FBG-Embedded 3-D Printed ABS Sensing Pads: The Impact of Infill Density on Sensitivity and Dynamic Range in Force Sensors

The 3-D printing process is a flexible, automated, customizable, and low-cost fabrication process. Fiber Bragg grating (FBG) sensors can be embedded into 3-D printed elements to obtain customized and low-cost sensing elements. However, the material infill is an important printing parameter that may affect the FBG response on both temperature and strain. This paper investigates the material infill influence on FBG-embedded 3-D printed sensing pads by both numerical and experimental approaches. The obtained sensing pads are able to withstand a force of 1 kN with sensitivities of about 0.7 pm/N and linearity higher than 98%. Numerical results show that the fiber has an influence on the strain distribution of the 3-D printed structure. Experimental results show that the infill’s thermal expansion-induced temperature sensitivity of the embedded FBG reported in the literature can be reduced by simply setting the correct infill density. The results obtained enable the application of 3-D printed sensing pads for structural health monitoring, soft robotics application, and force detectors for teleoperation in harsh environments.