Modeling and simulation of mechanical effects in two-photon lithography

Two-photon lithography (TPL) has emerged as a pivotal technique for fabricating highly intricate micro- and nanoscale structures with diverse applications, ranging from photonics and microfluidics to biomedical engineering. Despite its significant advantages, the manufacturing process is often compromised by defects such as structural collapse and deformation. These issues predominantly arise due to capillary forces exerted by solvents during the development stage, significantly affecting the structural integrity, quality, and throughput of the fabricated components. To address these challenges, this study systematically investigates the mechanical phenomena underpinning these defects, leveraging multiphysics simulations to identify their origins and propose effective modeling strategies. A dual-framework approach was employed to achieve these objectives. First, a structural analysis was performed to determine the critical aspect ratio that would help predict a collapse. This model was validated via finite element simulations. Second, a rheological flow model was formulated to simulate the polymer melt behavior. The models exhibit good agreement with the experimental data and provide useful pointers to the fabricators.