A Wearable Device Based on a Fiber Bragg Grating Sensor for Low Back Movements Monitoring

Abstract

<jats:p>Low back pain (LBP) is one of the musculoskeletal disorders that most affects workers. Among others, one of the working categories which mainly experiences such disease are video terminal workers. As it causes exploitation of the National Health Service and absenteeism in workplaces, LBP constitutes a relevant socio-economic burden. In such a scenario, a prompt detection of wrong seating postures can be useful to prevent the occurrence of this disorder. To date, many tools capable of monitoring the spinal range of motions (ROMs) are marketed, but most of them are unusable in working environments due to their bulkiness, discomfort and invasiveness. In the last decades, fiber optic sensors have made their mark allowing the creation of light and compact wearable systems. In this study, a novel wearable device embedding a Fiber Bragg Grating sensor for the detection of lumbar flexion-extensions (F/E) in seated subjects is proposed. At first, the manufacturing process of the sensing element was shown together with its mechanical characterization, that shows linear response to strain with a high correlation coefficient (R2 &gt; 0.99) and a sensitivity value (Sε) of 0.20 nm∙mε−1. Then, the capability of the wearable device in measuring F/E in the sagittal body plane was experimentally assessed on a small population of volunteers, using a Motion Capture system (MoCap) as gold standard showing good ability of the system to match the lumbar F/E trend in time. Additionally, the lumbar ROMs were evaluated in terms of intervertebral lumbar distances (Δ d L 3 − L 1 ) and angles, exhibiting moderate to good agreement with the MoCap outputs (the maximum Mean Absolute Error obtained is ~16% in detecting Δ d L 3 − L 1 ). The proposed wearable device is the first attempt for the development of FBG-based wearable systems for workers’ safety monitoring.</jats:p>

A Wearable System Composed of FBG-Based Soft Sensors for Trunk Compensatory Movements Detection in Post-Stroke Hemiplegic Patients

“…To address this problem, technological research has increasingly moved toward the development of soft, highly flexible, bendable sensors. Several soft sensors have been proposed for monitoring different joint angles, but only a few have been proposed specifically for the back area [ 21 , 22 , 36 , 37 , 38 ]. However, none of these are intended to detect CTMs.…”

“…Such sensors have been largely employed to design smart wearables for the detection of physiological parameters, such as respiratory frequency [ 25 , 26 , 27 , 28 , 29 ], heart rate [ 30 , 31 , 32 ], and joint movements [ 33 , 34 , 35 ]. In [ 34 , 36 , 37 , 38 ], our research team assessed the feasibility of a single FBG-based soft sensor to detect flexion/extension back movements, including the cervical spine. However, the proposed devices were not suitable to detect CTMs.…”

A Comprehensive Review on the Optical Micro-Electromechanical Sensors for the Biomedical Application

“…In such cases, detection of the wrong posture could give major advantages. Many wearable devices had been investigated for different applications, wherein the sensitivity of the sensor achieved as high as 0.2 nm/με −1 ( 60 , 61 ).…”

“…Neck movements during flexion-extension were investigated. In the meantime, FBG sensors were embedded in the human chest and monitored during quiet breathing and tachypnea ( 61 , 117 ). Figure 11A shows the different views of a person with a wearable device for experimentation.…”

Finger Bending Sensing Based on Series-Connected Fiber Bragg Gratings

“…This strain sensor can be used for real-time detection of breathing, vocalization, knuckle movements, and expressions. Martina Zaltieri et al [ 21 ] proposed a wearable device embedded with FBG sensors to detect the flexions and extensions of lumbar when seated. To measure the bending angle of knees, Shweta Pant et al [ 22 ] proposed a wearable device based on FBG sensors.…”