Linear volumetric additive manufacturing of polymer structures via light initiated direct growth

Additive manufacturing (AM) encompasses a variety of techniques for creating three-dimensional (3D) structures with intricate geometries, including droplet-based and layer-based methods.Among these, vat photopolymerization (VPP), a layer-based AM technology, stands out for its ability to achieve high resolution and relatively low cost.However, traditional VPP techniques face inherent challenges such as the stair-step effect and limited fabrication speed, which constrain their application for seamless, high-throughput manufacturing.To address these limitations, continuous and volumetric photopolymerization approaches have emerged, offering enhanced precision and faster production capabilities.This study introduces a novel linear volumetric printing technique, Light-Initiated Direct Growth (LIDG), which precisely controls light energy distribution in 3D space within a liquid resin.Unlike other methods, LIDG enables curing light to penetrate pre-printed regions, achieving continuous polymerization along the Z-direction.By leveraging controlled light projection, optical energy is manipulated to initiate photopolymerization at targeted voxels, facilitating the rapid and uninterrupted construction of 3D polymer structures.A detailed optical energy distribution model is developed for LIDG, accounting for light absorption and attenuation characteristics within photopolymer resins.Additionally, the effect of resin viscosity on printing quality is systematically analyzed.Demonstrations of LIDG's capability to fabricate large macro-scale structures with fine microscale features underscore its potential for advancing applications, including biomedical devices, optical systems, and soft robotics.