Fiber Bragg Gratings embedded inside 3D-printed Patches - sensor design and mechanical characterization

The application of optical fibers with fiber Bragg gratings (FBG) in the civil, biomedical and robotics fields presents several challenges related to the positioning and gluing of the sensor to the surface to be monitored. For this reason, the development of 3D-printed patches that embed optical fibers has become relevant in recent years. The studies existing in the literature focus on some specific process parameters, like the infill density and the choice of the material of the patch. However, a systematic analysis regarding the interaction between the material of the patch material and the embedded fiber coating to secure adhesion and strain transfer is still missing. This preliminary study aims at assessing the performances of 3D-printed patches embedding optical fibers in different combinations of filament materials and coatings of the fiber. Two sensors per combination of filament material (ABS, PLA) and coating of the fiber (acrylate, polyimide) are fabricated and mechanically tested. The results indicate that the fabrication process is more reliable when using polyimide-coated fibers, and the measurements of the resulting sensors are more repeatable.