Application of multi materials additive manufacturing technique in the design and manufacturing of hand orthoses

The objective of this study is to demonstrate the possibility of obtaining a completely customized orthosis through the use of multi-material 3-D printing technique. Additive manufacturing with multi-material enables to print objects with two different materials at the same time. Two immiscible materials Polylactic Acid (PLA), Thermoplastic Polyurethane (TPU) are chosen to give the orthosis a good trade-off between flexibility and rigidity. Results show that with this innovative technology it is possible not only create complex functional geometries but also to overcome some of the issues associated with traditional immobilization techniques (plaster of Paris splints). Tensile and impact tests are performed on 3D printed specimens to analyze their toughness, rigidity and flexibility. Three different prototypes are developed varying the composition and the organization of the materials used. Results show that the proposed approach is capable of addressing all the issues associated with conventional plaster casts.