3D-Printed Polycaprolactone Mechanical Characterization and Suitability Assessment for Producing Wrist–Hand Orthoses

Abstract

In this research, the mechanical properties of 3D-printed polycaprolactone (PCL), a biocompatible and biodegradable semi-crystalline polyester, available as feedstock for additive manufacturing technology based on the material extrusion process, were determined. The influence of the infill pattern (zig-zag vs. gyroid) and ultraviolet (UV-B) exposure over the specimens’ mechanical performances were also investigated to gather relevant data on the process parameter settings for different applications. Specimens and samples of 3D-printed PCL were analyzed through tensile and flexural tests. The experimental data showed the good repeatability of the manufacturing process, as well as a mechanical behavior independent of the specimens’ infill pattern at full density. No differences between the failure patterns of the tensile specimens were recorded. UV-B exposure proved to have a significant negative impact on the specimens’ tensile strength. The 3D printing of PCL and PCL blends is reported mainly for use in scaffold manufacturing or drug delivery applications. As another novelty, the suitability of commercial PCL filaments for producing patient-customized wrist–hand orthoses was also assessed in this study. Semi-cylindrical PCL samples mimicking the forearm part of a wrist–hand orthosis with hexagonal open pockets were 3D-printed and mechanically tested. The results were discussed in comparison to samples with a similar design, made of polylactic acid. The experiments revealed the need to carefully calibrate the manufacturing parameters to generate defect-free, good quality prints. Once settings were established, promising results were obtained when producing orthoses in a ready-to-use form. On the other hand, the attempts to thermoform flat 3D-printed PCL orthoses proved unsuccessful.

Accuracy of Photogrammetric Models for 3D printed Wrist-hand Orthoses

“…By its physical action, it can immobilize the limb to relieve the pain of a pathology and support recovery after an injury or an operation. A 3D printed WHO can be designed and fabricated by using reverse engineering and 3D printing techniques with some main steps as follows [2][3][4][5][6]: (i) Scanning the affected limb and converting the scanned model into a surface model, (ii) Designing the 3D model of the WHO, and (iii) 3D printing the WHO. The initial stage is associated with the process of reverse engineering, which allows for the digitization of a physical object and subsequently reconstructing its 3D model for additional applications [2,[5][6][7][8][9][10].…”

“…A 3D printed WHO can be designed and fabricated by using reverse engineering and 3D printing techniques with some main steps as follows [2][3][4][5][6]: (i) Scanning the affected limb and converting the scanned model into a surface model, (ii) Designing the 3D model of the WHO, and (iii) 3D printing the WHO. The initial stage is associated with the process of reverse engineering, which allows for the digitization of a physical object and subsequently reconstructing its 3D model for additional applications [2,[5][6][7][8][9][10]. It is evident that expert 3D scanning systems can produce very good results, but they are still costly and need highly skilled workers to operate.…”