Step Test for Rapid Screening of Material and Process Parameters for Resin Development in DLP 3D Printing

The success of 3D printing based on vat polymerization by spatially controlled UV light exposure strongly depends on appropriate resins. However, in search of new resins, optimizing a resin's composition as well as its printing parameters can be time-consuming and labor-intensive. To address these challenges, we present a rapid parameter screening that enables efficient evaluation of 24 printing parameter settings within one print focusing on exposure energy, exposure time, and layer thickness as the most crucial process parameters in 3D printing based on digital light processing (DLP). Our step test minimizes the required number of experimental iterations and 3D prints by relying on optical characterization without the need for special analytical devices, making it rapid and accessible for a broad range of users across different disciplines. For a proof of concept, the step test is applied to define optimal printing parameters of three commercial resins and evaluate the polymerization efficiency of two predominantly biobased, noncommercial resins containing either phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide or curcumin as photoinitiators. With that, we introduce a straightforward test that is easy to implement and adaptable to other UV polymerization-based printing methods, speeding up the time from resin screening to optimal printing parameters and products.