Design, fabrication and metrological characterization of a 3D-printed strain sensor based on fiber Bragg grating technology.

In the last decades, many smart sensing solutions have been provided for monitoring human health ranging from systems equipped with electrical to mechanical and optical sensors. In this scenario, wearables based on fiber optic sensors like fiber Bragg gratings (FBGs) can be a valuable solution since they show many advantages over the competitors, like miniaturized size, lightness, and high sensitivity. Unfortunately, one of the main issues with this technology is its inherent fragility. For this reason, various encapsulation modalities have been proposed to embed FBG into flexible biocompatible materials for robustness improvements and skin-like appearance. Recently, 3D printing techniques have been proposed to innovate this process thanks to their numerous advantages like a quick fabrication process, high accuracy, repeatability, and resolution. Moreover, the possibility of easily customizing the sensor design by choosing a set of printing parameters (e.g., printing orientation, material selection, shape, size, density, and pattern) can help in developing sensing solutions optimized for specific applications. Here, we present a 3D-printed sensor developed by fused deposition modeling (FDM) with a rectangular shape. A detailed description of the design and fabrication stages is proposed. In addition, changes in the spectral response as well as in the metrological properties of the embedded FBG sensor are investigated. The presented data can be utilized not only for improving and optimizing design and fabrication processes but also may be beneficial for the next research in the production of highly sensitive 3D-printed sensors for applications in wearable technology and, more generally, healthcare setting.