Toward High-Fidelity Fabrication: A Refinement Strategy via Decoupled Photopolymerization Modeling and Simulation for Projection Micro‑Stereolithography

High design-to-fabrication consistency is critical for microneedle (MN) arrays, as geometric fidelity directly governs mechanical and drug delivery performance. Traditional process control, relying on static models such as the Jacobs working curve and the reciprocity law, inadequately captures nonlinear polymerization kinetics, leading to defects like warping and distortion. To address this, we developed a photopolymerization kinetic framework that decouples exposure intensity from duration and incorporates dynamic light attenuation and polymerization progression into a multiscale finite element analysis via a custom UMAT subroutine. The results reveal that extreme exposure duration or intensity is deleterious, as the former induces over-curing and shrinkage, whereas the latter results in heterogeneous polymerization and warpage. Importantly, the simulation identifies a critical stress-minimization regime where slicing thickness (30 μm) aligns with the material's optical penetration depth (Dp ≈ 29.3 μm). Guided by this model, we fabricated gradient MN arrays with a tip precision of 12.8 μm, approaching the optical diffraction limit (10 μm) and representing a 68% accuracy improvement over conventional methods. This work provides a quantitatively driven methodology for defect-free manufacturing of complex microstructures, shifting fabrication from empirical iteration to model-guided precision.