3D microfabrication. As representative demonstrations, long single-clamped cantilevers and micro-biconvex lenses were fabricated with high geometric fidelity and surface smoothness. After selective removal of the soluble supports, the microstructures retained precise morphology and exhibited excellent optical performance. Overall, this work introduces a rapidly dissolvable photoresist and establishes a versatile materials-enabled fabrication strategy for constructing previously inaccessible 3D microarchitectures, opening new opportunities in micro-optics, photonics, and bio-integrated systems.