Stereolithographic 3D printing of graded porous materials via an integrated digital exposure and selective dissolution strategy

Graded porous materials (GPMs) with fine pore sizes (<50 μm) and gradient porosity are used in diverse fields such as biomedical implants, sensors, and soft robotics. Stereolithography (SLA) 3D printing has created new possibilities for fabricating intricate porous materials due to its high speed and excellent resolution. Nevertheless, for many commonly used low-cost SLA printers, the traditional SLA process is not ideally suited to print GPMs since only a single material feedstock is used for the entire print. Herein, we demonstrate how this limitation can be overcome by using a composite feedstock consisting of a photoresin and a polymeric filler in combination with voxel-level digital control over the light exposure. Based on this strategy, spatial control over the porosity, mechanical properties, and swelling behavior within the SLA prints is achieved. We expect that this scalable fabrication strategy will contribute to a variety of applications that require GPMs.