Research on a novel packaging configuration for a wearable flexible FBG sensor

Abstract

To address the stretching range limitations of traditional flexible fiber Bragg grating (FBG) sensors, this paper introduces a novel wearable FBG flexible sensor that employs a cross-shape packaging and a sinusoidal configuration. Initially, three configurations were subjected to finite element analysis and strain monitoring with a displacement from 1 mm to 8 mm. The sinusoidal configuration exhibited the least strain for the same displacement and achieved the widest test range. Subsequently, the selected configuration was packaged and integrated, then, three unidirectional tensile tests were performed on a displacement table. The sensor's length extended to 7 mm, providing a larger scale compared to traditional linear FBG sensors. The results also indicated an average displacement sensitivity of 51.53 pm/mm with a maximum sensitivity error of 2.50 %, demonstrating excellent linearity and repeatability. Ultimately, utilizing the flexible FBG sensor, a wrist angle test was conducted and compared with data from an Inertial Measurement Unit (IMU). The findings revealed an angle sensitivity of 16.94 pm/°, a maximum sensitivity error of 2.42 % and a maximum zero drift rate of 0.41 %, demonstrating high accuracy and recovery. This lays the groundwork for future advancements in wearable applications. The novel packaging configuration of FBG sensor proposed in this paper improves test range of the traditional linear configuration, and has high test sensitivity.