Achieving sub-pixel level feature size and continuous printing for projection stereolithography through spatiotemporal control of photopolymerization

Projection stereolithography is a prominent 3D printing technology known for its simple design, high surface quality, and material compatibility. However, printing features near the nominal optical resolution remains challenging due to complex reasons, including Gaussian pixel radiance, nanoparticle scattering, and radical diffusion. Here, we developed a reaction‒diffusion–scattering model to predict and visualize the photopolymerization reaction with sub-pixel spatial resolution for photosensitive resin and resin–ceramic composites. Based on this model, we developed a segmentation exposure strategy combined with a grayscale mask compensation scheme, which enabled the fabrication of feature sizes below the pixel size of the mask. The model further enabled the continuous production of parts with a mere baseline top-down printing system via precise control of the photopolymerization process. Our study provides a promising avenue for the low-cost and high-speed fabrication of assembly-free multi-body components with tight tolerances and high resolution, including pillar bumps, gearsets, and microfluidic channels.