High-Sensitive Double-Clad Fiber Bragg Grating Sensors for Real-Time Monitoring of Body Posture and Movement State

Abstract

Musculoskeletal disorders (MSD) are prevalent in society and currently lack effective treatments. The incidence of MSD appears to be increasing as the worldwide population ages and sedentary lifestyles. Real-time monitoring of the body posture and movement state may be an effective strategy for the prevention and treatment of MSD. We proposed a real-time monitoring system based on a wearable high-sensitive double-clad fiber Bragg grating (FBG) sensors and an integrated demodulation device to recognize the body posture and movement state. The results demonstrate that the double-clad FBG sensors exhibit a high measurement sensitivity of approximately 36 pm/° in elbow joint static tests and 7.5 pm/° in knee joint static tests, which is almost 1.4 times higher than that of a single-mode FBG. Furthermore, a dataset of six gestures was created based on time and wavelength information obtained from six double-clad FBG sensors monitoring subtle deformations of muscles of the arm. The accuracy of recognizing simple and complex gestures was close to 100% and about 88%, respectively. The static and dynamic measurements demonstrate that the double-clad sensors have high accuracy, improved sensitivity, excellent flexibility and good repeatability, and this work is expected to a reliable assessment tool for clinical trials of MSD.