Bio-Inspired 3D-Printed Polymeric Sheets for Orthoses: Predictive Modeling of Mechanical Integrity and Moisture Absorption.

The rapid development of additive manufacturing has enabled the production of personalized biomedical devices, including custom orthoses that must retain their structural integrity under demanding physiological conditions. This study evaluates the performance of 3D-printed polymers-blue and white polylactic acid (PLA), Standard Blue Resin, and an ecological soy-based resin-after exposure to simplified, controlled saline environments related to sweat contact and hygiene-associated conditions. Moisture absorption and Shore A hardness were analyzed as response variables to assess material stability under different experimental conditions. A surface methodology based on a Box-Behnken design was used to quantify the effects of specimen thickness (x1), NaCl concentration (x2), and immersion time (x3) on the selected dependent variables. The results indicate that Standard Blue Resin showed the greatest surface hardness stability, whereas the bio-based materials (PLA and ecological resin) were more susceptible to moisture absorption, particularly in thinner polymeric sheets. The fitted quadratic models provide a predictive framework for optimizing material selection and geometric design in biomimetic wearable devices, supporting the development of orthoses with improved durability, hygiene, and long-term functional performance.